Annual Flower

When to Plant Cosmos in Maryland

Delicate, daisy-like blooms that dance in the breeze. Cosmos thrive in poor soil and practically grow themselves.

The Short Answer

In Maryland, plant cosmos based on your regional frost dates. Western Maryland has a last frost around May 1 - May 15, while Eastern Shore sees frost end around Apr 1 - Apr 15. Moderate climate with four seasons. Hot, humid summers. Good growing season. Diverse growing conditions across the...

Maryland Frost Dates

Your planting dates depend on which part of Maryland you're in. Here are the frost date ranges by region:

Region Zones Last Frost (Spring) First Frost (Fall)
Western Maryland 5b, 6a May 1 - May 15 Sep 25 - Oct 10
Central Maryland 6b, 7a Apr 10 - Apr 25 Oct 10 - Oct 25
Eastern Shore 7a, 7b, 8a Apr 1 - Apr 15 Oct 20 - Nov 5

Cosmos Planting Schedule for Maryland

Western Maryland (Zones 5b, 6a)

Average last frost: May 1 - May 15 · Average first frost: Sep 25 - Oct 10

Start Seeds Indoors
4 wks before frost
Transplant Outside
1 wks after frost
Direct Sow
1 wks after frost

Central Maryland (Zones 6b, 7a)

Average last frost: Apr 10 - Apr 25 · Average first frost: Oct 10 - Oct 25

Start Seeds Indoors
4 wks before frost
Transplant Outside
1 wks after frost
Direct Sow
1 wks after frost

Eastern Shore (Zones 7a, 7b, 8a)

Average last frost: Apr 1 - Apr 15 · Average first frost: Oct 20 - Nov 5

Start Seeds Indoors
4 wks before frost
Transplant Outside
1 wks after frost
Direct Sow
1 wks after frost

Growing Cosmos in Maryland

Cosmos in Maryland's Climate

Cosmos are the zero-effort flower. Direct sow from mid-May. No fertilizer, no fussing, no deadheading necessary (though it helps). They grow 3-5 feet tall and self-seed prolifically. Perfect for filling unused garden edges with color and pollinator habitat.

Soil Considerations for Maryland

Clay soils in Piedmont. Sandy loam on Eastern Shore. Acidic in most areas. Rich alluvial soils along river valleys. Make sure soil has warmed to at least 60°F before planting cosmos outside.

Maryland Climate & Growing Season

Moderate climate with four seasons. Hot, humid summers. Good growing season. Diverse growing conditions across the state. Cosmos cannot tolerate any frost, so wait until all frost danger has passed before transplanting outside. Watch local forecasts carefully in spring.

Growing season length varies across Maryland: Western Maryland (5b, 6a) has a last frost around May 1 - May 15, while Eastern Shore (7a, 7b, 8a) sees frost end around Apr 1 - Apr 15. This difference matters for cosmos — transplant timing shifts by several weeks across the state.

Growing Tips

Don't over-fertilize — rich soil produces more leaves and fewer flowers. Let some flowers go to seed for next year's crop.

Companion Planting

Plant cosmos alongside these companions for better growth:

Tomatoes Squash

The Bottom Line

Cosmos can be grown successfully across Maryland, but your exact planting dates depend on which region you're in. Western Maryland gardeners should plan around a May 1 - May 15 last frost, while those in Eastern Shore can typically plant earlier. For exact dates based on your zip code, use our free planting date finder.

Related Guides

Cosmos Growing Guide National planting guide with all states Maryland Planting Calendar All plants for Maryland Cosmos in Alabama Alabama planting dates Cosmos in Alaska Alaska planting dates Cosmos in Arizona Arizona planting dates Cosmos in Arkansas Arkansas planting dates
Note: All dates are based on NOAA 30-year Climate Normals and represent historical averages, not predictions for any specific year. Always check your local weather forecast before planting frost-sensitive crops. Learn about our data sources.

Last reviewed: March 29, 2026

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