Growing beansprouts

Growing your own beansprouts is ridiculously easy and they are genuinely always much better than the bagged beansprouts you buy in the supermarket: crunchier, with a more pronounced flavour. And yours will not start to go mushy as soon as you’ve opened the pack.

Supermarket beansprouts are nearly always mung beans, but my two favourites are adzuki beans and fenugreek seeds.

1   Get your equipment together. There’s not much: a clean glass jar, and something which creates a mesh lid for it. It could be the lid, punctured in many places with small holes, rather as if you were going to keep a caterpillar in there. It could be a square from an old (but clean) jelly bag or net curtain. My preferred option is for a square cut from an old, clean pair of tights. You’ll also need a rubber band to keep the mesh securely on the jar. And your beans of course.

Secret gardeners with jars of beansprouts.

2  Put about a level tablespoon of beans in a colander or sieve and rinse them to remove and dust or dirt. Put them in the jar, cover with cold water and leave to soak for about 24 hours – overnight, anyway. This gives the sprouting process a bit of a kick-start.

3  The next day, drain the beans in a sieve or colander. Rinse them well, and drain again. Put them back in the jar, fix the mesh top on and stand them upside down on a draining rack or similar so that they are not standing in water.

4   The beans need to be rinsed and drained twice a day – morning and evening in practice. You can simply pour cold water through the mesh into the jar with the beans, swirl around a bit to rinse the beans well and then stand the jar upside down to drain.

5.  Ideally the jars should be kept in the dark, as the sprouts can turn green and more bitter to taste in daylight, but I keep forgetting about them if they’re put in a cupboard. Having them out on the drying rack makes it much easier to remember the twice-daily rinse.

6   You should start to see sprouts in about 48 hours (less for fenugreek). The best time to ‘harvest’ and eat them is when the sprouts are a couple of centimetres long and just beginning to push out leaves, usually after 3-4 days. You can eat the whole lots, bean + shoot, although some people like to rub off the skin of the bean before eating.

Korean chilli tofu with mangetout peas, served at the Secret Garden Club.

Growing microleaves

If you can remember growing mustard and cress on blotting paper at school then you are familiar with the idea of microleaves.

These are new-born baby versions of salad leaves, sown thickly and harvested when still just a centimetre or two high. You get all the flavour and nutrients from the full-size plant in a miniature package.

Microleaves were all the rage in restaurants not so long ago – around the time that making everything into foam was fashionable too. They’re used mainly for garnish, but also are good for adding flavour and texture to a salad.

Good varieties to try in microleaf form include mizuna, mustard, shiso, radish, rocket, basil, coriander, and peas. Especially peas - this is a quick and easy way to get pea shoots for a salad.

I sow microleaves when I have a few seeds left in the packet and no space left in the ground.

1. You need a shallow tray to grow microleaves in, one with drainage holes in the bottom. I use up these clear plastic supermarket trays which fruit, veg or even meat come in. The tray gets a good wash before we do any sowing! 
2. Helpfully, many of these trays already have holes punched into the bottom. If yours doesn’t you’ll have to add some, with a skewer or fork or scissors.
3. Cut a single piece of kitchen towel so that it fits snugly into the bottom of the tray. This is to stop your growing medium falling through the drainage holes while still letting water in and out.
4. Now add your growing medium – I’m deliberately not specifying what it is because there are a number of effective things you can use:

a.     Seed compost. There are plenty of people who say that using compost gives your microleaves the best flavour. 
b.     Perlite. These are particles of volcanic rock that have been heated to a very high temperature so that the granules become light and very porous. Good for anchoring the roots in place and absorbing water, which is then available to the growing plants. Looks like cat litter.c.     Vermiculite, a silicate mineral which provides a clean inert anchorage for the micro-seedlings. It also has the advantage of being much cleaner than soil.
d.     Cotton wool covered with kitchen towel (or blotting paper). This has to be the cleanest solution of all. My only objection here is that I’ve found I get patchy germination using kitchen towel to germinate seeds.

Whichever you use, it needs to be about 1.5 centimetres deep in the tray. Sprinkle it in and tap or shimmy the tray from side to side so that the granules are evenly distributed.

5.     Sow the seed on the surface. You should sow quite thickly, so long as the seeds remain in a single layer on top of the vermiculite. You don’t need to cover the seeds.
6.     Now place your tray in a shallow dish, into which it fits comfortably. Add water to the dish, not the seed tray. The water will be drawn up into the seed tray, moistening the seeds.
7.     Place the seed tray and dish somewhere bright and consistently warm – a south-facing windowsill, especially if you have double-glazing, is good.
8.     All you have to do now if to make sure that the bottom of the dish doesn’t dry out. Check it daily and top up with water if necessary. And wait. Your seed should germinate in 2-4 days (2 days for pea shoots and mizuna, 4-5 for shiso or coriander), and, if it’s on a windowsill, you may have turn it so that the shoots continue to grow up straight.

Pea shoots are my all-time favourite here. You know that distinctive taste of pea shoots in salad? This is by far the easiest way to grow your own tender pea shoots – if you pick the growing tips of the peas you’re growing for full-grown pods, you will reduce your harvest.

Orient Express - fast-growing veg from the Far East

A friend was musing that children these days learn to use chopsticks before they learn to tie their shoelaces. It’s true: a Chinese takeaway, sushi snacks, eating at Yo Sushi or Wagamama all give them the opportunity to practise their chopstick skills while shoes for the under 10s do all seem to do up with Velcro.

But if kids are all savvy enough to know their bok choy from their mustard greens in a Chinese restaurant or in the supermarket, there is still comparatively little being grown in our gardens. In many parts of China, Korea and Japan the climate is comparable to ours, so there’s no reason why we shouldn’t be raising our own oriental vegetables. Most supermarket pak choi, for instance, does come from the UK, but you still don’t see it being grown very often in the vegetable patch. We seem to prefer to stick to lettuce and the more traditional kind of cabbage. Which is a shame because these Eastern brassicas are fantastically rewarding crops to grow:

• They’re quick. At this time of year they’ll germinate in three days and be ready to eat in a month.
• They’re unfussy: you can sow and grow oriental greens just about any time of year. In fact they grow better from midsummer onwards as the days get shorter. If you have a polytunnel or a greenhouse you can keep them going overwinter – most are reasonably hardy.
• They’re versatile. You can harvest oriental leaves at just about every stage of growth. As microleaves for a garnish after about two weeks. As cut and come again leaves in a salad or in a stir fry. As a vegetable in their own right when the whole plant is cut. The younger the plant when you harvest it, the more delicate the flavour.
• They’ll grow anywhere. In the open ground, if you have it. In pots, in troughs, on windowsills, or patios. They don't need a vast amount of space.

At our Secret Garden Club afternoon discussing oriental vegetables, we showed leafy greens being grown a microleaves, in pots and troughs, and out in the open ground in the garden. By successional sowing, that is, sowing little and often, we can have leaves available for crunchy salads pretty much 365 days a year.

Types to try:

Mizuna

Mizuna is a brassica with bright green serrated leaves. It’s often used in salads, where it adds a slightly chewy texture and a bit of bite. I actually think a little mizuna in a salad goes a long way; I prefer to eat it either as microleaves, or as a whole plant, pak choi style, in a stir fry.

It’s easy to see why mizuna is popular though: it’s probably the easiest salad vegetable to grow anywhere. It will grow in most soils, at most temperatures. It’s hardy and vigorous.

Mustard

Also known as red mustard, red giant mustard, Chinese red mustard, mustard green or several other names. This is a pungent, peppery-hot leaf, oval-shaped with a serrated edge and coloured green streaked with purple. You may have also heard of Green in Snow, a lovely name, I think, for a particularly pungent mustard leaf.

Pak choi

If you look on the package label, you’ll see that nearly all pak choi sold in supermarkets is grown here in the UK. Pak choi grows exceptionally well: like mizuna, any time of year will do, though if you’re sowing in winter, a greenhouse or polytunnel will be needed or growth will be very slow.

The only drawback to pak choi is that I think it is the slug and snail’s favourite food. Well, possibly second favourite to hostas. Wherever you grow them they will need slug protection – we tend to use copper rings around each plant in the open ground, or copper tape around the rim of a pot.

Choy sum

Related to pak choi but with slimmer leaves and – I think – a less distinctive taste.

Morning glory

Also known as water spinach, this is an edible variety, Ipomoea aquatica, from the Ipomoea family, which also includes sweet potatoes (Ipomoea batatas). Common bindweed is also a  relative. There are edible and non-edible morning glory varieties. As the alternative name water spinach suggests, it likes to grow near water, and can become quite invasive – there are controls over the growth of morning glory in many US states for instance.

Chinese broccoli, kailans

If I had to pick a favourite from this list, it would be kailans (left). This is a type of broccoli where the stem is the interesting bit and a floret a bit of an afterthought. The stem is crunchy, and has a nutty, mustardy taste. You can also eat the leaves.

Grow kailans in rich soil, with lots of organic matter. The plants will grow quite big and may need support. When you cut the main stem to eat, it will grow again, so that in a season you will get 3-4 cuttings from one plant.

They are not quite so prey to slugs and snails as pak choi, above, but we still take precautions. I’d be much more upset about losing a Chinese broccoli plant to a slug attack than I would a pak choi or two.

Chinese cabbage

The Chinese cabbage you buy in the shops is only one type; there are plenty others, such as Tatsoi,which grows as a low rosette of dark green leaves rather than the firm-headed, pale yellow-green variety we’re all familiar with.

Komatsuna

Dark green fleshy leaves, ideal for making a salad seem substantial, also good in stir fries. Another easy one to grow, unfussy about soil and temperature.

Perilla (shiso)

This is a leaf more associated with Japan: you frequently find this heart-shaped, frilled-edged leaves garnishing sushi – or quite often, a plastic imitation shiso leaf in the bottom of your pre-packaged sushi.

Shiso leaves can be green (we have a couple of green plants here) or red. They have a slightly chewy texture and faintly minty taste.

Let’s look in detail at how you might grow these greens in a variety of ways.

Growing in the open ground

Although our oriental veg will grow very happily out in the vegetable bed, not all varieties want to start there. Mizuna, mustard, komatsuna and tatsoi will all germinate and grow very readily if sown direct into the spot where they are to grow. Kailans will do in theory but I have always found it easier to start kailans in modules and then transplant them when the weather warms up. The same with shiso.

It’s worth taking the time to prepare your ground. Weed it, remove stones, dig in compost, organic matter, or manure if you have it. Think of it as making a nice soft bed for them to grow in.

Sow as thinly as possible: you will only have to thin out seedlings later if you don’t … though when you do thin them, don’t forget to wash and/or trim the thinnings and add them to a salad as well. The other way to do it is to station-sow: make a little hole every four inches or so, drop one seed down that hole and fill, thus determining exactly where each plant is to grow.

Remember your slug protection before the seedlings germinate, or you may never see them at all. When the seedlings are tiny, they will need watering until the plants are established.

If the soil is nutrient-rich you shouldn’t have to feed the plants – you’ll be picking them before too long. If you think they would benefit from a feed, choose a nitrogen rich solution: nitrogen promotes leafy growth, and good leafy growth is what you want from these particular vegetables.

Growing in a pot

There are advantages to growing in a pot. Slug and snail control is easier: you can move the pot away from the pests, or run copper tape around the rim of the pot. You can control the growing environment: the temperature, the exposure to wind, how much water they get, and so on.

If you’re growing in order to pick cut-and-come-again leaves rather than whole plants, I’d say a pot is probably the best way to do it. It’s only when you think of growing a full-size plant – pak choi, says – and you realise you’ll need a very big pot to accommodate the plants and all their roots.

My solution here is to grow in a trough rather than a pot. More convenient for windowsills, anyway, and it seems to give the individual plants more room.

You can either sow your seeds in the pot directly, for salad leaves, or sow seeds in modules and transfer the plants. From March to September, the pot will be happy outside. In March, it might need some protection at night: put some horticultural fleece, or drape some bubble wrap or fit a clear plastic lid over the pot. Although many of the plants named here are hardy, they won’t grow fast in the cold.

In autumn and winter, move your pot into a polytunnel, greenhouse, or inside altogether. I have successfully raised pak choi indoors overwinter, although it does take much longer to grow. It’s not so much the cold that bothers them, as they can stay nice and warm indoors, it’s the low light levels of winter.

If your pots are indoors, you shouldn’t have to worry about slugs, snails or flea beetles. Look out for aphids, though, especially when it warms up in spring. They can get everywhere.

Dealing with pests

Most of these oriental vegetables are brassicas. That means they are vulnerable to the usual cabbage pests: cabbage white butterflies, whitefly, and also disorders such as clubroot. 

However, here’s another thing in the oriental veg’s favour: they tend not to be in the ground for long enough to be too bothered by these pests. By the time the pest finds them, you’ll be picking them.

They’re not entirely pest-free though. You’ll see we’ve had slug damage on the Chinese cabbages. Or maybe it’s snail damage, since we’ve been using biological controls to get rid of our slugs. If you’re growing in a pot or trough, then a line of copper tape along the rim of the pot should keep both slugs and snails away. In the open ground it’s a bit more tricky. We’ve put copper rings round the bigger plants, and we don’t really want to use pellets. If you don’t want to go down the admittedly expensive route of biological control (but then we did have a lot of slugs), try surrounding the plants with crushed eggshells, grit, or set beer traps.

Mizuna and mustard, particularly, also get eaten by flea beetles. You can tell flea beetle damage by the tiny perfectly circular holes in the leaf.  We’re lucky here in the Secret Garden in that we’re not really affected by flea beetles, but there's not much you can do about them except be thankful that the damage isn't usually bad enough to seriously reduce your crop. Some people recommend trying to catch the beetles by holding sticky tape under the plant so that when the beetles jump, they land on the tape, sticky side up, and get stuck. I'd say it's quite fun to watch people trying out this technique but it rarely seems to be very effective.

The very young seedlings are also attractive to aphids. These can usually be wiped off, or you can use a garlic solution spray to deter them.

Lilac sugar

 I have lilac only two or three weeks a year so I like to make the most of it. This time I'm picking off the blossoms to infuse in caster sugar. Later I'll make a syrup or a sorbet.

Syrup:
150g caster sugar
150g water
a few heads of dried hibiscus flowers (optional)

Heat the water and sugar together until the sugar is dissolved then add the lilac petals. Simmer for ten minutes. You can add the hibiscus flowers for colour if you like. Then strain the flowers out of the syrup into a jar or bottle. Keeps in the fridge for 2 weeks.

Use on icecream or in cocktails.


This Sunday we are having a grow your own oriental food workshop and supper at the Secret Garden Club. Tickets for workshop, supper and goody bag are £30.
Book here: http://www.wegottickets.com/event/197293%20£30

A potato feast

After our workshop on how to raise a successful crop of potatoes, the Secret Garden Club last Sunday retired for a potato-themed tea using many of the heritage varieties we grow in the garden.

Red Highland Burgundy and Salad Blue potatoes, scrubbed clean but
not peeled, ready for baking on a bed of salt.

The small baked potatoes were served with creme fraiche and some anointed
with caviar for a luxurious canape.

Waxy Cyprus potatoes were used in this salad with
wild garlic and feta.

MsMarmiteLover's homemade potato gnocchi, pillowy-light and
delicately flavoured. Once cooked very briefly, these were dropped
into a tomato broth.

Tomatoes and basil, ready for straining to make an intensely
flavoured liquor, the base for the gnocchi soup.

One potato, two potato ...

Now is the right time to plant potatoes, with the weather and the soil finally warming up. Traditionally, gardeners planted their potatoes on Good Friday, which could mean a chilly March start for the tubers, or a warm late April and a race to develop to maturity. This year with the prolonged cold, we’ve had little choice but to wait until the latter half of the month.

The Secret Garden Club planted out its maincrop potatoes this weekend at our annual potato workshop, where we demonstrated not only how to grow in the open ground, but also how to grow them in a restricted space – good for growers with a small garden or only a patio area, maybe.

We concentrate on heritage varieties which are not readily available in the shops. Some of our favourites are:

Pink Fir Apple

Pink Fir Apple was originally imported in 1850 but was unknown in the mainstream for decades, only recently becoming fashionable. The tubers are long and often rather knobbly, which can make them fiddly to peel. (I usually don't bother  and just scrub hard instead.) The skin is part pink, or brownish yellow with distinctly yellow flesh. Although grown as a maincrop for later harvest, the flesh is waxy with a good nutty salad potato flavour.

Red Duke of York

The tubers are large and round with distinctive crimson skin. The floury flesh has a creamy texture and a clear yellow colour, and is very versatile in the kitchen  - it can be boiled, fried, mashed, roasted or chipped. The Duke of York variety has been around since the 19th century but the first red-skinned tuber was discovered in Holland in among a crop of  white skinned potatoes in 1942.

Russet Burbank

A small russet or brown-skinned potato, rather like the russet apple. It has white flesh and holds its shape well in cooking. Originally developed in Lunenburg, Massachusetts, the variety is named after potato grower Luther Burbank). The original Burbank potato was identified in the 1870s; the Russet Burbank, with its rough skin, in 1914.

Yukon Gold

An Central/South American style potato – that very yellow flesh and buttery flavour is characteristic of American potatoes. Today Yukon Gold is mainly available in the US and Canada. Another versatile culinary variety and especially good for baking and mashing.

Salad blue

These unusual potatoes were first grown in Scotland in the 1900s. Both the skin and flesh is a deep indigo, tending towards purple, colour. The name is misleading, as the potato is best used in frying, baking and mashing rather than boiling up for a salad. It has a light, open texture and moist flesh with a mild flavour.  The blue colouring is an anthocyanin, which is an antioxidant, and the colour remains after cooking. Together with Highland Burgundy, below, and a more conventional white-fleshed variety, they make the most fantastic multicoloured chips.

Highland Burgundy

The Highland Burgundy potato is so-called, it's claimed, because it was used to provide an appropriate colour to a meal for the Duke of Burgundy back in 1936. The flesh is crimson or red with a distinct ring of white just below the skin, and the colour stays fast in cooking. The texture of the flesh is drier and denser than that of the Salad Blue, but the Burgundy should be cooked in similar ways: fry, bake, roast or mash, but don't boil.

Having discussed heritage (or heirloom) tomatoes in our previous Secret Garden Club afternoon, it’s interesting to see that there are less rigorous guidelines for a potato to qualify as a heritage variety. A heritage potato is, broadly, one which has been around since before 1950.

After World War II mass production of potatoes was needed to feed the population. Varieties which were high-yielding and reliable croppers were preferred to some of the quirkier, less prolific types, and it's those same potatoes that you find dominating the greengrocer and supermarket shelves today. Many of the potato varieties which had been grown on a small scale before the war became neglected and continued only by a few specialist growers. The growing interest in organic growing and farmers' markets has brought them to public attention again.

There are registered heritage varieties which have been grown for generations: Pink Fir Apple, King Edward, Duke of York and Arran Pilot are examples of these. Then there are non-registered varieties which have also been grown for many decades, often on smaller farms and smallholdings. Varieties such as Salad Blue and Highland Burgundy come into this category.

There is a useful articles on heritage guidelines and varieties on the BBC's gardening blog.

Diner beware

It’s worth pointing out that the tubers are the only part of the potato plant that are not poisonous. Potatoes are a member of the Solanum, or nightshade family, as are tomatoes, aubergines, and, yes, deadly nightshade. When you see your potato plants in flower you’ll see the family resemblance. 

Mayan Gold potato plant in flower.

Potato leaves, flowers and stems are all toxic. If you leave the plant to grow on after flowering, it will grow a small green berry on the central stem, which looks for all the world like a small green tomato. That’s also poisonous. So stick to the tubers, and spare a thought for Lords knows how many ancient Andean foragers who discovered the hard way which parts of the plant could be eaten and which couldn’t.

Growing in the open ground

Growing potatoes in the open ground takes up space. But if you have that space they’re an easy crop to grow. The hard work all comes at the beginning, when you need to get the ground ready for your tubers.

1. Buy seed potatoes to plant. You can try your luck with planting potatoes bought at the supermarket, but there are good reasons not to do this. Potatoes in the shops may have been sprayed with a shoot suppressant. They also may not have been grown in the UK and so won't be well adapted to grow here. Many, if not most, of the seed potatoes grown in the UK come from Scotland and are bred to grow well in our conditions. Seed potatoes should also be guaranteed free from viruses, which culinary potatoes won’t be. 

With seed potatoes you get a huge variety to choose from – we like potatoes from Carroll’s, Thompson & Morgan, and also Sutton’s have a wide variety available.

Salad blue potatoes with 'chits' - the little shoots which have already sprouted.
These give the potatoes a head start once they're planted in the ground.

2. Place your potatoes somewhere light and cool (but not cold – the tubers mustn’t be exposed to frost), like a shed, to ‘chit’. Chits are the growing sprouts that will develop on potatoes stored before they are planted out. There are two good reasons to chit your potatoes: 1) it gives them a head-start when they go into the ground as the growing shoots are already developing, and 2) it will help you to plant them the right way up.

3. When you’re ready to plant out, dig a trench up to eight inches deep for each row of potatoes in your intended bed. Each row needs to be 12-18 inches apart.

4. Line the bottom of the trenches with compost – multipurpose or dedicated potato compost – if you think the soil is poor. Potatoes like slightly acid soil; if you garden on clay as we do at the Secret Garden Club, you should be fine as clay is normally slightly acid itself.

5. Lay the seed potatoes at the bottom of the trench, shoots facing uppermost, about 12 inches apart.

6. Cover with soil, adding in more compost if you think the soil needs it.

7. Try to create a slightly ridged finish to the row. This will help you remember where the potatoes have been planted!

8. In clay soil, the plants should only need watering in times of drought.

9. The potato plants should start coming through after 3-4 weeks. Once they are 3-4 inches clear of the soil you can start gently ‘earthing up’, drawing soil from between the rows to accentuate the ridge over the potato plants. You can cover the growing plants so that just the top leaves are showing through – don’t bury them completely.

10. If you find earthing up difficult, use mulch or compost to cover the plants as above. We use grass clippings a lot – the lawn always needs mowing around the time the potatoes need earthing up – which is a bit unsightly, but effective. The idea is that the developing tubers need to be in darkness, so earthing up, or covering with mulch ensures they are not exposed to the light.

11. After the potato plants have flowered, they will usually start to turn yellow and die back. This is a good sign that they are ready to harvest. Dig up a plant in a corner to check. If the tubers are tiny, re-bury them and wait a couple of weeks. If the tubers are a good size, start harvesting!

As a general rule, ‘early’ potatoes – the kind you often associate with summer and potato salads, like Charlotte, or Nicola - take around 13 weeks from planting to maturity. These can be described as first earlies, or second earlies - the latter takes about a week or so longer. Maincrop potatoes, often bakers and mashers, will be ready 15-20 weeks after planting. But note these are guidelines – and before anyone writes in, there are lots of exceptions: Pink Fir Apple is a maincrop potato which is fantastic in potato salad, Red Duke of York is an early potato that makes terrific mash. When you buy your seed potatoes, it should say on the label, or bag, what kind the variety is. The terms ‘early’, ‘second early’ and ‘maincrop’ refer to the time taken to mature: an early potato will be ready earlier than a maincrop.

Growing potatoes in a bag

And if you don’t have enough space for trenches and rows of potatoes, don’t despair. You can grow potatoes quite easily in a container, and a bin liner, a strong heavy duty bin liner like a rubble sack, will be perfect for the job. Early potatoes grow best using this bin-bag method.

1. Take a clean, heavy duty bin liner that is either black or lined black on the inside. It needs to be light-excluding.

2. Punch two rows of holes at the bottom of the bin liner with a broken pencil. These are your drainage holes, and they’re very important - the potatoes mustn't get waterlogged.

3. Roll down the sides of the bin liner to about 3-4 inches from the bottom.

4. Cover the bottom of the bin liner with a 2-3 inch layer of multipurpose compost.

5. Place three seed potatoes on the compost, space evenly, chatted shoots pointing upwards. On Sunday we planted the early variety Swift, a tasty salad-type potato which is usually quick to grow and mature.

6. Cover again with compost until no chits are showing.

7. Place the potato bin-bag outside, somewhere outside and unlikely to be disturbed by stray cats, squirrels or footballs. One of our guests on Sunday says they have a problem with squirrels and some protection might be needed here such as placing the bin-bag under mesh. Footballs is my own concern – I once came home to find my (full) potato bags being used as goalposts.

8. After 2-3 weeks you should see the green leaves appear above the compost. Let the plants grow until they have 3-4 good leaves, then add more compost to the bag so that the leaves are just showing above the surface. You may need to start rolling the sides of your bag up to accommodate the compost.

9. Keep adding compost when there is 3-4 inches of stem showing above the soil.

10. Water if the compost seems very dry. Left outside and with a couple of downpours of rain a week, your potato bags may not need watering.

11. After a couple of months, you should have rolled the sides completely up and have a bag full of compost and three healthy potato plants laying down lots of tubers. Leave the plants to flower and wait until the leaves start to go yellow and die back. You can check if your tubers are ready by sticking a (gloved) hand into the compost and feeling around for them. If they are very small, leave for a while longer.

12. If your tubers are ready to harvest, simply up-end the bag and sort through the compost for your spuds. Put the remains of the plant on the compost heap and re-use the compost – not for potatoes again, but for another crop or as a general garden mulch.

Slugging it out - using nematodes as pest control

As the soil warms up and new spring growth appears, so the slugs and snails emerge again, looking for soft new leaves to devour. Sometimes gardening feels like a constant battle against the march of the munching molluscs. 

As we're getting to plant our potatoes ready for the Secret Garden Club workshop on heritage potatoes this Sunday, we've been looking for effective methods of slug control - they can cause major damage to growing potato tubers, especially in damp conditions.

There is no one-size-fits-all method to controlling slug and snail numbers. Certainly encouraging slug predators to visit, if not live in, your garden is a good start. Frogs, hedgehogs, beetles, and many birds including ducks, thrushes, robins and starlings, all consider slugs and snails to be a good meal.

Methods like traps baited with beer can work well in small areas like a patio or courtyard garden. For a bigger area or an allotment you could not hope to trap all your slugs and snails with a few beer traps.

Deterring them with coffee grounds or crushed eggshells can work for single plants - although I bet a slug would crawl over broken glass to get to a juicy hosta - and for anything bigger than that you would need a very large number of eggs or coffee grounds.

Pellets can be effective but the blue ones, containing metaldehyde, are also toxic to birds, frogs and hedgehogs, not to mention small children and pets - if they inadvertently ingest slug pellets, or a slug in the throes of pellet poisoning then they too be harmed, possibly fatally in the case of smaller animals. The white pellets, which are marked as being safe for wildlife, contain ferric phosphate. In practice, I've found these much less effective at killing the slugs and snails. 

Until now the Secret Garden has relied on deterrence, using copper rings around individual plants. Copper rings work as a barrier - slugs and snails won't cross copper as the metal reacts with the mucus coating their bodies. However, it's only a deterrent. It won't reduce their numbers, so while they won't munch your copper-protected brassicas, they will slink off elsewhere and eat something else instead. And the Secret Garden is very sluggy, and the wet conditions last summer were ideal for slugs and snails, making it likely that the population will rocket again this year with a bumper crop of eggs surviving the winter deep in the soil, now ready to hatch.

So the Secret Garden Club is going to war. We're fighting back with nematodes. Phasmarhabditis hermaphrodita, to be precise. And we have 24 million of them.

Nematodes are microscopic organisms, barely visible to the naked eye. Our particular nematode, P. hermaphrodita, is a slug killer. It seeks out slugs, penetrates their bodies, and poisons them. It will then reproduce, generating hundreds more nematodes hungry for more slugs.

These nematodes will also kill snails but because they live in soil they tend to encounter far fewer of them, since snails tend to live on the surface or climb walls and fences.

They have no effect on any other creature, so are safe to use around pets, children, and other animals.

1. What you need - a water supply, clean watering can and a packet of slug-killing nematodes. 2. Each 8-litre watering can will take
a quarter of a pack of nematodes. Add the nematodes to the can first.

3. Fill the can with cold water and mix well. It will look like a murky soup.
Water the nematodes into your soil evenly. An 8-litre watering can will cover
around 10m2.

4. Now refill the watering can, this time with clean cold water. 5. Cover the same area with plain water so that the nematodes are
thoroughly soaked into the soil.

One application of nematodes will last around six weeks, then the operation can be repeated. We'll be monitoring our population of slugs and snails and will report back on progress.

We bought our slug killing nematodes from Gardening Naturally. They're also available from Crocus, Unwins, and the Organic Gardening Catalogue.