Onions are some of the easiest things to grow and require very little looking after. As our friend Dermot Carey (last head gardener of Lissadell House) says if you can't grow onions you might as well hang up your gardening gloves and take up golf. Now, Dermot is a professional vegetable gardener and while I agree onions are an easy crop there are a couple of things worth looking out for to make sure you get a successful harvest. Most of us will know you can either grow onions from 'sets' or seeds so here's a little information on both: Onion Sets Onion sets are just immature or part grown onion bulbs from the previous year. They are produced by sowing onion seed very thickly which results in plants with very small bulbs. These little onions are sown the following spring to mature and produce full grown onions. Sets are the easiest way for the beginner to grow this essential crop as they are so easy and pleasurable to set out. You won't get as wide a choice of varieties but you will have a greater chance of success. When to sow onion sets The best time to sow onion sets is mid March to mid April. If you are sowing red onion sets is better to leave them till April as they are more prone to bolting and a later planting may help. Sets can also be sown in Autumn from September to early October. If you have a wet garden or live in an area of high winter rainfall growing in raised beds is recommended as sets left in wet soil are likely to rot. You can also plant sets in modular trays which can be kept in an unheated greenhouse or tunnel for planting out when the weather allows from mid March. Site and Soil Onions like an open sunny site. Your soil should be fertile with a good bucket or two of well rotted garden compost raked into the surface layer as onions have relatively small and shallow root systems. Avoid manure or high nitrogen feeds as this can result in thick necks which won't try properly and will rot from the inside out. If you are looking for a good soil amendment before planting onions I can happily recommend 'Envirogrind' soil improver which I use every year, I just spread it on the surface of my beds and cover with the 'Growgrid' onion planting mat I mention below. Sowing Onion Sets Once you have your bag of little golden onion sets you'll have to pick the best ones to sow. This is very important, if you're doing your job properly you'll end up throwing half of them out so bear that in mind when you're ordering. Here's a quick diagram to help you pick the best. From left to right:
- You don't want any shoots, you might think you're getting a head start but you'll just get a very poor quality bulb.
- Avoid any skinny looking ones.
- Discard anything with mould or brown patches on the skin.
- Any very big sets are more likely to run to seed.
- Now, that's the fella. Nice, tidy and round, will produce a perfect onion.