What vegetables to sow, where and when
If you’re new to gardening, two of the most important things to learn about are sowing vegetables and crop rotation. When, how, where and at what temperature is vital for successful seed germination.
Crop rotation simply means NOT growing certain types of vegetables in the same place year after year. This prevents the build-up of pests and diseases.
As the season warms up, it becomes possible to direct sow more and more vegetables. Even tender things like French and runner beans are OK to sow outside once the frosts have finished, if they’re in a warm position with rich, well-drained soil, although you may have a much shorter cropping season.
Too much heat can be a problem for some crops like lettuce – they appreciate a bit of shade in high summer or they’ll fail to germinate.
Successional sowing is the key to getting the most out of your plot. Fill any gaps with quick-growing salad crops.
Potted guide: sowing vegetables
Here’s a quick guide: what vegetable, when to sow, germination temperature, sowing depth, days to germination and any special instructions.
- BRUSSELS SPROUTS: February indoors; March-April outdoors; 15C; 6mm; 7 days; once germinated, grow on in cooler conditions.
- CARROT: January-February under glass; May-July and October outdoors; 15-21C; 1cm; 10-20 days; for early crops sow under glass in borders/pots; sow thinly; don’t transplant.
- CAULIFLOWER: January-February, March-June & October (depending on type); 21C; 1cm; 4-7 days; sow outdoors direct April-June.
- CHILLI: February-April; 18-25C; Cover with a sprinkling of compost; 7-10 days; do not exclude light.
- LETTUCE: November-March indoors; March-October outdoors; 7-24C; cover; 7-14 days; sow out of direct sunlight in midsummer.
- LEEK: January-April; 10-15C; 1cm; 14-21 days; direct sow outdoors late March-April.
- PARSNIP: March-May; min 12C; 2cm; up to 28 days; avoid heavy, stony soils.
- PEA: February-July; 15-20C; 4cm; 7-14 days; sow indoors February to crop under glass; sow in lengths of gutter indoors if mice are a problem.
- PEPPER: February-April; 18-21C; cover with a sprinkling of compost; 7-10 days; do not exclude light.
- SPINACH: January-September; 15-18C; 1cm; 7-14 days; high temperatures deter germination; sow every 10 days for season-long crops; buy new seed each year.
- TURNIP: February-April; as low as 5-20C; 1cm; 1-7 days; sow under cloches outdoors for earlier crops.
Rotating your crops
Growing the same crops in the same soil year after year is a recipe for disaster. Crop rotation is vital to the success of your plants and the health of your soil, so it’s used for most annual vegetable crops. Perennials (rhubarb and asparagus) aren’t included.
Some annual crops – courgettes, pumpkins, squashes, marrows, cucumbers, French and runner beans, salads and sweetcorn can be grown wherever there’s a space, but avoid growing them too often in the same place.
Plan your rotation before the growing season starts. This diagram is for three beds, but you can work on a four-year cycle if you have the room, giving legumes (peas and beans) a section to themselves.
So why do crop rotation? Changing crops annually reduces soil deficiencies; potatoes and squashes suppress weeds; pests and diseases tend to attack specific plant families, so decline when their host plants aren’t there.
Divide your land into sections of equal size, plus an extra section for perennial crops. Group crops as below:
- BRASSICAS: Brussels sprouts, cabbage, cauliflower, kale, broccoli, kohl-rabi, oriental greens, radish, swede, and turnips.
- LEGUMES: pea, broad beans (French and runner beans can be grown wherever convenient).
- ALLIUMS: onion, garlic, shallot, leek.
- POTATO FAMILY: Potato, tomato (peppers and aubergines can be grown anywhere in the rotation).
- ROOTS: beetroot, carrot, celeriac, celery, Florence fennel, parsley, parsnip and all other root crops (not swedes and turnips).
Move the crop in each bed a step forward every year so that, for example, brassicas follow legumes, onions, and roots; legumes, onions and roots follow potatoes and potatoes follow brassicas. The diagram is for a traditional three-year plan.
Sowing vegetables and crop rotation updated July 2022
