Just a wild guess, but standard to me sounds like they just take apple seedlings and graft to them named variety... I have a few seedling apples...they grow big and they grow fast.

I've only dealt with seedling rootstocks at a single site- ordered trees from Millers as they were the only ones I could find that carried this stock and would ship in Nov.

When some of the trees starting flowering on the third year i thought i'd been sold a different rootstock but after managing them for 15 years or so I've changed my mind- they are very vigorous but didn't take the ten years to fruit I'd been led to expect.

Since then the issue has been discussed here and folks have written that many varieties will fruit reasonably early on seedling rootstock.

However, I would guess your very early flowering may be due to having been kept in a pot for a time- a pot makes any rootstock dwarfing.

There are many things involved in precocity besides rootstock, including variety (Zestar is very precocious) soil and even climate.

So I contacted the nursery and they assured me i got standard apples from seedling rootstock. They did say the trees were at least 3, possibly 4 year olds, and that is likely why they flowered, as well as a few other ideas, ie varietal tendencies.

So I contacted the nursery and they assured me i got standard apples from seedling rootstock. They did say the trees were at least 3, possibly 4 year olds, and that is likely why they flowered, as well as a few other ideas, ie varietal tendencies.