Little Ken, I'm not familiar with the Pukekohe Long Keepers, but all onions are day-length sensitive. Good keeping onions, for the most part, are long-day-length types.

It could be that they aren't suitable for your area, because you might be in a short- or intermediate-day length area.

BTW, were you supposed to grow them over the winter? That, too, might have had an affect on bulbing---or the lack thereof.

Thanks for that. Last year was my first with the vege garden and I'm figuring things out all the time-

The onions were in the corner of my vegetable garden that gets the least sun - and probably also has poorest soil in the whole garden. It's very light and thin compared to the dark and heavier soil in the other beds. Also no worms in the planter box.

It grew really good tomatoes and the nasturtiums are very happy in there.

I'd planted the onions there so I could 'forget' about them till they were ready- it being the quiet back corner of the planter box where not much ever seemed to grow....

I've pulled them up and put some flowers (echiums, nasturtiums and borage)in instead -along with quite a lot of compost in an attempt to improve the soil.

I was working on the theory that if the plant centre sold the seedlings then it was a good time to grow them.

I have recently found the actual seeds for the same onion variety and they suggest planting in September for harvest in around March (the end of our summer and about 7 months of growing time).

So far everything has taken about a month longer to 'mature' than the tags suggest. I guess they're a guide and not a promise.

Days to maturity should always be thought of as a guideline rather than a hard fact. Too many variables are at work for DTM to be a promise.

Onions are heavy feeders, and that could be contributing to your problem. Except that you are apparently getting healthy plants. Bulbing is a function of daylight, and it's possible that where you have them situated they aren't getting the right light.

Other than those guesses, I'm at a loss.