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Overwintering Onions and Garlic

growing onions

Overwintering Onions

Autumn varieties of onions, such as Radar or Troy,  grow slowly over winter to give you a crop of fresh onions the following May or June, just as your stored onions will have started to sprout. It is advisable to follow a crop rotation.

Overwintering onions are often called ‘Japanese’ onions (because they were first developed in Japan), these can be sown outside from late September up to early November. The main benefit of growing overwintering onions is that you will have a crop of organic onion setsonions ready for eating about a month before your main crop is ready for harvest. The other major difference between Japanese and regular onions is that Japanese onions do not store as well as well as spring sown onions. They will store for about four weeks, when your main-crop onions should be ready.

Planting Overwintering Onions

Onions should be grown in full sun, in fertile, moist and well drained soil. Onions like most vegetables are quite demanding for Potash(K), medium for Phosphorus(P) and medium for Nitrogen(N). A good all-round fertilizer is ideal for them. Avoid planting onions in soil that’s been freshly manured or they will be too lush. Plant the sets about a 1-1.5cm deep and 3 - 5 cm apart with 30 - 40cm between the rows.

overwintering organic onions Good crop of overwintering onions

Over-wintered onions greatly benefit from an application of nitrogen-rich fertilizer in late winter. This not only enhances growth but can also suppress premature flowering.

  • Keep well weeded over winter - onions don't like competition.  It will also allow better air circulation through the crop.
  • To prevent birds pulling out your sets, cover them with a fleece or net, which should be removed when the first shoots appear.
  • If planting in a tunnel, try to avoid overhead irrigation as it can encourage  fungal diseases.

Overwintering Garlic

Garlic comes from the mountainous regions of Central Asia and has adapted to extreme changes in temperature including very cold nights. As a result, garlic performs best when subjected to a cold period of one or two months. Ground temperatures of between 0 — 10º celsius encourages optimum clove formation making it very suited to our Irish climate and autumn planting often produces better crops than garlic sown in spring. Garlic enjoys a long growing season, so if planted in October up to early November, the harvest usually occurs in August and the bulbs are much bigger. However, garlic can be sown until Christmas and will still have plenty of time to produce a great crop.

We have several varieties of overwintering garlic - including Vallelado and Morado. They are certified Organic and disease free. Avoid planting supermarket garlic as, chances are, it has come from China and will not adapt to our growing conditions. Neither will it be certified disease free.

Garlic is a member of the Allium family so be sure to follow a crop rotation and do not plant it in a bed where onions have been harvested. If your soil is very heavy, incorporate organic matter or plant in a raised bed. You may choose to plant your garlic through a ground fabric for that added bit of winter protection.

Planting Overwintering Garlic

Choose an open, sunny site and well-drained soil. High humidity around the foliage and wet soils make the crop more prone to disease. 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.  Avoid using fresh manure. Over-wintered garlic greatly benefits from an application of nitrogen-rich fertiliser in late winter.

Garlic cloves, organicGarlic 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 between individual cloves and 30cm between rows. Plant the cloves so the tips are 2.5cm below soil surface. Deeper planting can encourage better yields on light soils, but do not plant deeply on heavy soils

Keep well weeded over winter - garlic doesn't like competition. It will also allow better air circulation through the crop.

Varieties of Garlic

Our Garlic varieties comprise one Softneck (Allium sativum ssp. sativum) and one Hardneck (Allium sativum ssp. ophioscorodon) type.

Most varieties in shops are softneck Garlic types. They usually produce bigger bulbs with a smaller number but bigger cloves. They are said to be a little milder than hardneck varieties. They have very good storage qualities. The necks (stalks) are soft and if kept long enough after drying they are perfect for braiding. Our softneck is Vallelado.

Our hardneck variety is called Morado, a bulb with attractive pink stripes. Hardnecks are sometimes compared with wild garlic. Their flavours reflect very much the soil conditions and the climate in which they are grown - and can be different from bed to bed and year to year. They usually produce smaller, more tightly packed cloves with a stronger flavour.

Hardnecks often produce a hard stem with a little bud on top which is called a ‘scape’. That should be snapped off as soon as possible (and used for cooking!) to encourage the plant to grow a bigger bulb. A disadvantage of hardnecks is that they do not store that well. After drying it should be used within 3 - 4 months. And also - since it has a hard neck (stalk) - it is not suitable for braiding.

Harvesting Garlic

Lift the bulbs with a fork once the foliage starts to fade and go yellow – mid summer on. Avoid bruising the bulbs as it reduces their storage quality. Brush bulbs to clean off any excess soil. Dry them off thoroughly in a single layer in the sun (not more than 2 –3 days otherwise the Garlic bulbs can turn green) or in a dry, shaded, well-ventilated place such as a shed. Store in a dry place at 5-10°C

Storing Garlic & Onions

Stringing onions and garlic is easy and a great way to store your crop overwinter as you can keep a large number of bulbs in a small space. Hang them in a cool, dry, frost-free place - such as a shed - until you need to bring them into the kitchen. You can read more about how to string onions and garlic here.



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