How Big Does Cauliflower Grow?


If you are growing cauliflower for the first time, or if you got small plants last year, you might be wondering how big cauliflower plants can grow.  I wanted to know the same thing, so I did some research to find out how tall and wide cauliflower plants can get, and how large cauliflower heads can grow.

So, how big does cauliflower grow?  Cauliflower plants can grow 12 to 30 inches (30 to 76 centimeters) tall and 12 to 30 inches (30 to 76 centimeters) wide.  The central head of cauliflower can grow as large as 9 inches (23 centimeters) in diameter, but most are 5 to 8 inches (13 to 20 centimeters) in diameter.

Of course, the quality of your cauliflower (if you get any at all!) depends on the care that you give your plants.  Let’s take a closer look at cauliflower, including size, growing conditions, and time to maturity.

How Big Does Cauliflower Grow?

The average size of a head of cauliflower is 5 to 8 inches (13 to 20 centimeters) in diameter, depending on the variety and when you choose to harvest it.  Some cauliflower plants can grow heads as large as 9 inches (23 centimeters) in diameter.

cauliflower
A head of cauliflower can range from 4 to 9 centimeters (10 to 23 centimeters) in diameter.

There are also smaller, faster-maturing varieties of cauliflower that yield heads with a diameter of 3 to 4 inches (8 to 10 centimeters) throughout the growing season.

The cauliflower plants themselves will grow to heights of 12 to 30 inches (30 to 76 centimeters) tall and 12 to 30 inches (30 to 76 centimeters) wide.

Of course, the shorter, more compact varieties will often produce cauliflower heads of smaller diameter.  The trade-off is that the heads mature more quickly than larger varieties.

How Long Does It Take Cauliflower to Grow?

Some cauliflower plants, such as Fioretto from Burpee or White Corona from Burpee, can produce mature heads in as little as 30 days (4 weeks) after transplanting outdoors!  However, these heads tend to be on the smaller side, with a diameter of 4 to 5 inches (10 to 13 centimeters).

cauliflower
Most cauliflower plants will take 70 to 100 days from planting a seed to harvesting a mature head.

For cauliflower plants with larger heads, it can take 35 to 70 days (5 to 10 weeks) after transplanting to produce mature heads.  Of course, seeds need to be started indoors several weeks before transplanting outdoors.

Cauliflower seeds will take 4 to 10 days to germinate under ideal temperatures of 65 to 85 degrees Fahrenheit (18 to 29 degrees Celsius).  It will take at least a few weeks longer until the young cauliflower plants are ready for transplant.

This means that larger varieties of cauliflower will take 70 to 100 days (10 to 14 weeks) from planting a seed to harvesting a mature head.

How Many Heads of Cauliflower Do You Get From One Plant?

A cauliflower plant will produce one large, central head, as long as growing conditions are ideal.  This includes moist soil with organic matter and proper temperatures.

If the temperature is much higher than 70 degrees Fahrenheit (21 degrees Celsius), it may cause the cauliflower to “button”.  This means that the cauliflower plant forms small and underdeveloped heads, rather than growing a single well-developed head.

For more information, check out this article on cauliflower from the Old Farmer’s Almanac.

How Do You Know When to Pick Cauliflower?

A head of cauliflower should be firm, and the “bunches” should be compact and clustered close together.  If you wait too long to harvest, flowers will emerge from the plant, and the head will become bitter to the taste.

When cauliflower bunches start to open up, then flowering is imminent.  At that point, it is time to harvest the head, even if the size is smaller than what you were hoping for.

Most normal varieties of cauliflower will be ready to harvest when the head reaches a diameter of 6 to 8 inches (15 to 20 centimeters).  Smaller, more compact varieties of cauliflower that mature more quickly may be harvested when the head reaches a diameter of 4 to 5 inches (10 to 13 centimeters)

Of course, the diameter of a cauliflower head at maturity will depend on the variety, so check the seed packet or catalog to be sure.

What Does Cauliflower Look Like?

Cauliflower has an appearance similar to broccoli, except that its heads are normally white (although there are also yellow, orange, and purple cauliflower heads!)

purple cauliflower
Some cauliflower has heads that grow purple (as seen here). You may also see yellow or orange cauliflower heads. Most, however, are white.

Like broccoli, cauliflower heads are formed from clusters of tiny buds (they can eventually grow into flowers).  These buds (flower heads) are the part of the plant that we eat before the flowers bloom.

Why Are My Cauliflower Plants So Small?

Any conditions that stress your cauliflower plant will cause it to grow heads that are smaller than normal.  This is due to the fact that the plant will “go to seed”, or try to produce flowers to reproduce, due to a perceived shortage of resources.

Conditions that stress a cauliflower plant include drought, extreme temperatures, and a lack of nutrients in the soil.  I have included more information on watering, ideal temperature, and fertilizing for cauliflower plants below.

Are Cauliflower Plants Hard to Grow?

Cauliflower likes full sun, so be sure to plant them in an area where they get 8 or more hours of sunlight per day.  Avoid planting cauliflower in a place where it will be completely shaded by a tree or tall neighboring plants (such as tomatoes).

Cauliflower grows best in well-drained soil with a pH of 6.0 to 7.0 (slightly acidic).  However, there are many other factors that affect cauliflower growth, including temperature, watering, fertilizing, and spacing.  Let’s start with temperature.

Temperature for Cauliflower

The minimum temperature for cauliflower seed germination is 40 degrees Fahrenheit (4 degrees Celsius).  If the soil is any colder than this, you will see low germination rates – that is, if you can get any seeds at all to germinate!

This is nature’s way of protecting cauliflower seeds from sprouting at a time when they will be unable to survive.  This is why it is suggested that you start cauliflower seeds indoors to avoid cold soil temperatures in early spring.

The maximum temperature for cauliflower seed germination is 95 degrees Fahrenheit (35 degrees Celsius).  If the soil is any warmer than this, germination rates will decrease.

Combined with high humidity, high temperatures can encourage the growth of mold, which is another threat to your plants.  So, don’t wait too long to plant your cauliflower seeds and transplant your established plants outside!

You should start cauliflower seeds indoors 6 to 8 weeks before transplanting into the garden.

The ideal (optimal) temperature for cauliflower seed germination is between 65 degrees Fahrenheit (18.3 degrees Celsius) and 85 degrees Fahrenheit (29.4 degrees Celsius).

Keep in mind that these temperatures refer to soil temperature, not air temperature.  If you want to find out the soil temperature, use a probe-type thermometer to check.

If the thermometer reads a temperature that is too low, then you have some options.  One option is to wait until the sun warms up the soil.

To speed up this process, clear away any debris, such as leaves or grass clippings, from the soil surface.  Also make sure to choose a location for planting that gets plenty of sun, so that it can warm up the soil faster.

If you are worried about a short growing season, you can also use a cloche (a plastic or glass cover) to trap some heat and warm up the air and soil near your cauliflower seeds.

A cloche can be made from a plastic water bottle to retain warmth and humidity in the soil for seeds or seedlings as they grow.

For more information, check out the table below, and check out this article from the University of California on ideal seed germination temperatures.

Seed
Germination
Temperature
Temperature
(degrees
Fahrenheit)
Temperature
(degrees
Celsius)
Minimum 40 4
Ideal 65 to 85 18.3 to 29.4
Maximum 95 35

Watering for Cauliflower

Cauliflower needs regular watering, so keep the soil moist to avoid water stress.  This is a key factor for preventing “buttoning”, or premature flowering, which leads to small heads and bitter taste.

You may need to water more often for sandy soil, which drains quickly even when soaked thoroughly.  Dry, sunny weather also means you will need to water more often.

garden hose
Be sure to keep the soil moist for your cauliflower plants, to avoid bolting (premature flowering) and small, bitter heads.

Putting mulch on top of your soil will help to retain moisture.  If you find that you have a problem with dry soil, check out my article on how to treat dry soil.

On the other hand, over watering your cauliflower plants (or any plants for that matter) can lead to root rot and eventual death.  The best way to decide when to water is to feel the soil with your fingers.

If the soil feels dry 2 or 3 inches below the surface, then go ahead and water.  For more information, check out my article on over watering your plants.

Try to water early in the morning, rather than at night, to allow water to soak into the soil before evaporating.

For more information, check out this article on growing cauliflower from the University of Minnesota Extension.

Fertilizing for Cauliflower

Adding compost to your soil before planting cauliflower is a good way to improve drainage for clay soil, improve water retention for sandy soil, and add nutrients to your garden.

compost bin
Compost is a good way to add organic material and nutrients to your soil white recycling kitchen scraps and yard waste.

For more information, check out my article on making compost.

The University of Georgia Extension suggests using a 5-10-15 fertilizer at a rate of 2 pounds per 100 square feet of soil

Avoid excessive nitrogen or manure that has not decomposed completely, since this can burn your plants.

For more information, check out my article on over fertilizing your plants.

Spacing for Cauliflower

When starting cauliflower seeds indoors, sow the seeds 0.25 inches (0.6 centimeters) deep, 10 to 12 weeks before the last frost date.  You can find frost dates in your area on the Farmer’s Almanac website.

Transplant the young cauliflower plants outside 2 weeks before the last frost date.  Space the plants 18 to 24 inches (46 to 61 centimeters) apart in a row (leave more space for fall plantings).

Leave 30 inches (76 centimeters) between rows.  This will allow space for watering, weeding, fertilizing, and harvesting your cauliflower plants.

For more information, check out this article on cauliflower from the University of Illinois Extension.

Conclusion

By now, you should have a better idea of how big cauliflower can grow.  You also have some tips on how to help cauliflower plants to grow to their full potential.

I hope that this article was helpful – if so, please share it with someone who can use the information.  If you have any questions or advice of your own about growing cauliflower, please leave a comment below.

jonathon.david.madore

Hi, I'm Jon. Let's solve your gardening problems, spend more time growing, and get the best harvest every year!

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