I learned a few days abo that it's possible to regrow the ends of regular store bought onions by suspending the roots in water, and grow a who.e new edible onion. In the current spirit of self sufficiency I'm testing it out, and already see some new root tendrils on my spring onion ends.
I'd kinda had the impression that Monsanto and the like had rendered most store bought veg sterile due to absurd copyrights, so I'm happy to learn that's not always the case.
I have posted about this in many conversations over the many years I have been here.
Generally, if you are intending to plant the bottoms of fresh green spring onions AND you already have a garden bed prepared for just such a treasure, do not even bother with the roots in water trick. I keep a place for just these types of food scraps and I simply walk out with them after meal prep with a trowel and put them directly into the soil.
I place them about an inch deep and keep the area moist. I often see the first leaves above ground in just a few days.
I have also replanted fennel, lettuce, garlic (and mainly almost any vegetable that is complete with a root end attached will work) all which came from the grocery store.
Another tip about your spring onions: When you harvest, do not pull them up. Bring garden handheld clippers with you and dig just under the soil and clip them, instead of pulling the whole thing up. That way you are not pulling the roots out disturbing them quite dramatically and then replanting them. Just leave them in place, clip the part you want to eat and the remaining undisturbed root will regrow much faster.