Vegetables What vegetables to plant in May May is a busy time for seed sowing, especially in the vegetable garden. Although the weather is much warmer, there’s still a chance of cold snaps in early May, so some seeds are still better sown in pots or modules indoors and placed in a greenhouse or on a sunny windowsill to germinate and grow on until June. For seeds sown directly outdoors, prepare the ground first by digging it over, clearing weeds and stones, and raking it smooth. To harden off tender seedlings before planting them out, place them outdoors during the day and move them back inside at night. Do this for between 7-10 days before planting out. Sow indoors: Sweetcorn Courgettes Squash Pumpkins Lettuce Cucumbers Runner and French beans Kale Sow outdoors: Beetroot Broccoli Brussels sprouts Carrots Parsnips Radishes Swiss chard Swede Turnips Plant out: Leeks Tomatoes in greenhouses What vegetables to harvest in May May is a great time in your vegetable garden. You’ll really start to see all the hard work paying off, with the following vegetables ready to harvest in May. Asparagus Salad leaves Garlic Spring cabbage Artichokes Vegetable plant maintenance in May Transplant Brussels sprouts plants to their final cropping positions. As the weather warms up, weeds start growing and garden pests like slugs and snails become more active. Watch out for early signs of pests and disease and tackle them before they get out of hand. Remember that insects such as ladybirds help to tackle garden pests, so use pesticides with caution to avoid harming beneficial wildlife. Potatoes - earth up potatoes, drawing soil up around the lower part of the plant to exclude light from the developing tubers, which become green and poisonous if exposed to light. Tomatoes - start hardening off tomato seedlings for planting outdoors in June. Broad beans - pinch out the tips of broad bean plants once beans start to appear, to reduce the risk of blackfly. Weed beds regularly. Put up supports for climbing beans and pea plants.