With the help of the info on this lovely forum, I've delved into an espalier fruit tree project for a friend. A couple weeks back, I planted two pears and two apples on the East side of Mt. Tabor in Portland, OR: a Ubileen and a Bartlett on semi-dwarf rootstock, and a Gravenstein and Liberty on M-26 rootstock from One Green World. The soil drains well, there's good afternoon light, and a sloping fence from about 6 to 5 feet high with training wires already set up. I planted them bare root fairly loose, and I haven't yet watered them due to our recent wet spell.

My questions mainly revolve around espalier: I've zip-tied some of the small branches to the wires to secure and hopefully train them, but there must be a better resource out there on espalier technique specifically? Seeing as these trees are already about 5 ft. tall, I don't want to wait too long in pruning them back to training size (ie needs to happen before the spring growth, I imagine). Any successes/challenges with these varieties/rootstocks? Any problems with zip ties for training, and do you have a better suggestion?

Gravenstein's high vigor makes it hard to control. On M26 it will still be as big or bigger than other apples on M7 and will be hard to get into bearing.

My advice is to get rid of the zip ties while you're still thinking about this. I tied the little branches of six trees to my espalier wires with plain jute doesn't-take-long-to-rot twine, and in one season, some of them were almost girdled.