Cauliflower Seed Germination: Tips On Planting Cauliflower Seeds

Individually Planted Cauliflower Seeds In Gardening Tray
cauliflower seedlings
(Image credit: doidam10)

Cauliflower is a little harder to grow than its cabbage and broccoli relatives. This is mainly because of its sensitivity to temperature – too cold or too hot and it won't survive. It’s far from impossible, though, and if you’re looking for a little bit of a challenge in your garden this year, why not try growing cauliflower from seeds? Keep reading for a cauliflower seed planting guide.

Cauliflower Seed Germination

Cauliflower grows best at around 60 degrees F. (15 C.). Too far below that and the plant will die. Too far above it and the head will “button,” meaning it will break off into lots of small, white parts instead of the desired solid, white head. Avoiding these extremes means growing cauliflower from seeds very early in the spring, then transplanting them outside. The best time for planting cauliflower seeds indoors is four to seven weeks before the last average frost. If you have short springs that get hot quickly, you should aim for closer to seven. Sow your seeds in fertile material at a depth of half an inch (1 cm.) and water them thoroughly. Cover the soil with plastic wrap until the seeds have sprouted. Cauliflower seed germination usually takes eight to ten days. When the seedlings appear, remove the plastic and keep the soil evenly moist. Place grow lights or fluorescent lights directly over the seedlings and set them on a timer for 14 to 16 hours per day. Keep the lights just a few inches (8 cm.) above the plants to keep them from getting long and leggy.

Growing Cauliflower from Seeds

Transplant your seedlings outside two to four weeks before the last frost date. They’ll still be sensitive to cold, so make sure to harden them off carefully first. Set them outside, out of the wind, for about one hour, then bring them inside. Repeat this every day, leaving them outside an hour longer each time. If it’s unusually cold out, skip a day. Keep this up for two weeks before planting them in the ground.

Liz Baessler
Senior Editor

The only child of a horticulturist and an English teacher, Liz Baessler was destined to become a gardening editor. She has been with Gardening Know how since 2015, and a Senior Editor since 2020. She holds a BA in English from Brandeis University and an MA in English from the University of Geneva, Switzerland. After years of gardening in containers and community garden plots, she finally has a backyard of her own, which she is systematically filling with vegetables and flowers.