Things to do in the vegetable garden and the greenhouse during March, April and May.

Spring is the time for the bulk of seed sowing.   Early sown brassica and onion seed, once germinated, are removed from the propagator and placed on a shelf in the greenhouse to continue growing prior to hardening off and transplanting on the allotment.

Hardening off means to gradually prepare plants for growing in cooler conditions. One of the ways to do this is to move plants from a greenhouse to a cold frame. These are easily made using old windows leant against a sheltered, warm wall or laid on bricks. The other method is to transplant through black poly under cloches. If the soil is of a similar temperature to the soil in the trays, (ideally about 50 degrees), and the plants are protected from too much cooling by the use of cloches, in my experience, the young plants continue without a check. This method works particularly well if your young brassicas are pot grown and not transplanted with bare roots.

Crops grown in protapacs such as onions and beetroot must be gradually hardened off for a couple of weeks in a cold frame even if you intend to cover them with cloches once they are transplanted. The use of protapacs is becoming more and more popular but they need very careful watering to ensure the seedlings grow well without check.

There is no point in sowing seed into cold, wet ground. It won’t germinate, and if it does, the results will be poor and patchy. Better to sow a few weeks later and be sure of good germination. The crops will mature just as soon.

If you want to sow early, then you should protect the ground from waterlogging and put up cloches to warm the soil.



Early in March transplant young seedlings. Brassicas should be taken out of the propagator.   Potted up tomatoes and capsicums should stay in the propagator. Sow in gentle heat herbs like corriander and basil. Also, if the weather is cold and wet, (tell me when it isn’t at this time of year), I like to sow a few more lettuce seed and even beetroot. In the case of this vegetable, which hates to have its roots disturbed, I sow a few seeds into protpaks and transplant them as clumps to harvest later as mini-beetroot.. Similarly, with fast growing brassicas such as calabrese, it is better to sow a few seed into pots in the greenhouse in mid-march and transplant six weeks later under cloches in the garden, than to sow seed into chilly, wet ground. I sow celeriac and celery in the propagator now too

By mid-March I like to sow the next wave of brassicas for transplanting later: winter cabbage, red cabbage and spring cauliflower such as Purple Cape as well as autumn varieties like Romanesco. It’s also a good time to sow fennel into protapaks.

Pot up tomatoes and capsicums into 7.5 to 10cm pots on the propagator bench. Keep an eye on other seedlings, and transplant into trays or individual pots, brassicas and herbs. If you plan to grow outdoor tomatoes, now is the time to sow the seed.

In mid-April you can sow in moderate or gentle heat; cucumber, gherkin, courgette, climbing and dwarf French beans and sweet corn. Sow all these seed in individual pots or segmented trays. Also transplant greenhouse tomatoes into the border and pot up patio tomatoes and capsicums into eight inch pots. However, I have a preferred method for starting Runner beans outside using bottle cloches.



Transplant lettuce seedlings from the greenhouse after they have spent a couple of weeks or so in trays on the greenhouse floor from early march onwards. But do not transplant if there is a likely-hood of frost in the next day or so. Protect the seedlings after transplanting by sprinkling a few organic slug pellets around the base of the plant and placing a clear plastic bottle with its bottom cut off, over each individual plant. These mini-cloches can stay in place for several weeks, or until the plant is looking cramped inside. Remember to remove the caps to allow for ventilation.

Early in March, so long as it isn’t too cold I like to sow, (under cloches), peas, beetroot, radish and parsnip. I sow broad beans in the open ground

Hopefully, I will have got my early potatoes in before mid-March and transplanted globe artichokes if it has proved necessary. Also, now is the latest time to plant out shallots and garlic if you haven’t planted in the winter, or if your early planting has failed for some reason.

By mid-March, weather permitting, I like to get some more lettuce sown into open ground, as well as tasty salad crops such as rocket, spinach, beetroot, radish and carrots – all still under cloches. Onion sets can also be planted now.

By late March it is time to sow kohl-rabi and transplant onion seedlings and any brassicas that have grown six good leaves such as early cauliflower, calabrese and summer cabbage.


In early April I cover the ground I want to grow your French and runner beans in with a cloche. Towards the end of the month I sow climbing French beans and runner beans under this cloche. Blocks of dwarf French Beans can be grown under bottle cloches at the same time. By mid May and after the last frost the beans will have formed two or more true leaves. Now is the time to remove the cloche and stake the crops with bean sticks or netting.

Early in April sow more peas and mange-tout and try and catch up with sowing seeds that you were not able to sow early because of bad weather, laziness, forgetfulness, etc.

I’m a great believer in growing lots of small quantities of fast growing vegetables over a long season. This means successional sowings. It is not an exact science, trying to time cropping so that you minimise the amount of glut but sustain continuity of harvest and choice. So, in mid-April I sow, in the open ground, more beetroot, carrot, lettuce, turnip and spinach. I also hope to have my main crop of potatoes planted as well as brassicas for over wintering such as cauliflower and sprouting broccoli.

Further sowings of peas can be made early in May as well as endive, fennel and chicory.

My Allotment on 3rd May

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