my nephew planted red onion sets says we have to leave them until they get real big Do I break over tops after they bloom or do I leave them or is he right --they will grow big??? I wonder if they will just die before they get big HELP

If they send up seed heads, use them as green onions. They will not develop properly as cured onions. Sets are notorious for bolting, Plants are much more dependable as well as offering better varieties for a given location. Red onion sets are usually Red Weatherfield. I like red onions, but
I grow from plants. In my area, I use short day varieties.

So is Red Weatherfield a short day variety? I am struggling with getting onions to set bulbs...

I do not know what type these onions are as he bought them at our local grocery store. I thought he got sets for table onions but he says no they are to be left for large onions He know nothing about gardening he just is trying to help me and I have never tried to grow onions that you leave to get big. We live in Kansas and I grew vegetables when my kids were home but they are all grown so I am a flower gardener now. These onions are getting large flower heads on them now.

Sets will normally be Red Wetherfield a very long day storage onion. Since sets are second year onions they are very prone to bolt. Only storage onions keep well enought to use as sets. Onions are pretty easy, but timing is critical. Long day onions need the summer soltice daylight hours to trigger bulbing. In the south the soil temps at that time at too high for onions most years. We have had a cool wet June this year so my long Day Spanish onions (Golden Grande) are bulbing up. They don't require as much daylight as Red Wetherfield tho.

This is definitely a newbie question, but what do you mean by sets or plants? I've tried to grow onions twice now and never get the large ones that I'm hoping for. . . And where do you buy the plants? I'd really like to be able to grow medium/large red and yellow onions!

This year I bought a bag each of red and yellow onion "bulbs" (that's what I call them!) from Lowes and planted them really early in the spring, probably mid-April, which is our average last frost date. The greens grew really well, some flowered, and they started flopping over and turning brown at the beginning of July. I had read that you're supposed to wait for the greens to start to die before you pick them, so I did. But about 1/3 of them were no bigger than a green onion! The rest were small to medium size, and some of those were rotting in the ground. What am I doing wrong?? Other than buying at random from Lowes...

I have personally never seen onion plants for sale. Sets are those small onions that they often sell by the pound in feed stores or local nurseries.

Most feed and seeds in the east sell onion plants in the early spring (Bonnie plants) varieties are limited and not always suitable for the area. As mentioned before , for most states not sharing a border with Canada sets are best for green onions. They are long day onions with a very strong tendency to bolt. Dixondale is the most popular onion vendor. http://www.dixondalefarms.com/ Brown's Omaha plant farms is also excellent. bopf.com/Oniowww.n-Plant-Varieties/