May is one of the busiest months on the allotment as the days continue to lengthen and grow warmer. There are lots of jobs to do including sowing the last of the summer crops, such as courgettes and runner beans, earthing up potatoes, planting and, of course, harvesting.


Even if the days are warm, it can still be cold at night, so resist the temptation to sow or plant if the weather is bad. Protect outdoor sowings with fleece.

Here are some key allotment jobs for May.

Earth up potatoes

Potatoes planted up last month need to be earthed up this month. When the foliage is around 20cm tall, draw up the soil on both sides of the plants, creating a ridge about 15cm high that almost covers the foliage. This prevents the tubers turning green and protects the foliage from frost damage.

Earthing up potatoes

For help choosing the right spade see our Border spades buyers guide

Harvest crops

You can start enjoying the fruits of your labours this month - crops that should be ready to harvest include lettuce, spring onions, broccoli, cabbage, spinach, rhubarb, beetroot, radish and peas. You can also start harvesting asparagus - cut the stems from 5cm below the soil.

Harvesting lettuces

Sow seeds

Sow dwarf or climbing beans, runner beans, sweetcorn, indoor cucumber, courgettes, pumpkins and squash in the greenhouse or under cover. Continue to sow lettuce, radish, spinach and beetroot direct outside - little and often to keep the harvests coming - and parsnips. You can also sow cabbage, kale and purple sprouting broccoli, for transplanting next month. When sowing carrots, protect against carrot fly.

Sowing beans

Thin out crops

Thin out crops sown last month, including beetroot and carrots. Be sure to cover carrots with fleece afterwards, as thinning out releases a carrot smell that attracts carrot fly.

Thinning out carrots

Plant out young plants

Plant out young plants sown last month, including celeriac, courgettes, squashes, pumpkins and marrows and leeks. Hold off if the weather is cold, and protect young plants from cold or windy weather with a cloche or fleece.

Planting out a young veg plant

For help choosing the right hand trowel see our Hand trowels buyers guide

Protect plants from bad weather

There may still be frosts in May, not to mention cold winds and rain. The nights in particular can be cold. Find out how to protect your young veg plants in spring.

Covering young veg plants with fleece for protection

Put up supports

Put up supports for climbing beans and runner beans. You can either buy a ready-made support, or make a wigwam or row using bamboo canes or hazel poles.

Placing a wigwam support beside young runner bean plants

For help choosing plant supports see our guide to the Best decorative garden obelisk and plant supports for climbers

Carry on weeding

Weed, weed and then weed some more! Get on top of weeds now and you'll have less to do as the summer progresses.

A weed pulled up with its roots

Watch out for pests

Keep an eye out for blackfly on broad beans - pinching out the growing tip of the plants, where they congregate, can help. Also look out for greenfly on lettuce and carrots.

Gardening with a clear conscience - blackfly
An accumulation of blackfly