Can You Sow Foxgloves in September? What to Expect from a Late Sowing

Every August the same question arrives: is it too late to sow foxgloves? The short answer is no — you can still sow foxgloves in September, and in most gardens they will do perfectly well. But a September sowing plays by different rules from a June one, and whether you see flower spikes next summer or the summer after comes down to one thing: how big the plants are when winter arrives. Here is exactly what to expect from a late sowing, how to give it the best chance, and what to do instead if you would rather not gamble.

• Last call mid-September (mild areas), early September (cold)
• Germination 10–21 days at 15–20 °C, in light
• Flowers next June if rosettes reach hand-size by November
• Smaller plants simply flower a year later — nothing is lost

The short answer: yes — but the clock is ticking

Foxgloves (Digitalis purpurea) are biennials: they grow a leafy rosette in year one, sit through a winter, then flower in year two. The textbook sowing window runs from June to August, which is why our step-by-step biennials guide calls midsummer the sweet spot — sown then, plants have a whole warm season to bulk up. September sits right on the edge of that window, not beyond it. Seed germinates quickly in late-summer warmth, and the species is bone-hardy, so a September sowing is never wasted. The only open question is the timetable.

What decides that timetable is size. A foxglove must bank enough leaf area before winter to fund a flower spike the following June. Miss the target and the plant does not sulk or die — it simply spends next season growing and saves the show for the year after. If you are new to the plant, our full foxglove growing guide covers the whole life cycle.

The hand-size rule

Here is the honest benchmark we use on the nursery: a rosette roughly the size of your spread hand — 12–15 cm across, six to eight true leaves — by mid-November will almost always throw a proper spike next summer. Anything smaller overwinters happily (established rosettes shrug off −15 °C) but usually waits a year to flower.

Nature, incidentally, sows foxgloves in September all the time. Wild plants shed ripe seed from July onwards and it germinates within weeks, which is why you find carpets of self-sown seedlings under every established clump. If you are collecting seed from your own plants right now — and you should, one spike carries tens of thousands — our new seed saving guide shows how to gather and clean it; sow a pinch fresh today and save the rest for June.

How to sow foxgloves in September, step by step

In September, every day counts — so the method changes. Skip direct sowing and give the seedlings shelter and speed instead:

1. Sow in modules under cover, not direct A cold greenhouse, cold frame or bright windowsill gains you two to three precious weeks over open ground — and keeps slugs off the seedlings.
2. Surface-sow — never bury the seed Foxglove seed needs light. Press it onto damp compost, don't cover, and keep it gently moist at 15–20 °C. Expect green fuzz in two to three weeks.
3. Prick out early Move seedlings to individual 9 cm pots the moment they have two true leaves. Late pricking-out is the biggest hidden delay in autumn sowing.
4. Grow on cool and bright No heat, no feed — just light, air and steady moisture. Hard, compact growth overwinters; soft, forced growth rots.
5. Plant out by mid-October — or wait until March Hand-sized plants can go into their flowering spots now, hardened off first. Smaller plants overwinter better in the frame and plant out in early spring.

September sowing vs the classic June sowing

If you are reading this in early summer: sow now and spare yourself the sprint — the whole relaxed method is in our summer biennials guide.

Missed the boat? Three good alternatives

First, cheat the biennial clock altogether: the Dalmatian series flowers in its first year from a February–March sowing under glass, so you can skip winter worries and still have spikes next summer — browse the foxglove seed collection for options. Second, put the energy into what genuinely wants sowing now: violas and pansies for autumn-to-spring colour, plus cornflowers, nigella and the other hardy annuals that thrive from a September sowing — everything in season is gathered in our September sowing collection. Third, simply wait: store your foxglove seed cool and dry, and sow it in June when the odds are all on your side.

Common mistakes with late-sown foxgloves

• Sowing direct in September — open ground is cooling fast and patrolled by slugs. Late sowings belong in modules under cover.
• Covering the seed — foxglove seed is a light germinator. Even a thin layer of compost can halve germination.
• Feeding autumn seedlings — nitrogen now forces soft, sappy leaves that winter wet destroys. Feed in spring instead.
• Planting tiny plugs into the open border in November — small root balls heave out of cold, wet soil. Keep undersized plants in the cold frame until March.
• Expecting a record spike — a September plant that does flower next June often sends up a shorter, leaner spike than a June-sown one. Still lovely; just be honest with yourself.
• Giving up when nothing flowers — an unflowered rosette isn't a failure, it's a deposit. Year-after spikes are routinely the tallest of all.

Frequently asked questions

Will foxgloves sown in September flower next summer?
Sometimes. If the rosette reaches roughly hand-size — 12–15 cm across — by mid-November, expect a spike next June. Smaller plants overwinter fine but usually flower the following summer instead. Sowing under cover and pricking out promptly is what tips the odds.

Can I still sow foxgloves in October?
Realistically, no. Even under glass, October seedlings stay too small to be worth the bench space. Wait and sow the first-year-flowering Dalmatian series in February–March, or the species in June.

Do foxgloves self-seed in September?
Constantly — ripe seed sheds from July and germinates wherever it lands. Lift self-sown seedlings with a teaspoon of soil and pot them up now; they transplant beautifully at this size and cost you nothing.

Are September-sown foxgloves hardy enough for winter?
Yes — Digitalis purpurea rosettes are hardy to around −15 °C once established. Winter losses almost always come from waterlogging or slugs rather than cold, so drainage matters more than fleece.

So yes — sow your foxgloves this September, under cover and without delay, and think of it as buying a ticket to one of two good shows: spikes next June if the plants size up, or taller ones the year after if they don't. While you're at it, browse the rest of our flower seed range, check what else the month allows in the flower sowing calendar, or start from the beginning with our flower growing guide and the full library of growing guides.