Jackie French: knowing your onions

It is time to plant onions, or at least get the ground ready to plant onion seedlings in a few weeks’ time.

Why bother? After all they are cheap, readily available and you can buy plastic bags of frozen chopped ones that are so easy to bung into a stew or soup, unless it has an acid tomato base or wine content in which case their texture will stay as plastic as their packet.

But a home-grown onion will be a revelation. You will understand why many peasant cultures eat raw onion, with maybe a tomato in the other hand, and a slab of bread. They will have flavour, sweetness, subtlety. They will be delicious in their own right, not just a background flavour. Once you get the hang of it, they are easy to grow - and one of the few things you can plant in winter.

Onions probably originated in southern Russia and the Middle East. They were disseminated by just about everyone, from the primaeval Indo-European hordes to the Romans, all of whom took their favourite varieties with them. The ancient Egyptians worshipped the onion, as well as cats and garlic – hardy and useful creatures all of them.

Different onions need to be planted at different times – early ones early, late ones late etc – a reasonably simple system. Look at directions on the packet or just trust that the ones you buy as seedlings are timed properly for your area. Onions vary as much as apples – not just the red, brown and white ones we are used to in shops. Some are so mild and sweet you can chomp them like a peach – they are also reputed to be milder if grown in a hot, dry climate.

If you're growing your own it's a pity to stick to the conventional varieties – though even these will be infinitely more interesting if they are home grown.

Generally white varieties – especially flat white ones and red ones, should be used in the first six months after picking; brown onions keep longer. A garden and kitchen expert friend has fallen for Cabernet, with excellent cropping, long-lasting and fabulous flavor. Pukekohe is a sweet brown onion with superb storage qualities; Ailsa Craig is enormous but doesn't keep quite so well (and you run the risk of always having half an onion floating around the fridge waiting for the next time you need half a kilo of onion).

Early Barletta is one of the earliest. Hunter River Brown is an early brown. I love Odourless – a mid-season flat white-ish brown with mild creamy flesh that is very sweet and full of flavour. Redskin is another good mid-season variety and not a bad keeper. White Imperial and Brown Spanish are good long-keeping late onions.

But do prepare the soil first. Weeds grow fast. Onions don’t. They need to grow well and long to get good bulbs. The dedicated gardener digs the bed, waters it, waits a month, digs it again then plants the onions and weeds every two weeks after that.

An easier method is to rake your leaves now or, if you don’t have autumn leaves, smile nicely at someone who does and ask if they’d like them raked. Leave the pile on the garden bed for a month, then rake them away and plant the seedlings, either bought or from seeds planted now in pots filled with (weed-free) potting mix.

About 25 years ago I discovered the next trick to growing onions is to interplant them with pansy seedlings. The pansies cover the ground and so prevent weeds germinating – but they are lower than onions so don't crowd them out. I found I got twice as many onions (by weight) in the onion and pansy bed as I did in the onions alone but weeded bed (and almost no onions in the onions alone unweeded bed).

I've tried other flowers with onions since – snapdragons, calendula, heartsease, lupins, marigolds and a few others. All helped keep the weeds down a bit but not as well as the pansies, except the marigolds which helped keep the weeds down but also kept the onions down too. Pansies seem best.

Onions should preferably be planted into fertile soil. If it isn’t, feed while the tops are growing well in early spring, but not when the bulbs are fattening or you’ll get too much top and too little onion and the onion you do get won’t have the same keeping qualities.

Onions are ready when you want to eat them – baby onions sautéed in oil are a delight – or when the tops are dry. Pull them up and leave in the sun for a few days to harden and for the heat and sunlight to kill any fungi spores. Rub off any loose bits of skin and snip off the tops – or even better, plait them together and hang in a dark airy shed or even the kitchen if you're going to use them soon (kitchens are too moist and steamy to preserve onions for long – but they look good up on the wall for a couple of months).

All onions can be used as spring onions – just pick the tops off when they're young – but plant proper spring onions if you want to use them regularly throughout the year. Spring onions are also perennial so they can be cropped forever – just keep feeding and watering. We use masses of spring onions - a good standby when you've used up the last of the onion harvest.

A basket of tomatoes are a much-appreciated gift. A basket of avocados or limes will be accepted with delight. But only connoisseurs understand the charm of a home-grown onion. Prepare your beds now and you will be one of them.