Keep an eye on emerging cabbage leaves for tell-tale holes and pick off any cabbage white caterpillars you find before they do any more damage. To control them and stop the female butterflies laying their eggs, you need to keep fine mesh covers which were put on earlier in the season in place.

Check regularly that there are no holes in the netting and that the leaves aren’t touching the covers, as the butterflies will get through the smallest gap and lay their eggs on the leaves through the mesh. Squash by hand any you see.