How to grow common vegetables in your allotment

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Follow these tips to successfully grow the most common vegetables grown on British allotments.

How to grow broccoli


Sow between March and June, in a greenhouse until April and outdoors afterwards. Feed with liquid fertiliser once a week.

Plant into full sun when the rootball is well bound together, allowing 30cm between plants and 45cm between rows. Fertilise the ground well before planting. Until May, cover the seedlings with fleece to prevent cabbage root fly.

Water every 10–14 days during dry periods, and net the plants when heads start being produced to protect from birds.

Harvest when the flower buds are well formed but before they begin to open. Cut the central spear first. This will be followed by a series of sideshoots, which can be picked regularly over four to six weeks.

How to grow broad beans


Sow directly in to the ground between March and April, 5cm deep and 20cm apart. They grow best in rows 20cm apart.

The beans will need a structure to climb up, so construct a fence beside each row out of several robust stakes and string.

Don’t be tempted to overwater your broad beans. Unless there’s a prolonged drought, they only need watering when they begin to flower, and then once again two weeks later.

The pods are ready to pick when they are 7.5cm long, which will be approximately 15 weeks after they were planted.

How to grow carrots


Sow maincrop carrots from April to early July, 1cm deep in rows 15–30cm apart. When they start growing, thin them to around 5cm apart for the best results.

The key to growing carrots is good soil — if your soil is stony, shallow, or heavy clay, it will stunt the growth of your carrots, so you’ll be better off growing them in a raised bed. Short-rooted varieties, which you can grow in pots, are also an option.

Carrots rarely need to be watered — a thorough watering every 10–14 days will suffice.

Don’t allow weeds to grow between your carrots, as they’ll crowd them out. When weeding, be careful not to damage the foliage, as the smell will attract carrot fly.

Harvest your carrots 12–16 weeks after sowing by carefully lifting them with a fork.

How to grow courgettes


Courgettes should be sown in late May or early June. Two weeks before sowing, make planting pockets 90cm apart roughly the size of a spade’s depth, width, and height. Fill these with a 50/50 mix of compost and soil, and then cover with general fertiliser. Sow one seed about an inch deep in to each planting pocket and cover with a cloche or jar. Leave them covered until the plant has outgrown its container.

Courgettes can also be grown in growing bags or containers. Plant two per growbag, and one per 45cm-wide pot.

The most important part of growing courgettes is keeping the soil constantly moist. Do this by watering the soil around the plants, not the plants themselves. Once the fruit begins to appear, you should feed with a high potash liquid fertiliser every 10–14 days.

Harvest courgettes when they are approximately 10cm long. Picking the them regularly will promote a long cropping period.

How to grow onions


Plant onion sets from mid March to mid April on a sunny, sheltered site with deep soil. Onions are best suited to growing in the open ground, so avoid planting them in raised beds, pots, or growbags.

Plant onion sets 10cm apart in rows 30cm apart by pushing them into soft, well-worked soil until only the tip is showing, and then firming the soil around them.

Water them occasionally in dry weather, and mulch the ground around them to help them retain water. Give them a light feed of sulphate of potash in June to help ripen the bulbs ready for storage.

Remove any flower spikes as soon as you see them, and when the bulbs ripen, remove the mulch and some surface soil to expose them to the sun.

It’s time to harvest your onions two or three weeks after the foliage turns yellow and starts to topple over. Lift them out of the ground with a fork and leave them to dry in the sun or, if the weather doesn’t permit that, in a shed or garage.

How to grow potatoes


Maincrop potatoes should be planted from mid to late April. Before they are planted, they should be chitted. To chit your potatoes, stand them with the end with the most ‘eyes’ pointing upwards in an egg box, and place this on a windowsill that gets a lot of sunlight. They are ready to plant when the shoots are approximately an inch long.

To plant your potato tubers, dig a narrow trench about 12cm deep in a sunny site on your allotment. Line it with compost, and then place a tuber every 40cm along each trench. Trenches should be spaced 60cm apart.

When the stems of the potato plants reach approximately 20cm, start the process of ‘earthing up’ by drawing a mound of soil about two-thirds the way up the stems. This will protect your developing potatoes from sunlight, which can turn them green.

Keep potatoes well-watered throughout their growing cycle, and give them a liquid feed of general fertiliser once a fortnight.