Espalier is the ancient horticultural art of pruning and training a tree or shrub to grow flat against a support. I have a 7' high retainer wall below my driveway doing nothing, so last year I set out 4 pear trees at the base of it, spaced about 20' apart. Couple days ago, I got started on the trellis work. I drilled 2 rows of 17 1" holes 4" deep in the 12" concrete filled block, about 5' apart. Cut 34 pcs of 3/4" (ID) black iron pipe 12" long, and drove them in the holes along with some expoxy cement to make sure they stay. Hard as it was to get them in the holes, I don't think they will coming out, even w/o the expoxy. Then I put a slight bend (wall has a radius) in some 1" pipe (got a real deal on a whole bunch of scrap pipe at a local plumbing supply a while back.....probably thousand + bucks worth of metal for 100 bucks) and MIG welded it to the stubbed out 3/4" pcs. Now I'll get a couple coats of Rustoleum galvanizing paint (to keep the heat down on the metal), let that dry a while, then slowly start bending the new branches horizontal instead the straight up vertical pears like to grow. Hope in a few years to have the wall covered with pear branches. In addition to just being fun, I'm hoping the retained heat sink of this south facing wall will help mitigate late spring frosts we're prone to get here that kill off fruit blossoms and fruit buds. Time will tell.