Grow Your Own Cauliflower Heads

I love to think of vegetable plants as falling into nice, tidy categories like leaves, roots, and fruit. But then I come across oddballs like broccoli and cauliflower. We don't grow these plants for their leaves (though they are edible and full of nutrients!), their roots, or their fruit.

We actually grow them for their unopened flower heads. That's right. The part of a cauliflower plant that we eat is something called an inflorescence, or a collection of tiny flowers. If you grow your cauliflower plant long enough, each of those tiny white buds will open up into a beautiful yellow flower. The goal, of course, is typically to harvest the head, also called the "curd", before all those flowers open up.

Cauliflower is in the Brassicaceae family, making it cousins with kale, cabbage, mustard greens, arugula, and radishes. I typically find cauliflower much trickier to grow than the rest of the family. It's really the odd-man out again. So follow this guide to find success when growing cauliflower at home.

When to Grow Cauliflower

Cauliflower loves cool weather. It thrives when temps are between 50 and 70°F. It's frost tolerant and can survive temps as low as 28°F. You have a much bigger problem if your temps start swinging the other way. Cauliflower doesn't like warm weather, especially not when it's trying to produce a head.

This preference for cool weather is one of the things that makes cauliflower a little difficult to grow. Your cauliflower plant needs at least 70 days of temps between 45 and 80°F to complete its growth. So you really have to figure out your best growing window and then plan ahead.

That window for most of us will be in the spring and fall. I've personally had much better luck growing cauliflower in the fall. Spring temps always seem to warm up too fast just as my plants are trying to form their heads. Plus, the plants actually like slightly warmer weather while they're putting on their leaves. For fall planting, you'll start seeds indoors about 90 to 100 days before your first frost. Aim to transplant seedlings about 60 days before your first frost. You should be able to harvest a nice-size head before winter sets in.

For spring planting, count back 100 days before your last frost date, and that's when you should start seeds indoors. Move transplants out as soon as your soil is workable.

Note:

If you live in a warm climate like Houston, your growing window will be over your winter months.

Where to Grow Cauliflower

These are large plants that need a lot of personal space. I typically give cauliflower at least 2 square feet to spread out. I have clients who love to grow cauliflower in their raised beds, but these plants take up too much of that precious raised bed real estate for me. I prefer to grow cauliflower in the ground or in a large container on its own.

To grow cauliflower in the ground, amend your native soil with some compost first. I've found that cauliflower grows really well right alongside the flowers in my native plant space, as long as I give it plenty of organic matter.

You can also grow cauliflower in grow bags or containers 18" deep and wide. Make sure your container has at least one good drainage hole in the bottom. I bought 4 of those big whiskey barrels from Home Depot and added drainage holes; I grow potatoes in them from about March to August and then turn them over to my cauliflower and broccoli in the fall.

How much sun does cauliflower need?

Cauliflower needs 6 to 8 hours of sunlight to form a nice head.

If your cool season falls during the short days of winter, this makes meeting cauliflowers's ideal growing conditions difficult. Spots that received tons of summer sun might stay shady under low winter sun. Ideally, broccoli should be planted in a southern-facing location (if you're in the Northern Hemisphere), away from any large structures that might block sun.

The Best Cauliflower Companion Plants

Avoid planting cauliflower with other vegetables in the brassica family (e.g., broccoli, kale, mustard greens, etc.), as they may attract more of the same pests. There's just something about brassicas that makes them magnets for pests. Cauliflower also tends to hog all the nutrients, leaving leafy greens around it with not much to grow on.

Some plants actually help improve the growth and flavor of cauliflower when planted nearby. These excellent companions include:

• Beans
• Celery
• Onions
• Peas

Other plants with really strong scents help to repel common garden pests that feed on cauliflower: 

• Chives
• Dill
• Rosemary
• Mint
• Garlic
• Thyme

I like to plant lots of lettuce plants around the base of cauliflower because they have shallow roots and won't mind being shaded. 

How to Start Cauliflower Plants

Because cauliflower takes at least 70 days to grow from seed to harvest, I recommend starting cauliflower by seed indoors at least 30 days before transplanting. Place just one seed per cell and barely cover them with soil.

Cauliflower seeds germinate best in cool soil, so don't use a heat mat under your seed starting trays. Don’t allow the soil to dry out before seeds have germinated, which usually takes about 8 to 10 days. Make sure to harden off your cauliflower seedlings before moving them permanently to the garden space.

If seed starting indoors isn't for you, buy some plant starts from a local nursery or farmers' market.

Transplant your cauliflower plants to the garden once the temperature is ideal. Space each plant 2 to 3 feet apart in rows if you're growing in the ground. Cover your plants with a floating row cover or garden mesh just after planting to prevent caterpillars.

Water in plants well and keep the soil consistently moist for the first 2 weeks after planting.

How to Care for Cauliflower Plants

While you wait for the head to grow, these are your main tending tasks:

Feeding Cauliflower

Cauliflower is considered a heavy feeder. Fertilize three weeks after transplanting with some fresh organic compost. Repeat every couple of weeks. I also sprinkle some earthworm castings whenever I suspect my plants could use a little nutritional boost.

Watering Cauliflower

Cauliflower plants prefer their soil to stay on the moist side because they have pretty shallow roots for such large plants. Provide regular supplemental watering if you're not getting much rain. A good rule of thumb is about 1 inch of water per week.

Avoid getting the leaves or developing cauliflower head wet when you water. Aim your water at the roots, where it's needed.

Supporting Cauliflower

Cauliflower can become a little top-heavy as it grows, so it benefits from something called hilling. Once the plant has developed its first few sets of leaves, push fresh compost up around the base. If needed, use a stake and some twine to support your growing cauliflower plant.

Pruning Cauliflower

Each week, prune some of those lower cauliflower leaves to make sure that each plant is getting good airflow and keeping a good distance from neighbors. This is especially important if you're growing cauliflower in a raised bed. Good news: The leaves that you prune are edible. I like to toss them into salads.

If you're growing cauliflower in the ground, take this opportunity to weed around your plants so they don't face any competition.

Regulating Temperature

Use a frost cloth to protect spring-planted cauliflower seedlings from late-season freezes. You don't need to cover established plants in the fall unless you're getting a hard freeze.

If you're planting in the late summer or early fall, use shade cloth to keep the soil nice and cool in those early days.

Blanching Cauliflower

If you want your head to be nice and white at harvest time, you'll need to do one extra tending task as soon as you notice the head start to form. All you have to do is gather some larger leaves loosely around the head and tie them together with some twine. (Make sure the head is dry so it doesn't rot.) Basically, you want to block sunlight but still give the head a little room to grow. Check on the head each week to make sure there's no moisture or pests trapped inside.

Note: You can skip this step if you're growing a self-blanching variety or a colored head.

Common Cauliflower Growing Problems

I always say cauliflower and broccoli aren't for beginners. They're just a tad too picky about their growing conditions to make things easy on gardeners, and as you can see from the list of problems below, many things can go wrong during the long time cauliflower will spend in your garden growing.

Here are common problems and how to prevent or solve them.

Problem: Curds turning brown

If you notice that the developing head of your cauliflower is turning brown even though you're blanching it, this is likely a boron deficiency.

Solution

Sprinkle some earthworm castings around the base of the plant and water it in well. This is a natural way to increase the nutrients your plants receive.

Problem: Head not developing

If your plant has lots of leaves but still no head, or if the head seems on the small side, there might be several different culprits. Your plant might be low on nutrients or not receiving enough water. This is causing it to feel too stressed out to spend energy developing a large head. The weather could also be too warm.

Solution

Support your plants with some fresh compost around the base, and make sure they're getting consistent water. If it's above 85°F during the day, consider using shade cloth to keep your plants nice and cool.

Problem: Leaves turning yellow

If the leaves turn yellow, then you likely have a nitrogen deficiency or bad drainage.

Solution

Give your plant a high nitrogen (but low phosphorus) fertilizer or blood meal. Blood meal is a quick nitrogen fix for yellowing leaves. Make sure you only water your plant when the soil is dry 1 to 2 inches down.

Problem: Holes in cauliflower leaves

If you're finding holes in your cauliflower plant's leaves between the veins, you've got caterpillars, most likely cabbage loopers or cabbageworms.

Solution

Check the underside of the leaves for small green caterpillars, and pick them off by hand if the problem is small. If it's out of control, use Bt (Bacillus thuringiensis), a natural bacterial pesticide.

Remember, the best way to prevent pest issues is to cover your plant with garden mesh the day of planting.

One good thing about growing cauliflower in the fall is that the pests should stop bugging you once you hit your first frost of the season.

Problem: Cauliflower leaves curling

Curling leaves are often a sign that the plant's sap is being sucked by soft-bodied insects, typically aphids.

Solution

Apply soapy water to all sides of leaves.

When to Harvest Cauliflower

The trick to harvesting cauliflower is waiting long enough to get a nice-sized head (about 6" wide) but no so long that the flower buds start opening up. If you notice the little curds becoming looser instead of tighter, your plant is about to bolt, or send up flowers.

If your plant flowers before you can harvest, don't worry. Not only is it still edible—flowers and all—some people actually prefer the flavor of flowering cauliflower.

Don't forget that you can harvest those cauliflower greens whenever you like. Cook them just like you would kale or cabbage. They're full of nutrients!

How to Harvest Cauliflower

The best time to harvest cauliflower is in the morning, before the day grows warmer.

To harvest cauliflower, use a clean pair of pruners or a sharp knife to cut the stalk just below the head. Dunk your head in a large bowl filled with ice water to increase its storage time. Pull off the leaves wrapped around the head for storage.

Unfortunately, cauliflower won't produce side shoots after harvest the way broccoli does. You can go ahead and remove your cauliflower plant from the garden by cutting it at the base, just above soil level. Leave the roots in the soil, and compost whatever plant parts you're not interested in eating (assuming the plant's not suffering any major pest or disease issues).

Enjoy your cauliflower head as soon as possible, when it's at its flavor and nutritional peak (think vitamin C, minerals, and tons of cancer-fighting phytochemicals). I love to toss cauliflower into curries, soups, and stews. You can eat cauliflower raw with some ranch or hummus, steam it, bake it in a casserole, or even pickle it.

How to Store Cauliflower

Cauliflower will keep for about 2 weeks in the humid produce drawer of your fridge. If you have several heads you want to store long-term, it's best to blanche them and then freeze them. They'll keep in the freezer for up to a year.

Time to Grow Some Cauliflower!

I hope this guide helps you figure out how to grow this tricky veggie. If you get the timing wrong and end up with a small head, you still have lots of nutritious leaves to enjoy!

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Sources

• National Library of Medicine
• South Dakota State University Extension
• University of Minnesota Extension