Transplanting

Transplanting is the moment a plant you have nurtured under cover finally moves out to where it will live and crop. You raise seedlings indoors, in a greenhouse or on a windowsill to give them a head start, then shift them into a bed, border or large pot once the weather and the plant are ready. It is one of the most common jobs of the growing year, and getting it right makes the difference between a seedling that romps away and one that sulks for weeks.

Harden off first

Never move a plant straight from a warm windowsill into the open ground. A pampered seedling will be shocked by wind, cold nights and stronger light, and can be set back badly or killed outright. Always harden off first: over a week to ten days, stand the plants outside for longer each day, bringing them in at night to begin with, so they toughen up gradually. A cold frame makes this far easier.

Timing in the UK

Most tender crops, such as courgettes, tomatoes and runner beans, should only go out once the risk of frost has passed. Across much of the UK that means mid to late May, though in a cold spring or in the north it is worth holding off until early June. Wait for the soil to warm too, not just the air. Hardier plants like brassicas and leeks can be transplanted earlier in spring.

Firming in and watering

Water the plants well an hour or so before you move them, so the rootball holds together and slides out cleanly. Make a hole a little larger than the rootball, settle the plant in at the same depth it was growing before (tomatoes are the exception, as they root from a buried stem), then firm the soil gently around it with your hands. Firming removes air pockets and steadies the plant so the roots make good contact with the soil. Finish with a generous watering to settle everything in, and keep the new transplants watered for the first couple of weeks while they root out.

Crops that dislike being moved

Not everything enjoys the upheaval. Carrots and parsnips form a single long taproot, and disturbing it causes the roots to fork, split or stall. These are best sown straight into the ground where they are to grow, a method called direct sowing. The same goes for other taprooted crops such as swede and turnips, and for anything sown thickly that needs pricking out only into modules rather than bare-root. When in doubt, a plant grown in its own module or pot transplants far better than one lifted bare-root from a seed tray.