cardboard, enough to create a 6- to 8-inch circle to go around each plant or recycled rounds of cardboard from frozen pizzas

Adult cabbage root flies look a lot like bristly houseflies only slightly smaller. They’re about 1 centimeter long with bristly hairs all over their gray bodies. This European species is now found across much of North American and up into southern Canada. For consistent crops of tasty, high-quality caulis, it’s best to choose F1 hybrid varieties, and if you’ve ever had problems with clubroot disease, select resistant varieties. Look too for varieties with an RHS Award of Garden Merit (AGM), which shows they performed well in trials – see our list of AGM fruit and veg for RHS-recommended varieties of cauliflowers and many other crops. Gently place the plant in the hole, trying not to disturb the roots, then fill the hole repeatedly with water. Called ‘puddling it’, this also refills the hole with soil and ensures the plant is sitting in a large area of moist ground Durable – they will last a long time and can be reused (some plastic won’t hold up well in the sun, though). If you are worried about damaging the seedling, you can cut a line from the outer edge to the center hole and wrap the brassica collar around the seedling that way. You will then have to staple the cut edges together for the collar to be effective. Just be sure that the collar opening can be enlarged as the plant grows.

White colored varieties of cauliflower will need shading – also known as 'blanching' –to keep them from discoloring, so that they will be tender and white when they are harvested. There are lots of cauliflower varieties to choose from, grouped according to harvesting time. There are faster-growing varieties for summer and autumn crops, and slower-growing varieties for harvesting in late winter and spring. If you buy several different types, you can have cauliflowers practically all year round. We know how important your garden is to you. We've listened to our customers and introduced a new improved speedy delivery service, meaning Express deliverycomes as standard. Position the flaps so that they cover as much of the opening as possible, without damaging the plant stem. Crop rotation should be practised. Otherwise cabbage root fliescan emerge from overwintered pupae in the soil under the fleece or meshcover, if host plants are grown in the same piece of ground in successive years

While you can certainly buy brassica collars for your plants, these simple tools are just too easy to make at home with materials from your recycling bin to not try at least once. Personally, I prefer cardboard. It is easy to work with and will ultimately decompose. Just follow these steps to make your own brassica collars:

What Are Cabbage Root Flies?

To harvest, cut the stem with a knife, taking the head and a few of the leaves beneath it, to protect the curd.

As well as traditional white or cream cauliflowers, there are varieties with striking purple, orange-yellow or lime-green heads for added ornamental appeal, both in the garden and on the plate. They generally keep their colour when cooked, unless boiled for too long. Discoloured heads – protect the developing curds from sun and frost, which can turn them yellow or brown, by folding the leaves over the head and tying in place with string if necessary.The leaves should naturally curl over the head of cauliflower plants as they "self-blanch," but this often doesn't happen, so they need help being secured in place,' explain the experts at Bonnie Plants. Encourage predators and other natural enemies in the garden such as birds, hedgehogs and ground beetles. Some ground and rove beetles are efficient predators of root feeding maggots At the end of the growing season, the collars can be tossed onto the compost pile after pulling out and discarding the staples.