Successful planning can result in a year-round cauliflower crop. Some care is required with white varieties during spring and summer months to prevent yellowing.
Exposure to the sun can cause the heads of white cauliflower varieties to turn yellow, in some cases a light off-purple or off-grey colour, however, the seeds stocked here at Growseed are prone to yellowing more so than purple.
Some white cauliflower varieties are self-wrapping, which helps prevent this process from occurring.
Self-wrapping refers to when the leaves of the cauliflower grow to cover the head of the vegetable.
For varieties that are not self-wrapping, a simple method can be used to produce the creamy-white heads that many look for in cauliflower. If your cauliflower does suffer from yellow staining from the sun, you can still eat it! No need to compost the plant. The creamy white cauliflower is often a feature sought after if you are running a market garden!
Follow these tips for uniformly whiteheads.
The time to start protecting the head is when the developing heads are just visible through the leaves, about 1–2" in diameter (it will look like sprouting broccoli)
Gather the outer wrapper leaves and pull them over the heads, securing them together with garden twine, wire can be OK however in wind will rub too harshly against the leaves and risk damaging the plant.
Another method is to lightly break or "crack" the midribs of the leaves and fold them over the head until it is completely covered. Do not break the leaves, or they may blow away, nor should you bend them at the base as they will fall off and damage the plant's growth.
Check the heads as they develop.
Tied or covered heads may be subjected to increased humidity levels, increasing their susceptibility to diseases such as Alternaria.
The above method is only required during spring and summer crops, it becomes less important in the cooler, shorter days of autumn. Please note there is no need to tie the leaves around the heads of coloured cauliflower varieties (purple, yellow, green, orange) — they need exposure to sunlight to achieve the deep colouring!