May is the month when seed sowing is in full swing, space in the greenhouse is filling up fast with seed trays and pots. Hardier crops started earlier in the year should be hardened off during the day before planting into their final positions. Tender crops such as beans and squashes can be sown undercover now. If the weather is particularly fine, sow beans direct where they are to crop.
- Sow French and runner beans either in pots (undercover) or direct, depending on weather conditions
- Harvest asparagus spears
- Check growth of greenhouse seedlings and water as necessary. If the weather is warm ventilate the greenhouse.
- Sow sweet corn under glass or indoors using small pots or toilet roll tubes
- Continue hardening off crops before planting out
- Transplant or ‘dib in’ leek seedlings once they’re the width of a pencil.
- Sow beetroot, kohl rabi and Swiss chard direct
- Sow cucumber, pumpkins, courgettes and other squashes under glass or indoors for successful germination.
- Plant out Brussels sprouts, summer cabbages and summer sprouting broccoli
- Sow early purple sprouting broccoli direct or undercover depending on weather conditions
- Keep the hoe busy!
- Keep sowing radish, spring onions, lettuce and peas every two weeks
- Remove weeds around onions, shallots and garlic
- Support autumn sowings of tall variety broad beans with canes and string between each row
- Plant the last of your seed potatoes
- Cut out flower spikes from the middle of rhubarb crowns
- Check support for summer raspberries, blackberries and other hybrid berries, tie in canes.
- Thin out crowded raspberry canes
- Earth up second early and main crop potatoes, cover rows with pieces of thick cardboard for extra protection if severe frost threatens
- Plant out sunflowers and other half-hardy flowering annuals raised in pots at the end of the month (weather permitting) otherwise wait until next month
- Thin carrot seedlings and consider sowing more rows
- Plant out sweet pea once hardened off, pinch out the growing tips if you haven’t done so already
- Keep a roll of horticultural fleece to hand, cover outdoor peas and greenhouse seedlings at night if very cold or frost threatens
- Succession sow herbs such as coriander, dill and parsley. Undercover if necessary.
- Check developing gooseberry fruit for signs of mildew.
Allotment Haven 