Garlic is a fantastic crop to grow in a polytunnel, not only because it is such a versatile ingredient that can be used in so many different recipes but also because its strong smell will help repel a range of pests that can plague other plants. Garlic is also really healthy and is really easy to dry and store for use throughout the whole year.
Garlic is relatively simple and easy to grow. Garlic is grown from cloves that are planted in the autumn or early winter, or in the spring in some more southern reaches of the UK. Most UK gardeners will plant garlic cloves before Christmas, ideally in around early-mid November. This will allow the cloves to root and establish themselves over winter before they really get growing in the spring. Do not be tempted to plant the cloves from a bulb of garlic that you have bought in the supermarket as these are generally not suitable for growing in your area and can also harbour all sorts of disease.
Plant cloves just below the soil surface at a spacing of around 15cm in any fertile and sunny site. If you have a problem with birds lifting the cloves then you may have to use a bird scaring device (though these only tend to work for a short while), netting or fleece. Since garlic casts little shade, it can very easily get smothered by weeds. Weed well to prevent this. When spring arrives, you can also help to keep weeds down by the application of a good quality organic mulch. This will also help to feed the garlic and can increase yields. There is usually no need to water garlic much except during periods of more extreme drought. You should certainly not water once bulbs begin to form as this can encourage rot. Snip off any flowers stalks that form.
As noted above, garlic is a fantastic companion plant for a range of other crops, including tomatoes, potatoes, brassicas, carrots, and many more. Though if planting garlic in your polytunnel, it is best not to plant them too close to and peas or beans.
Garlic is usually harvested between June and August, depending on the weather conditions as well as when it was sown. You can harvest some leaves from your garlic without disturbing the bulbs and these can be used in salads or as a garnish. If 'top sets' form on the garlic stalk then you can harvest and use these as you would other garlic cloves. The bulbs, however, should be left until the leaves have turned yellow. Do not try to pull garlic out of the ground by hand. Instead, lift the bulbs gently with a fork once the tops have yellowed. Garlic should then be left to dry – a wire shelf in your polytunnel is ideal for this. When the garlic is dry enough that it rustles and feels papery, it can be braided and hung or stored in ventilated containers for later use.
Planting – October to November or February to March if heavy ground.
Expect to lift – September to October.