What to Plant in September — Zone 4

September is the closing stretch of zone 4's season — the average first frost (Oct 1) is only weeks past month's end, so this is fall-sowing and garlic-planting territory.

Fall planting — Counted back from the first fall frost.

🥬 Lettuce Aug 6 – Sep 3 45–60 days to maturity
🌿 Arugula Aug 20 – Sep 3 30–40 days to maturity
🌶️ Radishes Aug 20 – Sep 3 22–30 days to maturity
🧄 Garlic Aug 20 – Sep 17 plant cloves; harvest next summer

Windows use zone 4's typical frost dates (May 5 / Oct 1). For your own city's dates, run the frost lookup — the planting calendar then localizes everything automatically.

Frequently asked questions

What can I plant outside in September in zone 4?

4 crops can go in the ground: lettuce, arugula, radishes, garlic. Exact windows are in the tables above — early and late in the month can differ by a full frost date.

Is September the right time for tomatoes in zone 4?

The spring window has passed; tomatoes set out this late won't beat the Oct 1 average first frost to ripeness. Plan for next spring's seed-starting instead.

September in other zones

Zone 1Zone 2Zone 3Zone 4Zone 5Zone 6Zone 7Zone 8Zone 9Zone 10Zone 11Zone 12Zone 13

Zone 4, month by month

← August October → All months

Zone 4 frost dates near you

Anchorage, AKCaribou, MEDuluth, MNGreat Falls, MTFargo, NDBismarck, NDSioux Falls, SDMontpelier, VT