Why Are My Cauliflowers So Small?

Cauliflower, with its tasty and nutritious florets, is a favorite vegetable in many households.

Usually creamy white in colour there are also colourful varieties that come in shades of orange, purple, and green.

Why Are My Cauliflowers So Small - Different Coloured Califlowers

Gardeners, however, may encounter a common issue: cauliflower heads that are smaller than expected.

If you have ever wondered “Why are my cauliflowers so small?” you are not alone.

In this article, we’ll have a look at the factors that cause undersized cauliflower heads and how to fix them.

Small cauliflower heads can be caused by the variety you are growing, or environmental factors such as sunlight, water, temperature, spacing and nutrient levels. Keep an eye out for fungus or disease, and consider netting to keep pests at bay.

Varietal Characteristics

The choice of cauliflower variety can definitely affect head size.

Some varieties naturally produce smaller heads, while others are bred for larger, heavier heads.

There are mini varieties that only grow to the size of a tennis ball.

How to fix:

  • When choosing seeds or plants, research the growth habits of different varieties.
  • Choose cauliflower varieties that are known for producing larger heads.
  • Read seed catalogs, gardening references, and online resources to find varieties with good head development.

Environmental Factors

Environmental factors like poor air circulation, competition from weeds, and not enough sunlight can slow cauliflower growth.

You want the best start for your crop so planning and preparation is needed.

How to fix:

  • Before you start planting, choose an area that has good sunlight (at least 6 hours a day) and has some protection from wind.
  • Make a raised bed, or set aside a large, deep area.
  • Prepare the soil by weeding and tilling, to create a clean and aerated substrate for your plants.
  • You can then add some organic matter to enrich the soil if needed.
Why Are My Cauliflowers So Small - Cauliflowers Growing

Plant Spacing

Proper spacing between cauliflower plants is essential for the best growth.

Crowded plants compete for nutrients, sunlight, and space, which can result in smaller heads.

How to fix:

  • Follow the spacing guidelines provided for your specific cauliflower variety.
  • Remember that the adult plants will be quite large, so you will need about 50cm to 70cm (approximately 20 – 30 inches) between each plant to account for the spread.
  • Adequate spacing allows plants to receive the necessary sunlight, nutrients, and airflow for healthy growth.
  • Make sure the beds are quite deep too, to give the roots enough space to grow.

Nutrient Availability

Cauliflower requires a steady supply of nutrients to support its growth.

Low amounts of nutrients, especially a lack of nitrogen, phosphorus, or potassium, can reduce cauliflower growth and lead to smaller heads.

How to fix:

  • Apply a balanced fertiliser or compost before planting and top up every now and again throughout the growing season.
  • Keep an eye on plant health and adjust fertilisation based on how the cauliflowers are looking.
  • Be careful not to over fertilise as this can cause lots of leaves to grow, but a small head.
  • If you soil is rich to begin with, you may need little or no fertiliser.
  • Weed regularly to stop the nutrients being taken by other plants.
Why Are My Cauliflowers So Small - Small Cauliflower Head With Leaves

Soil Quality and pH

Cauliflower loves well-draining, fertile soil with a slightly acidic to neutral pH (around 6.5 to 7.0).

Compacted or heavy soil structure, poor drainage, or the wrong pH level can interfere with nutrient uptake and root development, which will then affect head size.

How to fix:

  • Prepare your planting area by enriching the soil with organic matter like compost.
  • Make sure the soil is aerated, loose and with good drainage – add some sand or grit if you have heavy soil.
  • You can use a soil test to determine nutrient levels and the pH level if necessary.
Why Are My Cauliflowers So Small - Cauliflower Head Growing

Water Management

Cauliflower prefers consistent moisture, but overwatering or underwatering can affect its growth.

Inconsistent watering will cause stress, reduced growth, and smaller heads.

How to fix:

  • Provide even and sufficient water, particularly during the critical head-forming stage.
  • Mulch around plants to retain soil moisture.

Temperature Fluctuations

Cauliflower growth can be affected by temperature fluctuations, especially during the early stages of development.

Exposure to extreme heat or cold can result in stress and smaller head formation.

In some regions, cauliflower is grown as an autumn or winter crop, preferring cooler temperatures.

This means sowing in spring and harvesting in autumn.

Planting too late in the season or during unfavorable conditions can lead to smaller heads.

How to fix:

  • Plant cauliflower at the right time for your region, taking advantage of cooler seasons.
  • Consider using row covers or shade cloth to protect plants from extreme heat or cold.
  • Mulch around the base (avoid touching the stem). This will protect the soil and help in maintain an even temperature.
Why Are My Cauliflowers So Small - Small Cauliflower

Pests and Disease

Pests and diseases can weaken the health and vitality of cauliflower plants which then limits the size of the head.

Regular monitoring and good garden hygiene are really important.

How to fix:

  • Regularly check your plants and take appropriate action to stop pest infestations.
  • This can be as simple as picking off bugs when you see them (I then put them out for the birds to eat).
  • Net cauliflower beds to prevent caterpillars and birds eating the leaves (you will need quite a fine net).
  • Clean all tools before and after use to minimise the spread of disease or fungus that may be present.
  • Regularly clear debris and decomposing matter from around the base of the plants.
  • This will improve airflow and discourage fungus build-up.
  • When watering, water from the base rather than from overhead. Wet foliage can lead to fungus forming on the leaves.
  • Prune away any yellowing or damaged leaves to promote healthy growth.
Why Are My Cauliflowers So Small - Caterpillar On Cauliflower

Not Ready To Harvest

Small cauliflower heads may simply be because they are not yet ready to harvest.

Cauliflowers will usually take about five to six months to grow from seed to full development.

How to fix:

  • Keep checking your cauliflowers as they approach the autumn.
  • Harvest before the florets start to separate, at this point the heads can become bitter.
  • Too much sun can cause discoloration, so if they look like they are discolouring but need more time to grow then you can cover the head with picked leaves to protect them as they mature.

Final Thoughts

In order to have your cauliflowers reach their full size, preparation and ongoing care are needed.

When grown to their full potential, cauliflowers can produce a really good size yield.

It can take time, and trial and error – my first crop of cauliflowers were entirely eaten by pigeons before they could even grow heads!

My second attempt was more successful as I used a fine net to protect the crop.

So don’t give up, keep trying and keep learning!

Some other great crops to try are courgettes (zucchini) and cavolo nero.

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