How to Grow Cauliflower in the UK: A Detailed Guide

Growing above the soil, cauliflower is part of the Brassica family along with Brussels sprouts, collards, kale and broccoli. There are more varieties, however,the main three types of cauliflower are mid-summer, autumn, and winter varieties. Although it’s a cool season crop, depending on your location and the variety, you can plant and harvest them for most of the year. 

If you’re looking to learn more about growing cauliflower in your allotment, read on. In this guide, we share all the tips and tricks that you need for successful cauliflower crops, from when to plant cauliflower to when to pick cauliflower. 

How to Grow Cauliflower

You can start as early as February by sowing indoors, in seed trays. When sowing your cauliflower seeds, it is good to have a surplus for any that fail. However, cauliflowers tend to be ready all at once and you can find that you have too many! 

You can sow them until May time and again in autumn for over wintering varieties. If you are doing both, you will likely be able to harvest cauliflowers for most of the year, depending on sowing times and weather conditions.

When to Plant Cauliflower

Sow outdoors or plant out during spring for those early varieties. You can usually harvest approximately 3 to 6 months later however it can take a lot longer, depending on the conditions. 

Cauliflowers like fertile soil and plenty of water at the roots. It is worth digging in lots of well-rotted manure or organic compost when you are preparing your soil. Space the cauliflower plants approximately 2 ft apart and allow a bit of extra space for winter cultivators. Cauliflower plants should be planted deeply; up to the bottom leaves. Do check your seed packet guidelines, also factoring in your soil type, weather conditions and positioning of the soil bed. 

When to Pick Cauliflower 

The formed head may differ depending on your variety and its stage of growth. When a cauliflower is ready to harvest, it should be white and firm. If the florets begin to separate it will be past its best and needs to be harvested before this happens. Once the heads do form, they can appear and grow quickly, so you need to check them regularly. Some varieties come with yellow and purple heads! Some may be larger or smaller than others. 

How to Harvest Cauliflower

Leave the cauliflower head to grow to about 6 to 8 inches or as long as it stays compact. To harvest your cauliflowers, cut them off at the stem so that you have the head with some leaves surrounding it. You can clear the bed of root and debris once all your crop is lifted.

Growing Cauliflower in the UK - Common Problems

Cauliflowers, like most brassicas, attract pests and are best protected by mesh or fine netting. This is  to prevent insects, caterpillars, slugs and snails from eating the leaves as well as butterflies and birds that will eat the heads. 

Insects such as aphids, loopers, root maggots, cabbage worms, stink bugs, and thrips can cause your cauliflower plant to develop yellow or misshapen leaves and stunt their growth. Thrips leave white patches or silver streaks on the base leaves and leave brown streaks on cauliflower heads. 

Clubroot, white rust, black rot, and downy mildew are common fungi affecting cauliflower plants. They’ll often cause blisters, yellow leaves, and leave white, purple or grey cottony growth on the undersides of leaves.

Removing affected plant debris, destroying any crop residue, growing companion plants, and spraying with bacterial pesticide can help deter further attacks from pests and fungi.

A cauliflower plant deficient in nitrogen will often develop yellowed bottom leaves and if left untreated can continue to the top of the plant. Ensure you supply your plant with a fertiliser high in nitrogen but low in phosphorus.