This Allotment Pro editorial draft summarises the cited RHS guide. Check the source and adjust timings for local conditions.RHS source guide
Garlic is a hardy member of the onion family, grown from individual cloves rather than seed. It takes little space and minimal maintenance, thriving in full sun and free-draining soil. Autumn planting is usually most reliable because most varieties need cold before they divide into a full bulb.
Named planting stock from a reputable horticultural source is preferable to supermarket garlic, which may be unsuited to the British climate and can carry biosecurity risks. Each planted clove forms a new bulb for harvest the following late spring or summer. After thorough drying, bulbs store for several months.
Hardneck garlic forms fewer, larger cloves with a strong flavour and generally stores for four to six months. It readily produces flower stalks, which can reduce bulb size and storage quality if left in place.
Softneck garlic packs more, smaller cloves into each bulb and rarely bolts except under stress. It stores longer: an autumn-planted crop can keep into the following winter, while spring-planted bulbs may last until the middle of the next spring.
Elephant garlic is closer to a leek and needs a long warm season. Its very large mild cloves may remain as a single round; planting in October reduces this, and a solo bulb can be eaten or replanted to form a divided bulb.
An attractive, well-storing softneck with ivory-white bulb skin around pinkish cloves.
A well-storing softneck with pure-white bulbs, a strong flavour and comparatively light aroma.
A familiar reliable softneck producing large bulbs with a fairly mild yet rich flavour.
A softneck well adapted to the British climate, producing bulbs with good storage performance.
Choose an open sunny site with free-draining soil. Wet winter ground encourages disease, especially around autumn-planted cloves. Where soil stays heavy and saturated, establish garlic in modules under cool protection and transplant in spring, or use a deep container.
Garlic dislikes strongly acid soil below pH 6.5. Test the bed and apply lime in autumn or winter if needed. Remove perennial weeds, then incorporate about two bucketfuls of well-rotted manure or garden compost per square metre or square yard. Never use fresh manure immediately around cloves. In a no-dig bed, apply organic mulch before planting; a biodegradable membrane can further reduce later weeding.
Most garlic benefits from one to two months at 0–10°C (32–50°F), so plant from mid-autumn to early winter. Use late-winter or early-spring planting only for suitable varieties.
Split each bulb immediately before planting, retaining sound cloves. Set the flat basal plate down and the pointed tip up. Space cloves 15cm (6in) apart in rows 30cm (1ft) apart, with the tip 2.5cm (1in) below the surface. Deeper planting in light soil may support larger bulbs, but avoid deep planting in heavy ground. Protect newly set cloves from birds with plastic-free netting or fleece until roots anchor them.
Part-fill deep modules with peat-free multipurpose or soil-based compost, insert one clove per cell and cover its tip with about 2.5cm (1in) compost. Keep modules slightly moist, never wet, in an unheated greenhouse, ventilated cold frame or sheltered outdoor place protected from excessive rain. Plant out in spring at 15cm (6in) spacing.
Choose a pot at least 25cm (10in) deep and fill it with peat-free multipurpose compost. Use the same 15cm spacing and 2.5cm cover as in open ground; container width determines the number of cloves. Check moisture regularly because compost dries faster than garden soil, while ensuring drainage holes remain clear.
Garlic needs little intervention beyond weed removal, occasional watering and prompt removal of flower stems. Preserve full sun by hand-weeding close to plants; hoe blades can cut developing bulbs. Cardboard or another organic mulch between rows suppresses weeds without disturbing roots.
Water through prolonged dry spells in spring and early summer to improve bulb size, directing water to the soil rather than foliage. Stop once bulbs are large and well formed, usually as leaves begin yellowing, because late watering encourages rot. Avoid routine watering of autumn crops in wet soil.
Cut any flower stalk as soon as it appears so energy remains available for bulb swelling and storage quality. Young scapes still in bud are edible and can be sautéed, roasted or barbecued. Hardneck types produce them readily; softnecks may do so after heat, drought or other stress.
A small number of green leaves can be taken while plants grow, but leave enough foliage to feed the bulb. Changeable spring weather may produce cloves on the stalk, called top sets, which can be used like ordinary garlic.
Lift bulbs when foliage turns yellow: autumn-planted crops from late spring to early summer and spring-planted crops from mid-summer to early autumn. Do not delay, because overmature bulbs open and store poorly. Loosen with a fork rather than pulling, and handle gently to prevent bruising.
Lay bulbs in a single layer in sun, a well-ventilated greenhouse or a dry airy shed. Avoid temperatures above 30°C (86°F). Initial curing takes two to four weeks. When foliage is completely dry and rustling, cut it away and store bulbs somewhere cool and dry at 5–10°C (41–50°F). Hardnecks keep about four to six months; well-cured softnecks may last up to a year.
Rotate alliums and source clean named planting material. Free drainage, correct planting depth and dry mature bulbs reduce many problems. Bulbs that fail to divide usually lacked sufficient winter cold; green cloves indicate shallow planting; split bulbs usually remained in the soil too long. Remove scapes promptly and lift on time.
Where allium leaf miner is established, insect-proof mesh during adult activity in March–April and September–November can protect foliage, but rotation remains necessary because flies may emerge beneath covers from a previous crop.
Garlic shares several pests and diseases with onions and leeks. Inspect foliage, roots and bulbs rather than treating yellowing as maturity automatically. Destroy badly rotted bulbs and avoid moving contaminated soil or planting stock.
Larvae tunnel through leaves, stems and bulbs, leaving white mines, maggots or brown pupae and allowing secondary rot. Rotate crops and protect during adult flights.
Problem sourceBright-orange raised pustules develop on garlic leaves and reduce vigour in heavy attacks. Improve airflow, avoid excessive nitrogen and remove affected debris.
Problem sourceDowny mildew damages allium foliage and bulbs, reducing yield. Avoid persistent leaf wetness and crowding.
Problem sourceThis persistent soil-borne disease causes yellowing and wilting above white fungal decay around roots and bulbs. Do not replant susceptible alliums into contaminated ground.
Problem sourceCaterpillars tunnel within allium leaves and bulbs, with secondary rot often following. Distinguish the brown-headed legged larvae from leaf-miner maggots.
Problem sourceOnion-fly maggots damage roots and bulbs and can kill young plants. Rotate alliums and remove seriously affected material.
Problem source
