This is not as straight forward as it seems, because there are some plants that don’t get on with onions. Depending which type of onions you grow will determine how late in the season you have this problem. Over wintering onions are lifted earlier than spring sown, so what to plant after onions depends on many factors.
What to Plant After Onions
As I said earlier, time is the main problem here, and this is where forward planning is needed. If you have some winter squash, Pumpkin, Swede, Winter Cabbage, Chilli or Tomato plants in pots, these can be planted after onions. Your climate will determine how long you have left in your growing season and that will affect your choice of plants.
Over wintering Lettuce and Radishes can also be grown after onions along with members of the brassica family (if time allows). Late carrots will benefit from the strong aroma left in the soil from the onions. This will confuse the carrot root fly and stop them from laying their eggs.
What Not to Plant After Onions
Never plant legumes which includes all beans and peas, in the same soil that onions have just been lifted from. Onions contain certain compounds that inhibit legume growth, and this will remain in the soil on broken roots etc… Asparagus is another plant that does not get on with onions so should never be planted together or in succession.
The most obvious plant not to grow after onions is… Onions. This is because of the build up of pathogens and pests in the soil and this is why we rotate crops. I use a 4 crop rotation plan ensuring that my soil is fresh for every crop.
Companion Planting Onions
From a companion plant perspective, onions and all of their relatives in the allium family, are helpful to many plants. Plants like:-
So if you are short on space you can grow your onions alongside, or below any of the above list.
The Benefits of companion planting Onions
I briefly touched on this above and I cannot stress enough just how beneficial the aroma of onions is as a companion plant. This pungent smell will repel and confuse many insects including:-
- Aphids (greenfly, black fly etc…)
- Carrot Root Fly
- Flea Beetles
- Japanese Beetles
- Cabbage White Butterflies
- Tomato Moth
- Corn Moth
You can benefit from this by growing onions with plants affected by these pests and by growing plants in the same soil after the onions are lifted. This works best with onions grown from sets and not seed. Onions grown from seed are not as pungent.
What To Grow After Onions
In conclusion, there are many plants that will do well in the same soil that onions have been lifted from. As long as they have time to grow and in most cases that means having them in pots and ready to go. The exceptions being Legumes, Asparagus, and more Onions.