Oranges and lemons

Citrus are not tropical plants and will grow naturally in fairly specific climatic conditions. The southern Mediterranean is in many ways an ideal climate as is parts of Asia around the Himalayas and south-east Asia where they have grown for thousands of years. They like to be warm during the day and cool at night, warm in summer and cold in winter – without any frost. A few modern citrus hybrids will withstand some light frost, but oranges in particular like warmer temperatures.

Citrus fruits came to Europe from Asia in numbers in the early middle ages, although there are reports of lemons being grown in Italy in the third century AD, and also in the middle east after around 700 AD. 

Lemons arrived in the Caribbean with Christopher Columbus on his second voyage west, and spread slowly through the islands and on to the north American mainland until mass cultivation began in Florida and California in the early 1800s.

These days most citrus grows in Italy, Spain, Greece, Turkey, Cyprus, Lebanon, South Africa and Australia. Australia has native citrus varieties which have evolved in isolation away from the trading routes of Asia, Europe and most recently the Americas. Citrus grows rather well in hilly rather than mountainous terrain. High enough for it to get cold at night and in winter, but not high enough for ice and snow. 

In northern Europe, growing oranges and lemons in glasshouses became very popular for the wealthy from the 1600s onwards. It was only the rich who could afford to build big enough glasshouses to house their trees and to keep the servants who would haul the trees, planted in huge wooden crates with handles, outside in late spring and back in October before the first frosts struck.

As the vast majority of citrus plants are non-hardy, it’s a mistake to think that any garden or patio in the UK is sheltered enough to grow them outside on a permanent basis. So grow them in pots, and keep them outdoors in summer, but bring them in in winter. 

The citrus plants we have at the Secret Garden Club are:

• 2 different types of lemon, a Eureka, and a Meyer lemon. Meyer lemons can withstand the occasional low temperature. That still means you bring it in overwinter.
• A kaffir lime - the aromatic leaves are used in Thai cuisine, as is the zest of the knobbly fruits.
• A grapefruit tree – this particular tree is relatively new to me. I don’t even know if this is the sort of size of fruit I should expect. 
• A calamondin – another example of a relatively hardy citrus. There are always plenty of these little fruits on the tree – they are startlingly tart to taste, but make a fantastic lime pickle (calamondin pickle), great in a gin and tonic, and I’m told, make very good marmalade.
• A kumquat tree.This has already produced a heavy crop of ripe fruit and a second crop is developing now.

You might be surprised to know that these are all hybridised types of citrus, except possibly the kumquat, which is odd as until a few years ago, the kumquat was thought not to be a citrus at all but a more distant relation.

Citrus fruits for tasting at the Secret Garden Club. Clockwise from top left: pomelo, pink grapefruit, limettas (sweet lemons), clementines, yellow limes, green Mexican limes, oranges, lemons, kumquats

Origins and hybridisation

The ancestry of citrus plants would keep several series of Who Do You Think You Are going for months. There are over 300 different varieties, with many hybrids, either varieties occurring naturally, or cultivars which have been deliberately crossed by horticulturists. In the last few years botanists have been able to use DNA testing to ascertain precisely how some varieties have occurred and which plants are their  ‘parents’, as it were. Before DNA testing, they had to look at external characteristics, habitat, etc.

Keeping track of citrus is complex, but if you’re interested, there is a fantastically comprehensive website called Citrus Pages, which attempts to catalogue all varieties of citrus, with photos and descriptions. Although it's quite scholarly in places, it's also immensely readable, and if you've ever wondered how a lime is related to a grapefruit, or just how many varieties of tangerine there might be, this is the place to visit.

I have also attempted to show the relationships between the common varieties you find in UK shops in this diagram here. Looks complicated? It’s actually over-simplified and any botanist would probably look at it and say, “We-e-e-ell …”

All the evidence suggests that there are three ‘original’ citrus types which have hybridised and crossed to create all the others: the citrons, the mandarins and the pomelos.

Citrons (Citrus medica)

Citron is the oldest known variety of citrus, and were originally used as perfume and a insecticide. Citron seeds have been found in archaeological excavations in Babylon (now Iraq), in ruins which date back to 4000 B.C. They’re known to have been cultivated in the middle east since around 700BC.

Lemons, limes and bergamots all have a citron variety as one of their 'parents'.

Mandarins (Citrus reticulata)

Mandarins originate from China and Japan (hence two of the names to describe mandarin varieties – mandarin and Satsuma – and were brought over to England at the beginning of the 19^th century. During the course of 1800s they were introduced into Italy and other Mediterranean countries and into the USA (a variation from the more conventional wetsward Mediterranean to GB route).

Satsumas, tangerines and clementines are all varieties of mandarin – clementines a hybrid between mandarins and sweet oranges. Other hybrids with mandarins as a parent include minneolas, tangelos, ortaniques and other less well-known varieties.

Pomelos (Citrus maxima)

You mainly see pomelos in Asian stores rather than supermarkets. It’s a deceptively big fruit, as the peel and pith are often quite thick; the taste is like a milder, less acidic - and much less juicy - version of the grapefruit. 

Pomelos originate from south east Asia, mainly Malaysia. These days it is also grown in Fiji and other Pacific islands but although it was introduced into the Caribbean and the Americas as were other citrus it has never really caught on there.

Pomelo hybrids include grapefruit and sour and sweet oranges (pomelo x mandarin) - the sour varieties inheriting more pomelo features, the sweet versions with more mandarin characteristics. 

How to grow a citrus plant

You can raise a plant from sowing citrus pips fairly easily. With oranges and lemons in particular, if you sow in good compost and keep the pot warm, you should get several seedlings from a single pip. If you’re just after an ornamental tree, then that’s a highly cost-effective way to do it.

But if you want fruit I wouldn’t recommend sowing a pip.  If your seedling grows true to type (it may well do so, but there’s no guarantee), it will take about 10 years before it produces any fruit. If you want to guarantee fruit, buy a named cultivar from a reputable dealer. This will be a grafted plant, where the top of one plant is melded on to the rootstock of another – grafted citrus will fruit much earlier.

Garden centres will often get deliveries of citrus trees around now, just before Christmas – because they make good Christmas presents, and then again in spring at the start of the new season. Beware of buying a Christmassy citrus – I’ve seen some unsuitable ones. Oranges, for example, like it warmer than other citrus fruits and their fruit are rarely good to eat unless kept in a proper greenhouse – lemons are more suited to our climate. A table of mandarin plants up at a garden centre near here were being kept in conditions that were too warm and sure enough when I lifted up a pot to take a closer look, all the developing fruit fell off. £40 is a lot to ask for a plant that has just lost all its fruit.

You can buy from a specialist, or an outlet which regularly sells citrus - the Secret Garden Club likes M Lanza in Crews Hill - or you can go online. I've had good experiences with the following:

• Plants4Presents
• Crosscommon Nursery

I also like the look of Global Orange Groves and have spent much time browsing there but haven't bought anything from them yet. If I was going to buy any of their trees, it would be this one, a Citrus medica ‘Fingered’, or Buddha’s Fingers, where the segments of the fruit grow inside out, as it were. Ornamental only!

So, you’ve bought your plant, whether it’s a lemon, a Kaffir lime, or a calamondin, and let’s say you’ve bought it round about now. How to care for it? Citrus plants have very specific care requirements depending on the time of year and all relating to the ideal conditions they would like in the wild. If you’re able to meet these requirements, then you’ll find citrus an easy plant to look after. Otherwise, they can appear to be very fussy. It’s worth working out in advance whether you have a good environment for a citrus plant as they can be expensive to buy – but then, looked after well, they can last a lifetime. 

Standing plants in a moist gravel tray keeps the air around the plant relatively humid 

• Find a cold room – they like a winter temperature of between 7-13 degrees C, no draughts and with relatively humid air. A light unheated bathroom is your best bet, an unheated spare bedroom the next best. Below 7 degrees, the plant will become dormant and won’t flower. Over 13 degrees, and developing fruit may drop (so may the leaves).
• Ensuring relatively humid air can be a challenge. One way to increase the ambient moisture around the plant is to create a gravel tray as we have here. Stand the pot on a tray of gravel and keep the gravel moist – don’t let the water come up to the level of the bottom of the pot, though, you don’t want to waterlog it.
• Another way is to get one of those spray misters and keep it full near the plants. Whenever you go past, give the plants a squirt from the mister.
• In winter, let the soil in the pot dry out between watering. When you do water, give it a good soak and make sure that any excess water can drain away. Standing plants in the (empty) bath is a good way to do this.
• Ideally, water with rainwater. (I have to confess I do this in summer, but not winter.)
• Buy a pot of citrus winter feed – this contains a balance of nutrients that will supplement the nutrients in your soil. Use the feed according to the instructions when you water, or about once every fortnight.
• Check your plant regularly for signs of pests or disease. We’ll talk about these in more detail, but you can keep plants clean and healthy by getting rid of any problems as soon as they arise and before they take hold.
• Remove any leaf fall, bud fall straightaway to keep the areas below and around the plants clean and debris free.
• In springtime, you may well see fruit starting to form – although both lemons and oranges will flower in autumn, winter or spring, so you can get fruit and flowers on the tree at the same time.
• Once all danger of frost is past, and the night temperature no longer goes below 7 degrees, the plant should go outside. It’s not really a kindness to keep them in. Oranges, however, which like warmer temperatures, may well benefit from being kept in an unheated, well-ventilated greenhouse in summer. Generally, citrus will benefit from the fresh air outside and also the difference in temperature between night and day – the bigger the difference, the juicier the fruit, or so people say. This temperature difference is also what deepens the red colour in a blood orange.
• Put the plant somewhere light and bright and preferably south facing to make the most of summer warmth. BUT, not in full sun – under another bigger plant would be ideal. Even more important is that it should be sheltered – a light breeze may be welcome, but it won’t like being exposed to wind.
• Once you see fruit forming, keeping the plant sheltered is even more important, so that the fruit doesn’t drop. If a plant has a lot of immature fruit forming, some fruit drop will be inevitable and not unhealthy.
• Now switch to a citrus summer feed – this will be one high in nitrogen and feed the plant around once a week.
• In summer the soil can be kept lightly moist, but never let it become waterlogged – it must always have good drainage. Ideally water with rainwater.
• If you want to transfer you citrus to a bigger pot, first, desist. Citrus do not need yearly repotting, but will be happy in the same pot for 2-3 years. 
• When you do repot, you can use a proprietary citrus compost.

Lemons like slightly cooler conditions than oranges or grapefruit - its green fruit will ripen to yellow during the colder winter nights, but it will still be killed off by any frost. Oranges, however, are more of a sub-tropical plant, more suited to the southern Mediterranean than the cool UK, even in summer. Even so, they, like lemons, need a wide difference in temperature between day and night to help ripen the fruit and turn it from green to orange.

This requirement for warm days and cooler nights also partly explains the colouration of blood oranges. Blood oranges are a mutated variety of sweet oranges, and the greater the difference in temperature, the deeper the red colour of the flesh. 

Limes are related to lemons and to papedas, a particular type of ancient wild citrus originating from Asia. The kaffir lime, whose leaves and zest are used in Thai curries, is perhaps the best-known example in the UK of the papeda subgenus.

Pests and problems

The most common pests most likely to attack your citrus plants are scale insects, mealybugs and citrus leafminers. Scale insects look like little brown and white discs (or indeed scales) adhering to the trunks and branches. Mealybugs look like wisps of cotton wool stuck in the crooks between stem and leaf, or on buds. Inside that cotton wool there is a little bug, which will look superficially like a tiny woodlouse has been dusted with talc.

Both of these can be most easily removed with a damp toothbrush. Pinch out any badly affected leaves. 
Leafminer larvae will actually burrow inside the leaves, leaving discoloured trails on the surface. Any damaged leaves should simply be removed from the tree.

Remove scale, mealybug, or leafminers as soon as you see them – operate a zero tolerance policy. If any of these get a hold on your plant they will debilitate it severely.

The other main problem often suffered by citrus trees is the propensity of the leaves to fall off. The most common reason for this is overwatering in winter, when the plants really can be left to dry out a bit. However, draughts, being moved around too much, or being kept too cold, or, more likely in winter, being kept too warm, will also lead to leaf fall.

You can worry less about the fruit that fall off when they are still very tiny. Some fruit drop is inevitable - like airlines overbooking their flights, many types of fruit tree will set far more fruit than the tree can handle.

Citrus crafts and gifts for Christmas

Still not got round to finishing (or even starting) your Christmas shopping? We have some quick and easy gift ideas for you, using citrus fruits. This month's Secret Garden Club meeting looked at growing and making use of citrus, including some great ideas for some home-made gifts.

Usually we like to look at how best to cook and eat our produce, but on Sunday, the Secret Garden Club looked at more ornamental and decorative ways of using lemons and oranges. Guests concocted a jar of refreshing lemon bath salts and made a spiced orange pomander, as well as learning how to make Moroccan style preserved lemons.

Lemon bath salts

2 tbsps Epsom salts – available from the chemist

½ tbsp fine sea salt

Zest of two lemons

A clean, airtight jar.

These amounts can be scaled up or down to suit the size of jar and the number of lemons you have. You can also add more lemon zest to make the lemon fragrance even more intense.

Mix all ingredients well. A whisk is a good way to get all the zest incorporated without clumping. Store in an airtight jar and sprinkle as much as liked in your bath for an aromatic, revitalising soak.

Spiced orange pomander

As long ago as mediaeval times people would hang perfumed pomanders up in rooms, or carry them around with them to disguise bad smells – of which there were many in the olden days.

We may not have foul-smelling rooms or bodies these days, but a spiced pomander will still fill a room, or cupboard, with fragrance and will last for years. This combination of orange and spices gives these pomanders a distinctly Christmassy aroma, ideal as gifts at this time of year. 

1 orange

A toothpick (optional)

1 cup cloves

Masking tape

Ribbon

Spice mix:

1tbs ground cinnamon

1tbs gound nutmeg

1tbs ground ginger (dry ginger)

1tbs ground coriander

1 tsp sandalwood powder

Orris root powder is more traditionally used as a preservative and fixative, but quite a few people turn out to be allergic to it, so we used sandalwood powder at the Secret Garden Clubas it’s less likely to cause upset.

Mix the spices together and pile into a paper bag.

Mark out the orange into quarters with the masking tape. (This makes it easier to fix the ribbon later. For less artistic types, like me, it also helps to keep the patterning neat.) If the orange peel is at all hard, make a hole in the orange first with the toothpick, then push a clove into the hole just made. You should cover the whole orange apart from the masking tape – you can choose patterns or arrange the cloves in rows. Don’t pack the cloves together too tightly as the orange will shrink slightly as it dries out. Put the orange in the paper bag with the spices and toss it so that the gaps between the cloves are well covered with spice mix.

Keep the oranges in their paper bag and put somewhere warm and dry – the airing cupboard is ideal. Turn the orange every day or so.  When the orange is hard to the touch, it’s ready - in a week or so. Carefully remove the masking tape and tie a ribbon around the orange so you can hang it up.

Preserved lemons

This is an essential condiment in middle eastern recipes, livening up casseroles, tagines or rice. Although the only two ingredients are salt and lemons, the flavour is surprisingly soft and mellow. It's so simple to make that I feel it hardly counts as a recipe - here's what to do.

6 unwaxed lemons, washed and dried (to fill a 500ml jar)

Sea salt

Making preserved lemons, clockwise from top left: slice five of your lemons into four wedges but don’t cut right through the lemon – leave the wedges attached at the stem end; next, rub the sea salt into the wedges (shown cut all the way through here); bottom right, pack the cut lemons into a wide-necked jar, and sprinkle with a tablespoonful of salt. Juice your last remaining lemon, add the juice to the jar, and top up with boiling water until full; Finally, seal the jar and leave for at least a month before using.

These keep really well and shouldn’t even need refrigerating – to be sure they’re not in danger of spoiling, use a sterilised jar. I’m told that sometimes a white lacy curd develops on the surface of the liquor, which is harmless. I’ve never seen this – perhaps I eat my preserved lemons before any such layer can develop.

Making spiced orange pomanders at the Secret Garden Club.

Downton Abbey at the Secret Garden Club

The Secret Garden Club has been visited by a celebrity! Do you remember Cousin Patrick, the mysterious Canadian bandaged possibly fake long lost heir who poor Edith (of course) started to fall for? Yes, he who is also indelicately known in Viv Groskop's Downton columns as 'melty face', came to the Secret Garden Club for dinner!!
He even wrapped some napkins around his head so we could recognise him better.
Anyway even actor Trevor White, for that's his real name, thought the storyline was rather abruptly finished. I thought we were in for a long 'Return of Martin Guerre' type story. Spoiler alert: Trevor has not been asked back. So it seems we won't see the imposter Patrick Cousin Meltyface again.
We ate an autumnal feast of roast pumpkins, roast chestnuts, puffball mushrooms, truffle tagliatelli, pears poached in red wine and drank lots. We didn't do any canning at all. I was too tired and the guests were too drunk.

Puff ball mushrooms fried in butter and garlic

Spaghetti squash being forked at the table, tons of butter in it.

Riverford Organic pumpkin box and our own Secret Garden Club pumpkins. Plus one 'chestnut' flavoured pumpkin from Israel, where I met the guy who 'designed' it. 

Pumpkins roasted with achiote paste, red peppers, smoked paprika. 

Truffle tagliatelli and pink peppercorns.

Never mind, we do have a canning demonstration/workshop and jar meal set for next year. On March 3rd, we have the hugely talented and probably only British expert on pressure canning, Gloria Nicol of The Laundry, coming down to London to teach. We will go through pressure canning, water bath canning and preserving. Jars will be provided by Le Parfait (love their jars). Gloria and I will then make a stunning supper, using our home-canned goodies, all in jars.
March 3rd 2013: Sunday, starts at 2pm. Book here: £60 for workshop and supper. Bring your own alcohol.

Grow Your Own Curry

MsMarmiteLover's aubergine curry

Think of curries, whether an Indian dhansak or jalfrezi, or a hot and sour Thai jungle curry, or a Malaysian laksa rich with aromatic flavours, and we think of exotic ingredients. A curry made with all-purpose curry powder will never taste as good as a bespoke curry in an authentic Indian restaurant. Ready-made pastes for specific dishes – like a Mussaman, or a Tikka Masala – are convenient but to me at any rate they all taste rather too alike to be seriously credible.

Before I grew my own curry ingredients, I knew that on the occasions when I’d planned ahead and bought fresh ingredients to make my own curry powders and pastes that the resulting dishes were streets ahead. But there are ingredients that are very difficult to get hold of, even here in London where we’re lucky enough to have food shops of the world on our doorsteps. So you leave out the curry leaves, or the kaffir lime leaves, or the holy basil and the curry still tastes great, but is missing something.

Ingredients like lemon grass, ginger, turmeric, cumin, etc, are invariably imported and so by the time they reach even a high turnover oriental supermarket they will have lost a significant amount of freshness. But what many people don’t know is that it’s perfectly possible to grow many of these supposedly exotic ingredients here in the UK, here on your patio.

Make a curry from ingredients you have grown yourself, that can come straight out of the ground into your pestle and mortar and the flavours will sing out loud. No longer will the curry be simply hot with a vaguely warm spicy taste, it will be aromatic and you’ll taste all the sweet-sour, hot, salty, mustardy, clovey, aniseedy flavours as they should be.

There’s a convenience factor as well. I have cobbled together a Thai green curry paste from scratch, added coconut cream from the store cupboard, some rice plus whatever was lurking at the bottom of the fridge and made a fantastic fresh curry in less than half an hour, no shopping needed. It takes a bit longer than using a packaged paste, but it’s much nicer and much more satisfying.

Let’s start though with some core ingredients of any spice paste. Onions and garlic form the basis of many curry and curry pastes and these are two ingredients that grow very happily here in the garden.

Onions

Onion sets can be planted out either in autumn or spring. The advantage of planting onions in autumn is that they will get a head start in spring next year as soon as the weather warms up and you should be lifting your onions to eat in May. There should be just enough time to plant overwintering onions now, but don't leave it any later. We planted Senshyu onions in the Secret Garden, a type specifically bred for autumn planting, spacing the onions evenly and planting them just deep enough to leave the tips slightly exposed above the soil - not too much top showing or else they will be dug up again by birds who appear to enjoy tossing freshly planted onions around the garden.

In the summer we ran a workshop on companion planting – the beneficial effects of positioning certain plants close to each other. Onions and garlic are well-known companion plants – the onion smell and garlic smell are said to deter some insect pests. Onions are good for repelling carrot fly - the onion odour masks the smell of carrots - while garlic is good to plant under roses as the smell deters greenfly.

Garlic

Now is the optimum time to plant garlic. We would always recommend a UK-bred variety such as Solent Wight for best results here. Check the weather forecast and aim to plant just before a cold snap: garlic cloves like to be chilled after planting to stimulate growth. Separate the garlic bulb into individual cloves and push each one into the ground, closing the soil over the tip so they are covered.

Fennel

Another spice ingredient suitable for growing outdoors is fennel. Fennel seeds are an integral part of a number of spice mixes and this herb fennel (this isn’t the type that grows a swollen bulb at the base) produces edible leaves, edible flowerheads and then of course, after flowering, the seeds. These seeds are mature right now - try biting into a fresh fennel seed and see how pungent the flavour is. 

There’s one other thing I like about growing hot chillies, ginger, turmeric and so on. There’s something a bit subversive about it. You’re not supposed to be able to grow these plants here in Britain, which makes it all the more fun to try and all the more fun when you get a half-decent crop.

Chillies

Chillies are a great example of a plant that is ridiculously easy to grow. I’ve been raising chilli plants for 10 years now, and I can’t remember the last time I bought a chilli pepper in the shops. There’s something incredibly satisfying – almost addictive - about growing chillies.

Not only are they easy to grow, but they mature into extremely attractive plants laden with fruit. In the Secret Garden we've grown Jalapenos, which are piquant and which are also traditionally smoked to make the Mexican chipotle sauce, and also the miniature Basket Of Fire variety, which we picked and used in the curries served at the Grow Your Own Curry afternoon. Basket of Fire is a very hot, birds-eye style chilli – ideal for Chinese, Thai or Vietnamese dishes.

      

Ginger

Ginger is a tropical plant, but it’s perfectly possible to grow ginger in a pot, indoors, in a conservatory or on a sunny windowsill. First you will need to find a piece of ginger root with small yellow nodules (see picture) protruding from it - these will develop into shoots. You may have to hunt around in your local mini-market and greengrocers to find suitable roots for planting.

Plant up in rich moist compost and keep the soil moist, but not wet. Keep temperature as constant as possible: bright windowsill against a double-glazed window is good, heated conservatory is good. They prefer not to be in direct sunlight. Anything above 20 degrees is workable, above 25 degrees better. The root will take up to a month to sprout but will then grow quickly throughout the summer before dying back at the beginning of autumn - anytime from October is a good time to harvest. Do not expect to become self-sufficient in ginger unless you have a lot of pots.

There's a step-by-step guide to how we grew our ginger plants here.

Turmeric

Growing turmeric in the UK is very similar to ginger: you need to plant a piece of rhizome with a nodule on it that looks as though it might sprout. However, turmeric will withstand slightly lower temperatures than ginger – down to around 18 degrees Celsius is OK, and also its leaves are edible and can be used for flavouring.

However, don’t imagine that you can just snap off a leaf and start chewing on it. The leaves tend to be used either in the same way as banana leaves, for wrapping food in, or ground up into a paste, or pickled. Or the leaves are picked and soaked to get some of the sourness out of them – then the soaking water is used in the recipe and the leaves thrown away.

The picture here shows part of the fresh root which can be cut from the plant and used fresh, or dried and then ground into powder.

Curry Leaves

Pictured above is a Murraya koenigii, or curry leaf tree and it’s one of those times when Latin or botanical names comes in handy because this is a very different plant to the curry plant which you find on sale in garden centres all over the country.

Murraya koenigii is the plant whose leaves are used throughout Indian and Malaysian cooking, usually quickly fried in oil and then added to a curry as a finish or garnish.

I find fresh curry leaves practically impossible to find over here, and dried ones seem to me to have lost much of their flavour. They do freeze well, but again, I don’t have much luck finding even the frozen versions.

So instead I have my little curry tree. And it is very little –this is a young plant and in its natural habitat it will grow into a full-sized tree, over 10ft tall. 

I bought this plant from Plants4Presents and they’re also sold in the UK by Poyntzfield Nursery up in Scotland. The two things to remember about keeping a curry leaf tree happy is that 1) they’re not frost hardy so you will need to grow them in a pot, outdoors in summer, indoors in winter; 2) in their natural habitat they grow on the forest floor, so don’t put them out in the sun. Put them under a tree.

Lemon grass

Lemon grass is well worth growing in the UK – even outside. Once established, the plants will grow vigorously, giving you fragrant leaves for flavouring, for making herbal teas, or scenting your bath. It will also grow offshoots, which the close-up photo here shows clearly at the base of the plant, which you can use as the classic lemon grass stalk in Thai curry pastes.

There are three ways you can get a lemon grass plant going. You can buy seeds fairly readily from garden centres and nurseries. Sow these in a seed tray in February and keep warm – cover with clear plastic lid or polythene bag until the seeds have germinated. When the seedlings are big enough they can go into a big pot, a number of smaller pots, or, once the danger of frost is over, outside in a sunny sheltered spot in lots of good rich compost.

The second way is to find some very fresh-looking stalks either in the supermarket or more likely an Asian supermarket. Trim the stalks lightly then sit them in water – stuffed into the neck of a cleaned-out Coke bottle or a plastic water bottle that supports the stalks is a good idea. Change the water daily and you should see white roots begin to appear. The time taken for the stalks to develop roots varies enormously: it can be a few days, or it can be several weeks. 

Thirdly, you can divide your own established plants once they’ve developed side-shoots. Instead of using all the side-shoots for cooking, select some for removing from the mother-plant and planting up separately.

By September you will need to harvest your lemon grass – any that isn’t used at the time can be sliced and put in the freezer, where they will keep very well.

Otherwise, bring your pots of lemon grass in over winter. They will not survive temperatures of less than 5 degrees. Give them a haircut, trimming them down to about six inches, then continue to water them sparingly, just enough to prevent them from drying out, and they should come back to life in the spring.

One other point to be aware of, if you have cats, is that the cats love lemon grass. Mine regularly likes to sit on the kitchen table and chew away at the leaves. Not great if you’re planning to harvest them later.

Kaffir Lime

The kaffir lime is a member of the citrus family which produces highly fragrant leaves used in Thai cooking, and also knobbly-shaped limes with, again, highly fragrant zest. I’ve had a Kaffir lime bush for five or six years now and while it isn't very prolific in terms of producing fruit, it earns its keep by giving me a hassle-free supply of Kaffir lime leaves 365 days of the year. I find fresh leaves practically impossible to find in the shops, and the dried versions have lost much of their flavour.

Citrus trees have quite a precise set of requirements to keep them healthy. If you’re able, either by luck or design, to provide a suitable environment for a citrus tree then it will appear to need very little maintenance. If your conditions aren’t ideal then they’ll prove troublesome.

In summer, in the UK, they’ll like to be outdoors, somewhere sunny and sheltered. A south-facing patio is ideal.  They don’t however like frost or wet winters so you will need to bring your tree indoors in winter. They do, however, like to be kept cool in winter, somewhere between 7 and 13 degrees. I move mine to an unheated loft bathroom under the skylight – it’s not too cold because of all the heat coming up from the floors below and it’s nice and bright with the big skylight window. If you have a light, bright conservatory that’s ideal so long as you don’t turn the heating up in winter.

In summer, keep the soil moist; in winter keep it dry and water very sparingly. However, it may well be worth standing the citrus pot in a tray of gravel which you keep wet, to raise the overall humidity around the plant – they do tend to find the air in our centrally heated houses very dry. (Another reason why the unheated bathroom works well.)

We’re doing a citrus workshop next month with lemons, limes, oranges, and kumquats when we’ll go into specific detail. However, I usually say that if your citrus looks happy: plant looking perky, leaves nice and glossy, then it is happy. A characteristic of any citrus plant that is struggling, whether too wet, too dry, too hot or too cold, is that all its leaves will fall off. A bald plant is one that is in trouble.

Coriander

Coriander can be grown both for its leaves - and roots and stems, which are often used in Thai dishes - and also for its seeds, which are commonly used in spice mixes and powders. 

When growing for its leaves, I find I get the best results by sowing the seeds thickly in a seed tray, keeping the tray warm and harvesting as microleaves - snipping off the leaves when the seedlinsg are just a couple of inches high. 

Growing for seed is almost easier as coriander is a notorious 'bolter' - the plants often to seed. Simply collect the seeds as soon as they turn brown on the plant and let them finish drying on a plate in the kitchen before storing in an airtight jar. 

You may often see what looks like coriander referred to as cilantro. I used to think it was simply that cilantro was the American word, but since I’ve started growing it as well as eating it I keep coming across cilantro in a British context. I have seen it suggested that coriander is grown for seed and cilantro for leaf but also that coriander refers to the whole plant: roots, stem (which are also edible and much used in Thai cooking) and all, while cilantro is the leaf only.

Thai basil

Until about six weeks ago I would have been recommending these wholeheartedly as the kind of herb which is not only easy to grow but also impossible to buy in the shops. Then my local Waitrose started stocking it in the fresh cut herbs sections. Thai basil is the variety that gives Thai curries that sweet licorice scent, and ordinary basil leaves just don’t work the same way. It’s incredibly easy to grow Thai basil in a pot on a sunny windowsill and one medium-sized pot will keep you in basil all summer long.

I grow lots of different types of basil, all in the same way. Get a medium pot with drainage holes and fill it full of good compost – multipurpose will do but it needs to be fine rather than rough-cut. Water it well. Sprinkle the seed over the surface – be generous, but keep the seed in a single layer. Cover very lightly with a layer of fine compost, so that the seed are just covered. If you’re sowing before April, cover the pot either with a fitted cloche, or a clear polythene bag stretched over the lip of the pot. April or after, you can leave the pot uncovered.

Put the pot in your sunniest windowsill: basil likes lots of light. The seeds should germinate by the end of a week – just three or four days at the height of summer – and once they’re through you can remove the polythene covering.

Keep them growing on the windowsill and start cutting when the leaves are big enough. Try to snip leaves from all over the pot: if you completely denude one seedling down to a bare stalk it won’t grow any more leaves. But if you pinch out the leaves at the very tip of the plant it will regrow quite happily. Water regularly to keep the compost moist and your pot should last all summer. Thai basil will start producing purple flower buds which can be snipped out and used as well as a garnish and flavouring.

After much experimentation I have come to the conclusion that here in the Uk, basil is an indoor plant. Outdoors, they fall prey too easily to aphids (greenfly), they get watered too irregularly and blown about in the wind. A warm sunny windowsill with still air and not so much temperature fluctuation will give you much more succulent leaves.

Holy basil

Often confused with Thai basil, this has smaller, more rounded leaves which are a matt green (or flushed with red, if it’s holy red basil) and slightly hairy. It looks frankly a more nondescript plant than the striking Thai basil. The flavour of the leaves is spicier, hotter, less sweet. Holy basil is also associated with Thai cooking, in stir fries, stews and rice dishes.

You can grow holy basil in exactly the same way as any other basil, but I’ve found it less prolific than the other basils and slower to grow.

Fenugreek

Like coriander you can grow fenugreek, or methi, for the leaves or seeds, both of which will give your dishes a distinctive mustard flavour and aroma. You can grow fenugreek from the seeds you buy in the supermarket. You can grow as separate plants or, a better solution at this time of year, is to grow as microleaves (pictured, left). Soak the seeds for about eight hours or overnight in clean cold water, then spread them evenly over a seed tray filled with compost. Cover the seeds very lightly with compost, and place a clear lid or polythene bag over the seed tray. Place somewhere light, bright and warm and the seeds should germinate in just two to three days.

There are two distinct types of fenugreek. The more common large-seeded variety has white flowers, and can only be cut once so once you've harvested, you'll need to sow some more. The smaller seeded variety has slightly smaller leaves, yellow flowers and will regrow after cutting.

If you're growing to raise single plants to maturity, soak the seeds first as above, then sow directly in a well-drained sunny spot. Sow the seeds thinly and just cover with soil, any time between April and August. Fenugreek will survive a light frost so is worth sowing sowing successionally throughout the growing season.

Cumin

There’s no reason why you can’t grow your own cumin plant in a sunny sheltered spot in the garden or in a patio container, or on a windowsill if you have the space. It’s an umbellifer, so related to caraway, fennel, and also carrots and parsnips. However, most of the world’s cumin is grown in the Middle East – it prefers daytime temperature consistently in the mid-20s Celsius.

If you’re going to try them outside, sow the seed indoors and keep warm until the seeds germinate. Once the seedlings are large enough to handle, transplant to pots, about three to four seedlings per pot. These can be then be kept indoors to grow on, moved outdoors once all danger of frost is past (say, late April), or the plants can be transferred to an outside border. Then pray for a long hot summer.

Simpler is to sow the cumin seeds directly in the large pot you plan to raise them in. Sow indoors as above, thin the seedlings once they have all germinated and decide whether to keep it indoors or move it outside depending on how the weather pans out. Last summer, for example, they would have stayed in.

It’s an attractive plant with feathery leaves, but you will be growing it for the seeds – another reason for needing a long season. The flowers are white (sometimes pink), after flowering you should see the seeds form. Pick them off the plant when they turn yellowy in colour and let them dry somewhere sunny – on a plate in the kitchen, say – until they go brown. Then they’re ready to be stored in a clean airtight jar and used as you would use the shop-bought version. Cumin seeds mature at different rates – there won’t be one single day when you can go and harvest all the seeds – so you will need to keep an eye on the plants and pick off the seeds as and when and add them to the kitchen plate.

I think it would be going some to grow enough cumin to become self-sufficient, but you should get enough for a few special occasion meals.

Fancy a challenge?

The plants listed above are all relatively easy to grow, whether indoors or outdoors, and should give you a decent harvest in favourable conditions. The spices and aromatics listed below present far more of a challenge - often because even if you managed to raise a tropical plant in the UK climate, you would have to wait many years for the plant to mature and produce its edible seed. It's not too surprising, therefore, that spices have been so highly prized and priced throughout history.

Cinnamon

Cinnamon is grown mainly for its bark, though its leaves are used in curries as well. It has been a much-prized spice for hundreds of years - there is a fascinating history of the trade in cinnamon here . 
You won't be able to grow cinnamon for its bark in the UK, but you could grow it in a pot in a conservatory and use leaves in teas and curries.

To use as a garnish, try growing cinnamon basil – a basil variety whose leaves have a definite cinnamon aroma. This can be grown exactly as Thai or ordinary basil.

Cardamom

Cardamom is a tropical rainforest plant. Best place would be a steamy bathroom, or an indoor heated swimming pool, should you have one. Kew Gardens has some advice on growing cardamom plants here, and Plants4Presents currently has plants for sale.

Don’t sow the culinary seeds that you buy in the shops, as they’re harvested unripe and then dried for kitchen use. 

Saffron

Saffron is extracted from the stamens of the saffron crocus. It's a painstaking process which must be done by hand, which is why saffron has traditionally been one of the most expensive spices in the world. I have tried growing crocuses for saffron, with dismal results, but there is a good online guide at Nurseries Online here. You plant in the summer and harvest saffron from the stamens of the flowers in autumn. You’ll need a pair of tweezers and it’s very fiddly.

Star anise

In theory, growing star anise, which is native to China, would be perfectly possible as a pot plant, indoors in winter, outdoors in summer. If only I could find one - and if anyone knows of a star anise plant supplier in the UK, please tell me! 

The star anise likes acid soil – it’s distantly related to magnolia – and lots of water. Once you get the plant established, it could be up to 10 years or more before it bears flowers and fruit – the star anise itself is the dried egg-shaped fruit in the star-shaped casing. The star anise ‘flowers’ that you buy here have been picked when immature and unripe and then dried, so you can’t reconstitute the seeds and grow the plant from there, unfortunately: the seeds are undeveloped and empty.

Peppercorns

The peppercorn vine is native to India and grows happily in Vietnam, but temperatures here, even in a greenhouse, are just too low. Peppercorns are the fruit of the vine, which are dried and can then be further treated. Black pepper, for example is cooked and dried peppercorns; green pepper is dried unripe fruit and white pepper is made up of dried ripe seeds. Pink peppercorns, however, are from a different plant: the Peruvian pepper tree, Schinus molle, or its relative the Brazilian pepper tree, Schinus terebinthifolius.

Although conventional pepper can’t be grown here, you can always try Szechuan pepper, which is comparatively easy - see Mark Diacono's guide in his book A Taste of the Unexpected.

Szechuan pepper is botanically related to citrus plants rather than pepper vines, but it will still give you a hot peppery hit along with some more complex citrus notes as well. It’s hardy in the cold and so long as you plant two of them (a male plant and a female plant), they will supply with you fruits – the Szechuan peppers – for a good few years.

Cloves

Originally from the Indonesian spice islands, cloves like it hot and humid. In its natural habitat a clove seed will develop it a full-grown tree up to 12 metres tall and spreading eight metres; it's next to impossible to recreate the conditions it likes in the UK outside a very large heated glasshouse. Bear in mind also that what is sold in the shops is a dried flower bud, not a seed, so cannot be planted, and that it takes 20 years for the trees to start producing flower buds.

Nutmeg

See cloves, above, for the optimal growing conditions, although they are speedy developers in comparison since the first nutmegs, the seeds of the tree, will be produced about 7-9 years after planting.

General tips for growing spice plants

• These will tend to be tropical plants; by default in the UK they will have to come indoors in winter;        
• Many also tend to grow in rainforest conditions; they don’t necessarily need lots of hot sun, but moist warm shade;
• Plants which grow on the forest floor are used to lots of organic matter but not necessarily very fertile soil;
• Don’t assume that a plant with edible seeds will have other edible parts, eg, cumin. (Although it might have, eg, turmeric);
• Choose whether to try to grow your plant from seed – may be cheaper and more obtainable, or whether to buy a plant to nurture – may be the only viable way to acquire;
• When searching the Internet for cultivation advice, check whether the site is referring to the UK, US, Australia or indeed anywhere else. You’ll find sites telling you how easy it is to grow cinnamon or talking about the benefits of growing lemon grass as hedging, and then find they are talking about Louisiana and Brisbane respectively.

The Secret Garden Club's ginger harvest 

Guests were able to take away a selection of  seeds, a handful of overwintering onions and chillies picked fresh from the plant, to try raising their own spice plants.