For apples in your zone, I think either fall or spring is ok, with some qualifications. If you're planting bare-root stock, fall planting would be OK as long as it weren't too late, early to mid October. Much later, and they might not have enough time to establish before freeze-up. Potted stock doesn't matter quite so much. As far as the shipping policies, it seems to vary quite a bit, but there are some nurseries which will ship in the fall. St. Lawrence Nursery in Potsdam, NY ships trees in the fall.

I have around 100 different fruit trees all less than about 7 years old and most planted in the fall. It's definitely better to plant in the fall than in the spring. Peaches, apples, cherries, nectarines, pears, plums. All better in the fall. I tried pomegranates and a couple service trees, but they perished within a year of planting. Not sure the pomegranates were ready for the ground, but that's how they were advertised and I treated them the same as the others. Tried figs both mail order and from Lowe's and none of them worked out in the open. I'll keep trying them with cuttings I'm taking myself from neighbors. Benefit to planting in the fall is that the roots are growing even if the tops aren't doing anything. The tops will start putting out red/dark brown growth in late January into February and leaves later on when they're supposed to. I've only lost a few other trees, two cherries last summer because they flooded the weekend we had 10 inches of rain here. But that's rare and the rest of the trees in the immediate area were fine. One apple elsewhere because of all the rain and probably weak root system. But all else look good. I even had a couple crabapples and pears this summer that the deer got before I could. One of these days I'll be busy... :-) Stark Bros, One Green World (Pacific NW nursery), and Willis Orchard Co. (southern GA) are my favorites to mail order fruit trees from. All quality products for the most part, all packaged well. I like Miller nursery as well for their berry plants. And I just tried to go to their website and it says they're merging with Stark Bros, so that tells me they really did have a quality product. I hope that's what that means. :-)

As far as currants, I've trimmed currant bushes in late sept and pushed the trimmings into the ground and watered until winter hit and had almost all go into full leaf and some even fruited the next spring. Most currants are hardy down into zones 3&4, so zone six shouldn't be a problem. ~Chills

I've planted many perennials, trees, and more in the fall. Great time for there is no harsh, hot and dry summer conditions. Plant wakes up in the spring like it has always been there. You will need to look at only US vendors as I seem to recall this plant is covered by CITES and import/export is strongly controlled. In looking at vendors be sure to look for how they get their plants. I would avoid wild collected over "farmed" plants - no sense in supporting the further depletion of wild plants. FataMorgana