Onion Sets in Containers

I have just bought a red shallot onion set from Wilkos (75% off ! ) I have never grown onions in a container before. Will I need to plant them in a full depth container ( 8-10" ) or could they grow in a deep seed tray of 3" ?
Also how long will they take to grow ?

TIA

 

Hello HarryS. Onion sets will do well in a container. You won't need 8 - 10 inches but 3 inches might not be quite enough. 4 - 6 inches will be plenty. As for how long they take to grow it depends what size you want them to be. I plant them quite close together and use them like spring onions taking every second one while they are still small and leave the others to grow on, then back to every second one until they are used.

 

I do exactly as Alice says above, probably because I got the tip from this forum!

A normal seed tray will be of insufficient depth, so I use old plastic mushroom boxes (free) with some weed suppressant material (1 x 15m for £3.99 from HomeBargains, so approx 8p and re-usable) and a rectangular piece of old compost bag in the base with some drainage holes cut in it:





But could probably just be lined with some old compost bag with a few drainage holes and costing absolutely nothing (it's just that I had some of that fabric left over looking for a use).

 

I think that's just exactly it Scrungee. And garlic will do well the same way.

 

Thanks Alice , I have planted them up in a full depth container , about 4" apart. The idea of picking alternate onions and letting the others grow on is very neat
Scrungee - the plastic mushroom boxes lined with weed material is another great idea for container growing Are these the boxes the supermarkets throw out , are they about 6" deep ?
Now my 3" seed trays - could I grow spring onions in this size of container ? I have heard of people growing them in length of guttering.

 

I'm still rather new to using these in this way, but I like to experiment with quite a few new things every year. Here's examples of what I have:



Obtained from markets, local restaurants, etc.
Mushroom boxes 85mm deep
Tomato boxes 100mm deep
Veg boxes 125mm deep (Hmm, is there potential for a modular, portable raised bed system here?).

And for comparison my seed trays are only 50mm deep.

Whether or not a standard seed tray is deep enough, it may well dry out exceeding fast with loads of thirsty onions in it. When I'm planting up a couple more boxes later today I'm just going to use some pieces of compost bags as the liners with some drainage holes cut in the bottom.

Does that mean containers of autumn planted garlic could be left out until they've had the necessary period of cold conditioning, then be moved to somewhere warmer to bring them on faster for an earlier crop?

 

Yes, Scrungee. you can grow garlic in those containers no problem at all. I've had great crops out of containers just like that.

HarryS - You can grow spring onions in ordinary garden pots. They don't have to be too big but they give you just a bit more depth than a seed tray will give you. I find spring onions a slow crop so I start them early (Feb) in 3" pots on the windowcill. You can keep them in the pots all their lives or plant them out later by just knocking the pot out and planting the whole bunch together. They grow on fine.
PS You can grow shallots in containers just like the garlic too. Space them out a bit to leave room for all the shallots you'll get from the 1 you planted.

And you can plant red onion sets in containers just about shoulder to shoulder thinning them as you go and using the thinnings as spring onions. That's what I do while I'm waiting for those slow spring onions to be ready.

 

Thanks again Alice I am going to use your onion growing strategy next year. It sounds like a great system for maximising a containers yield.
Now I am off to tour our local convenience stores rubbish bins. To try and get some of Scrungees plastic veg trays :D They are perfect for the area I plan to grow some veg in next year !

 

I have planted my spring onion seeds in containers 6" deep , provided by my local Co-op , a-la Scrungees suggestion , and Alices planting method
Now there is one thing I cannot understand . You plant seeds 2-3" apart in the seed rows , but leave 6" between rows !!! :gaagh:Obviously veg grows in an oblong form . Or am I missing something