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SUS Farms · Utah Seed Library

Growing Zinnia in Utah

flower · Asteraceae · warm season · 70 days to harvest

MethodIndoor or direct
Days to maturity70 days
Seed depth0.25″
Plant spacing12″
Row spacing18″
Germ. temp70–85°F

Schedule (May 15 last frost · Sevier County)

Start indoors4/17
Transplant out5/22
Direct sow5/22
First harvest7/31

Planting depth, drawn to scale

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

Step-by-step

  1. 1. Start indoors 4 weeks before last frost. Seed-starting mix in 2-4" cells. Bottom heat at 70–85°F until germination, then drop to room temperature. 14-16 hours of light from clip-lamp 2" from leaves.
  2. 2. Harden off for 7 days. Day 1: 1 hour outside in shade. Add an hour and more sun each day. Skip if windy or below 50°F.
  3. 3. Transplant 12″ apart in rows 18″ apart. Soil should be at least 70°F before planting. Black plastic mulch laid two weeks ahead helps in cool springs.
  4. 4. Mulch and water consistently. 2" of straw or wood chip around the base. Drip line at surface. 1" per week including rain.
  5. 5. Harvest around day 70. Cut and come again — the more you cut, the more it blooms. Benary's Giants are the cut-flower workhorse.