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SUS Farms · Utah Seed Library

Growing Cosmos in Utah

flower · Asteraceae · warm season · 75 days to harvest

Methoddirect
Days to maturity75 days
Seed depth0.25″
Plant spacing12″
Row spacing18″
Germ. temp70–85°F

Schedule (May 15 last frost · Sevier County)

Direct sow5/22
First harvest8/7

Planting depth, drawn to scale

0"1"2"3"4"5"6"0.25" deep

Step-by-step

  1. 1. Direct sow 0.25″ deep, 12″ apart. Soil should be at least 70°F before planting. Black plastic mulch laid two weeks ahead helps in cool springs.
  2. 2. Mulch and water consistently. 2" of straw or wood chip around the base. Drip line at surface. 1" per week including rain.
  3. 3. Harvest around day 75. Self-sows aggressively. Don't fertilize — rich soil makes huge plants with few flowers.