What to plant in March — zone 5a
Zone 5a averages its last spring frost around May 10 and its first fall frost around October 1. 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 1
Alliums need 10-12 weeks under lights before they go out — the earliest sowing of the year.
- Onionaround Mar 1
10 weeks of indoor growth before your last frost (05-10). Match day-length to your latitude — long-day north of 37°, short-day south.
- Pepperaround Mar 15
8 weeks of indoor growth before your last frost (05-10). Pinch first flowers on transplants so the plant invests in roots before setting fruit.
- Parsleyaround Mar 15
8 weeks of indoor growth before your last frost (05-10). Soak seeds 24 hrs before sowing. Cut outer stems and it comes back for years in mild zones.
- Chivesaround Mar 15
8 weeks of indoor growth before your last frost (05-10). Divide the clump every 3 years — one plant becomes six with no effort.
- Oreganoaround Mar 15
8 weeks of indoor growth before your last frost (05-10). Harvest just before flowering for the strongest flavor. Dries beautifully.
- Thymearound Mar 15
8 weeks of indoor growth before your last frost (05-10). Needs sharp drainage — plant in gravelly soil or a raised bed edge. Never wet feet.
- Sagearound Mar 15
8 weeks of indoor growth before your last frost (05-10). Prune hard in spring to prevent woody stems and keep the plant productive for 5+ years.
- Tomatoaround Mar 29
6 weeks of indoor growth before your last frost (05-10). Bury 2/3 of the transplant stem — roots form along the buried stem for a stronger plant.
- Kalearound Mar 29
6 weeks of indoor growth before your last frost (05-10). Fall crop sweetens after first frost — plan a July sowing for the best flavor.
- Broccoliaround Mar 29
6 weeks of indoor growth before your last frost (05-10). After cutting the main head, side shoots keep coming for weeks — don't pull the plant.
- Basilaround Mar 29
6 weeks of indoor growth before your last frost (05-10). Pinch tips weekly. Once flowers open, leaves lose flavor — snip them fast.
- Basilaround Mar 29
6 weeks of indoor growth before your last frost (05-10). Pinch flower spikes the moment you see them — leaves stay sweet all season.
Dormant care
- Check season-extension geararound Mar 15
Patch row cover, cold frames and hoops now so a late freeze can't catch you unprepared.
- Pre-sprout seed potatoesaround Mar 29
Chit potatoes in a bright, cool spot for 2 weeks — sprouted pieces jump ahead once planted.
Transplant out
- Raspberryaround Mar 29
Goes out 6 weeks before last frost — it takes the cold.
- Blueberryaround Mar 29
Goes out 6 weeks before last frost — it takes the cold.
- Blackberryaround Mar 29
Goes out 6 weeks before last frost — it takes the cold.
- Grapearound Mar 29
Goes out 6 weeks before last frost — it takes the cold.
- Applearound Mar 29
Goes out 6 weeks before last frost — it takes the cold.
- Peararound Mar 29
Goes out 6 weeks before last frost — it takes the cold.
- Peacharound Mar 29
Goes out 6 weeks before last frost — it takes the cold.
- Rhubarbaround Mar 29
Goes out 6 weeks before last frost — it takes the cold.
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