At home with Jackie Why you need to grow pansies with your onions

When planted with pansies, onions grow mysteriously bigger, and the vegie patch prettier, writes JACKIE FRENCH

The first time was an accident. I’d planted out our winter vegie garden weeks before with leeks, red cabbage, broccoli and lots of onions. Then a bench of bright pansy seedlings caught my eye at the garden centre. You know how it is – you go in thinking you’re only going to buy a bag of potting mix and you come out with an apple tree and flowers you couldn’t resist.

I couldn’t resist those pansies. Sadly, the wallabies at our place can’t resist pansies either – they munch them for dessert.

The only wallaby-proof area is the vegie garden, so the pansies went between the onions – or, rather, half the onions. (Since I found out how good home-grown onions are, I’ve been planting lots of them.)

Weeds grow fast. Onions grow slowly. Onions need to be planted in weed-free ground. I usually cover the bare soil with clear plastic for a fortnight to encourage weed seeds to germinate before planting onions but, even then, seeds blow into the garden. Some weeding is usually essential if you want a crop of crisp, sweet onions.

I’m not sure when I noticed that I didn’t have to weed between the onions where I’d planted pansies. The pansy leaves were shading the soil and stopping weeds from germinating in their patch. By harvest time, there was an even more obvious difference – the onions grown with pansies were bigger than those grown without!

The next year I did a trial: one patch with onions and no weeding; one patch with white alyssum and no weeding; one patch with pansies and onions and no weeding; one patch with mulch between the onions and no weeding; and one patch with just onions and weeding. The pansy patch won – bigger onions and far less work, plus the joy of pansy flowers. Pansies are prettier than onions, and this way we had both.

why pansies?

I’m not sure how it works. It’s possible that pansies exude something that stimulates onions to grow fat. But I think it’s more likely that pansies and onions are just compatible. Onions grow tall and fat-rooted, while pansies grow outwards, not upwards, and have thin, straggly roots, so they don’t compete much for nourishment.

Onions and pansies both like fertile soil that isn’t too high in nitrogen – you don’t want onions that are all top and no bottom, or pansies with more leaves than blooms.

Most importantly, pansies grow best as the garden cools in autumn, fast enough to spread their leaves over the soil. It’s possible, too, that pansies insulate the soil, keeping the onions slightly warmer in winter or cooler in spring, so the roots get just that little bit fatter. Maybe the presence of so many lushly flowering pansies also slightly disguises the onions from aphids and other damaging pests.

optimal onions

Timing matters. The onions need to be about 15cm tall before the pansies go in, or the pansies may suffocate the onions. Different varieties of onions have different planting times. This trick works best with onions that need to be planted in autumn.

Onions are ready to harvest when their tops have withered, although you can pull them out as ‘spring onions’ at any time. Pansies are a short-lived perennial, which means that, with pruning, feeding and a bit of luck, they survive for more than a year. But young plants are more vigorous. By late spring, pansies can be looking straggly, and they are prone to summer mildews, so pull them out and plant some more in autumn.

I grew veg for almost a decade before I bothered growing onions. Supermarket onions are cheap. Why bother? Except, as I discovered, a home-grown onion is sweeter, crunchier and far more vivid taste-wise than the long-stored ones in supermarkets. They are as much a luxury as a home-grown tomato. And with the addition of pansies, you’ll have the most gorgeous onion patch in the district.