Garlic and onions belong in every kitchen garden. They're undemanding, keep well and you can't cook without them. Yet a number of myths and inaccuracies circulate about growing them — especially around planting times. Let's clear up when and how to plant them correctly.
Garlic: autumn planting
Most garlic in Central Europe is planted in autumn, usually in October. The ideal window is from the beginning to the middle of October — the cloves need enough time to root (3–4 weeks) before the frosts arrive, but must not start sending up foliage above ground.
Choose the largest, best-looking cloves from the bulb. Don't use garlic from the supermarket — it's usually treated to prevent sprouting and comes from climatically very different regions. Ideally use certified planting stock or cloves from a trusted grower in your region.
Soil preparation and planting
Garlic prefers medium-heavy, humus-rich soil with a neutral pH. Prepare the bed at least two weeks in advance — dig it over, remove weeds and work in well-rotted compost. Don't use fresh manure — garlic can't tolerate it.
Plant cloves point upwards to a depth of 5–7 cm. Space 10–15 cm apart within the row and 25–30 cm between rows. After planting, mulch with a layer of straw or leaves (5–10 cm) to protect against frost and retain moisture.
Care and harvest
In spring, when the garlic begins to shoot, remove the mulch and apply a nitrogen fertiliser. In May and June, snap off the flower stems (garlic scapes) so the plant directs energy into the bulb. Scapes are edible and delicious grilled or stir-fried.
Garlic is ready to harvest in July, when the lower third of the leaves have turned yellow and dried. Lift with a fork rather than pulling on the foliage. Leave bulbs to cure for 2–3 weeks in a shaded, airy spot. Then clean off the soil and store in a cool, dry room. Properly stored garlic keeps until spring.
Garlic: spring planting
If you missed the autumn window, you can plant garlic in spring — ideally in March. Spring-planted garlic produces smaller bulbs and keeps less well. For spring planting use specially designated spring varieties — autumn varieties planted in spring will not form quality bulbs.
Onions: three growing methods
Onions can be grown three ways: from sets, from seed and from transplants. Each method has its advantages and optimal timing.
From sets (the easiest)
A set is a small onion bulb about 1–2 cm in diameter, bought from the garden centre. Plant from mid-March to mid-April, once the soil is workable. Plant point upwards so that the tip just peeps above the surface. Space 10 cm apart in the row, 25 cm between rows.
Advantages of sets: simplicity, faster harvest (July), reliable results. Disadvantages: higher cost, limited variety choice, tendency to bolt (flower prematurely).
From seed
Sow in rows from mid-March. Onion seeds germinate slowly (2–3 weeks), so be patient. Mark rows with canes so you don't confuse seedlings with weeds. Thin to 8–10 cm spacing once established. Harvest in August to September.
Advantages: cheaper, wider variety choice, better-keeping onions. Disadvantages: slower, more demanding in the early stages.
From transplants
Transplants are bought from the garden centre from April onwards. These are young plants raised from seed. Plant into prepared beds 10–15 cm apart. This method combines the advantages of both previous approaches — relatively simple and producing quality onions.
Caring for onions
Onions need a sunny position and lighter, free-draining soil. They dislike waterlogging and fresh manure. Weed regularly — onions are poor competitors against weeds. Reduce watering once the foliage begins to naturally topple over.
Harvest once most of the foliage has fallen over and begins to yellow. Leave onions to dry out in the sun on the bed for a few days (if no rain is forecast), then finish off under an airy shelter. Properly cured onions with firm, dry necks will keep in nets in a cool room until spring.
Crop rotation
Never plant garlic or onions after each other or after other alliums — this risks a build-up of diseases in the soil. Good predecessors are legumes, cucumbers or lettuce. Allow at least a three-year gap before returning any alliums to the same spot.