The Short Answer

Brussels sprouts need 80 to 100 days from transplant to harvest, and they produce the best-tasting sprouts when they mature in cool weather — ideally with temperatures between 45 and 65 degrees Fahrenheit. This means you’re working backward from your first fall frost to figure out when to plant.

In most of the United States, Brussels sprouts are a fall crop. You plant them in mid to late summer, and they mature as temperatures drop in autumn. The cold actually improves the flavor — frost converts some of the starches in the sprouts to sugars, making them sweeter and less bitter.

Some regions can also grow them as a spring crop, but this is trickier. If warm weather arrives before the sprouts mature, the plants bolt or produce loose, bitter sprouts. Spring planting works best in cooler climates with long, mild springs.

Understanding the Basics

Before diving into regional specifics, a few fundamentals:

Days to maturity. Seed packets list “days to maturity” from transplant, not from seed. If you’re starting from seed indoors, add 4 to 6 weeks to the total timeline. A variety listed at 90 days needs roughly 130 to 135 days from seed to harvest.

Frost tolerance. Brussels sprouts are remarkably cold-hardy. Mature plants can survive temperatures down to about 20 degrees Fahrenheit. Light frosts (28 to 32 degrees) actually improve flavor. This is why fall planting is preferred — the sprouts taste best after a few frosts.

Heat sensitivity. Temperatures consistently above 80 degrees Fahrenheit cause problems. Growth slows, sprouts loosen, and flavor turns bitter and sulfurous. This is the main challenge for southern growers.

Transplant vs. direct sow. Starting seeds indoors and transplanting gives you more control over timing. Direct sowing works but extends the total growing time and makes it harder to hit the right harvest window.

For a deeper look at cultivation techniques, see the full guide to growing Brussels sprouts.

Region-by-Region Planting Calendar

Northeast (Zones 5-6)

States: Maine, Vermont, New Hampshire, Massachusetts, Connecticut, Rhode Island, New York, New Jersey, Pennsylvania

Fall crop (primary):

• Start seeds indoors: May 15 to June 15
• Transplant outdoors: June 15 to July 15
• Harvest window: October to December

Spring crop (possible but challenging):

• Start seeds indoors: February 15 to March 15
• Transplant outdoors: April 1 to April 30 (after last frost)
• Harvest window: Late June to July

The Northeast is excellent Brussels sprouts territory. Cool autumns, reliable frosts, and moderate summers make for ideal growing conditions. Most experienced gardeners here plant exclusively for fall harvest. The long, cold autumn gives sprouts plenty of time to mature in cool weather, developing peak sweetness.

Southeast (Zones 7-9)

States: Virginia, North Carolina, South Carolina, Georgia, Florida, Alabama, Mississippi, Louisiana

Fall/winter crop (primary):

• Start seeds indoors: July 1 to August 15
• Transplant outdoors: August 1 to September 15
• Harvest window: November to February

Spring crop: Generally not recommended. Springs warm up too quickly, and the transition from cool to hot happens before sprouts mature.

The Southeast is challenging for Brussels sprouts, but not impossible. The key is planting late enough that the crop matures during the cooler winter months. In zones 8 and 9, Brussels sprouts are essentially a winter vegetable. Choose quick-maturing varieties (80 to 85 days) to shorten the time the plants spend in heat.

In Florida and the Gulf Coast, only the northern portions of these states are realistic for Brussels sprouts. Gardeners in zones 9b and 10 are better off buying them at the store.

Midwest (Zones 4-6)

States: Ohio, Michigan, Indiana, Illinois, Wisconsin, Minnesota, Iowa, Missouri

Fall crop (primary):

• Start seeds indoors: May 1 to June 1
• Transplant outdoors: June 1 to July 1
• Harvest window: September to November

Spring crop (possible in northern areas):

• Start seeds indoors: February 1 to March 1
• Transplant outdoors: April 15 to May 15
• Harvest window: Late June to August

The Midwest is prime Brussels sprouts country. Cold winters mean reliable frost to sweeten fall crops. The main risk is an early hard freeze (below 20 degrees) that kills plants before all the sprouts are harvested. In Minnesota and Wisconsin (zone 4), this can happen as early as mid-October, so planting on the earlier side of the window is wise.

Great Plains (Zones 4-7)

States: North Dakota, South Dakota, Nebraska, Kansas, Oklahoma, Texas (northern)

Fall crop:

• Start seeds indoors: May 15 to June 15 (north), June 15 to July 15 (south)
• Transplant outdoors: June 15 to July 15 (north), July 15 to August 15 (south)
• Harvest window: September to November (north), November to January (south)

Wind and temperature extremes are the main challenges on the Great Plains. Consistent wind dries out plants and can physically damage tall Brussels sprout stalks. Staking plants and applying mulch to retain soil moisture are more important here than in other regions.

In Kansas and Oklahoma, heat is also a factor. Choose heat-tolerant varieties and provide afternoon shade if possible during July and August.

Mountain West (Zones 3-7)

States: Montana, Wyoming, Colorado, Utah, Idaho, Nevada, New Mexico, Arizona (northern)

Fall crop:

• Start seeds indoors: April 15 to May 15 (high elevation/zone 3-4), May 15 to June 15 (zone 5-6)
• Transplant outdoors: May 15 to June 15 (zone 3-4), June 15 to July 15 (zone 5-6)
• Harvest window: August to October

The Mountain West offers excellent growing conditions at elevation. Cool nights, low humidity, and intense sunlight produce dense, flavorful sprouts. The short growing season in zones 3 and 4 means you need fast-maturing varieties — look for anything under 90 days from transplant.

At lower elevations in Nevada, New Mexico, and Arizona, summer heat makes Brussels sprouts impractical except as a late fall/winter crop in irrigated gardens.

Pacific Northwest (Zones 7-9)

States: Washington, Oregon

Fall/winter crop (primary):

• Start seeds indoors: May 1 to June 15
• Transplant outdoors: June 1 to July 15
• Harvest window: October to February

Spring crop (viable):

• Start seeds indoors: January 15 to February 15
• Transplant outdoors: March 15 to April 15
• Harvest window: June to August

The Pacific Northwest is arguably the best region in the country for Brussels sprouts. Mild, wet winters and cool summers create conditions very similar to the maritime European climates where Brussels sprouts originated. Commercial Brussels sprout farms in the US are concentrated in western Washington and Oregon for exactly this reason.

Winter harvesting is the standout advantage here. In zones 8 and 9 west of the Cascades, Brussels sprouts can survive the entire winter outdoors. You can pick sprouts from November through February, harvesting from the bottom of the stalk upward over several months.

California (Zones 8-10)

Coastal:

• Start seeds indoors: June 1 to August 1
• Transplant outdoors: July 1 to September 1
• Harvest window: November to March

Inland valleys:

• Start seeds indoors: July 1 to August 1
• Transplant outdoors: August 1 to September 1
• Harvest window: December to February

California’s coast has mild enough weather to grow Brussels sprouts nearly year-round in some microclimates. The Monterey Bay area and the central coast are major commercial production zones. Home gardeners along the coast should plant for winter harvest, when the cool, foggy conditions are perfect.

Inland California (Central Valley, Southern California inland) is too hot for summer growing. Treat it like the Southeast: plant in late summer, harvest in winter.

Choosing Varieties by Region

Your choice of variety should match your climate:

Short-season varieties (80-90 days): Best for zones 3-4, the Southeast, and anywhere the growing window is tight. Look for Jade Cross, Diablo, or Franklin.

Mid-season varieties (90-100 days): The sweet spot for most regions. Long Island Improved and Churchill are reliable all-purpose choices.

Long-season varieties (100-130 days): Best for the Pacific Northwest, coastal California, and zones 7-8 with long, mild autumns. Nautic and Dagan produce large harvests but need time.

For more on selecting the right type, see the Brussels sprouts varieties guide.

Succession Planting

Most gardeners plant Brussels sprouts all at once for a single harvest. But if you have room, succession planting — setting out transplants every 2 to 3 weeks over a 6-week window — extends your harvest season. Instead of all your sprouts maturing in the same week, you get a rolling harvest over 2 months.

This works best in regions with long, cool autumns: the Pacific Northwest, coastal California, and the Northeast. In regions where winter arrives abruptly (Midwest, Mountain West), succession planting is riskier because later plantings may get killed by hard freezes before maturing.

Extending the Season

Frost protection. Row covers and cold frames can extend your harvest by 3 to 6 weeks. In zones 5 and 6, a simple row cover over mature plants can push the harvest window from November into January.

Mulching. A thick layer of straw mulch (4 to 6 inches) around the base of plants insulates roots and keeps the soil from freezing solid. This keeps plants alive and productive longer into winter.

Container growing. Growing Brussels sprouts in large containers (15 gallons or bigger) lets you move plants to sheltered locations when hard freezes threaten. This is a viable strategy in zones 4 and 5 where early hard freezes can cut the season short. See growing Brussels sprouts in containers for the full approach.

Common Timing Mistakes

Planting too late for fall harvest. This is the most frequent error. People plant in August expecting a November harvest, forgetting that days to maturity assumes ideal growing conditions. Heat stress, transplant shock, and pest pressure can add 2 to 3 weeks to the timeline. Plant earlier than you think you need to.

Ignoring microclimates. Your specific yard may be warmer or cooler than your USDA zone suggests. South-facing slopes warm up earlier. Low spots collect cold air. Urban gardens near pavement and buildings stay warmer. Adjust your timing based on what actually happens in your garden, not just what the zone map says.

Forgetting about day length. As days shorten in fall, plant growth slows. A Brussels sprout plant that needs 90 days in June might need 100 or more days if those 90 days fall in September through November when daylight hours are declining. Build in extra time for fall crops.

Waiting for all sprouts to mature at once. Brussels sprouts mature from the bottom of the stalk upward. You don’t have to wait for the top sprouts to be ready before harvesting the bottom ones. Start picking when the lowest sprouts reach about 1 to 1.5 inches in diameter, and work your way up over several weeks.

The Bottom Line

For most American gardeners, the formula is straightforward: count back 100 to 120 days from your first fall frost date, and that’s when you should transplant Brussels sprouts into the garden. Start seeds indoors 4 to 6 weeks before that transplant date.

Cool weather is the single most important factor. If you can time your crop to mature during consistently cool (45 to 65 degree) weather, you’ll get sweet, dense, flavorful sprouts. If the sprouts mature during warm weather, they’ll be loose, bitter, and disappointing.

Work with your climate, not against it. In the north, that means fall. In the south, that means winter. On the coast, you might get lucky with year-round growing. Whatever your region, the sprouts are worth the planning.