Onions

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Onions are raised either from seed, plants or from sets (small bulbs), each has pros and cons:

Sets Advantages – easier to grow, less prone to pests and diseases, matures earlier. Disadvantages – less choice of variety, more prone to bolting, more expensive.

Seed Advantages – available for all varieties, less prone to bolting, more flexible sowing times, cheaper. Disadvantages: more labour, longer growing season, more susceptible to pests and disease.

Plants Advantages – easier to grow, less prone to pests and diseases and have had a head-start on arrival, meaning a shorter growing season for you. Disadvantages – Less choice of variety, more expensive.

Different types available which have different growing times and methods:

  • Autumn planting onion sets: small bulbs which are cleaned, graded and stored, ready to plant out in the autumn. Gives an earlier crop than spring planted varieties.
  • Spring planting regular onion sets: small bulbs which are cleaned, graded and stored, ready to plant out in the spring.
  • Spring planting heat prepared onion sets: the heat-treatment minimises bolting and extends the growth period, meaning much greater yields can be achieved.
  • Autumn planting shallots sets: small bulbs which are planted in autumn and grow to form a cluster or shallots the following summer.
  • Spring planting shallot sets: small bulbs which are planted in spring and grow to form a cluster or shallots slightly later in the summer than the autumn-planted sets.
  • Autumn sowing onion seeds: Sow in autumn for a crop of onions from early summer the following year. These varieties don’t keep as well as spring sown varieties but are useful for plugging the gap earlier in the season.
  • Spring sowing onion seeds: Sow in early spring for a crop of onions from mid-summer through to autumn. These onions can be stored until spring the following year.
  • Onion plants: Plant in mid-spring for a crop from mid-summer to autumn.

Bulb onions, such as Red Cross, Troy and Red Barron, can be grown from sets or seed and can be eaten fresh, or dry them out for storage.

Spring onions, such as White Lisbon and Guardsman, are grown from seed. Depending on whether their variety is winter hardy or not, you can sow them anytime between March and October for a long harvest between February and September. They don’t store well but only take around 12 weeks to be ready to harvest and can be sown throughout most of the year.

Site and Soil Onions prefer an open, sunny site with light, free-draining soil. Avoid planting onions in very heavy or freshly manured soil. Onions are sensitive to acidity, so if you know you have acid soil it’s a good idea to dig in lime to the planting area beforehand. For best results, dig a pre-planting fertiliser into the ground.

How to Grow Onions and Shallots from Sets

When to plant Autumn planting onions: September – November Spring planting onions: March – April Autumn planting shallots: September – December Spring planting shallots: February – March

Harvest time Autumn planting onions: June – July Spring planting onions: August – September Autumn planting shallots: June – July Spring planting shallots: July – September

Planting: Both autumn and spring varieties can be planted straight outside into prepared soil. If the soil is loose and well dug you should be able to push the sets into the ground, or use a dibber to create a hole first. Plant them, pointy-end up, in rows at a spacing of about 15cm.The tips of the sets should be just level with the soil surface.

How to Grow Onions and Shallots from Seeds

When to Sow Autumn sowing onions:  August – September Spring sowing onions: January – March Spring sowing shallots: January – March

Harvest Time Autumn sowing onions:  June – July Spring sowing onions: August – September Spring sowing shallots: August – September

Sowing Autumn-sowing onions can be sown indoors to be transplanted outside at a later date, which will give them a bit of a head start, or they can be sown directly into the growing position. Spring-sowing seeds are usually sown directly into their growing position.

Sowing indoors: For an earlier start, especially in colder areas, sow seed in a cool greenhouse in late winter or early spring. Once the seeds have germinated and are about 1cm tall and at ‘crookneck’ stage, they should be pricked out at a spacing of about 5cm. Start to harden them off once they reach 2-3 leaf stage before planting out into eventual growing position in mid – late spring.

Transplant the seedlings into rows outside in mid – late spring, at a spacing of around 15cm, or allow up to 25cm for larger bulbs.

Sowing outdoors: As soon as the soil is workable in spring, or before it becomes in mid-autumn prepare it by digging and raking it to a fine texture. Avoid sowing into very cold or wet soil. Sow thinly into rows at a depth of about 2cm. The rows should be about 30cm apart from each other. As the seedlings start to grow they will need to be thinned every now and then to create space for bulbs to develop. Use the removed seedlings as spring onions or chives. Once they reach a spacing of about 15cm you’ll no longer need to thin them.

How to Grow Onions and Shallots from Plants

When to plant: April Harvest time:    August – September

Planting: Onion plants are delivered in early April when they’re ready to be planted outside. Make sure the soil is well dug and crumbly before planting. Remove the plants from each cell one at a time by pushing them out from underneath. Using a dibber, create drills (the same depth as the plant cell) in rows at a spacing of 15cm. The plants should be planted no deeper or shallower than they were in the cell tray. Firm them into the ground and water-in.

How to Grow Spring Onions

When to sow: Spring onions: March – July Winter hardy spring onions: August – October

Harvest time: Spring onions: May – September Winter hardy spring onions: February – May

Sowing: Sow winter hardy spring onions, such as White Lisbon, in autumn and spring varieties from March. You can continue to sow spring onions throughout summer to provide a continuous harvest. Prepare the soil by digging and raking it to a fine, crumbly texture. Avoid sowing into very cold or wet soil. Sow thinly into rows at a depth of about 2cm. The rows should be about 10cm apart from each other. As the seedlings start to grow they will need to be thinned every now and then, but whatever you remove doesn’t have to go to waste. You can use the removed seedlings as spring onions or chives. Once they reach a spacing of about 2cm, you’ll no longer need to thin them out.

Further Growing Information for Onions and Shallots

Growing: Onions and shallots prefer light soil, but where this isn’t available you can dig a generous amount of grit into the planting area to ensure any water can drain away from the bulb.

Protecting growing onions and shallots with netting should help prevent bird and insect damage. It’s also important to keep the area around them weed free.

Onions and shallots benefit from watering during dry spells in the middle of summer. But generally, once established, they require little attention other than occasional weeding and feeding with a liquid feed.

Harvesting: For fresh use, lift onions when they reach a usable size. If harvesting for storage, wait until foliage starts to die down and the tops bend over naturally. Ease the bulbs gently from the ground. In dry weather you can leave them on wooden benches or boxes to dry outside for a week or so, but if it’s damp you may be better off drying them in a greenhouse.

Harvest shallots from mid–summer onwards. They form clusters of bulbs that should be lifted whole, using the same method as lifting bulb onions.

Spring onions don’t keep for long, so it’s best to harvest them as and when needed. They’re easy enough to harvest without tools, simply by gently easing them from the ground by pulling on them gently.

Storing: Onions and shallots are ready for storage when the skins have gone dry and papery, then they should be kept in a well ventilated place. Our onion storage nets are ideal for storing onions, shallots and garlic, helping to keep them in top condition for as long as possible.

Health Benefits: Onions have been used in the past as a treatment for angina, coughs, colds and asthma. It’s also found to help reduce blood pressure and cholesterol levels.

Onions Pests and Diseases: Rust disease – rusty spots form on the leaves, sometimes killing them off completely, often resulting in smaller bulbs size. This commonly happens when growing onions sit in damp soil for too long, it also happens if grown in soil where either onions, garlic or leeks have been grown before. There isn’t a cure for rust disease, but if you see any leaves with rust-coloured spots on, remove them and throw them away to help prevent the rust from spreading. Don’t grow garlic, onions or leeks in areas that have been affected by rust for 4 to 5 years.

Onion white rot – the leaves turn yellow and wilt, preventing the bulb from forming properly. The bulbs will have white, fuzzy spots on if they have onion white rot. There isn’t a cure, the best thing to do it remove the bulbs from the area completely to avoid the disease spreading.

Onion fly – the leaves start to wilt and turn yellow, preventing the bulbs from developing. Onion fly can affect garlic and leeks as well as onions. The larvae of onion fly live in the soil and eat the roots of the bulb, and eventually burrow into the bulb itself. Discard any bulbs you discover with onion fly. Try preventing onion fly by planting next to carrots.

Potatoes

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Potatoes require a fairly long growing season. Potatoes are grown from seeds, which look like small, soft potatoes which sometimes have ‘eyes’ on. There are four main types of seed potato available:

  • Salad potatoes: Known for their firm, waxy flesh and unique flavour, these are ready relatively early in the season.
  • First Earlies: These are the very first potatoes to be ready in the year, maturing from as early as May when planted in February. These are often known as ‘new potatoes’.
  • Second Earlies: These follow-on from the first earlies and are usually ready to harvest from June as well as being suitable for storing until August.
  • Main crop: Ready to be lifted from September to October, these can be eaten straight away or stored for up to three months.

Site and soil: Potatoes grow well in most soil types but ideally they should be grown in well-drained, loamy soil that is not too heavy.  The soil needs to be deep, well dug and with plenty of well-rotted organic matter incorporated.  The plot should be cleared and dug over in late autumn/early winter so that the frost can break down the soil structure, which will make for easy planting in the spring.

Ideally, potatoes should only be planted in the same part of the garden once every 7 years but, given that this is not practical for the vast majority of gardeners we recommend a minimum of 3 or 4 years.  Aim to develop the longest rotational system you can accommodate in your garden.

How to grow potatoes from seeds When to plant: Salad potatoes: March – April First Early potatoes: February – April Second Early potatoes: March – May Main Crop potatoes: March – May

Harvest time: Salad potatoes: June – July First Early potatoes: May – June Second Early potatoes: July – August Main Crop potatoes: September – November

Preparation: To get your potatoes off to a flying start it is often recommended that you ‘chit’ them before planting.  This allows strong chits (sprouts) to develop on the tubers before planting.  Whilst this process is not essential for main crop varieties, it is strongly recommended for First Earlies and, to a lesser degree, for Salad varieties and Second Earlies.

To chit seed potatoes, place them just touching in a seed tray or individually in the sections of egg boxes.  Make sure the ‘rose’ end (where most of the ‘eyes’ are) is uppermost.  It is these eyes that will form the chits.  Place the trays in a cool, light frost-free environment at a temperature of about 45oF/7oC.

The aim of chitting is to produce plump, dark green or purple shoots about 1in/2.5cm long.  Thin, long white shoots are a sign of too much heat and not enough light.  If shoots are slow to appear, about 3 weeks before planting move the tubers to a warmer position for a couple of weeks and then back to the original, cooler place for the final week.

Planting in plots A few days before planting, fork over the plot, incorporating some fertiliser in the top few inches – our pre-planting potato feed is ideal.  Set the tubers in rows, either at the bottom of a ‘V’ shaped trench or in individual small holes made with a trowel.  Many gardeners aim to have the rows running north-south as this allows the sun’s rays to warm both sides of the ridges.

First Earlies, Second Earlies and Salad varieties should be positioned 30cm apart and 10cm deep in rows 45cm apart; Maincrop varieties should be spaced 40cm apart and 10cm deep in rows 60cmapart.

As soon as shoots start to appear above the soil, it’s time to start ‘earthing up’ the rows.  This means pulling soil over the shoots from either side of the row to form a ridge.  This protects the plants from late frosts and prevents the tubers from becoming green and inedible.  Repeat this regularly until the ridges are about 20cm high.

Potatoes need plenty of moisture, particularly round about flowering time which is when the tubers start to form.  In dry spells it is recommended that the crop is watered every 10 days or so.  An occasional heavy watering is better than little and often as this does not get down far enough and encourages shallow rooting.

Harvesting: Harvest times depend on planting dates, weather and temperature at planting time, weather during the growing season, variety maturity and weather and temperature at harvest time.

First Earlies are best harvested in small quantities and eaten straightaway when fresh in June and July.

Second Earlies and Salad varieties can also be harvested in small quantities and eaten when fresh in June and July.  Alternatively, if the skins are allowed to ‘set’ – i.e. they don’t rub off when the potatoes are lifted – cut the foliage down to stop continued growth, lift in September and store as per Main crop varieties.

Main crop varieties can be lifted from September onwards and stored as long as the tubers are lifted in dry conditions or are dried properly before being put away. Store in a cool, dark, frost-free area.

Storing Maincrop varieties can be lifted from September onwards and stored as long as the tubers are lifted in dry conditions or are dried properly before being put away. Store in a cool, dark, frost-free area..

Potato Pests and Diseases

Potato Blight – Worst in warm, moist conditions from mid-summer onwards. Brownish black spots appear on leaves and stems and eventually spores from these spots can wash into the soil and effect the tubers. You can reduce risk by wide spacing or growing in Gro-Sacks, as this reduces the risk of infection from one plant to another. Remove and destroy effected leaves and leave the potatoes in the ground for three weeks before lifting, so that the spores on the soil surface die.

Potato Cyst Eelworm – This is a widespread problem in soil where potatoes are often grown. The plants’ growth is stunted and the leaves turn yellow and die. Your yield of potatoes will also be reduced. Unfortunately there isn’t a lot that can be done about eelworm, apart from to avoid growing potatoes in affected areas.

Virus diseases – Potatoes are susceptible to several aphid-borne virus diseases. Leaves become mottled and the plants stunted. Any diseased plants should be lifted and destroyed. Preventative measures include: buying new seed rather than saving your own, bin old tubers instead of adding them to the compost heap.

Potato Blackleg – Leaves become pale and curly inwards and the stems begin to rot at the base. Affected plants should be dug up and destroyed.