It's waiting to surprise you.

Dax

Ha ha, a longer wait than grafts though my august 2014 graft is pushing after a wait of 40 weeks!

Yo, I almost commented on those same lines in terms regarding grafts. I've waited 2-years for grafts to break.

Dax

I've noticed that grafting delays and limits the push just like a transplant can do. My 2013 grafts have pushed a month earlier and much more strongly. I expect next year they'll be at their usual pace.

In my calculation a graft that has been off the mother plant for say 39 weeks (3/4 year) must have taken even if it then doesn't push.

If the bark of the scion isn't dried out (very noticeable) then you simply wait. You may see callous, but if that bark isn't healthy, it's game over.

A conifer graft actually callouses in 7-10 days. It's the aftercare (weening off humidity and weening/acclimating them to the outdoors) where most are lost; and over watering prior to the new growth being hardened. After that you may keep them pretty moist, but it's best to let them dry out a bit between watering(s).

Dax

I believe the UK is the climate cradle for graftings. Simply the temps over the first six months are very benign usually. I graft, wrap and seal in a cocoon of beeswax, keep indoors for two weeks at unheated room temp (Feb 12c) with plastic bagging, and then outdoors without. Seems to work a charm.

You said your plastic bag system was pretty much that but of course you have to combat much higher temps = drying out. Hence you need to keep the mist count up. I won't lose moisture from the rootstock like you would.

A european grafter could not teach a US grafter the critical higher temp techniques I reckon.

Yep, a grafters 'paradise'. My friend near Portland Oregon grafts a full flat and carries the flat to a hoophouse with the doors wide open and throws a piece of plastic over them. Does nothing else. Light, temperature, and then continuation of temperature and sunlight arriving during summer with those temps at the most 75 F / 24 C for three months and then cloudy days and moisture again for nine months.... it's damn near impossible to kill grafts.

Dax

On the flipside I'd kill for your land space. Have you ever considered growing the species contorta? The ones I've seen here are so dense and quite narrow (not sure if that is certain type) but I would certainly grow one given room.

I chose to plant (4) species in the very beginning with a few random's as I went along. Pinus contorta definitely grows well here but I hadn't considered growing the species. Any room I've made and have now will go to nut trees and fruit trees.

Dax