These dates are distilled from 35 of years trial and error in my gardens, where my results have served to highlight best timings for best results.
You can sow these seeds at different times and they will grow, but the outcomes will be different, such as lower yield, more pest and disease, perhaps a tendency to flower rather than leaf. Hence for example I do not recommend sowing salad rocket and mizuna in the spring because it’s their flowering season, although many gardeners do and are happy with the smaller yield and insect-damaged leaves, compared with healthier leaves and more weeks, even months of picking, from August sowings.
Dates are based on the climate of Somerset in south west UK, USDA zone 8-9, last frost mid May and first frost mid October.
Best start date is Valentines Day
Sow undercover broad beans, spinach, lettuce, peas for shoots, onion, salad onion, early brassicas (cabbage, calabrese, kohlrabi, cauliflower), radish, parsley, coriander, dill. With warmth aubergine, pepper, chilli – sow these by early March
Sow outside broad beans, garlic if not already
Sow undercover as for February plus peas, Boltardy beetroot, celery & celeriac mid month. With warmth tomatoes – sow before mid month for undercover cropping, melon at month’s end
Sow outside broad beans, garlic if not already, and after mid month sow lettuce, spinach, peas, onion, salad onion, early brassicas, parsley, coriander, dill, parsnips, first early potato late March.
Sow undercover as for March (except its getting late for celeriac, sow asap), leeks, leaf beet, beetroot (all varieties), chard at month’s end, tomatoes for outdoor growing. With warmth and around mid month, cucumber, courgette, squash, sweetcorn
Sow outside all potatoes, broad beans, lettuce, spinach, peas, salad onion, early and autumn brassicas, parsley, leeks, leaf beet, carrots
Sow undercover Courgette, French and climbing beans, leaf beet, beetroot, chard, lettuce, winter brassicas, salad onion. Plus leeks and winter squash by early May.
Swede at end May
Sow outside same as undercover, also maincrop potatoes in early May, carrots, parsnips but keep seedbed moist until germinated.
Sow undercover beetroot, swede, lettuce, leaf beet, chard, kale, purple sprouting broccoli, cauliflower for both autumn & spring, calabrese for autumn harvests.
After solstice sow endive, chicory, kohlrabi and Florence fennel.
Sow outside same as undercover, also carrots.
Sow undercover Kohlrabi, lettuce, leaf beet, chard, endive, chicory, Florence fennel, chervil, coriander. Plus beetroot and savoy cabbage in first week.
After mid month, land cress, wild rocket, Chinese cabbage and spinach.
At month’s end, mustards, pak choi, salad rocket – though first week August is often better.
Sow outside same as undercover, and carrots until mid July.
Sow undercover endive and Florence fennel until 10th, lettuce (late August sowings to overwinter as small plants), claytonia, oriental leaves, salad rocket,
- chervil – coriander – dill – land cress – wild rocket -spinach by mid August for autumn cropping,
- any salads in mid August for planting September and to grow under a cloche,
- spinach – spring onion – spring cabbage late August for overwintering small.
Sow outside same as undercover but approximately a week earlier
- For outdoor planting to crop in autumn/winter lambs lettuce, mizuna, salad rocket,
- For outdoor planting to overwinter small, in early September sow lettuce, spinach, chervil, coriander, dill.
- For undercover planting sow in early to mid September all salads (includes spinach, chard mustards, kale etc which you can grow large for cooking), spring onion.
Sow outside same as undercover but a week earlier, last salad sowings by 10th September.
Outside sow garlic. You can also sow onion sets though I recommend caution with these as they risk harbouring mildew over winter which infects onions in May and thus reduces growth/storage potential of spring-sown onions. Spring onions sown in August, White Lisbon type, seem less prone to this.
Depending where you live, from early November its worth sowing broad beans to overwinter as small plants, such as Aquadulce Claudia and Monica; sowing in December is possible too, both undercover (unheated) and outside, likewise for garlic.