Lavender is the plant that makes a garden smell like a holiday: grey-green mounds topped with purple spikes that hum with bees all summer. Growing it from seed is the cheapest way to fill a border or a row of pots, and it is also the slowest — lavender seed is famously unhurried, and the seedlings are tiny and delicate for their first month.
That slow start is exactly why indoor sowing pays off. Seed sown outdoors often dries out or gets swamped by weeds before it ever germinates, while a tray on a bright windowsill gives you control over moisture, light and temperature. This guide walks through the whole process: when to sow, the light the seeds need to germinate, how to keep the seedlings alive through their fragile early weeks, and how to move them outside without losing them. Lavender is a start-indoors crop — its sowing method is "start indoors" — so the steps below are the standard route, not a workaround. A tray indoors gives you control over warmth, moisture and light that outdoor sowing cannot match. This crop is in the Lamiaceae family, needs full sun, and takes 90–120 days to reach maturity, so the timing below is built around those facts, not guesswork.
Lavender at a glance
| Growing factor | What lavender need |
|---|---|
| Days to germination | 14–28 |
| Sowing method | start indoors |
| Days to maturity | 90–120 |
| Soil pH | 6.5–7.5 |
| Spacing | 18–24 inches |
| Sun | full sun |
| Cold tolerance | hardy |
When to start lavender seeds indoors
Lavender is slow, so start early. In Zones 3–5, sow indoors 10–12 weeks before your last frost so the seedlings are big enough to plant out in late spring. In Zones 6–8, 8–10 weeks before last frost is enough. In Zones 9–10 you can start in late winter and plant out as soon as frost danger passes, and in frost-free Zones 11–13 sow any time the weather is mild — there the calendar is about heat and rain rather than frost. Check your local extension service for the last-frost date in your area, or use our frost-date calculator and seed-starting calculator to work backwards from it.
As a rule, work backwards from your last frost: sow indoors 10–12 weeks before it if you are starting indoors at all, and check the seed packet against the germination time of 14–28 days. Our seed-starting calculator does the backwards maths for you, and the germination-time calculator helps you plan around that 14–28-day window. If you are unsure of your zone, the hardiness-zone finder will confirm it.
What you need
a seed tray or small pots with drainage holes, fine seed-starting mix (not heavy potting soil), a clear lid or cling film, a spray bottle, a grow light or the brightest windowsill you have, small labels, and a weak liquid feed for later. Lavender hates wet feet, so a free-draining, gritty mix matters more than a rich one — stir a little perlite or fine grit into the mix if it feels heavy.
You will also want a spray bottle or a watering can with a fine rose, and a notebook to record the sowing date — germination takes 14–28 days, and it is easy to forget when you sowed.
Step by step: starting lavender seeds indoors
- Fill your containers. Fill trays or pots with fresh, damp seed-starting mix — not garden soil, which is too heavy and can carry disease. Press it down lightly and level the surface.
- Sow the seed. Lavender seed needs light to germinate, so sow on the surface of the mix and press the seeds in gently rather than burying them. Cover the tray with a clear lid or plastic to hold humidity, and keep it at ordinary room temperature. Germination takes 14–28 days, and it is uneven — some seeds pop in two weeks, others take four, so do not throw a tray away too soon.
- Cover and label. Cover the tray with a clear lid or cling film to hold humidity, and label it with the crop and the date. Put it somewhere warm and bright, out of direct sun until seeds sprout.
- Wait for germination. Germination takes 14–28 days. Check the tray daily, mist the surface if it dries, and be patient — uneven germination is normal, especially for slow crops. Our germination-time calculator helps you track the window.
- Remove the cover. As soon as seedlings emerge, take the lid off. Good airflow from this point on is what prevents damping off.
- Give them light. Move the tray under a grow light or to your brightest window immediately — seedlings stretch within a day or two if the light is weak.
- Thin and pot on. Thin to one seedling per cell once they have two true leaves, snipping the extras rather than pulling them. Pot on into larger pots when roots show at the drainage holes, keeping the seedlings at the same depth.
- Feed lightly. Once seedlings have two sets of true leaves, feed with a half-strength liquid feed every week or two. Do not overfeed — soft, overfed seedlings are more likely to damp off and less likely to harden well.
Light for seedlings
Lavender seedlings stretch fast in dim light, and a stretched seedling rarely recovers into a sturdy plant. Give them 14–16 hours of bright light a day from the moment they emerge, with the light just a few inches above the leaves. A sunny windowsill can work in spring, but a simple LED grow light is more reliable — our grow-light calculator helps you work out how much light your setup gives. Turn the tray daily if you use a window so the stems grow straight.
Watering seedlings
Lavender is a Mediterranean plant with low water needs, and its seedlings are no exception. Keep the mix just damp, never soggy: water from below by standing the tray in a shallow dish for a few minutes, then let it drain fully. Overwatering is the quickest way to kill lavender seedlings — damping off turns the stems brown and pinched at soil level, and there is no rescue once it starts. Let the surface dry slightly between waterings. Our watering calculator can help you work out how much water your seedlings need as they grow.
Hardening off
Lavender is hardy once established, but a seedling raised indoors is still soft. Harden off over 7–10 days: put the plants outside in a sheltered, shaded spot for a few hours on day one, lengthening the time and the sun exposure each day, and bring them in at night. By the end of the week they should be spending full days outdoors and coping with a breeze, which thickens their stems.
Transplanting outdoors
Move seedlings out after your last frost, when the soil has begun to warm. Lavender needs full sun and sharp drainage — a raised bed, a sunny slope or a pot with gritty mix all suit it. Space plants 18–24 inches apart so air moves freely around them; crowded, damp lavender is prone to rot. Our plant-spacing calculator works out how many plants fit your bed. Plant at the same depth as in the pot, water in once, then leave them alone — they prefer neglect to fussing. For the full picture — soil, feeding, pests and harvest — see our complete growing lavender guide.
Common problems and fixes
| Problem | Fix |
|---|---|
| Seeds do not germinate | Lavender seed can take 14–28 days and germinates unevenly. Check the seeds are on the surface, not buried, and that the mix stays damp but not wet. Old seed is a common cause — test a batch with our seed-viability checker before sowing the whole packet. |
| Leggy, pale seedlings | Not enough light. Move the grow light closer — a few inches above the leaves — and give 14–16 hours a day. A fan on its lowest setting a few feet away also helps stems thicken. |
| Damping off | Stems collapse at soil level. The mix was too wet or air circulation was poor. Sow thinner, water from below, remove the lid once seeds sprout, and always use fresh seed-starting mix. |
| Seedlings stall and stay tiny | Lavender grows slowly for the first month — that is normal. Keep them warm and bright, feed very lightly once they have two sets of true leaves, and pot on into slightly larger pots if roots show at the drainage holes. |
Seeds do not germinate
Lavender seed can take 14–28 days and germinates unevenly. Check the seeds are on the surface, not buried, and that the mix stays damp but not wet. Old seed is a common cause — test a batch with our seed-viability checker before sowing the whole packet.
Leggy, pale seedlings
Not enough light. Move the grow light closer — a few inches above the leaves — and give 14–16 hours a day. A fan on its lowest setting a few feet away also helps stems thicken.
Damping off
Stems collapse at soil level. The mix was too wet or air circulation was poor. Sow thinner, water from below, remove the lid once seeds sprout, and always use fresh seed-starting mix.
Good companions for lavender include tomatoes, peppers, marigolds, cabbage. Watch out for aphids, spider mites, whiteflies — check young plants regularly, and deal with pests early while plants are small. Our pest-identifier helper can help you work out what you are looking at.
Frequently asked questions
How long do lavender seeds take to germinate?
14–28 days, and germination is uneven. Some seeds sprout in two weeks and others take four, so keep the tray damp and lit for a full month before deciding a batch has failed.
Do lavender seeds need light to germinate?
Yes. Sow them on the surface of the mix and press them in gently. Burying them is the most common reason a tray never sprouts.
Can I grow lavender from seed in a pot?
Yes — lavender does well in pots with gritty, free-draining mix. One plant per 10–12 inch pot works well, and pots are a good choice if your garden soil is heavy or wet.
Why are my lavender seedlings so slow?
Lavender is a slow grower for the first 6–8 weeks. Small, steady growth is normal; what matters is that the stems stay green and upright and the leaves stay grey-green, not yellow.
When can I plant lavender seedlings outside?
After your last frost, once seedlings have several sets of true leaves and have been hardened off for a week. They need full sun and soil that drains freely.