Onion Farming: How to Grow Onions Successfully in the UK
When you think about onion farming, the practice of cultivating onions for home use or small-scale sale, often involving careful soil prep, timing, and variety selection. Also known as onion cultivation, it’s one of the most practical skills for UK gardeners who want fresh, homegrown bulbs without the supermarket markup. Unlike fancy crops that need greenhouses or special care, onions are tough, reliable, and surprisingly forgiving—if you get the basics right.
Most people assume onions just grow from a seed or a bulb stuck in the ground. But onion varieties, specific types like Stuttgarter, Senshyu, or Red Baron, each with different day-length needs and storage qualities make all the difference. In the UK, long-day varieties work best because our summers have more daylight hours than southern regions. Plant the wrong type, and you’ll get tiny bulbs or no bulbs at all. Then there’s onion soil requirements, the need for well-drained, loose soil with plenty of organic matter and a pH between 6.0 and 6.8. Heavy clay? Add compost and sand. Acidic soil? Lime it. Skip this, and your onions will struggle, rot, or grow misshapen.
Timing matters too. You can’t plant onions in March just because the weather feels nice. Most UK gardeners start with sets (small bulbs) in late February to early April, depending on frost risk. If you’re growing from seed, you’ll need to start them indoors in January. And don’t forget spacing—crowded onions compete for nutrients and end up small. A good rule? Keep them 10–15cm apart in rows 30cm apart. Water them early in the day, and stop watering once the tops start to yellow—that’s your signal they’re ready to harvest.
There’s also the question of pests and diseases. Onion fly and white rot are common in the UK, and both can wipe out a crop fast. Crop rotation helps, so never plant onions where onions or garlic grew the year before. Mulching with straw cuts down on weeds and keeps the soil moist without encouraging rot. And if you’ve ever tried to store onions only to have them go mouldy in a week, you know storage matters too. Cure them in a dry, airy spot for two weeks after harvest—no exceptions.
What you’ll find in the posts below isn’t a textbook on onion farming. It’s real advice from people who’ve tried it, failed, and figured it out. You’ll see how to fix hard soil before planting, why vinegar sprays sometimes help with weeds near your onion rows, and how to pick the best compost to feed your bulbs without burning them. There’s even a guide on what to do when your onions start leaning over—because that’s not always a bad sign. These aren’t theories. They’re the kind of tips you’d get from a neighbour who’s been growing onions for 20 years.