What to plant in September in Delaware
In Delaware (DE), September sits about 5 weeks before the average first fall frost (October 22). The state averages 191 frost-free days a year (last frost April 14, first frost October 22; USDA zones 7a, 7b).
19 crops have a sowing or planting window this month, including bok choy / pak choi, borage, dill, fava bean (broad bean), green onion / scallion, kohlrabi - and 17 of those windows close during September.
Dates here come from Delaware frost dates (last frost Apr 14, first frost Oct 22). For one crop in detail, see when to plant lettuce, spinach or arugula in Delaware.
Delaware: planting activity through the year
Last chance in September
Bok Choy / Pak Choi (sow for a fall crop, by Sep 3) · Borage (sow for a fall crop, by Sep 3) · Dill (sow for a fall crop, by Sep 3) · Fava Bean (Broad Bean) (sow for a fall crop, by Sep 3) · Green Onion / Scallion (sow for a fall crop, by Sep 3) · Kohlrabi (sow for a fall crop, by Sep 3) · Lettuce (sow for a fall crop, by Sep 3) · Mache (Corn Salad) (sow for a fall crop, by Sep 3) · Mizuna (sow for a fall crop, by Sep 3) · Rapini (Broccoli Raab) (sow for a fall crop, by Sep 3) · Chervil (sow for a fall crop, by Sep 10) · Mustard Greens (sow for a fall crop, by Sep 10) · Spinach (sow for a fall crop, by Sep 10) · Tatsoi (sow for a fall crop, by Sep 10) · Turnip (sow for a fall crop, by Sep 10) · Arugula (sow for a fall crop, by Sep 17) · Watercress (sow for a fall crop, by Sep 17)
For fall and winter harvests (18)
Sowings counted back from Delaware's first fall frost, so the crop matures before the cold - or, for garlic and similar, planted after it.
| Crop | What to do | Window | This month |
|---|---|---|---|
| Bok Choy / Pak Choi | Sow for a fall crop | Aug 17 – Sep 3 | Last chance - ends Sep 3 |
| Borage | Sow for a fall crop | Aug 17 – Sep 3 | Last chance - ends Sep 3 |
| Dill | Sow for a fall crop | Aug 17 – Sep 3 | Last chance - ends Sep 3 |
| Fava Bean (Broad Bean) | Sow for a fall crop | Aug 17 – Sep 3 | Last chance - ends Sep 3 |
| Green Onion / Scallion | Sow for a fall crop | Aug 17 – Sep 3 | Last chance - ends Sep 3 |
| Kohlrabi | Sow for a fall crop | Aug 17 – Sep 3 | Last chance - ends Sep 3 |
| Lettuce | Sow for a fall crop | Aug 17 – Sep 3 | Last chance - ends Sep 3 |
| Mache (Corn Salad) | Sow for a fall crop | Aug 17 – Sep 3 | Last chance - ends Sep 3 |
| Mizuna | Sow for a fall crop | Aug 17 – Sep 3 | Last chance - ends Sep 3 |
| Rapini (Broccoli Raab) | Sow for a fall crop | Aug 17 – Sep 3 | Last chance - ends Sep 3 |
| Chervil | Sow for a fall crop | Aug 24 – Sep 10 | Last chance - ends Sep 10 |
| Mustard Greens | Sow for a fall crop | Aug 24 – Sep 10 | Last chance - ends Sep 10 |
| Spinach | Sow for a fall crop | Aug 24 – Sep 10 | Last chance - ends Sep 10 |
| Tatsoi | Sow for a fall crop | Aug 24 – Sep 10 | Last chance - ends Sep 10 |
| Turnip | Sow for a fall crop | Aug 24 – Sep 10 | Last chance - ends Sep 10 |
| Arugula | Sow for a fall crop | Aug 31 – Sep 17 | Last chance - ends Sep 17 |
| Watercress | Sow for a fall crop | Aug 31 – Sep 17 | Last chance - ends Sep 17 |
| Radish | Sow for a fall crop | Sep 7 – Sep 24 | Sep 7 – Sep 24 |
Keep sowing (succession)
Repeat sowings of crops already in the ground, for a steady harvest instead of a glut.
- Basil: sow again on Sep 1
Harvesting in September
First harvests expected this month from crops sown or planted on time earlier in the season.
Planting dates for popular crops in Delaware
Every crop has its own full-year dates for Delaware: indoor start, transplant or direct sowing, and harvest.
Spring bulbs to plant in September in Delaware
Tulips, daffodils, hyacinths and crocus are planted in fall, once the soil has cooled and before it freezes. The exact window depends on the state, so our bulb guide quotes what each extension service says.
Fall garden season: September garden jobs in Delaware
- The average first frost is October 22, about 5 weeks away. Pick tender crops (tomatoes, peppers, squash, beans) before it, or cover them on cold nights.
- Still time to sow or plant: bok choy / pak choi, borage, dill, fava bean (broad bean), green onion / scallion, kohlrabi. Fast greens and radishes are the safest bets this late.
- Row cover buys 4-6°F of frost protection and weeks of extra harvest - see season extension.
- Pull finished crops and sow a cover crop (cereal rye or crimson clover) into empty beds before the soil gets cold.
Questions gardeners ask
What vegetables can I plant in Delaware in September?
19 crops have a window in September: bok choy / pak choi, borage, dill, fava bean (broad bean), green onion / scallion, kohlrabi, lettuce, mache (corn salad), mizuna, rapini (broccoli raab) and more. The tables above give the exact dates for each.
Is it too late to plant garlic in Delaware in September?
Not too late - it's actually a little early. In Delaware the next garlic window opens around November 2: plant in fall, after first frost.
Is it too late to plant tomatoes in Delaware in September?
For this year, yes - the tomato windows in Delaware have closed. The next step is to start seeds indoors from about February 17.
When is the first frost in Delaware?
The statewide average first fall frost is around October 22 and the last spring frost around April 14. Your town can be a week or two either side - look yours up by ZIP code.
What can I harvest in Delaware in September?
From plantings made on time: celery, luffa (loofah gourd), peanut, sweet potato, chayote, zucchini / summer squash, cucumber, broccoli, cauliflower, cabbage.
What to plant in September in other states
Dates are computed from Delaware’s statewide average frost dates (from NOAA/NCEI climate normals) and each crop’s timing in our crop database. Your garden may be a week or two either side - for dates tuned to your ZIP code, use the planting calendar.