Onion Allium cepa

The onion has to be one of the most commonly used vegetables in our kitchens. Year round we sizzle and sauté our way through recipe after recipe that starts out with a finely chopped onion. These essential ingredients are all the sweeter for being grown and fattened in our very own gardens.

Companions Parsley, carrot, lettuce, beetroot, tomato, cabbage, broccoli, cauliflower.

Quantity 15 to 20 per person.



  • Full sun
  • Fertile sandy soil
  • Keep weed free
  • Constant soil moisture
  • Eat young or mature

Our Top 6 Varieties

Onion varieties: There are three main types of onion. Bulbs: Your standard onion with purple and white-fleshed varieties – these take anything from 4 to 6 months to reach maturity. Sow in autumn or late winter. Multiplier Grown from bulbs – or ‘sets’ – these produce a bunch of swollen bulbs at their base. Shallots are a form of multiplier - planted as bulbs from autumn to mid winter, they develop into bunches of bulbs that are sweeter and milder than your average onion. Spring onion: Easiest onion to grow from seed, they grow fastest and are eaten raw in salads or cooked in stir fries and curries. Sow in spring or late summer (warm areas)

Red Brunswick (bulb) an heirloom medium to large dark red onion with flattened bulbs. Good storer with a milder flavour than many white onions. Best grown through summer and harvested in autumn.

Italian Long Keeper(bulb) open pollinated variety with very large, rounded, golden brown skinned bulbs. Sweet and pungent. Very good for storing if harvested with care. Sow spring/summer for autumn harvest.

Picador (Multiplier) hybrid variety producing elongated, oval-shaped bulbs with a rich sweet flavour.

Ambition (Multiplier) a hybrid variety producing round, tear-drop shaped bulbs with mild flavour that is popular in French cooking. Good for pickling and stores well.

White Lisbon (spring onion) very popular variety with succulent white stems that have a characteristic bite.

Ishikura (spring onion) open pollinated variety with tall white stems that produce almost no bulb at their base. Mild flavour.

Getting started


Sow February to May in warm areas and June to August in colder areas.


Onions like plenty of sun as this helps to swell their bulbs to tear-jerking perfection.  Give them an airy, open space – especially if you get warm, moist weather in late summer when they are ripening and can be susceptible to mildew.


Fertile, free draining soil is essential for onions, the sort of soil that your hand might feel comfortable pushing its way through – loose, deep and without any lumps or a soggy bottom.  Raised beds are a good option if your soil is on the sticky side. Onions are hungry feeders so ideally you have pre-composted the planting area so that by the time you sow or plant it is full of well-rotted manure, kitchen compost, leaf mould etc. and well dug over. Should be like a crumble mix before it goes into the oven. You can still do this at the time of planting as long as the compost you mix in is well-rotted and well mixed in - a la crumble.
As a general rule, if you get onto your bed preparation a few weeks before planting, add a dusting of lime (about half a cupful per square that measures a stride by a stride) and dig into the soil. Add untreated wood ash from the wood burner and this will provide a welcome boost of potash – essential for strong, healthy roots which will in turn produce fat juicy bulbs.



You can sow bulb onion seeds in autumn and late winter as long as the soil is workable and not water-logged.  Generally seed is sown outdoors in warmer areas between March and April and from June to August in cooler areas. Spring onions are sown in spring countrywide and can also be sown late summer in warmer areas.

To sow: Drag your finger along the top of the soil to create a shallow trench about a finger-tip deep. Sow seed along the trench and cover with soil before patting gently down as if flattening a crumble mix over concealed fruit in a dish. Rows should be about a generous hand’s length apart. Thin seedlings down to finger-length spacings when they are big enough to get hold of.

Sowing indoors: In some parts of the country and in some gardens sowing directly into beds can prove unreliable. As a result many home gardeners sow their seeds into trays filled with seed raising mix and grow them to about a finger’s length or buy and plant punnets of ready-sprouted onion seedlings in winter and spring.


Carefully ease your seedlings from their punnet or tray and gently shake or rinse away the soil. Using a pair of household scissors, shorten the roots back to about the length of your finger tip and then trim the leaves back by about a third (this technique is also used on leek seedlings and should prevent seedlings suffering from moisture loss until they develop new roots in the garden soil). Drag your hand through the soil so that you create a trench about half a finger deep. Seedlings should be spaced about a fingers’ length apart in the row. Plant them so that only the white lower base of the stem with the roots below is covered by soil. Rows should be spaced about a generous hand’s length apart.
If planting shallots as bulbs – or sets – space them around a hand’s length apart with the fat, scarred base pointing down and the pointy end sticking upwards. The top of the bulb should be just below the surface with any dead foliage sticking out above this. (You may want to cover with mesh for a while to stop inquisitive birds from pulling them out.)


Moisture levels need to be fairly constant as your seedlings grow. So have your watering can and rose attachment or hose with shower fitting ready for any dry spells. Every couple of weeks you can give seedlings a feed with liquid comfrey or liquid cow manure until the bulbs start to swell. Onions grow well on open un-mulched soil so it is important to keep weeds down and periodically to loosen the soil’s surface with a niwashi or a hoe to facilitate good aeration of the upper levels. If you are in a really hot, dry area then you might want to use a pea straw mulch once your onions are around a foot tall.


As with garlic you can harvest onions at any time and enjoy their fresh, sweet flavour when still young. Generally though, they are harvested when mature. Again, like garlic, onions will often tell you they are ready by wilting their tops and then toppling slightly as roots dry and become wiry. You’d be expecting this to happen around February. Once the tops have wilted and the roots shriveled in this way all you have to do is pull the onions and lay them on their sides for a few days – turning them now and again in the sun to dry their outer skins (If its wet then lay them carefully under cover on slatted shelves or a piece of mesh or chicken wire that has air flowing beneath it). If there is no sign of wilting by March then you can speed the process by grasping the leaves and bending them towards the ground – this should start the wilting process.
Any onions that still have thick stems above their bulbs once harvested are not suited for storing and should be used first in the kitchen.