Combat Planting & knowing your onions


With more and more people trying grow-your-own in small gardens, there’s quite a bit of interest these days in  ‘Companion Planting’. Where most veg need a certain amount of space to get the nutrients, water and sun they need to grow to full potential, ‘Companion Planting’ suggests certain crops grown close together actually augments their productivity.  A classic example is what’s sometimes referred to as the 3 Sisters: sweetcorn, squashes and beans. I’m trying it again this year, as last year was a wash-out for the sweetcorn and butternut squash… ‘Fingers crossed’ for a warm summer this year!

I wondered aloud on Twitter the other day whether there were also groups of plants that positively hated being next to each other. Could one accidentally become the innocent instigator of ‘Combat Planting’?


This sparked quite a conversation. Two new things I came away with were Mark’s (of @marksvegplot) mention of the term allelopathic – plants that repel other plants from growing nearby – and Beryl’s (of @mudandgluts) top-tip that legumes and alliums shouldn’t be planted together. I remembered my peas last year having a decidedly small harvest… And then I remembered they had been planted right next to some dastardly onions!


This year, I’ve got two patches of red onions that have overwintered, both planted from the same bag of onion sets back in November. One is sharing a bed with the broad beans (uh-oh), the other has a bed to itself.

The onions in their own bed are just dandy. Getting on with it. The onions planted with the broad beans have started to bolt (sending up flower buds).

So there we have it. Don’t put legumes and onions too close together. Interestingly, it’s the legumes that have the upper hand this time… Maybe because they flowered abundantly earlier, and are already setting fat pods of beans, signalling their fecund superiority? It’s a bit of a mystery. I’ve also read that onions can bolt after a particularly cold and wet spring. Which we’ve had.


What’s a certainty is that once young onions bolt, all they can think about is their reproductive parts. Even snapping off the emerging bud will not do anything to reverse the plants broody bent. The bulb will not get any bigger.

All is not lost as you can still eat what little of the bulb has developed. But they won’t keep like a fully developed onion, so you might as well pull them up now, enjoy them fresh and make room for some new crops. (But leave any that haven’t shot a flower bud as they might well go on to develop into proper onions.)

Here’s what I did with mine:

I removed the outer layer and leaves, washed then sliced them lengthways, removed the flower stem, and drizzled them with olive oil before cooking them in a hot oven for 40 minutes. Then I served them up with some balsamic vinegar and S&P. They were delicious if a tad fibrous, especially at the stalk-end, so I’d recommend slicing again crossways a couple of times too (after first removing the flower stem).

Please let me know your thoughts on Companion or Combat planting. What’s your experience been? Any more top-tips?

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