Common Brassica Problems & How To Fix Them

Common Brassica Problems & How To Fix Them!

Sharing is caring!

If you are growing brassicas, you probably have run into some of the issues I highlight below. If you have, then you will want them fixed, and quickly.

That’s why I created this quick guide, to both show the potential issues you may encounter and, more importantly, show you what to do about them!

Seedling Problems

As with all young seedlings, brassicas are vulnerable to slugs and snails. In fact I would say they are usually more vulnerable than a lot of others.

This is because they can often grow when not much else is in the garden.

This puts a target on their back for hungry slugs and snails.

The usual control methods apply here, you can use slug pellets, but I don’t recommend this (even the organic ones), Nematodes (my favourite method), or slug traps.

The best way to keep slugs away from your brassica seedlings is to sow them indoors and only move them out onto the slug’s territory once they are more established plants.


Cabbage whitefly can be an issue with all brassicas despite the name. The adults (which look like a small white moth) lay their eggs on the underside of the leaves.

You can tell you have a whitefly problem if you notice many adults flying from the leaves whenever they are disturbed. The juvenile larvae will still be stuck to the underside of the leaf.

These hatch and the tiny larvae then start feeding on the leaf.

They are so small that they don’t usually cause too much of an issue. But they do excrete a sticky honeydew substance that can then cause mould to appear.

You can shake the leaves to remove a lot of them, also blasting with a hose can dislodge them. If you have a bad infestation, think about using an organic insecticide.

Cabbage Whitefly adults and larvae
Cabbage Whitefly adults and larvae


Caterpillars are going to be your main issue when growing brassicas and is the reason that many growers use netting and brassica cages.

Simply put, a caterpillar problem can annihilate your crop in a few short days.

The easiest solution is the one I mentioned above, netting.

You can set up a full cage that covers your brassicas or put a net over the specific crop, but either way, you usually have to do something.

Brassicas Under netting
Brassicas Under netting

If you notice a caterpillar problem, you can pick them off. This is very effective, and I like to chuck them onto my compost heap rather than killing them.

That way, the birds will get them, or they will munch on the plant leaves in the heap.

The only issue is that it is very labour intensive and you will be doing it all summer long.

You will be amazed and the sheer number of caterpillars you will find. I made the mistake of growing cabbages out in the open one year, and it is relentless!

Cabbage Flea Beetle

These tiny black beetles can affect any plant in the brassica family. The telltale sign is a lot of small holes all over the leaves.

You can also spot the beetles leaping from the leaves when disturbed.

These usually are more of an issue for commercial growers rather than home growers.

This is because the damage is usually just cosmetic and only impacts the saleability of the crop.

In severe cases, they can cause enough damage to kill the plants. They can be treated with an insecticide.

Cabbage Flea Beetle on a Kohlrabi plant
Cabbage Flea Beetle on a Kohlrabi plant


While you may not think it if you have never grown brassicas, pigeons can actually be very destructive.

This is particularly true for autumn and winter-grown crops where there is not much else around for the pigeons to eat.

Again netting is the best defence and is another good reason to net your brassica crops.

Club Root

This is a pretty nasty disease, and if your brassicas have it then there is a good chance they are done for.

It is a slimy mould that infects the root of your plant. There is no cure or treatment, and the spores can survive in the soil for 20 years or more!

You will generally notice it by your plants looking very unhealthy. They will often wilt and turn yellow.

This is simply because their roots are damaged and can no longer take up the necessary nutrients.

You can do things to reduce the chances of club root occurring. The mould is best suited to wet, acidic soils.

So improving drainage and making your soil more alkaline are great ways to reduce the chances of club root.

Club root in Brussel sprouts
Club root in Brussel sprouts

If you dig your plant up and the roots look like this above, then you have club root. Notice the swollen and usual root system.

This is the giveaway for club root being the cause of your problems.

Cabbage Root Flies

These nasty little pests like to lay their eggs next to your brassicas.

The larvae will then work their way into the roots of your plants, where they will begin to feast.

Because this is happening below ground, it can be really hard to spot until the damage is quite severe.

Again netting your brassicas with insect-proof netting will stop this from happening, as the flies won’t be able to get near your brassicas to lay their eggs.

(Cabbage) No Heart Forms

If your cabbage grows but never forms a large heart or centre, it is usually caused by poor growing conditions.

With cabbage, this is often poor soil without enough nutrients. Before growing cabbage again, improve your soil by adding compost or well-rotted manure.

(Cabbage) Splitting Hearts

This is usually caused by intermittent watering, much like tomato splitting. If we have a dry period and then suddenly lots of water, then the heart of the cabbage can split.

A split cabbage heart
A split cabbage heart

Sharing is caring!

Similar Posts


Leave a Reply

Your email address will not be published. Required fields are marked *