Everyone knows they should prune their tomatoes and raspberries, but not everyone knows about pruning brassicas, but there are good reasons why you should. Let’s get into it!
Why Prune Brassicas
As your plants grow, the older leaves will start to yellow and die; this is just one thing that happens as brassicas age.
At this point, these leaves are not doing much for the plant.
Almost all photosynthesis will happen in the new young leaves at the top of the plant.
These leaves, though, are often the largest ones on the plant, and large leaves need a lot of water to maintain.
So these leaves aren’t helping the plant, but they are taking up a lot of water, so removing these leaves doesn’t harm the plant’s growth but reduces the amount of water it needs.
Removing these leaves can differentiate between a plant struggling or thriving during lower rainfall.
Disease
These older leaves will become yellow and eventually fall off the plant.
If left lying around, they can be a serious vector for fungal disease.
Tidying them up and getting them out of the way is a great way to reduce the chances of your plants suffering from fungal disease.
Slugs
Slugs love brassicas and are attracted in by dead and decaying matter.
A healthy leaf is less of a target than a battered old leaf. By removing the older leaves and chucking them on the compost heap you make your brassicas less attractive to slugs.
If you let the old leaves fall off the plant and lay on the ground, they are even more of a target for slugs and make a nice little B&B for them to hide under too!
Caterpillar Spotting
Another great reason for removing brassica leaves is that it allows you to spot any potential caterpillar issues before they arise.
Cabbage white butterfly lay their eggs on all brassicas, and then the young caterpillars get to work munching their way through the leaves.
When pruning your brassicas, you should be on the lookout for any eggs laid on the underside of the leaves. Get rid of these before they have a chance to hatch.
Another benefit is that large leaves will often touch any netting you leave over your brassicas.
This allows the butterflies to lay their eggs through the netting, so just because your brassicas are netted, don’t think they are safe from the dreaded cabbage white!
How To Prune
Pruning is simple enough, grab a pair of sharp snips or secateurs and remove the leaves where they meet the main stem of the plant.
You want to prune from the bottom up, removing the older leaves that are starting to yellow.
You can see on this purple sprouting broccoli below that the leaf is just starting to turn and yellow.
It is also huge, and we arent getting much rain here right now, which is another reason why I want to get it off the plant.
Here you can see the after-effects of pruning off these leaves.
As this purple-sprouting broccoli grows, you will end up with a tall main stem with many scars at the bottom where the leaves have been removed.
The process is the same for all brassicas; remove the outer – older leaves at the base of the plant.