🌱✗ Tested and false“Leave spring onions in the ground longer to get a bigger, better crop”
These are best pulled young and small, about 15cm tall with the bulb no more than 1-2.5cm across, for a sweet, mild flavour. Left longer, the bulb swells and the flavour coarsens.
Our read The instinct to let a vegetable grow on for a bigger harvest works against you on this one specifically, which is easy to miss if you're used to treating 'bigger' as the same thing as 'better' for most crops.
What to do: Pull them young and small, and sow little and often rather than trying to get more out of each plant by waiting.
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- RHSBest harvested young for sweet, mild flavour, at about 15cm tall with the bulb no more than 1-2.5cm across
“Spring onions are only a summer crop, sow them in spring and that's it”
A hardy variety such as White Lisbon can be sown in late summer or early autumn and left to overwinter, cropping the following spring well ahead of anything sown fresh that year.
Our read The name does this crop no favours: 'spring onion' describes when you eat it, not the only time you can sow it.
What to do: Sow a hardy, overwintering variety in late summer for an early spring crop, alongside your usual spring-to-autumn succession sowings.
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- RHS'White Lisbon' AGM is suitable for successional sowing and overwintering
“Spring onions are different enough from bulb onions that they don't need the same rotation break”
Spring onions are the same species as bulb onions, harvested young. Onions, scallions (spring onions), shallots and garlic should all be grouped together in rotation planning, with a 4-5 year break between any of them on the same ground.
Our read Because spring onions look and taste like a completely different vegetable from a stored bulb onion, it's easy to assume the soil-borne disease risk doesn't carry over. It does.
What to do: Track spring onions in the same rotation slot as your other alliums, not separately, and leave 4-5 years before returning any of them to the same bed.
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- TeagascAllow a break of 4-5 years between all crops in the onion family, including onions, scallions, shallots and garlic, to limit white rot
“Growing mint alongside spring onions deters onion fly”
Gardener's World suggests this, but it's the only source we found making the claim, and neither RHS's growing guide nor its companion planting feature mentions mint in connection with onions or onion fly at all.
Our read One secondary source with no corroboration isn't enough to call this evidence-based, and mint spreads aggressively by runners, so planting it alongside anything is a decision with a cost attached whether or not the onion-fly benefit is real.
What to do: If you want to try it, keep the mint in a buried pot to stop it taking over the bed, and don't rely on it in place of proper crop covers if onion fly has been a real problem for you.
1 source
- Gardener's WorldTry growing mint alongside your onion crops as a deterrent against onion fly
