The germination window printed on a seed packet is almost always a range, not a fixed number of days, and there's a good reason for that. The same seed can sprout in half the time in warm, evenly moist starting mix compared with cold, unevenly watered soil on a chilly windowsill. The chart below gives you a realistic benchmark for 40 common vegetables, herbs and flowers, so you know roughly when to start watching closely — and when to simply be patient.
Beyond the chart, this guide covers what actually controls germination speed, which seeds sprout fastest and slowest, and exactly what to do when nothing has happened after the "expected" number of days has come and gone.
Quick facts on seed germination
| Key figure | Value |
|---|---|
| Fastest in this chart | Radish and turnip, often 3–7 days |
| Slowest in this chart | Parsley and parsnip, often 14–28 days |
| Typical for most vegetables | 5–14 days at the right soil temperature |
| Single biggest factor | Soil temperature, not air temperature |
| Second biggest factor | Even moisture — never bone-dry, never waterlogged |
| Seeds that need light to germinate | Lettuce and celery among others — don't bury them |
| When to suspect a real problem | Once double the stated maximum has passed with no sprouts |
Contents
- What actually affects germination time?
- Germination time chart for 40 common seeds
- Which seeds germinate fastest?
- Which seeds take the longest to germinate?
- How to help your seeds sprout faster and more evenly
- Timing sowing by USDA zone
- How to test viability on old or suspect seed
- What to do when seeds haven't come up on schedule
- Common mistakes
- Frequently asked questions
What actually affects germination time?
The germination window on a seed packet is measured under fairly controlled conditions: steady warmth, even moisture and fresh seed. In an actual home or garden bed, rarely are all three ideal at once, which is why real-world results often land at the slow end of the range, or slip past it.
Soil temperature is the single biggest factor, and it isn't the same as room temperature. Potting mix in a container on a cool windowsill can sit several degrees colder than the room around it, especially overnight. Heat-loving seeds like chili peppers and eggplant can simply sit still for weeks in soil that's too cold, without being dead — they're waiting for conditions to catch up.
Even moisture comes second. A seed that has just begun to germinate has no reserves to fall back on if the surface dries out, and a sprout that dries out once rarely recovers. Waterlogged, oxygen-starved soil suffocates a seed just as effectively as drought does — both extremes stall or stop germination.
Seed age matters too. Older seed tends to germinate more slowly and less evenly than fresh seed, even under perfect conditions, because viability drops gradually for most species over time. For a broader look at how long different seeds stay viable in storage, see our guide on how long seeds last.
Good to know. Seeds with a hard coat — peas, beans and parsnip among them — often sprout faster and more evenly after a few hours soaking in room-temperature water before sowing. Don't soak longer than about 24 hours, or the seed risks rotting before it ever reaches soil.
Germination time chart for 40 common seeds
The figures below are approximate benchmarks at the recommended soil temperature, compiled from multiple growing sources. Expect the slower end of the range if your soil sits toward the bottom of the temperature window, and always check your own seed packet — germination time can vary somewhat between varieties of the same species.
| Seed | Germination time | Ideal soil temperature | Sowing depth |
|---|---|---|---|
| Tomato | 5–10 days | 20–29°C (68–84°F) | 0.5–1 cm (1/4 in) |
| Chili pepper | 10–21 days | 24–32°C (75–90°F) | 0.5–1 cm (1/4 in) |
| Bell pepper | 10–21 days | 24–29°C (75–84°F) | 0.5–1 cm (1/4 in) |
| Eggplant | 7–21 days | 24–32°C (75–90°F) | 0.5–1 cm (1/4 in) |
| Cucumber | 5–10 days | 21–29°C (70–84°F) | 1–2 cm (1/2 in) |
| Courgette / zucchini | 5–10 days | 21–32°C (70–90°F) | 2 cm (3/4 in) |
| Pumpkin | 6–10 days | 21–32°C (70–90°F) | 2–3 cm (1 in) |
| Melon | 5–12 days | 24–32°C (75–90°F) | 1–2 cm (1/2 in) |
| Carrot | 14–21 days | 18–24°C (64–75°F) | 1–2 cm (1/2 in) |
| Parsnip | 15–28 days | 16–21°C (60–70°F) | 1–2 cm (1/2 in) |
| Radish | 3–7 days | 10–29°C (50–84°F) | 1–2 cm (1/2 in) |
| Beetroot | 7–14 days | 16–29°C (60–84°F) | 2 cm (3/4 in) |
| Turnip | 4–7 days | 16–29°C (60–84°F) | 1–2 cm (1/2 in) |
| Lettuce | 4–10 days | 15–22°C (59–72°F) | 0.5–1 cm, sow shallow |
| Spinach | 7–14 days | 7–24°C (45–75°F) | 1–2 cm (1/2 in) |
| Swiss chard | 7–14 days | 18–29°C (64–84°F) | 2 cm (3/4 in) |
| Kale | 5–10 days | 18–24°C (64–75°F) | 1 cm (1/2 in) |
| Broccoli | 5–10 days | 18–29°C (64–84°F) | 1 cm (1/2 in) |
| Cabbage | 5–10 days | 18–29°C (64–84°F) | 1 cm (1/2 in) |
| Cauliflower | 5–10 days | 18–29°C (64–84°F) | 1 cm (1/2 in) |
| Leek | 10–18 days | 18–29°C (64–84°F) | 1 cm (1/2 in) |
| Onion, from seed | 7–14 days | 18–29°C (64–84°F) | 1 cm (1/2 in) |
| Sweet corn | 6–10 days | 18–35°C (64–95°F) | 3–4 cm (1.5 in) |
| Peas | 7–14 days | 5–18°C (41–64°F) | 3–4 cm (1.5 in) |
| Fava / broad beans | 7–14 days | 5–20°C (41–68°F) | 3–4 cm (1.5 in) |
| Bush beans | 6–14 days | 18–29°C (64–84°F) | 3–4 cm (1.5 in) |
| Snap peas | 7–14 days | 5–18°C (41–64°F) | 3 cm (1 in) |
| Celery | 14–21 days | 18–24°C (64–75°F) | Surface-sown, needs light |
| Dill | 14–21 days | 15–21°C (59–70°F) | 1 cm (1/2 in) |
| Parsley | 14–28 days | 18–24°C (64–75°F) | 1 cm (1/2 in) |
| Basil | 5–10 days | 21–29°C (70–84°F) | 0.5 cm (1/4 in) |
| Cilantro / coriander | 7–14 days | 10–29°C (50–84°F) | 1 cm (1/2 in) |
| Thyme | 14–21 days | 18–21°C (64–70°F) | 0.3–0.5 cm, barely covered |
| Rosemary | 14–30 days, often uneven | 15–18°C (59–64°F) | 0.3–0.5 cm, barely covered |
| Oregano | 7–14 days | 20–30°C (68–86°F) | Surface-sown, needs light |
| Chives | 14–20 days | 15–20°C (59–68°F) | 0.5 cm (1/4 in) |
| Marigold | 5–14 days | 21–24°C (70–75°F) | 1 cm (1/2 in) |
| Zinnia | 5–10 days | 24–27°C (75–80°F) | 1 cm (1/2 in) |
| Sunflower | 7–10 days | 18–27°C (64–80°F) | 1–2 cm (1/2 in) |
| Cosmos | 7–14 days | 20–24°C (68–75°F) | 0.5–1 cm (1/4 in) |
Once you're past germination and ready to plan backward from your last frost date for the whole season, our guide to starting seeds indoors covers weeks-before-transplant timing for two dozen crops.
Which seeds germinate fastest?
Radish and turnip lead the pack and can show their first sprouts after just three days in warm soil, which makes them a satisfying choice if you want quick results with kids or you're simply testing out a new bed. Lettuce, cucumber, zucchini, tomato, basil and most brassicas follow closely at 5–10 days under decent conditions.
What the fastest seeds tend to share is a relatively large size, a thin seed coat, and origins in climates where quick germination was a genuine survival advantage. That combination also tends to make them more forgiving of imperfect conditions than the slow growers.
Which seeds take the longest to germinate?
Parsley and parsnip are famous among gardeners for being notoriously slow and sometimes uneven, taking up to four weeks from sowing to visible sprouts even under good conditions. Rosemary is another classic example — not only slow, but often wildly uneven, with some seeds up after two weeks and others still nothing after a month from the very same batch.
Chili peppers, bell peppers and celery also test your patience, with 2–3 weeks being the norm rather than the exception. That's a big part of why these crops are almost always started indoors well ahead of the outdoor season — they simply need a long head start to reach harvest before the weather turns.
Common mistake. Giving up on parsley, parsnip or rosemary too early and resowing unnecessarily. Wait at least three to four weeks with even moisture and the right temperature before concluding the seed is dead — these species are genuinely slow, not necessarily bad.
How to help your seeds sprout faster and more evenly
- Check soil temperature, not just air temperature. A soil or meat thermometer pushed 2–3 cm (about an inch) into the mix gives a far more accurate reading than trusting the room thermostat.
- Use fresh, pre-moistened seed starting mix. Wet the mix before sowing rather than watering heavily afterward, so the seed makes even contact with moisture from the start.
- Sow at the right depth. A seed sown too deep may lack the energy to reach the surface before its reserves run out. Too shallow, and it dries out faster than a properly buried seed would.
- Keep moisture even, never soaked. A thin layer of plastic wrap or a humidity dome over the tray keeps conditions steady until sprouts appear — remove it the moment the first green tips show.
- Add bottom heat for warmth-loving seeds. A seedling heat mat under the tray can roughly halve germination time for chili peppers, eggplant and bell peppers compared with a cool windowsill.
- Check whether the seed needs light. Lettuce, celery and oregano germinate poorly if buried — press them gently into the surface instead and leave them uncovered.
Good to know. Extra grow-light exposure makes no difference to germination itself for most species, since the seed lives off its own reserves until the first true leaves appear. Light only becomes critical right after sprouting, when it determines whether seedlings stay compact or turn leggy. Our guide to grow lights for seedlings covers that stage in detail.
Timing sowing by USDA zone
The germination times in the chart above don't change based on where you garden, but the right calendar date to start sowing absolutely does. A shorter frost-free season means crops with long germination and long days-to-harvest generally need an earlier indoor head start the colder your zone runs.
Exact last-frost dates shift noticeably from year to year even within the same zone, so treat the table below as a rough starting point rather than a fixed rule, and always work backward from your own area's typical last frost date.
| USDA zone | Typical climate | Reasonable window to start heat-loving seeds indoors |
|---|---|---|
| Zone 3 | Very cold winters, short season | Mid to late April |
| Zone 4 | Cold winters, short-to-moderate season | Early to mid April |
| Zone 5 | Moderate winters, moderate season | Late March to early April |
| Zone 6 | Milder winters, longer season | Mid to late March |
If your garden falls outside zones 3–6, the same backward-planning logic still applies — just shift the window earlier in warmer zones and later in colder ones, based on your own average last frost date. For a full month-by-month rundown, see our seed sowing calendar.
How to test viability on old or suspect seed
If you're not sure whether a leftover packet from last season is still worth planting, a simple viability test is faster and more reliable than guessing. It takes a few minutes to set up and gives you an answer within one to two weeks, depending on the species.
- Dampen a couple of layers of paper towel. It should be thoroughly moist but not dripping — wring out any excess by hand.
- Lay out 10 seeds with even spacing. A round number makes it easy to convert straight into a percentage afterward.
- Fold the paper towel and place it in a plastic bag. Leave the bag loosely closed so a little air gets in while moisture stays trapped.
- Keep it somewhere warm, ideally 20–25°C (68–77°F). On top of the fridge or near a heat source usually works well.
- Check daily and count sprouted seeds. Compare the timing against that species' normal range in the chart above before drawing conclusions.
- Calculate the germination rate. If 7 of 10 sprouted, you're looking at roughly 70 percent viability — sow more thickly than usual if you decide to use the rest of the packet.
A germination rate under about 50 percent usually means it's time to buy fresh seed rather than trust the old packet, especially for crops that are expensive or awkward to resow late in the season.
What to do when seeds haven't come up on schedule
| Situation | Likely cause | Fix |
|---|---|---|
| Nothing at all after double the maximum time | Soil too cold, seed too old, or seed rotted in soil that was too wet | Check soil temperature, carefully dig up one seed to see if it's firm or soft and rotten, test fresh seed viability in damp paper towel |
| A few sprouts but very patchy | Uneven sowing depth or uneven moisture at sowing | Resow with consistent depth, water gently and regularly until sprouts appear |
| Seedlings collapsed right at the soil line | Damping off from soil that's too wet and poor air circulation | Cut back on watering, improve airflow, avoid sowing too thickly |
| Same variety germinated fine last year but not this year | Seed has aged past its reliable window, or storage conditions were poor | Run a viability test on a sample before sowing the rest of the packet |
| Some seeds in the same batch sprouted, others haven't | Natural variation, especially in slow or uneven species like rosemary and parsley | Wait another one to two weeks before writing off the rest of the batch |
Common mistakes
- Giving up too soon. Many slow seeds like parsnip and parsley are still perfectly normal at three weeks, even when other crops sown the same day are already up.
- Trusting air temperature instead of soil temperature. A cool windowsill can leave the soil several degrees colder than the room, especially overnight.
- Burying light-dependent seeds. Lettuce, celery and oregano germinate poorly or not at all if buried instead of gently pressed into the surface.
- Watering too rarely but too heavily. Germinating seeds want steady moisture throughout, not swings between bone-dry and soaked.
- Sowing old seed without testing it first. A simple paper-towel viability test takes a few days and saves you the disappointment of an empty tray weeks later.
- Confusing germination time with time to harvest. Germination is only the starting line — carrots sprout in 2–3 weeks but then need several more months before they're ready to pick.
Frequently asked questions
Why are my seeds taking longer to germinate than the packet says?
Most often the soil is cooler than the ideal temperature in the chart, even if the room feels comfortable. Other common causes include uneven moisture, seed that's simply too old, or seed sown a bit deeper than it can handle.
Does using grow lights make seeds germinate faster?
No, not for germination itself. The seed lives off its own stored reserves until the first true leaves appear, and light doesn't affect that process for most species. Light becomes important immediately after germination, to keep seedlings from stretching and turning leggy.
Can I speed up germination by soaking seeds first?
Yes, for hard-coated seeds like peas, beans and parsnip, a few hours of soaking in room-temperature water can noticeably shorten germination time. Don't soak longer than about 24 hours, or the seed risks rotting before it ever reaches soil.
How do I know if a seed is dead versus just slow?
Wait at least double the upper end of the range in the chart before assuming a seed is dead, especially for notoriously slow species like parsley and rosemary. If you're still unsure, carefully dig one up — a healthy seed usually feels firm, while a rotten one is soft or discolored.
Do all the seeds in one packet germinate on exactly the same day?
No, and that's completely normal. Natural variation in seed size, maturity and position in the soil spreads germination out over several days or sometimes weeks within the same sowing, especially for uneven species like rosemary.
Do older seeds germinate more slowly than fresh ones?
Often, yes. Viability declines gradually with age for most species, which can show up as both slower germination and a lower percentage of seeds sprouting at all. Our guide on how long seeds last covers roughly how long different types stay viable in storage.
Does germination time differ between containers and garden beds?
The baseline times in the chart apply either way, but potting mix in a container heats up and cools down faster than open garden soil, which can make germination either quicker or more erratic depending on where the container sits. For sowing straight into the ground, our guide to direct sowing outdoors covers the practical details.
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