September can feel like a transition month, but it’s one of the most productive times to be in the garden if you know what to do. For some zones, it’s the start of a long fall season. For others, it’s time to think about indoor seed starting and cold-hardy crops.
This guide breaks down what to plant in September by zone, so you’re not guessing. Whether you’re direct sowing outside or getting seeds going under lights, there’s something here for you.
Understanding Your Zone Before You Plant
Your USDA hardiness zone tells you a lot about your frost dates — and frost dates drive everything in September planting. A gardener in zone 5 and a gardener in zone 9 are doing completely different things this month.
If you’re not sure of your zone, look it up before reading further. The advice below is organized from coldest to warmest zones to make it easy to find what applies to you.
Keep in mind that microclimates matter. A south-facing raised bed or a cold frame can extend your season by several weeks even in colder zones.
Zones 3–4: Wind Down Outdoors, Think Indoors
If you’re in zones 3 or 4, September is often your last chance to harvest before hard frosts arrive. But that doesn’t mean you stop planting entirely.
Outdoors, focus on cold-tolerant crops that can still mature before a killing frost. Indoors, September is a good time to start seeds for transplants you’ll move outside next spring.
| Type | What to Plant |
|---|---|
| Outdoors (quick-maturing) | Radishes, spinach, arugula, lettuce |
| Indoors (for spring) | Onions, leeks, cold-hardy herbs |
| Cover crops | Winter rye, clover |
Stick to varieties that mature in 30–45 days. Anything longer is risky. Row cover fabric can buy you an extra week or two of growing time.
Zones 5–6: Fall Planting Season Is Here
Zones 5 and 6 hit a sweet spot in September — warm enough to germinate seeds, but cooling down in ways that favor leafy greens and root crops.
This is one of the best months for direct sowing in these zones. The heat of summer has passed, pest pressure drops, and cool-season crops thrive.
| Type | What to Plant |
|---|---|
| Direct sow outdoors | Kale, spinach, lettuce, arugula, radishes, turnips, beets |
| Transplant outdoors | Broccoli, cabbage, cauliflower (start indoors in late August) |
| Start indoors | Onions, leeks (for next spring) |
In zone 6, you have a little more runway. Aim to get brassica transplants in the ground by mid-September for best results. If you want zone-specific seed starting timing, the guides for zone 6b and zone 6a go deeper on this.
Zones 7–8: Peak Fall Garden Month
For zones 7 and 8, September is one of the most exciting months in the garden. Fall planting here is serious business, and the variety of crops you can grow is impressive.
You’re not just growing lettuce. Think garlic, carrots, fennel, chard, collards, and more. The fall and winter garden in these zones can be as productive as spring.
| Type | What to Plant |
|---|---|
| Direct sow outdoors | Carrots, beets, turnips, radishes, spinach, arugula, lettuce, kale |
| Transplant outdoors | Broccoli, cabbage, cauliflower, chard, collards |
| Plant bulbs/cloves | Garlic (late September in zone 7) |
| Start indoors | Onions, leeks |
Zones 9–10: Transition Out of Summer
Zones 9 and 10 are just starting to cool down in September, and it can still feel very warm. The key is timing — start too early in the month and the soil heat will challenge germination for some crops.
The second half of September is usually more reliable for planting outdoors. Early in the month, starting seeds indoors in a cool spot gives transplants a head start.
| Type | What to Plant |
|---|---|
| Direct sow outdoors (late Sept) | Beans, cucumbers, squash (zone 10), leafy greens, radishes |
| Transplant outdoors | Tomatoes (zone 10), peppers (zone 10), broccoli, cabbage |
| Start indoors (early Sept) | Broccoli, cauliflower, kale, lettuce for transplanting |
Zone 10 gardeners can still plant warm-season crops like beans and squash in September for a fall harvest. If you want detailed timing, the zone 10a seed starting guide breaks it down month by month.
Zone 11: Year-Round Growing, September Included
Zone 11 is a different world. Frost is essentially a non-issue, and September often marks the return to more comfortable growing temperatures after a brutal summer.
This is a great time to get warm-season crops going again and start transitioning toward cool-season vegetables as the month progresses.
- Tomatoes, peppers, eggplant (direct sow or transplant)
- Beans, cucumbers, squash
- Leafy greens and herbs
- Root vegetables like carrots and beets
September planting in zone 11 leads to harvests through the winter and into spring. It’s genuinely one of the best times of year to garden there.
A Few Crops That Work Across Many Zones in September
Some vegetables are reliable September picks across a wide range of zones. If you’re not sure where to start, these are worth focusing on.
- Radishes: Fast, easy, and cold-tolerant. Zones 3–10.
- Spinach: Loves the cooling temps. Zones 4–9.
- Lettuce: Direct sow or transplant. Zones 4–10.
- Kale: Slow but worth it. Zones 4–9.
- Garlic: Plant cloves in September or October depending on zone. Zones 5–9.
Frequently Asked Questions
Is it too late to plant vegetables in September?
It depends on your zone. In zones 7–11, September is one of the best planting months of the year. In zones 3–5, you’re limited to fast-maturing crops and cold-hardy greens, but it’s not too late for those.
What vegetables can I start indoors in September?
In colder zones, September is a good time to start onions and leeks indoors for spring transplanting. In warmer zones, you can start brassica transplants indoors early in the month to set out once temperatures drop a bit.
Can I plant garlic in September?
In zone 7 and warmer zones, late September works for garlic. In zones 5–6, October is usually better. Garlic wants to establish roots before the ground freezes but shouldn’t push up too much top growth before winter.
What should I do if it’s still very hot in September?
Focus on starting seeds indoors in a cool space, and wait until the second half of the month to direct sow outdoors. Shade cloth over your beds can also help cool the soil by several degrees for better germination.
Free tools for every gardener
Stop guessing. Start growing with confidence.
Whether you’re a seasoned grower or just getting started, mysimpleseed has you covered — from timely email alerts for your zip code to a personalized beginner plan built around your space and budget.
Gardening Alerts
Get email reminders for seed starting, sowing, transplanting, watering, and harvesting — timed to your exact location.
Free Beginner Plan
Enter your zip code, space, and budget. We’ll pick 2–4 easy crops and send you personalized alerts to grow them successfully.