May is probably one of the busiest months on the allotment. As the days continue to lengthen and grow warmer there are lots of jobs to do. Even with warm days it can still be cold at night, so don't be to hasty to sow or plant if the weather is bad. Protect outdoor sowings with fleece.
Now is the perfect time for sowing dwarf, runner or climbing beans, sweetcorn, cucumbers, courgettes, pumpkins and squash in the greenhouse or under cover and parsnips. You can continue to sow lettuce, radish, spinach and beetroot direct outside, little and often will allow you to keep the harvests coming. Sow cabbage, kale and purple sprouting broccoli, for transplanting next month. When sowing carrots, protect against carrot fly with horticultural fleece.
Young plants sown last month can be planted out now including celeriac, courgettes, squashes, pumpkins and marrows and leeks. You can put this job on hold if the weather is cold even holding off till warmer weather in June won't do them any harm.
Potatoes that were planted last month will need to be earthed. When foliage gets to around 20cm tall, draw up the soil on both sides of the plants, creating a ridge about 15cm and just cover the foliage. This will prevent the tubers turning green and protects the foliage from frost damage. This month you can start enjoying the fruits of your labour. Crops that should hopefully be ready to harvest include lettuce, spring onions, broccoli, cabbage, spinach, rhubarb, beetroot, radish and peas. You can also start harvesting asparagus by cutting the stems from 5cm below the soil. Thin out any crops sown last month, including beetroot and carrots. Remember to cover carrots with fleece afterwards, as thinning out releases a smell that attracts carrot fly. Put up supports for climbing beans and runner beans. Get on top of those weeds, the more you do now the less (hopefully) there will be to do as the summer progresses. Keep an eye out for those pesky bugs especially blackfly on broad beans – pinching out the growing tips of the plant where they congregate can help. Also look out for greenfly on lettuce and carrots.