This is the time of year when you really appreciate having a glasshouse. It buys you extra growing time while the weather outside is erratic. Sow crops in the propagator if you have one or in a cold greenhouse and cover with fleece. Plants can be potted on, if necessary, before hardening off and transplanting outdoors later in the season.
Sow the following in peat free compost in modules or trays: celery, courgettes, beetroot, kohl-rabi, carrots, chard, leeks, kale and spinach protect broad beans, peas mangetout and sweet peas from hungry mice.
Sow brassicas in 7cm pots or modules. Celeriac are also better in modules as they dislike root disturbance.
Sow French Beans for an early crop in June and lettuce in pots every two or three weeks, five to ten at a time to fill gaps in the vegetable plot when needed. Sowing this way avoids gluts. Sow 2-3 seeds per module then thin to leave the strongest seedling.
Sow tender climbers in modules including golden flowered Thunbergia alata, the ‘Moonflower’ Ipomoea purpurea ‘Heavenly Blue’ and other cultivars plus Ipomoea lobata the wonderfully coloured ‘Spanish Flag’ whose flowers range from red to cream. Harden off ‘Moon Flowers’ carefully, once the weather warms as they dislike the sudden shock of cold, turn yellow and either stop growing until they recover – or not.
Sow tender exotics including Amaranthus tricolor ‘Red Army’ boasting flamboyant purple-pink stems, deep purple leaves and deep reddish-purple flower heads, for wonderful for late colour in the ornamental or vegetable garden.
Herbs that can be sown too later in the month include basil, coriander, dill, chervil, lemon balm, rosemary, sage, oregano. Warm the compost for 48 hours in the greenhouse before sowing.
Don’t forget to label your plants and write them in your garden book. Labels have a knack of getting lost.
Water overwintered cannas to encourage early growth. Use tepid water, a little at first, gradually increasing the amount as growth speeds up. They need a long growing season to flower so it is great opportunity to get ahead. Hardening them off and transplant in borders once the danger of frost has passed.
Buy plug plants of hanging basket plants or tender vegetables. They can be ordered, transplanted and grown on quickly if you didn’t get round to sowing seed earlier this season.
Check plants daily to see if they need watering. Seedlings need daily attention. Make sure you give plants more space as they put on new growth. This improves air circulation and helps to prevent disease. Keep a look out for early pest infestations and control them immediately.
Look out for slugs and snails under pots and around the greenhouse.
Open doors and vents on greenhouses to increase ventilation on warm, sunny days but take care not to create cold draughts. Close them before temperatures drop in the afternoon.
Sow cleome seeds on in an unheated greenhouse. They need fluctuating temperatures to germinate and this will happen when the temperature drops at night. Happy gardening – there’s lots to do! Matt