Let’s talk about flat bottomed onions

It’s already August and the days and weeks are flying by at an alarming rate. We survived the almost-39C heatwave last month, and by early August the onions and shallots were ready for harvest.

This year I opted to grow Stuttgarter Giant. I usually go for Hercules, as the flavour is just out of this world, but having had some pretty miserable crops for the last couple of years, I just wanted to try something a little different.

I planted the onions around April time, and despite not feeding them as often as I should have, the bulbs swelled and grew at a good rate. By late July the stems were starting to flop over – a sign that they’re approaching harvest time – and by early August the stems were yellowing and the bulbs were clearly ready to be pulled up.

I waited for a clear, cloudless day to pull the bulbs and lay them out under the hot summer sun to dry out. I gleefully selected the first bulbous beauty to lift out of the soil, the top half a whopping globe, but what I unearthed wasn’t a naval-orange sized specimen… in fact, there was barely much more onion lurking under the surface of the soil at all. And this is when I learned of the existence of flat bottomed onions.

Not All Onions Are Round

I’ve been growing my own fruit and veg as a hobby for a good twelve or thirtreen years. I feel like I (pardon the pun) know my onions. Turns out, I still have a lot to learn. At first, I thought my Stuttgarter Giant onions must have been stunted in growth by my no-dig approach to gardening. Perhaps the soil was too firm, or I hadn’t watered them enough to allow them to swell and grow as normal? I couldn’t work out why I kept pulling up flat bottomed onion after flat bottomed onion.

Some quick Googling quickly provided an answer; it turns out that Stuttgarter Giant onions are, indeed, just flat-bottomed, and some varieties are like this – flat onions. I’ve been growing Hercules for so many years that I just assumed all onions were globe-shaped, sometimes a bit oval, sometimes a bit wonky, but essentially round.

Flat Onions

Turns out they’re not. Dome shaped with a flat bottom is a thing. Taste-wise, the Stuttgarter Giant is just like any other onion, ie delicious. Other well-known (well, not to me) flat onions are Cipollini onions, an Italian variety, which are generally smaller than your average round onion but with a much sweeter flavour. Vidalia are also smaller, mild and sweet onions. It’s said that the smaller the flat onion, the sweeter it will be.

It’s also suggested that when buying sets, you can tell whether you’re buying flat onions or round onions. Apparently the longer and more elongated the onion set (the mini bulb you buy to plant in the ground), it’s likely to grow into a flat bottomed onion. Squat, round sets will grow into round onions, like the Spanish onions and red onions that we regularly see in the supermarket.

After lifting my onions I let them dry in our greenhouse for around 4-5 days, by which time the papery skins had hardened off a little and I was able to clean them up. I found a reusable hessian onion bag in Dunelm for about £4.50, so that will store my onions for as long as they last this year. We only managed a small crop of around 75 onions plus about ten groups of shallots – so around 50-60 super-flavoursome bulbs.

I’d love to be able to plait them, but time and inclination made the onion bag a necessity this summer!