Cauliflower Planting Guide: Tips on How To Grow Cauliflower Plants

Cauliflower can be a little more demanding than some of its brassica relatives such as cabbage and kale, but growing it at home is entirely possible when you give the plants the conditions they need. This cool-season vegetable is especially sensitive to temperature, moisture, and other stressors, so pay attention to timing in order to produce a well-formed and delectable-looking crop.

Cauliflower is grown for its edible head, or curd. This is actually a cluster of undeveloped flower buds. Most cauliflower has a white to cream-colored head, but other varieties can produce purple, orange, and even green curds. Unlike broccoli, which can produce multiple side shoots, cauliflower generally produces a single main head.

The trick to growing cauliflower is to give plants enough time to develop before temperatures become too hot, while also protecting young plants from damaging cold. With an eye toward timing, fertile soil, consistent moisture, and regular attention, cauliflower can be a rewarding cool-season crop for anyone starting a vegetable garden.

Quick Cauliflower Facts

What is Cauliflower?

Cauliflower (Brassica oleracea var. botrytis) is a member of the Brassicaceae, which also includes broccoli, cabbage, kale, Brussels sprouts, kohlrabi, and turnips. The part we eat is the curd, or a compact cluster of undeveloped flower buds.

Cauliflower is generally grown as an annual vegetable, although it is botanically a biennial. In its first year it produces leaves and a head; if unharvested and allowed to remain in the garden, it can flower and produce seed in its second year.

Cauliflower is particularly sensitive to temperature compared to the other common brassica crops. Plants grow best in cool conditions, with temperatures around 60–65°F (16–18°C). Temperatures that are too high, too low, or that fluctuate sharply can interfere with head development.

Types of Cauliflower

Cauliflower comes in more colors and forms than the familiar white heads you find in the supermarket. Whatever color you decide on, choose a variety suited to your climate and the season in which you plan to grow it.

• White cauliflower: The classic cauliflower, with a white to cream-colored curd. Many white varieties need blanching to protect the developing head from sunlight and keep it pale.
• Purple cauliflower: Purple varieties contain anthocyanins, pigments that give the curds their distinctive color. Some purple tint can also develop on white cauliflower because of environmental conditions and sun exposure.
• Green cauliflower: Green varieties retain their color when exposed to sunlight and do not need blanching in the same way white varieties do.
• Orange cauliflower: Orange varieties contain pigments that give the curds their characteristic color and, like green and purple varieties, are generally grown without blanching.
• Romanesco: Romanesco is a distinctive green, pointed form related to cauliflower and is suited to cool-season growing.

A few varieties to consider include Sicily Purple cauliflower and Early Snowball cauliflower. For a classic white cauliflower, consider 'Snowball Y’ cauliflower seeds from Burpee.com, an early variety that produces 6-in., snow-white heads that can be grown for either spring or fall harvests.

Planting Cauliflower

Again, timing is the most important consideration when planting cauliflower. This crop needs cool weather to form a good head, but young plants can be damaged by hard freezes. Plan the crop so the plants can mature before the hottest part of the season. If an unexpected frost threatens your cauliflower crop, cover plants with a frost cloth such as the Agfabric 1.2 oz. Frost Cloth from Home Depot, which helps protect plants from freezing temperatures while allowing light and moisture to reach them.

When to Plant Cauliflower

Cauliflower grows best at around 60 °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 seeds germinate in 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.

For a fall crop, start seeds in midsummer or direct sow them in the garden according to the expected fall harvest date. Fall planting can be particularly useful because cauliflower develops best in cooler weather.

Because cauliflower is sensitive to temperature, use the seed packet's days-to-maturity information along with your local frost dates to determine the best planting window.

Best Soil for Cauliflower

Choose fertile, well-draining soil that is rich in organic matter. Cauliflower needs consistent access to moisture and nutrients. Improving your soil with compost or leaf mulch will help the soil retain moisture and access to nutrients.

Light Requirements

Give cauliflower at least six hours of direct sunlight each day. Full sun supports strong leaf growth and head development. In very warm conditions, protecting the crop from intense afternoon heat may help reduce plant stress.

How to Plant Cauliflower Step-by-Step

Follow these steps for planting to get your cauliflower crop off to the best start possible.

1. Start seeds. Sow seeds about ¼ inch (6 mm) deep in a well-draining seed-starting medium. Keep seedlings evenly moist and provide bright light.
2. Harden off. Gradually acclimate seedlings to outdoor conditions for about a week before transplanting.
3. Prepare the bed. Work compost or other well-rotted organic matter into fertile, well-draining soil.
4. Transplant. Set plants out on a cool, cloudy day or in late afternoon to reduce transplant stress. When transplanting cauliflower seedlings, a lightweight transplanter such as the Fiskars Lightweight Transplanter Garden Tool from Target makes it easier to dig an appropriately sized planting hole without disturbing the surrounding soil.
5. Space plants. Space plants about 18–24 in. (46–61 cm) apart, with 30–36 in. (76–91 cm) between rows.
6. Water. Water thoroughly after planting and be sure to keep consistently moist through the growing season.
7. Mulch. Apply a light layer of mulch around young plants to conserve moisture and suppress weeds.

Cauliflower Care

Once you’ve addressed the correct timing for planting your cauliflower crop, your crop’s success comes down to consistent maintenance.

How Often to Water Cauliflower

Steady and reliable moisture is essential for cauliflower’s proper development. Keep the soil evenly moist but not waterlogged, especially as the cauliflower head develops. Allowing the crop to experience drought stress can lead to small, poorly formed, or loose heads. Water deeply enough to moisten the root zone. Keep in mind that as the plants grow bigger aboveground, their root zones are expanding as well. Avoid letting the soil dry completely!

Fertilizing

Cauliflower is a relatively heavy feeder and will do well in fertile soil amended with compost before planting. Fertilize at transplanting time according to the directions of whichever product you’re using, then side-dress with a nitrogen-rich fertilizer or compost once plants are established. A balanced vegetable fertilizer such as Scotts Flower and Vegetable 10-10-10 All Purpose Plant Food, available from Lowe's, can provide supplemental nutrients during the growing season. Avoid excessive nitrogen; too much can contribute to loose heads and excessive leafy growth.

Mulching

A light layer of mulch helps conserve soil moisture, moderate soil temperatures, and suppress weeds. Keep mulch away from the cauliflower’s stem and avoid creating persistently wet conditions right around the plant.

Protecting Cauliflower Plants

Cauliflower is cold hardy, but it’s not invincible, especially when it’s young and tender, so some cauliflower frost protection is necessary in the spring. Start your cauliflower seeds indoors and transplant them outside around the time of the average last frost. If a later frost is likely, protect your young plants with row covers. Likewise, cauliflower has just as hard a time with hot weather. If grown too late into the summer, the plants are likely to get leggy and bolt. Protect them by starting them early enough in the spring or close enough to autumn that they avoid the hottest days.

Blanching Cauliflower Plants

Heads of white cauliflower are often protected from direct sunlight to prevent the development of color. This is called blanching. If heads are not protected, the curds will turn greenish brown and the flavor will also be much strong, even bitter.

When the head is the size of a golf ball or an egg, gently pull the large outer leaves over it and secure them loosely with a soft tie or clip. Some varieties are self-blanching and naturally curl their leaves over the head. Also pay attention to the time of day you do this. Cauliflower is extremely susceptible to fungus. Tie the leaves during the driest part of the day so you don't trap moisture inside your leaf cover.

Green, orange, and purple cauliflower varieties, on the other hand, generally need sunlight to develop their color and should not be covered in the same way as white varieties.

Harvesting Cauliflower

Keep a close eye on developing heads because cauliflower can move from harvest-ready to overmature in quick fashion. Harvest while the curd is firm and compact and before the individual flower buds begin to separate.

For many plants, the head is ready to harvest when it reaches about 6 in. (15 cm) or more across, although the mature size depends on the variety. Use a sharp knife to cut the head from the plant, leaving some of the surrounding leaves attached to help protect it.

Propagating Cauliflower

The simplest way to propagate cauliflower is from seed. Because cauliflower is a biennial, if you allow a healthy plant to remain in the garden through its second year, it can flower and produce seed.

Cauliflower is insect-pollinated and can cross with other members of the Brassica oleracea group, so harvesting and saving seed requires careful isolation if you want to maintain the exact variety from year to year.

Cauliflower Problems

Cauliflower is particularly sensitive to environmental stress, so problems with head formation are often related to temperature, moisture, nutrition, or timing. Pests and diseases can also damage plants and reduce the harvest.

• Insect pests: Aphids, flea beetles, slugs, snails, leafhoppers, and caterpillar larvae can damage cauliflower foliage and heads.
• Diseases: Cauliflower can be affected by fungal, bacterial, and soilborne diseases, including downy mildew, bacterial soft rot, blackleg, damping off, clubroot, and wilt diseases.
• Wilting plants: Heat stress, inadequate or excessive moisture, and diseases such as clubroot or wilt can cause cauliflower plants to wilt.
• Headless cauliflower: Stress from temperature extremes, drought, inadequate nutrition, root restriction, insects, or disease can prevent normal head formation.
• Loose heads: Heat, drought, inconsistent growing conditions, and excessive nitrogen can result in loose curds.
• Fuzzy or “riced” heads: Temperature fluctuations, moisture stress, and nutritional problems can cause the curd to develop a fuzzy or velvety appearance.
• Purple tint on cauliflower: A purple tinge is not necessarily a disease. Sun exposure and environmental conditions can cause purple coloration in otherwise white cauliflower.

Growing Cauliflower in Containers

Cauliflower can be grown in containers because its roots are relatively shallow. Be sure the container is wide enough to accommodate the plant. A container about 12–18 in. (31–46 cm) wide and at least 8–12 in. (20–30 cm) deep is suitable for one plant.

Use a lightweight, well-draining potting mix rather than garden soil. Place the container in full sun and keep the potting mix consistently moist. Container-grown plants may need regular feeding because nutrients leach from potting mix more quickly than they do from garden soil.

Growing Cauliflower Indoors

Cauliflower can be grown indoors, although it needs plenty of space and strong light to produce a full-sized head. Choose a large container about 12–18 in. (31–46 cm) wide with good drainage. Place it in a sunny location that receives at least 6–8 hours of direct light daily, or supplement with grow lights. If your indoor growing space doesn't provide enough natural light, a grow light such as The Sill's Aspect Gen 2 LED Grow Light can provide supplemental illumination for cauliflower plants.

Keep the soil consistently moist and provide good air circulation around the plant. Because cauliflower prefers cool temperatures, avoid placing it near heat sources or in a warm room.

Companion Planting with Cauliflower

The best companion plants for cauliflower include vegetables and herbs that can help deter pests, attract beneficial insects, or make efficient use of garden space.

The most beneficial companion plants for cauliflower include:

• Beans: Help deter pests and attract beneficial insects, making them a good companion for cauliflower.
• Celery: Attracts beneficial insects and uses plenty of water without competing heavily with cauliflower for nutrients.
• Onions: Pair well with cauliflower and can help deter pests with their strong scent. However, don't plant onions, beans, and cauliflower together because beans and onions are not compatible companions.
• Beets: Make good companions for cauliflower and can be grown nearby without competing heavily for space.
• Broccoli and Brussels sprouts: Share similar growing conditions with cauliflower and can be grown together in the same cool-season vegetable garden.
• Chard and spinach: These leafy greens are recommended companions that can be grown alongside cauliflower without taking up excessive space.
• Cucumber: Can be grown near cauliflower as part of a diverse vegetable garden.
• Corn: Provides a taller companion crop that can be grown near cauliflower.
• Radishes: Make useful companions for cauliflower and can be harvested relatively quickly, making efficient use of garden space.
• Sage and thyme: Their strong scents may help deter some pests, while their flowers attract bees and other beneficial insects.

Avoid planting these crops near your cauliflower:

• Peas: Can stunt the growth of cauliflower.
• Strawberries: Can attract slugs, which may then become a problem around cauliflower.
• Tomatoes: Are heavy feeders and may compete with cauliflower for nutrients.

Cauliflower Growing Essentials

• Looking for a classic white cauliflower variety? Consider 'Snowball Y’ cauliflower seeds from Burpee.com. This is an early variety that produces 6-in., snow-white heads that can be grown for either spring or fall harvests.
• A grow light such as The Sill's Aspect Gen 2 LED Grow Light can provide supplemental illumination for cauliflower plants.
• A balanced vegetable fertilizer such as Scotts Flower and Vegetable 10-10-10 All Purpose Plant Food, available from Lowe's, can provide supplemental nutrients during the growing season.
• Cover plants with a frost cloth such as the Agfabric 1.2 oz. Frost Cloth from Home Depot if and when freezing temperatures are expected.
• A lightweight transplanter such as the Fiskars Lightweight Transplanter Garden Tool from Target makes it easier to transplant your cauliflower seedlings into the garden.