Robin Gale-Baker, from Sustainable Macleod, discusses growing cauliflower. She has also written articles for this website about growing broad beans, eggplants and capsicums, other vegetables, apricot trees, persimmon trees, other fruit trees, herbs and growing techniques.
Cauliflower is sometimes avoided by gardeners because of poor results but it is actually very easy to grow large, beautiful, compact, snowy headed plants. The cauliflower head is the flower and it consists of unopened curds or florets which should be tight and white. When they are loose and yellow, they are unappealing and this is usually caused by exposure to strong sunlight. To avoid this, tie the inner leaves over the cauliflower head. Some varieties called ‘protecting’ or ‘self blanching’ will naturally do this but other varieties will need your intervention. Don’t worry if the leaf breaks. It will still do its job. This process will also protect the heads from frosts.
There are two main reasons why cauliflowers develop small heads. The first is caused by hot weather – they are, after all, a winter crop requiring cold soil and air. The second is wobbly stems which are, in turn, caused by seedlings not being planted deeply enough in the soil. As the wind blows the stem from side to side, the plant loses traction in the ground and the roots become loose and don’t do their job.
Plant seedlings so that their base leaves are covered in soil. If you find that your stem is too high then dig it out and plant it deeper or, if you only notice this at a later stage, then hill the soil up the stem so that it covers the base leaves. In fact, it would be difficult to plant a cauliflower too deeply! If the top leaves are exposed, it will grow well. The stem will not rot (which seems to be many peoples’ concern). You could also hill the plants in the first place, a practice that was normal for both my grandfathers, and one I am experimenting with this year.
In Autumn, prepare your garden beds by forking over your soil to break up the surface crust, aerate it, and allow moisture to penetrate. It is important that you spend time watering and moistening your soil which is likely to be quite dry after summer. Make sure your site is well drained, however, as cauliflowers do not do well in water logged soil. Remove any stones, sticks and break up clods. Then dig in lots of compost and low nitrogen manure (high nitrogen manure such as chicken or fish leads to leaf development at the expense of cauliflower heads).
The pH should be 6.5 – 7.5. Acidic soil results in deformities such as whiptail and clubroot that cannot be later remedied. If your soil is acidic, it may need lime or dolomite but test first. If you do need to add one of these, your preparation time will be extended as liming needs to happen a month before the addition of manure or it ties up the nutrients in the manure.
For good heads, regular watering is essential throughout, and mulching is important for weed suppression and moisture retention.