I haven't grown onions in containers, but I can't imagine 6-8" wouldn't be enough. Some "root" crops will want more depth such as carrots and potatos, but other things like radish, onion and garlic should do fine with 6-8".

I know of people who grow onions in Earth boxes and those have a 6" potting mix depth. Anything where the roots can spread laterally doesn't need a lot of depth, just sufficient volume of soil to hold water and nutrients until you next add them.

JAG

I had to do some digging for the information but did find the site below, UC-Davis, and have decided to go with a 12 inch depth of soil for onions in my container.

The recommended depth for them is 9-12 inches (partway down the page). There is an implication that the deeper than expected soil levels are recommended since they're less likely to quickly dry out. IOW, I don't see anything stating that the roots need this much soil, but I think I'll go with it anyway.

Here is a link that might be useful: Grow Vegetables in Containers

Should work just fine, Anney.

FT

Very nice! Soil about 6 inches deep?

Okay, this is probably a really stupid question. Last summer I grew onions for the first time from sets. The containers were about 6 inches deep and I buried the set so just a tiny bit of the top was sticking out of the mix. The onions grew but they were on the small side. Now having seen franktank232's GORGEOUS photo I noticed all the onions are on TOP of the soil. What gives? Am I supposed to just "set" the sets on top of the soil and let the roots grow downward?

Please help this onion newbie!

BD

It's my understanding that onion SETS don't do as well as onion transplants, often producing very small onions, sometimes large ones, depending on several factors.

All the "growing onions" sites say to plant the sets or transplants in the soil, though not very deep. [Not on top of the soil.] 1" deep for transplants is recommended, and maybe someone else who plants sets can give you a depth for them.

Some people remove the soil around the tops of onions after a while to keep an eye on how large they grow, so I don't think FT planted his on top of the soil, but he'll have to answer you himself!

About 6 inches...

I don't bury them at all, just put them in at the level they were growing in before transplanting. The key i guess is if you are starting from seed, do it now! The earlier, the bigger the onion... Onion roots don't seem to get that big...so i think they are perfect for container growing. Get about 20 plants and 4 or 5 of these small containers...throw in some compost.

June 9
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I'm growing Alisa Craig this year, i guess they are world record sized onions or something like that.

Even after seeing Frank's piccies, I still lean toward what justaguy wrote above. Everyone has their own system, but until you get it down you should go with what the pros say until you are ready (sez the UC Davis alum). Even though onions are pretty resilient, I have some extra onions from seed and I'm going to throw them in some extra 7-gal landscaping pots I dumpster dived freecycled and see what happens...that said, I'd be interested to read what anney ends up with and how successful it is.

Dan

Thanks for the tips - I didn't know that about sets vs. seeds. I was planning on using sets again but I may have to reconsider.

It's hard to believe it's already time to start thinking about gardening. Last night's Nor'easter dumped 12" of snow on the ground and another 3"-4" is on the way. Grrrrrrr.

I grew onions in a 5 gallon bucket years ago on my front porch. I would recommend at least a container this big. I started mine from seed. I'm growing some this year but I will be using a 4 gallon bucket which should also be fine. I also recommend organic soil since you are growing root vegetables. Don't forget the drainage holes so your onions don't rot when you water them. I come from a family of professional farmers on both sides so I've spent my childhood in fields as well as home gardens as a favorite pastime in the country. Good luck.

10 inches is fine for onions and most crops. If you can manage a bit more height all the