The onion roots themselves are usually not more than 4” long. If you are planting sets (looks like the onion bulb but less than 1” across), and you want big round onions for slicing, then you just depress the set into the soil but leave the top exposed. If you want spring onion or scallion type, then press the set into the soil about 2”. If onions are too deep, they will not make big round onions. Round Slicing Onions grown commercially are half in and half out of the ground, in fact they make a special tool to pull soil away from the onion. Also, know that onions love nitrogen.
Johnny, are you digging in your scrap pile for your howitzer before you photograph the rebel tobacco this week?
I've been busy as a one armed paper hanger. Maybe I'll get some photos posted tomorrow.
/johnny
Thanks so much for explaining how onions grow. The bag of 80 onions are bulbs less than one inch across but I see some that might be one inch.
Going by the depths you said, I can make some of these onions spring onions or scallions by putting them 2 inches down, and make some be slicing onions by leaving the top exposed.
I’ve got onions up from seed and those looks like spring onions right now and I need to put them in their final containers. When I plant those in containers, can I also plant some barely covered and some two inches deep or do these have to stay spring onions? I’m so glad to have your information.