What to plant in March — zone 4b
Zone 4b averages its last spring frost around May 15 and its first fall frost around September 25. Everything below is timed from those two dates, so it stays useful whether you're planting for summer or for a fall harvest.
Start indoors
- Start onions and leeks indoorsaround Mar 6
Alliums need 10-12 weeks under lights before they go out — the earliest sowing of the year.
- Onionaround Mar 6
10 weeks of indoor growth before your last frost (05-15). Match day-length to your latitude — long-day north of 37°, short-day south.
- Pepperaround Mar 20
8 weeks of indoor growth before your last frost (05-15). Pinch first flowers on transplants so the plant invests in roots before setting fruit.
- Parsleyaround Mar 20
8 weeks of indoor growth before your last frost (05-15). Soak seeds 24 hrs before sowing. Cut outer stems and it comes back for years in mild zones.
- Chivesaround Mar 20
8 weeks of indoor growth before your last frost (05-15). Divide the clump every 3 years — one plant becomes six with no effort.
Dormant care
- Check season-extension geararound Mar 20
Patch row cover, cold frames and hoops now so a late freeze can't catch you unprepared.
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