When to plant broccoli in Baltimore, Maryland

February 24 – March 10

Transplant outdoors · typical Baltimore year

Climate basis: NOAA station Md Sci Ctr Baltimore, MD (USW00093784), 1 mi (2 km) from downtown Baltimore (ZCTA 21202 centroid), elevation 20 ft, on the 1991–2020 climate normals. Transplant broccoli outdoors from approximately the dates above, anchored to the median last spring 32°F freeze (March 24). One year in ten still freezes after April 4.

Last spring freezeMarch 241-in-10 after Apr 4

First fall freezeNovember 211-in-10 before Nov 7

Frost-free season≈ 244 daysmedian at 32°F

Hard freeze, 28°Mar 11 – Dec 5kills even hardy greens

USDA zone8a10 to 15°F winter low — not frost timing

The Baltimore year

Start seeds indoorsJan 13 – Jan 27

Transplant outdoorsFeb 24 – Mar 10

Fall plantingSep 26 – Oct 24

indoors under lights
in the garden
frost-free season
1-in-10 years still freeze to Apr 4

Broccoli in Baltimore · freeze context from Md Sci Ctr Baltimore, MD, 1991–2020 normals.

Every method, with its sources

Start seeds indoors

Jan 13 – Jan 27

Sow 4–6 weeks before the set-out window opens (UNH 4–6 weeks; Missouri G6570 6–8 weeks). Anchored to the median last spring freeze (Mar 24). University of New Hampshire Extension · University of Missouri Extension

Transplant outdoors

Feb 24 – Mar 10

UNH: set out 2–4 weeks before the last frost; Purdue's hardy class allows 4–6 weeks before. The later UNH range is used. Anchored to the median last spring freeze (Mar 24). University of New Hampshire Extension · Purdue University Extension

Fall planting

Sep 26 – Oct 24

Purdue Table 2: plant fall broccoli at least 4–8 weeks before the first fall frost. Anchored to the median first fall freeze (Nov 21). Purdue University Extension

Variety assumption: Assumes an average heading variety (about 60–70 days from transplant).

These windows describe typical years (1991–2020 climate normals), not this year's forecast. Freezes happen outside them — especially in frost pockets, valleys, and urban edges. Watch the forecast before committing tender plants.

This week, not a typical year:

Crop rule sources (3)

University of New Hampshire Extension: Growing Vegetables: When to Plant Your Vegetable Garden [fact sheet] (accessed 2026-07-24)
Per-crop 'time from seed to transplant' and 'safe to set out in garden' relative to last frost.
University of Missouri Extension: Starting Plants Indoors from Seeds (G6570) (accessed 2026-07-24)
Weeks needed to grow vegetable transplants indoors (Table 2).
Purdue University Extension: Indiana Vegetable Planting Calendar (HO-186-W) (accessed 2026-07-24)
Hardiness classes: hardy = plant 4-6 wk before last spring frost; semi-hardy = 2-4 wk before; tender = after average last frost; very tender = at least 2 wk after. Table 2: fall planting at least 4-8 wk before first fall frost.

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