When to plant grafted rootstock outdoors?

I've grafted my scion's to the rootstock, but have been told I need to keep them dormant (below 60 degrees, as best I can) until after the last threat of a heavy frost or freeze.  Here where I live that could be into late May or even later. So is this really a concern or can I plant them and just cover them with a 5 gallon bucket on nights it gets near freezing?  I only have 5 to plant.  The weather has been unusually warm this spring and the ground is warming quickly.  I'm a bit worried that they'll dry out, even though I am keeping them moist in sawdust and sphagnum   Thanks, Bill

i've read that 2-4 weeks at 50 degress or so inside a unheated shed or basement or cellar. Then slowly introduce the trees to 'real life' conditions when your outdoors as tree would experience from that dormant state via natures progression in the seasons.  Which tells me when your night temperatures are about 50F then you can place the trees out side in a shaded area for a week, then to a bit more sunny area the following week and so on until you reach full sun, keeping the plants in their pots (3-5 gallon). Possibly planting them in the ground in full sun during the Fall and deeply mulching or bringing them in for the winter.  

this is not pro advice, but i am in a similar situation to yours and this is my plan thus far...

Hey, Blaze...it seems I'm learning that putting them in pots for this first year is the way to go, as Randy Bucher suggested this could help with bug control as well.  I was just going to plant them directly to the "orchard" but am having second thoughts.  What medium (potting soil?) did you use in your pots for planting them?  I like how you are thinking of acclimating them to the "real world".  I also posted this question under "Bench grafting question" in the apple trees forum where my education on grafting began!    

i'm using (the ratios are 'rough estimates')

2 parts humus/composted manure
2 parts peat moss
1 part  perlite

I do outdoor grafting while snow is still on the ground. I plant bare-root trees any time that the ground isn't frozen. The grafts and trees grow fine. If the trees had been indoors, and were ahead of the season, I might wait to plant them out until after the leaves had emerged on the outside trees.

I grafted about 260 apple trees last April/May outdoors and it is looking like 100% mortality of the grafted scions, the rootstocks are growing fine. I am in a Zone 2b/3 area and our coldest temp was about -38C last winter. I am ready to graft some more trees but I am not sure how to approach the outdoor tree grafting thing, most of my rootstocks are growing outdoors. All my scion wood is from trees that grow in zone 2b in Canada. Anybody have any thoughts?

Robert Baerg wrote:I grafted about 260 apple trees last April/May outdoors and it is looking like 100% mortality of the grafted scions, the rootstocks are growing fine. I am in a Zone 2b/3 area and our coldest temp was about -38C last winter. I am ready to graft some more trees but I am not sure how to approach the outdoor tree grafting thing, most of my rootstocks are growing outdoors. All my scion wood is from trees that grow in zone 2b in Canada. Anybody have any thoughts?

I've been advised to graft outdoors when the buds are just starting to break, which is what I've always done in the past, with mixed success. Last year I read online that grafting is feasible up until the end of bloom, so I tried that and had nearly 100% take. Not sure why; maybe the warmer weather helps them join faster. I used parafilm and completely covered the scion as well as the graft union, but forgot to do that on three grafts and those took about two weeks longer to push out, so I think that's important too.

Thanks Victor. I am also using the parafilm. I was a little premature in saying 100% mortality. Some of the trees are actually started to break bud. I have trees that I bud grafted in Aug 2015 that took and grew in 2016 and they appear to be doing significantly better than the scion/ whip and tongue grafts I did last May. The bud grafts survived a winter and they are also lower down on the rootstock stem than the scion grafts. Have you had equal success with bud grafts and scion grafts? Did you protect the newly grafted trees the first winter? I started scion grafting at the beginning of May and continued almost to the end of the month so the scion wood and the rootstocks were in different condition by the end, from when I started. What varieties have you grafted and what rootstocks are you using?

I've done very little budding, not enough for valid comparison. We use baccata and ranetka for rootstock around here; others perish in a cold winter if there's not sufficient snow. Haven't had to protect against cold, but the new grafts are vulnerable to vole damage. We have about 20 bearing trees--Heyer 12, Heyer 20, Sunnybrook, Lee 21, September Ruby, Rosthern 18, Prairie Sun, Altai Mountain, Trailman, Amber, Red Star, Norland, Alyenushka, Parkland, Norkent, Norda, Lee 35, Gold Egg, and a few others, and probably 40-50 different cultivars which haven't fruited yet, plus a few plums and pears that produce.