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Cauliflower Seed Starting Tips

Seedling Cauliflower
Cauliflower seedlings
Cauliflower seedlings

Cauliflower is a cool-season crop; it thrives in temperatures between 57°F and 68°F (14°C-20°C).

Plant fast-maturing cauliflower varieties in spring or fall. Any variety that requires more than 80 days to mature should be planted for fall harvest. Purple varieties are both heat and cold tolerant.

Cauliflower matures in 50 to 85 days depending on the variety.

Cauliflower Sowing and Planting Tips

  • Start cauliflower from seed or transplants.
  • Seed is viable for 4 years.
  • Start seeds indoors 6 to 4 weeks before the last frost or 12 to 10 weeks before the first frost for a fall crop.
  • Seedlings started indoors can be planted out 2 to 3 weeks before the last frost.
  • Sow outdoors from the last frost to early spring for late spring or early summer harvest or in summer 12 weeks before the first frost for a fall crop.
  • Start seeds in individual pots or flats.
  • Sow seed ¼ to ½ (6-8 mm) inch deep in the seed-starting mix.
  • Keep the mix moist but not wet.
  • Seeds should germinate in 6 days at an optimal temperature of 70°F (21°C) or thereabouts.
  • Transplant seedlings into the garden when they are 4 to 6 inches (10-15 cm) tall with 2- to 4-leaves and daytime temperatures reach 50°F (10°C); firm transplants into the soil by hand.
  • Cauliflower prefers a soil pH range of 6.0 to 7.5.
  • Grow cauliflower in full sun for best yield—plants tolerate partial shade.
  • Add 3- to 4- inches of compost and well-aged manure into planting bed, before transplanting; cauliflower needs friable, moisture-holding soil.
  • Avoid planting cauliflower where cabbage family crops have grown recently.
  • Space plants 15 inches (38 cm) apart.
  • Space rows 20-24 inches apart.
  • Protect the seedlings from the cold for 2 to 3 weeks after planting covering them with a cloche or plastic tunnel or cold frame.
  • Keep soil moist after transplanting seedlings; this will ensure rapid growth.
  • Feed with an organic fertilizer such as fish emulsion at half strength; be sure cauliflower get potassium, phosphorus, and magnesium.
  • Common pest enemies are aphids, flea beetles, cabbage worms and loopers, cabbage worms, and cutworms.

 Cauliflower Planting Calendar

  • 10-6 weeks before the last frost in spring: start seed indoors.
  • 6-4 weeks before the last frost in spring: transplant seedlings under a plastic tunnel or cold frame
  • 4-3 weeks before the last frost in spring set transplants out in the open garden.
  • 3-2 weeks before the last frost in spring: direct-sow in the garden; protect emerging seedlings from the chill with a spun poly row cover; minimum soil temperature should be at least 40°F.

For Fall Harvest:

  • 12-10 weeks before the first frost in fall: start seeds indoors.
  • 10-8 weeks before the first frost in fall: transplant seedlings into the garden for fall harvest.
  • 8-6 weeks before the first frost in fall: transplant seedlings into the garden for late fall harvest; protect plants from frost under spun poly floating row covers.
Cauliflower plant
Cauliflower Seed Starting: Time the planting of cauliflower so the crop does not mature in hot weather; hot weather will stunt heads. For a fall crop, sow seed in early- to mid-summer.

Recommended Cauliflower Varieties

  • ‘Early Snowball’, small, quick maturing.
  • ‘Amazing’ self-blanching.
  • ‘Fremont’ self-blanching.
  • ‘Snow Crown’ tolerates frost to 25°F.
  • ‘Graffiti’ bright purple heads.
  • ‘Violet Queen’ purple head.
  • ‘Alverda’ and ‘Panther’ green heads.

Interplanting: Interplant with beets, green onions, spinach, and herbs.

Container Growing Cauliflower: Choose a container with a minimum depth of 20 inches (51 cm).

Botanical Name: Brassica oleracea var. botrytis

Cauliflower is a member of the Brassicacea (Cruciferae) or cabbage family.

More tips: How to Grow Cauliflower.

Written by Stephen Albert

Stephen Albert is a horticulturist, master gardener, and certified nurseryman who has taught at the University of California for more than 25 years. He holds graduate degrees from the University of California and the University of Iowa. His books include Vegetable Garden Grower’s Guide, Vegetable Garden Almanac & Planner, Tomato Grower’s Answer Book, and Kitchen Garden Grower’s Guide. His Vegetable Garden Grower’s Masterclass is available online. Harvesttotable.com has more than 10 million visitors each year.

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