The seed-starting master chart
Most sowing failures come down to two things: soil that is too cold, and seed planted too deep. For 31 vegetables this chart gives the soil temperature at which seed starts to germinate, the best temperature and the upper limit, the days to sprout at that best temperature, the sowing depth and how many years seed keeps - each from a university extension table named under the chart. Herbs and flowers are not in those tables, so their rows show a dash. New to raising your own? Work through the Seed Starting Masterclass alongside it.
| Crop | Germinates from | Best soil temp | Up to | Days to sprout at best temp | Sowing depth | Seed keeps | Repeat sowings |
|---|---|---|---|---|---|---|---|
| Aubergine | 60°F | 85°F | 95°F | 6-8 | - | 4 yrs | one sowing |
| Basil | - | - | - | - | - | - | one sowing |
| Beetroot | 40°F | 85°F | 95°F | 5 | 1/2" | 4 yrs | yes |
| Broccoli | 40°F | 85°F | 95°F | 5 | 1/4-1/2" | 3 yrs | one sowing |
| Brussels sprouts | - | 80°F | - | 5 | - | 4 yrs | one sowing |
| Bush beans | 60°F | 80°F | 95°F | 6 | 1" | 3 yrs | yes |
| Cabbage | 40°F | 85°F | 95°F | 4 | 1/4-1/2" | 4 yrs | one sowing |
| Carrot | 40°F | 80°F | 95°F | 5 | 1/4-1/2" | 3 yrs | yes |
| Cauliflower | 40°F | 80°F | 95°F | 5 | 1/4-1/2" | 4 yrs | one sowing |
| Celery | 40°F | 70°F | 85°F | 7 | - | 3 yrs | one sowing |
| Coriander / cilantro | - | - | - | - | - | - | yes |
| Courgette & squash | 65°F | 95°F | 105°F | 4 | 1" | 4 yrs | one sowing |
| Cucumber | 60°F | 95°F | 105°F | 2-5 | 1" | 5 yrs | one sowing |
| Dill | - | - | - | - | - | - | yes |
| Fennel | - | - | - | - | - | - | one sowing |
| Kale | - | 80°F | - | 4 | 1/4-1/2" | 4 yrs | yes |
| Kohlrabi | - | 80°F | - | 4 | 1/4-1/2" | 3 yrs | yes |
| Leek | - | 70°F | - | 7 | - | 6 yrs | one sowing |
| Lettuce | 35°F | 75°F | 75°F | 2-3 | 1/4" | 5 yrs | yes |
| Marigold | - | - | - | - | - | - | one sowing |
| Melon | 65°F | 95°F | 105°F | 3-4 | 1" | 5 yrs | one sowing |
| Nasturtium | - | - | - | - | - | - | one sowing |
| Okra | 60°F | 95°F | 105°F | 6 | 1" | 2 yrs | one sowing |
| Onion (from seed) | 32°F | 80°F | 95°F | 4-5 | - | 1 yr | one sowing |
| Pak choi | - | 80°F | - | 4 | 1/4-1/2" | 3 yrs | yes |
| Parsley | 40°F | 75°F | 90°F | 13 | 1/4" | 1 yr | one sowing |
| Parsnip | 35°F | 65°F | 85°F | 14 | - | 1 yr | one sowing |
| Peas | 40°F | 75°F | 85°F | 6 | 1-2" | 3 yrs | yes |
| Pepper & chilli | 60°F | 85°F | 95°F | 8 | - | 2 yrs | one sowing |
| Pole / runner beans | 60°F | 80°F | 95°F | 6 | 1" | 3 yrs | one sowing |
| Pumpkin | 65°F | 90°F | 105°F | 4 | 1-2" | 4 yrs | one sowing |
| Radish | 40°F | 80°F | 95°F | 4 | 1/2" | 5 yrs | yes |
| Rocket / arugula | - | - | - | - | - | - | yes |
| Spinach | 32°F | 70°F | 75°F | 5 | 1/2" | 3 yrs | yes |
| Spring onion | - | - | - | - | - | - | yes |
| Sunflower | - | - | - | - | - | - | one sowing |
| Sweet pea | - | - | - | - | - | - | one sowing |
| Sweetcorn | 50°F | 85°F | 105°F | 3 | 1-2" | 2 yrs | yes |
| Swiss chard | 40°F | 85°F | 95°F | 4 | 1/4-1/2" | 4 yrs | yes |
| Tomato | 50°F | 80°F | 95°F | 6 | - | 3 yrs | one sowing |
| Turnip | 40°F | 80°F | 105°F | 3 | 1/4-1/2" | 4 yrs | yes |
No crop matches that.
Temperatures are the soil the seed sits in, not the air, so a cold spring bed can lag weeks behind a warm windowsill or heat mat. Sow small seed shallow, big seed deeper, and keep everything evenly moist until it is up. Turn these numbers into dates with the frost-date sowing calendar, keep the salad coming with the succession planting calculator, and see what to sow now with what to sow this month.
Sources. Soil temperatures (minimum, optimum, maximum) and days to sprout under optimum temperature and moisture: University of Nebraska-Lincoln Extension, Vegetable Garden Seed Storage and Germination Requirements (G2090, 2011), Table II. Seed life for seed stored cool and dry: the same publication, Table I. Sowing depth: Mississippi State University Extension, Planting Guide; crops that guide sets out as transplants (tomato, pepper, aubergine, onion) have no depth there. A dash means the source has no figure for that crop. Days to sprout are for ideal conditions; a cool spring bed takes longer.
For the seed chart
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