Frequently Asked Questions

Alliums (onion family)

Why are my onions always small?

According to most experts, the number of leaves the plant produces before the days get shorter (after June the 21st) determines the size of the onion bulb. Therefore, the earlier you plant the seed (or plant the sets), the bigger the onions you will grow. If your onions won’t grow big, then either:

    1. the soil is impoverished & needs feeding (obvious)

    2. they’ve been sown/ planted too late or

    3. the effects of a cold & wet spring hinders their initial growth – thereby again - reducing the number of leaves  produced before the longest day

The other big factor is whether they’ve been buried or just grow ON the soil surface with just their roots in the soil. Some growers actually go to the bother of removing soil away from the bulbs as they grow to maximise the amount of bulb exposed above the ground. The exact opposite to what you do when you earth up potatoes.

Onions are also very sensitive to competition. They should be weed free at all times. They require constant watering (after all the bulb is mostly made up of water), and should never be allowed to grow in drought conditions.

Conversely, they should never be grown on very wet, water-logged and cold soil as they are also susceptible to rotting, if the bulb is left to rest on water-logged soil. Wet & especially cold soil conditions can also promote the dreaded ‘white rot’ fungus. If that happens the soil will be contaminated with the fungus for many years.

Onion sets and onion plants require loose soil and should be planted early (end of February or March). Dig a shallow trench, working in compost or fertilizer for big onions. Likewise, raised beds can be implemented. Plant the onions about an inch deep and 4-5 inches apart.

Wider spacing makes it easier to control weeds, which can compete for nutrients. Keep the area weed free; otherwise, the onions won’t grow big. Once onion bulbs begin to swell (in late spring), ensure that they remain above ground. Onion plants will continue to increase in size until the middle of summer, at which time their tops begin to fade. Once these tops have completely faded and fallen over, onion plants can be pulled and left in the sun to dry for several days before storing in a cool, dry area.

All this sounds complicated, in reality, given reasonable conditions, onions are a relatively easy crop to grow and usually give good results in most rich, well drained soils.

What are Egyptian Onions?

Egyptian Onions  (Allium proliferum)

(Also referred to sometimes as "Walking Onions", "Tree Onions", "Egyptian Tree Onions", "Top Onions", "Winter Onions", or "Perennial Onions" amongst other names)

 A genuine member of the  onion (Allium) family, it is believed that they are a hybrid cross between the common "bulbing" onion and the Welsh onion. They have characteristics of both.

 Garlic is also from this family and the Egyptian onion also shows a remarkable resemblance to hard necked garlic - the ones that develop scapes.

 As their scientific name "Allium proliferum" states, these hardy little onions are very "prolific." After planting them in your garden or allotment you will have onions every year for years to come!

 Egyptian onions are very hardy, and can be planted in the autumn.

 They are called "walking" onions because of the unique way the bulbs clusters bend down from the weight of the bulbs as they grow, eventually touching the ground, and taking root. As the picture on the right shows you can see them "walking" from the mother plant by bending down under the weight of the bulbils (or bulblets) at the top of the stalks.

 You can divide these clusters and plant as you would other onion sets in the autumn. They do have a rather strong taste, so you won't need many! You can also use the green stalks, which are edible, much like spring (bunching)  onions or chives. If you allow the new bulbs to fall over and root, these will sprout for you to use. They are best before the bulbs start to form on the new stalk because they do become tough at that point. There will be enough to use for the stalks, the bulbs and some for planting.

 In the early spring you'll be able to dig some of the onions up to use as bunching or green onions.

 Plant the small bulbs in soil that is well dug and amended with organic matter such as peat and compost. As mentioned, they are very hardy so should do well even in very cold climates.

 The phenomenon of forming bulblets instead of flowers is also seen in garlic and other various species of Allium, which sometimes may also be referred to as top onions or tree onions. The bulblets are generally marble-sized, usually within 0.5 cm to 3 cm in diameter, although sizes may differ out of this range from time to time.

 Many Egyptian onions are very strong flavoured, although some cultivars are relatively mild and sweet. The underground bulbs are particularly tough-skinned and pungent, and can be quite elongate, like giant scallions or leeks, or in some types may form bulbs up to 5 cm (two inches) across. Young plants may be used as scallions in the spring, and the bulblets may be used in cooking similarly to regular onions, or preserved by pickling.

Some thing is eating the tops off onions not an insect what could it be?

There is hardly anything that munches on alliums (onion family) - anything big anyway! The culprits are usually onion thrips, allium leaf miners, onion fly or leek moth caterpillars. With onion fly - as with most similar pests of onions - the damage is usually to the bulbing area of the plant. You say your damage is on the leaves. Slugs will very OCCASIONALLY attack small onion leaves - if you have a slug plague and they are limited to what's available to eat. However as a rule they would prefer to eat almost anything else, before attacking onions!

Without a picture of the damage, it is hard to make a diagnosis. It's most likely to be thrips or miners.

Onion thrips (Thrips tabaci) is a world wide pest of onions, other allium species and several crops, such as cabbage, cotton, celery, tomatoes, beans, cucumber and pineapple. Thrips are easily detected by visual inspection of the onion plant as their feeding activities produce silver or whitish streaks on leaves. The damaged young, expanding leaves become distorted and the onion bulb growth is smaller. Severely damaged leaves and plants may turn brown and die.

The allium leaf miner was first detected in Britain in 2002, since when it has spread in the Midlands and has also been found in Surrey. The larvae bore into the stems and bulbs of leeks, onions, chives and garlic with devastating consequences. Affected plants often develop secondary infections and rot. As I understand that your plot is in the Midlands - the finger points to the miner!

The first sign of an attack from allium leaf miner is the presence of the adult fly. The greyish brown flies are 3mm long. Before laying eggs, the female flies feed by making punctures in the leaves and sucking up the exuding sap,  this causes distinctive lines of white dots on the foliage.

Next seen is damage from the maggots. The larvae are white, headless maggots without legs, hese make tunnels in the stems (and bulbs) of their host plants. However, it should be noted that similar damage CAN be caused by the caterpillar of the Leek Moth. That pest has creamy white larvae with brown heads and small legs. Perhaps the most obvious signs of a problem appear when rotting sets in.

Plants affected by both allium leaf miner and leek moth tend to rot due to secondary infections from fungi and bacteria that develop in the damaged tissues. On closer inspection, cylindrical brown pupae may also be found embedded in the stems and bulbs.

As a point of interest, mice to my knowledge don't go for onions (peas & beans are a different story!) HOWEVER hamsters WILL eat onions. It's pretty unlikely that you have a wild hamster on your plot! Do you have rabbits though? They are pretty curious and will eat a surprising range of food. It is really down to how big and complete your damage is.

I'm also told you have holes in the ground around the area. THAT could be voles - I'm not sure if they eat onion leaves, they certainly love liles, which are a close relative. The bulbous onion and its numerous relatives belong to the Lily family. So on reflection it could certainly be voles.

Voles, which are prolific breeders, are the most common mammal on earth. Voles can be a real nuisance on vegetable plots. They live all year-round in a series of connecting underground tunnels that protect them from predators. They are quite small but have huge appetites!

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