May is always looked forward to as the first month of summer but it marks the end of the spring. It is a month when we can get caught out by mini droughts and heat waves. The biggest threat is to any young plants that have that have recently been transplanted into the open ground and any freshly emerging seedlings. Be sure to keep all of them well watered and if the young transplants look as if they are flagging give them some shade protection from the heat of the sun or drying winds. On the other hand May can be a complete disaster month bringing damaging frosts, cold winds with heavy rain or hail, so be prepared to take steps to protect plants if it is necessary.
Sprouting broccoli, cabbage, spinach, rhubarb, spring onions, early sown lettuce, beetroot, radish andpeas. Cut asparagus regularly to maintain the supply. Start to remove the side shoots on tomatoes.Use up of the last leeks. Clear away any old or finished crops and dig over the soil and prepare the site ready for the next crop.
Plant in pots or trays under glass, Dwarf and climbing French beans, runner beans, sweet corn, outdoor cucumbers, courgettes ,pumpkins, squashes, outdoor cucumbers – all which can be planted out next month.
Savoy cabbage, winter cabbage, endive, kale and sprouting broccoli can all be sown in the open ground now, ready to be planted out next month.
Continue making direct successional sowings in the soil of lettuce, radish, spinach, turnips (switch to kohl rabi when the weather becomes hot) beetroot for summer use and also maincrop beetroot to put into store at the end of summer. While the leeks, Brussels sprouts and French beans sown last month under glass, can now be planted out.
This is also your last opportunity to sow peas and parsnips this year
Thin out whilst still very small, the seedlings of beetroot, carrots, lettuce, onions, parsnips, turnips and always water along the row to settle the disturbed seedlings back in, once the job is completed.
Put up poles for runner and climbing French beans. Support peas and broad beans before they become too tall. Start to earth up potatoes especially if a frost is forecast.
Keep hoeing between crops to control weeds and also create a “dust mulch” to conserve precious soil moisture. Try to water in the cool of the evening if possible using a watering can to direct the water around the root area of the crops.
If you can get it, put some straw underneath the developing strawberry fruits to keep them off the soil and try to avoid watering overhead to reduce any problems with mildew
Look out for blackfly on broad beans, greenfly on peas, lettuce, cabbage root fly, carrot fly, thrip damage on brassicas especially when the plants are small. Spray the affected plants with soapy water (diluted washing up liquid) or squash the flies with your thumb and finger. You can buy insecticides if you prefer, including a fatty acid soap to spray on the plants.
Advice courtesy of The National Allotment Society