Onions are an essential crop for most vegetable gardeners and can do very well when sown in a polytunnel. There are a wide range of white skinned and red skinned varieties, some better for autumn planting, some better planted in the spring. In addition, there is a further range of onions available that are perennial and will offer crops year after year. To help you decide which ones you should grow, here is a brief guide to choosing onion varieties for polytunnel planting:
Most onions have white flesh, with yellow, white or brown skins. These varieties vary in reliability, storage capability and size. While onions can be grown from seed, most gardeners will choose to grow their onions from sets. Some white onions are better for planting in the autumn, while other cultivars do best when planted in the spring. White onions tend to have a stronger taste than red onions and a less distinctive flavour than shallots.
Red onions can also be found in different sizes and again, different cultivars will have different strengths and weaknesses. Red onions tend not to store for as long as white onions. They have a more subtle flavour and can also be used to great effect to create a more interesting visual element to a variety of meals. As with white onions, some are better for autumn planting, some better for planting in the spring.
Shallots are smaller than onions and yet produce multiple bulbs from each one planted, rather than just one bulb from each set. This means that single bulbs can produce a yield and still provide extra for re-planting the following year. Shallots have a more distinctive flavour than onions and find their application in a range of different recipes. They are used in pickling as well as in cooking.
Several alternatives to annual onion crops are available which offer the same benefits as shallots in that new sets will not need to be purchased each year. Options include walking onions, also known as tree onions or Egyptian onions, potato, ground or hill onions and bunching or Welsh onions. None provides the large bulbs of annual onions, but all offer an alternative, low effort way to get the allium flavour for your kitchen.
Growing onions of some form or another is practically essential for every grow-your-own gardener. Choose wisely and you can enjoy their flavour in many dishes throughout the year.