Your organic vegetable garden in March 2014
February was the wettest on record for most of us. Many soils are still waterlogged and far too wet for cultivating, sowing or planting. Wait until ground conditions have improved before starting to sow into open ground. To help things along start plants off indoors to get a march on the weather. Cover ground with cloches or plastic sheeting to warm the soil.
Starting crops off in trays and paper pots is a good way to get ahead of the game while the weather is still unpredictable – or the soil unworkable.
Things to do in the vegetable garden
- General jobs
- Sowing and planting – what to sow now
- Soil assisted modules for leeks raising
- Quick guide to growing potatoes
- Pest watch
Veg growing doesn’t have to be complicated. Treat yourself to a copy of Pauline Pears’ Organic Guide to Growing vegetables for some good clear advice on the matter.
- ‘Pre-warm’ cold soils with a cloche or sheet of clear or black plastic for a week or two before sowing or planting if the weather stays wintery. To help the soil warm up more quickly, pull back any organic mulches.
- Hoe regularly, when weeds are small. Do so on a dry day but collect up the weeds and compost if rain is likely, to prevent re-rooting.
- Sow green manures where soil is bare and awaiting tender crops to be planted in May/June. – Mustard or phacelia will provide ground cover for 2-3 months, and provide cover for beneficial insects emerging from hibernation.
- ‘Top dress’ overwintered crops, such as autumn planted onions and spring cabbage, to give spring growth a boost. Use a good rich garden compost, well-rotted manure or chicken manure pellets (or animal free equivalent).
- Finish digging in overwintered green manures such as grazing rye and winter tares. To make the digging easier, cover the area with black plastic or cardboard for a couple of weeks; or dig it roughly once, leave for a week, then dig again.
Remember not to follow grazing rye with a direct sown, small seeded crop such as carrots or parsnips as the decomposing rye foliage can temporarily inhibit germination. Leafy crops such as cabbages and spinach beet do well after tares, thriving on the nitrogen released as the foliage and root nodules decompose.
- It’s not too late to dig a compost trench for your runner beans. They benefit from good moisture retentive material at the roots. Dig down to a spades depth, fill the bottom of the trench with raw kitchen peelings, old Brussels sprout and broccoli stems, the last of the rotting apples from store, newspaper and cardboard. Cover with soil. Sow runner beans outdoors from mid- May, depending on local temperatures.
- What you feed your vegetable plots with will depend on what you are going to grow next, what was there last, and the basic fertility of your soil. Root crops and legumes (peas and beans) should thrive without any additional feeding. Other crops may benefit from a dressing of manure, well-rotted compost or an organic fertiliser. Use compost at a rate of up to 2 wheelbarrow loads per 10 square metres, manure at half that rate.
- Don't forget to plan a crop rotation taking into account the fertility of your plot. See our factsheet, crop rotation
Growing conditions can vary dramatically across the country, and also even within a locality. If you are new to growing and are unsure about exactly what to do when, try asking other vegetable growers nearby. And be guided by the weather and soil conditions.
Sowing and planting out doors
Start sowing hardy veg directly outdoors as soon as the soil is workable. If the grass has started to grow, that's a good sign that the soil is around 5-6° C - warm enough to allow the hardiest seeds to germinate and grow. If you have a heavy clay soil that is slow to warm, wait a few weeks. Seeds sown in too cold or wet soil are liable to rot and unlikely to thrive.
Find hints and tips on successful sowing in our downloadable activity sheet ‘Sowing Seed’.
- Broad beans
- Beetroot (early varieties)
- Early carrots
- Maincrop peas
- Spinach beet
- Onion sets
- Jerusalem Artichokes
- Broad beans
- This is a good time of year to prepare an asparagus bed if you have not done it already. Dig a trench about 1m (3.5ft) wide and as long as you like; incorporate lots of organic matter such as garden compost or well-rotted manure. Add horticultural grit to improve the drainage, especially if you have heavy soil. Make the bed slightly higher than the surrounding soil. If you are buying crowns then all male varieties such as 'Lucillus' and 'Dariana' are the heaviest croppers.
To plant asparagus crowns dig a shallow trench 15cm (8in) wide in a prepared bed, and mound up the bottom to make a ridge in the middle. Place the crowns on top of the ridge 45cm (18in) apart and spread the roots downwards on either side of the ridge. Replace the soil and keep well watered. Do not harvest any spears until the second year and even then only a third of them. True cropping can begin in the third year.
Raising plants to transplant outdoors (or under cloches or in a greenhouse/ tunnel) gives you a head start on the season. It is simple to provide extra warmth for a few pots and trays of seeds - in a warm room, or on a heated mat on a greenhouse bench for example. But remember - the seedlings that appear will also need somewhere warm with good light levels.You can make a reflective light box to give windowsill seedlings more light. Click here for full instructions.
Kohl Rabi - best sown in
modules for transplanting
Block sown onions
Sow in trays and modules
- Baby beetroot M
- Brussels sprouts - for early crops
- Kohlrabi M
- Early cabbage
- Summer cabbage
- Early cauliflower
- Bulb onions
- Spring onions
- Tomatoes - for growing in a cold greenhouse or tunnel
M - these plants resent root disturbance and are best raised in module trays only.
If you are new to growing from seed, check out the information in our Get Started guide to growing from seed (available online to Garden organic members).
Raising seeds outdoors for transplanting
Winter brassica and leek plants can be raised in a ‘nursery’ bed, before being planted out in their final growing position.
Where leek moth or allium leaf
miner are problem pests, raise and
grow leeks under a fine mesh
cover – such as ultrafine enviromesh
- Choose an area - a corner of your vegetable plot for example
- Remove weeds and rake soil to a fine tilth. Disturbing the soil stimulates weed seeds near the surface to germinate.
- Leave the prepared seedbed for 2-3 weeks, then hoe off the emerging weeds. This is often called the ’stale seed bed' technique
- Sow immediately into the prepared, weed free bed .
Brassicas, cabbage, Brussels sprouts, kale, sprouting broccoli, cauliflower - sow at 4-5 cm x 20 cm (2in x 8in)
Leeks - sow at 2.5 x 15cm (1in x 6in)
Protect the seedlings: Leek moth, allium leaf miner and cabbage rootfly are pests that may attack seedlings in your seedbed. A well secured covering of horticultural fleece, or ultrafine enviromesh will keep them out.
Organic Growers Alliance. It combines the benefits of both module and seedbed raising.
1. Sow leek seed in module trays, 1-3 seeds per module depending on module size.
2. When roots begin to show underneath, place the tray on a prepared seedbed, indoors or out. Press down gently and water well.
3. Water as required. This should be less frequently than is usually necessary for a normal module tray.
4. Feeding should not be necessary as leek roots grow down into the soil.
5. When seedlings are ready to transplant, undercut the tray with a spade, then cut off roots flush with the bottom of the tray.
6. Transplant as usual.
If you try this technique, please let us know how you get on. Send an email to firstname.lastname@example.org
Direct sowing under cover
Vegetables in a polytunnel
Hardy crops that are usually grown outdoors can be grown under cloches or in the soil beds of an unheated greenhouse or polytunnel. They will romp ahead and give welcome fresh produce at a lean time of year.
Suitable crops for sowing under cover
- Lettuce - loose-leaf or seedling varieties are best
- Kohl rabi
- Baby beetroot - use an early variety, resistant to bolting
- Salad onions
- Peas - mangetout or sugar snap are best
- Potatoes - compact early varieties
- Globe artichokes
Unless your greenhouse or polytunnel is frost free you will need to protect tender plants if a frost is forecast. Horticultural fleece, in single, or double or even triple layers works well. Keep a few pieces, cut to suitable lengths, on hand.
Store the seed tubers in a light, cool (10°C), frost-free spot and leave them to sprout. This is known as chitting. Egg boxes make good chitting trays. Make sure you put the tubers with the ‘eye’ end (where the sprouts will grow from) upwards.
Dig in well-rotted manure or garden compost (apply no more than one wheelbarrow-full of well-rotted strawy manure, or two of compost, per 10 sq metres of ground). Plant tubers into trenches or in individual holes, 7-15cm in depth. Cover with soil.
- 1st early – 28-36cm apart, 38-50cm between rows.
- 2nd early & maincrop – 36-45cm apart, 65-75cm between rows.
Potato planting can start from mid March in milder areas, where frost is rare (or protect early plantings with fleece or cloches). If the soil is slow to warm, wait until April or May. Never plant into cold or waterlogged soils.
Parsnip in flower
- Grow a diverse range of plants and flowers amongst the vegetables to attract beneficial predators, such as hoverflies, to avoid the need for sprays. See our organic factsheet: Attracting beneficial insects for more information. If you have a parsnip leftover in the ground, or in store, replant it near your veg plot and let it ‘bolt’ and flower. The flowers are great feeding stations for predators and parasites.
- Our 2012 Allium leaf miner (leaf mining fly) survey received over 100 responses. The map below, showing the location of every respondent, shows how this pest is spreading. We can’t of course be sure that every respondent had identified the pest correctly.
New factsheet : Allium leaf mining fly
The allium leaf mining fly is only 3mm,
but its effects can be devastating.
Image courtesy The Food and Environment
Research Agency (Fera), Crown Copyright
Allium leaf miner
- Check the leaves and stems of vegetables for pests and diseases, at least once a week. Identifying problems before they get out of control will save you a lot of time and trouble. For help with identification, members can send in a sample to our Organic Gardening Advice Service. For more details, go to the Members' Enquiry form in the member's area, where you will see a link to the factsheet about sending in samples.
- Dig up any 'volunteer' potato plants growing from tubers left in the ground from last year, they could be carrying the potato blight fungus. Find out more in our potato blight factsheet.
Slug trap made from
- Bury stems and stumps of overwintered brassicas as soon as they have finished cropping. Bury them in a compost heap, or in a trench in the ground. This will help reduce the population of mealy aphids and whitefly which otherwise would simply move on to your spring planted crops.
- Clear up any plant debris, and remove diseased leaves from overwintered crops; put them on the compost heap.
- Put out slug traps a week or two before making new sowings and plantings and maintain them whilst seedlings are vulnerable. Check regularly and keep topped up with bait such as beer or formulated bait available from the Organic Gardening Catalogue.
- Don't plant potatoes into cold, dry soil. The potato shoots are more prone to attack by the fungus, Rhizoctonia solani causing stem canker, in these conditions. Shoots may fail to emerge when attacks are severe.
- The Organic Gardening Catalogue is available on-line at www.OrganicCatalogue.com or you can request a paper copy by ringing 01932 253666. It is worth a good read before you plan your cropping.