Why You Shouldn't Plant Onions In Autumn

If you are a gardener who spends much time online, you will have seen all the advice telling you to plant your onions in Autumn/Fall.

I don't agree with that, and I will explain why in this article, so if you are thinking of planting onion sets, give this a quick read first.

So, Why Not?

If most people tell you to plant your onion sets now, then why do I think it isn't a good idea? Well, there are two main reasons: the timing can be hard to get right, but the main reason is bolting.

Tricky Timing

Plant your autumn onion sets too early, and they will grow quickly, if they are well developed by winter, then they will be at risk.

Too much foliage puts them at a higher risk of damage during the winter.

Conversely, If you wait too long, then they won't have enough time to establish themselves enough before the bad winter weather arrives.

This will again put them at risk of damage during the cold winter months.

So, it is a delicate balancing act. And this balancing act can often be made harder by the unpredictable weather we get in autumn - it is a season of change, after all.

Take this October, for instance; we are predicated a mini heat wave here in the UK - bringing unseasonably warm temperatures with it.

Any onion sets in the ground during that time will romp away, and they may grow too large to survive the winter.

But equally, the weather often goes the other way, and a cold snap could kill your onions off before they even have a chance to get going.

Bolting

This is the main reason I don't recommend planting autumn onion sets - they are very prone to bolting.

This happens when the onion flowers early and tries to go to seed.

When this happens, the onion needs to be immediately harvested, otherwise it becomes inedible.

I lost most of my crop last year because of this, so I will not grow from sets anymore.

Bolting is much more likely to happen if we have a warm and dry spring, which seems to be happening more and more often.

Onions are biennial and flower in their second year, because onion sets are allowed to grow for a while before being halted and sold as sets they can get confused as to where they are in their development cycle.

When this is coupled with warm weather, they think it is time to flower and develop seed rather than growing a nice big root for you to eat.

In my experience, this is a lot more common with red onions, infact i think every single one of my red onions bolted this year!

What To Do Instead?

If you cant plant your onion sets in autumn, then what can you do?

Plant In Spring

For me, planting in spring - around March/April is the better option.

When planted in spring, your sets are much more likely to survive and also shouldn't bolt.

Grow From Seed

Instead of growing from sets, why not try growing your onions from seed?

This is cheaper than buying sets and also gives you much more choice.