There are several items essential to large onions:

- Buy onion plants as opposed to sets
- Grow a long day variety in CT (Walla Walla works very well)
- Plant at the right time (for CT that's around April 15)
- Give them room, spacing onions 6" apart in rows that are 12" apart.
- Fertilize with a high nitrogen fertilizer for strong top growth, starting three weeks after planting, then every month ending in mid May.
- Keep the onions weed free - they do not like competition. A good mulch helps.
- Water at least 1" per week - onions like water.

TomNJ

onions like a very light soil around them. What I do is use a hose end sprayer and wash most of the soil away from the bulb so it is just bearly there. if planted too deep they will stay small no mater what.

I agree with TomNJ but I plant mine in a wide row of 4 on 10 inch centers.and I plant them to the depth of the first joint on my index finger.Walla walla is a very good onion but the regular candy will keep longer.Everyone gardens a little different experment a little and do what works best for you!!! Good gardening to ya!!! YOPPER