🧅 Can I Plant Onion in Baltimore, MD?

2026 planting guide for Zone 7b · Last frost ~March 28 · Growing season ~230 days

✅ YES — Good temps, but watch for heat — highs near 90°F

Temperature conditions are suitable for Onion. Highs near 90°F are on the warm side — make sure plants have plenty of water.

Planting window: Jul 2 – Jul 16
Good to go — plant now while conditions are right.
Live result based on current forecast for Baltimore, MD · Updates every 6 hours
USDA Zone
7b
Last Spring Frost
~March 28
First Fall Frost
November 13
Growing Season
~230 days
Ideal Temp for Onion
45–75°F
Frost Risk
✅ Tolerant

Growing Onion in Baltimore

Baltimore's Zone 7b Mid-Atlantic climate offers around 230 frost-free days — one of the longer seasons in the Northeast. The Chesapeake Bay moderates temperatures, and the city's urban core often runs a week or two warmer than surrounding suburbs. Tomatoes, peppers, and eggplant do especially well here, and the long fall window allows excellent brassica crops.

In Baltimore (last frost around March 28), onion can go out around February — approximately 6 weeks before the last expected frost, making it an early-season opportunity. Starting seeds indoors 10 weeks before the last frost date gives you a significant head start.

Onion thrives between 45°F and 75°F. It tolerates temperatures as low as 28°F, making it a candidate for early spring planting before the last frost date. Expect 100–120 days from transplant to first harvest. Long season. Start early indoors or use sets.

Frequently Asked Questions

When can I plant onion in Baltimore, MD?

In Baltimore (last frost around March 28), onion can go out around February — approximately 6 weeks before the last expected frost, making it an early-season opportunity. For best results, start seeds indoors 10 weeks before that — giving you strong transplants ready to go out at the right time.

What is the USDA hardiness zone for Baltimore?

Baltimore, MD is in USDA Plant Hardiness Zone 7b. The last expected spring frost is around March 28, and the first fall frost arrives around November 13. This zone classification helps you understand which perennials survive winter and when annual vegetables can safely go outdoors.

Is it safe to plant onion outside in Baltimore right now?

That depends on the current weather forecast. Onion needs temperatures above 28°F (ideally 45–75°F) to thrive. CanIPlant checks your real 7-day forecast and any active frost alerts to give you a live YES, NO, or WAIT answer — just enter your ZIP code.

Can I grow onion in Baltimore 2026?

Yes — Onion grows well in Baltimore, MD. With a Zone 7b climate and a growing season of ~230 days, Baltimore is well-suited for cool-season crops like onion. As a frost-tolerant crop, onion can even go out a few weeks before the last frost date.

Grow Onion in Other Cities

New York, NYLos Angeles, CAChicago, ILHouston, TXPhoenix, AZPhiladelphia, PASan Antonio, TXSan Diego, CA

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