GROW GUIDE - ONIONS, SHALLOTS & GARLIC
Onions are a staple of the kitchen, wildly versatile and used in many foods it can surprise people just how many varieties there are and how different they can taste to the supermarket brands! It is highly advised to try onions at least once and they are very easy to grow, often rewarding a gardener for simply keeping the patch weed free.
Onions can be planted either from seed (very economical) or from onion 'sets' which are bulbs that are not allowed to grow to their full size, therefore growing faster and into larger bulbs.
Although many onions are grown in the spring, by overwintering onions you can often achieve earlier crops (up to a month before spring sown) that have had longer to mature and a slower growth meaning an increase in flavor. These are best sown through September to October as this gives them time to develop roots before the cold slows growth (although it is possible to grow them any time the ground is not frozen).
The best onions to overwinter are the Japanese cultivars as they are the most cold tolerant and Electric is a fantastic red onion to grow. Otherwise, follow the instructions normally used for spring sown onions below.
SPRING SOWN ONIONS
The key to growing onions well is to have a well drained soil that is nonetheless firm, to this end it would be advisable to add organic matter in the form of well rotted manure or a peat/peat substitute compost. By digging this into the ground you increase the drainage in a clay soil and increase the substance of a sandy soil. Fresh manure should never be used with onions as it leads to rot. It is a good idea to reserve some manure for mulching after the onions have been planted.
If you have a sandy or light soil it is ideal to firm the soil lightly with your feet. This can be achieved by raking the area over then stepping and treading on the soil. This can also be useful to get rid of clods of soil.
Particularly with onions and shallots the organic no dig method could be useful.
HOW TO GROW
Onions are very simple to plant, all that is required is a weed free bed, well drained soil and sun, In March/April push the onion sets into the ground with a 10cm distance (30 cm between rows). Onions can be grown in small amounts in troughs or tubs but should never be grown in growbags. After the bulbs have been planted it is best to weed and then mulch with any remaining manure (although this is not required it will defiantly help). Keeping the ground clear of weeds should be a high priority as onions are very poor competitors and other plants encroaching on them will drastically reduce bulb size. If this cannot be guaranteed then look to using Centurion which is fast growing and avoid using seed as they are slow to establish.
Water onions if the weather is dry but be aware it is very possible to over water them so a small amount is often better than a deluge as any mulch will help maintain the moisture below the surface. giving a feed of liquid fertilizer (liquid growmore or a specific vegetable feed is best). Any onion flowers stalks should be immediately removed as they cause the bulb to warp and reduce in size.
Tip: If you have trouble with birds attacking onion sets then it is worth taking the top dead leaves off the bulbs, occasionally it seems birds mistake the tips for worms!
Tip: Onions are day sensitive biennials meaning they will start to bulb according to light levels, no matter how big or small they are, If you can, plant early as you will get stronger plants with bigger bulbs but beware the weather.
HOW TO HARVEST
Tip: Try applying potash around and on the bulb three weeks before harvesting, this toughens the outer layer of skin meaning it is less prone to bruising and damage when harvested.
Onions should be harvested when approximately half the row's leaves turn yellow and collapse or individually if the leaves are 75% yellow (if you are worried about rot then harvest them when the leaves are only 50% yellow), however if rain is due it is a good idea to harvest all mature plants as moisture can lead to rot. To do this feel the neck above the bulb for a 'soft spot' this is a sign that the bulb itself has stopped growing and can be harvested. At this point the bulbs will be soft and tender so great care should be taken not to bruise or damage them, gently loosen the soil around them and lift with the leaves of the plant. After shaking off any large clods of earth and any rotten leaves then air dry the bulbs for a few days. By applying a dose of sulphate of potash to the bulbs as the leaves yellow you can harden the skins and this helps reduce the loss from damaged bulbs.
After the bulbs have hardened it is time to cure them, gently clean the onions but leave as many of the outer scales intact as possible, then leave them to dry, ideally outside under cover (They may have a strong onion smell) or in bad weather inside with 30cm of the green growth left. After 2-3 weeks the bulb will be ready for its second cleaning, trim the roots off and green growth down to 2" and wipe any soil off, by then the plants will be hardened enough physical damage is unlikely.
After another week the onions will be ready for use and storage, Onions that do not keep well should be kept in the fridge however other onions may be kept in any dry cool place (ideally with airy space so they do not sweat.)
The centurion F1 Hybrid is notable for its rapid maturation, the onions are large globe shaped and quite suited to the UK fickle weather. These have a good flavour and are ideal for beginners or those with little time. The fast rate of growth minimise weed competition problems.
Hercules is one of the few onions to have the award of garden merit from the RHS and it has certainly earned it. The onion it produces slightly flat well flavoured reliable onions which have a gold-brown skin, store well and are extremely bolt resistant.
Picko Bello is an improved Dutch Sturton cultivar that is very high yielding. It stores very well and is a early cropper and bolt resistant.
Sturton is an early main crop which produces medium onions that has proved very popular in recent years. It has a good taste and like most modern varieties is quite bolt resistant.
Stuttgart Giant lives up to his name. It is very productive cultivar with a mild taste. Ideal for adding some light flavour to meals. It stores well and is well known amongst gardeners.
Red Barron has the Award of Garden Merit and is considered one of the best red onions. Ideal as a salad onion to add colour to a meal. They have a mild taste with fantastic colour and very reliable.
What are Shallots?
Shallots are a distinct botanical variety of onions which rather than producing a single large bulb, produce numerous smaller ones. They have a very distinct mellow taste (often slightly garlicky) and are considered superb for pickling with a stronger taste than standard onions and an increased firmness. Shallots are ideal for meals where smaller amounts of onion are called for (as opposed to using 1/4 a bulb) and where useing garilc may not be ideal. In addition they mature faster than onions (although they do not keep as well) and importantly they produce no irritant compounds making cooking with them far easier! Shallots can be grown from seed (which whilst being economical takes longer and produces fewer bulbs) and sets which can produce 12 or more large bulbs, whilst maturing faster.
HOW TO PREPARE
Shallots, being Alliums like onions require the same preparation, They benefit from organic matter being added to the soil to increase drainage whilst requiring sun to achieve the full effect. They are again quite suitable for the organic no dig method however fresh manure as always should be avoided.
HOW TO GROW
Shallots have a tendency to splay everywhere when mature so it is always advised to plant them further apart than base onions (25cm apart with 40cm between rows), otherwise they are very similar to onions in that they should be pushed into the soil and left with the tip above ground (unlike with onions do not remove the tip). As the shallots grow it is important to reduce weeds in the bed as although they are more competitive than onions, any local weeds will still reduce the output of the bulb. Using a mulch of manure or black membrane will reduce weeds and retain moisture making them easier to maintain.
HOW TO HARVEST
Shallots unlike onions have a tendency to fall when mature as they develop into a 'nest' of bulbs which means you should harvest individually rather than an entire row as you would onions. Gently lift them by first loosening the soil around them with a garden fork and take large clumps of earth off them but then leave them allowing them to dry as after harvest the skin and interior scales will be soft and easily damaged. By applying sulphate of potash to the bulbs a few days before harvest then the bulbs can be hardened and reduce this problem.
After drying for a few days (if weather is damp then this can be done indoors) then take them inside the house in the warm, gently wipe the worst of the dirt off and trim the leaves down to 15cm. After curing them for 1-2 weeks you can then separate them, gently clean them, trim the roots and take the green growth down to 1". After a further 1 week then take the leaves off entirely and they are ready to be stored. they store well and can often be kept for over 6 months!
Red Sun has an attractive red skin and is believed by many to be the best red shallot, it is worth noting it has white flesh not red.
Biztro is a fantastically tasty pale red shallot, it is often labelled as a premium shallot, it grows rapidly, resists bolting and produces an even crop.
Yellow Moon can be grown either in the Autumn or Spring, it has a low bolting risk , well flavoured and popular.
Golden Gourmet is a traditional flavoured shallots, it is very versatile and well suited to a number of jobs. It has earned the award of garden merit and has a fantastic yield.
Picasso has a shiny light-red skin with a mild taste and good crunch. Excellent for pickling.
Different types of Garlic