When did those larger onions go in? What is the weather there? Cooler?
I live 30 miles south of Nashville TN. Our last frost is usually April 20. Our first frost is about Nov 4. I planted onions March 1st. I usually plant sets because onion plants are hard to find not many people sell them. Sets are 1 year old so they will not usually grow a large onions I get a lot of 1 1/2" diameter onions & some 2" onions from sets. Onion plants are usually 2 months old they will grow to be large bulb onions if your growing the correct onions for your area. I am at 34 degree latitude. People north of 34° need to grow long day onions. People south of 34° need to grow short day onions. Intermediate onions grow ok here too. I have Red onions I don't recall if they are long or short day, most of them are ping pong ball size but some times I get some 2" diameter. I planted Vidalia onions from sets they are not growing large most are ping pong balls & have no flavor. I planted Candy onions from sets & plants, sets are ping pong balls, plants are 4" diameter. I plant 400 onions every year if they are all ping pong balls or golf balls we have an ok number of onions 8 small onions equal 1 grocery store onion. LOL. Trick to growing onions is to fertilizes with a lot of nitrogen 21-0-0 until day length becomes 13 hours long then switch to 0-20-20 fertilizer. Nitrogen grows tops the goal is to grow 10 to 12 leaves on each onion, each leaf is a ring, 12 leaf onion has 12 rings. Once you have 12 rings you try to grow larger bulbs with lots of P & K. Stop giving plants nitroger and start giving them 0-20-20 fertilizer. Onions need lots of water when growing larger bulbs. I planted onions sets & plants too on the soil surface then cover with 2 1/2" of mulch. Mulch is soft it lets bulbs grow larger. If onions try to grow seed tops cut tops off. If tops get heavy and fall over don't worry about it plants are at the stage where they are growing large bulbs. Keep a close watch on bulbing onions sweet onions might try to rot and need to be pulled up. When temperature gets above 90° onions don't like it, shade cloth keeps plants cooler in hot weather, sometimes I shade onions and sometimes I don't. I use all my 7 ft tall stakes on peppers & tomatoes I have none left for shade cloth this year. Yellow onions last a long time in the pantry about 2 to 3 months. Sweet onions don't last long. Red onions have the best strongest flavor but don't last long either. If you can plant onion seed about Jan 1 st in 12" pots they be ready to transplant March 1 st. If I could buy 100 onion plants very March 1st I would only need to grow 100 BIG 4" onions instead of 400 ping pong ball onions not many people sell 2 month old onion plants. I don't have a good way to grow 100 plants in a 12" pot it needs read sunlight and be kept warm about 65° for them to grow. This year out weather temperature has been 10° below average we should be having 90 & 95 degree weather already but its only been 70, 75, 80 for a month that is good for onions. Dickson Dale farms sells onion plants but price + postage cost more than 70 lbs of grocery store onions already grown. Sets are $6 per lb but you need to grow a lot of small onions to equal a grocery store onion.
