Cultivation notes

Site and soil

Choose an open, sunny site and well-drained soil. High humidity around the foliage and wet soils make the crop more prone to disease, particularly if planted in the autumn. Garlic does not thrive on acid soils (below pH 6.5). Reduce acidity by applying lime in autumn and winter. 

Prior to planting, improve the soil’s structure, moisture retention and nutrient levels by incorporating organic matter. Apply about two bucketfuls of well-rotted manure or other organic matter such as garden compost every square metre (yard). Avoid using fresh manure.

Little fertiliser is required at planting. On average soils apply a balanced fertiliser such as Growmore at 25g per sq m (1oz per sq yd). Where organic matter was not applied, double the amount of fertiliser.

Planting in the open

After planting, garlic needs a cool, one- to two-month period at temperatures of 0-10°C (32-50°F) for good bulb development. Planting in late autumn (late October to November) or in early spring (depending on the cultivar) will provide the necessary chilling period.

• Garlic is planted from bulb segments (cloves), so break up the bulb carefully into individual segments prior to planting
• Make sure that the cloves are planted the right way up: the flatter basal plate should be facing downwards
• Allow 15cm (6in) between individual cloves and 30cm (1ft) between rows. Plant the cloves so the tips are 2.5cm (1in) below soil surface
• Deeper planting can encourage better yields on light soils, but do not plant deeply on heavy soils

Planting in modules

On heavy, wet soils garlic is best started off in modules in the autumn, overwintered in a cold frame and planted out in the spring.

• Partly fill the cells of a module-tray with multi-purpose or soil-based compost
• Insert the cloves individually into the cells and cover with compost
• Keep in a cool place – a well ventilated cold frame is ideal – to provide protection from the harshest winter weather
• Make sure that the compost is moist but not wet
• Plant out in spring

Aftercare

As the foliage of garlic casts little shade, the crop can be easily swamped by weeds, which would negatively affect the plants’ growth and subsequent yields. Hand weed regularly. Hoeing can be tricky as the foliage and top of the bulb is easily damaged. To avoid this, consider planting through black plastic sheeting to suppress weeds.

Water every 14 days during prolonged spells of dry weather. Cease watering when the foliage begins to go yellow indicating onset of maturity. Try to avoid overhead irrigation that encourages fungal diseases.

Harvesting

Harvest autumn-planted garlic in early summer and spring-planted from mid-summer to early autumn.

Lift the bulbs with a fork once the foliage starts to fade and go yellow. Avoid delay as the bulbs open up and store less well if lifted late. Handle gently as bruising also reduces their storage potential.

Dry them off thoroughly in a single layer in the sun, under a cloche or in a greenhouse is ideal, taking care to avoid excessive (>30°C) heat by generous ventilation. Alternatively, place in a dry, well-ventilated shed or similar environment. Expect drying to take two to four weeks depending on the weather. If mould is detected deploy a fan heater, but this should be necessary only under exceptional circumstances. Once foliage is no longer moist sever stalks and store bulbs in a dry place at 5-10°C (41-50°F) where further drying will take place.

Propagation

It is best to obtain bulbs from a garden centre or mail order suppliers. Garlic bought from a supermarket may not be suitable for UK climate and can carry diseases and viruses.

Cultivar Selection

It is a common misconception that garlic bulbs are always white. The tunics, as well as the cloves, often come with tinges of pink, red, purple or brown. Garlic cultivars are split into two main groups – hardneck and softneck.

Hardneck garlic is a group of cultivars selected from Allium sativum var. ophioscorodon originating from climates with colder winters. It has the following characteristics:

• Flower stalks appear readily
• Fewer, larger cloves covered with a looser tunic are produced
• It is considered to have stronger and more interesting flavour
• It is best gathered when the foliage has changed colour
• It stores only until mid-winter

Softneck garlic (Allium sativum) generally produces smaller, more tightly-packet cloves;

• Does not produce flower stalks unless stressed
• It is best harvested when the foliage starts going over
• It has better storage qualities than hardneck varieties
• If autumn planted it will keep until mid- to late-winter
• If planted in early spring softneck varieties it can be stored until mid-spring

Hardneck varieties:

‘Chesnok Wight’: Good cropper, early summer maturing cultivar, skin and cloves with deep purple veining, strong flavour.
‘Lautrec Wight’: Maturing in early summer, suitable for both autumn and early spring planting, does not perform well on heavier soils and cold areas. Considered to be one of the best flavoured cultivars.
‘Red Sicilian’: Early summer maturing, spicy flavour, good for roasting.

Softneck varieties:

‘Early Wight’: Early maturing; can be harvested at end of May from autumn planting, best used soon after harvest as it is not good for storage.
‘Solent Wight’: Late summer maturing, very good for storage.
‘Germidour’: Late maturing, purple skinned cloves.
‘Purple Heritage Moldovan’ or ‘Purple Moldovan’: Late maturing, heirloom cultivar, producing large purple cloves.

Elephant garlic – Allium ampeloprasum – is often sold as garlic, but it actually more closely related to leeks. It produces a small number of very large cloves of mild flavour. It needs good, long, warm growing season to grow well. It is best planted in October.

The cloves sometimes do not divide, producing just slightly larger single-clove (solo) bulbs. Early planting often reduces the occurrence of solo bulbs. The single-clove bulb can be harvested or planted again the following season, when it will often produce segmented cloves.

To view the most current fruit and vegetable list of Award of Garden Merit (AGM) plants click here.

Problems

Garlic suffers from similar pest and disease problems as onions and leeks.

When garlic is exposed to adverse weather condition, such as fluctuating temperatures in spring, the plants may produce garlic cloves above the ground in the stem. They are sometimes called top sets, which can be used in the normal way. There is nothing that can be done about it.

Hardneck garlic cultivars readily produce flower stalks. The developing flowers should be removed as soon as they appear and can be used for stir fries. Softneck cultivars occasionally produce flower stalk if exposed to adverse growing conditions such as high temperatures or drought.

If the bulbs start splitting the crop was harvested too late.

Shallow planting and late harvesting can lead to some of the cloves going green. They can be used as normal, but they are unlikely to store well.

There are a few fungal diseases to watch out for;

• If the foliage develops orange pustules the crop may be affected by leek rust, that garlic is very susceptible to
• Withering of the foliage in dry weather may be a sign of onion white rot. The base of the bulbs and roots develops white fluffy mould
• Onions and shallots are very susceptible to downy mildew, when the leaves start turning yellow and die off from the tip downwards. In wet weather white mould develops on dead parts often turning darker colour later. However, garlic seems to be seldom affected

Two leaf mining pests that can cause damage to the foliage of garlic and other members of the Allium family are the allium leaf-mining fly and leek moth.