Pruning is “logical and simple,” according to Ann Ralph. She quoted nurseryman Ed Laivo: “You don't need a bunch of fancy rules.” Ralph talked about growing small fruit trees at last month's San Francisco Flower and Garden Show.
It helps to understand the two types of pruning cuts and the consequences of making them. Heading cuts remove part of a limb, which results in bushy growth near the cut. The cut should be “near a node, so that it can heal nicely.” Thinning cuts “remove the entire branch at the point of origin,” which “creates space and redirects growth.” Most cuts should be thinning cuts.
Though she focuses on deciduous fruit trees, Ralph shared some simple, common-sense rules that apply to pruning in general.
Rule 1. If you don't know what to do, cut some stuff out. “Use your native intelligence,” Ralph said. Observe the tree and “ask what's bugging you about it.” Since you can't undo a pruning cut, she suggested that beginners get some blue masking tape and place it where they want to make cuts, then stand back and reassess. Typically you want to remove dead, diseased, dying, and damaged branches, as well as suckers and selected crossing branches and water sprouts (twigs that grow straight up from a normal branch). “Prune to reveal the shape of the tree,” she said.
Rule 2. Prune to keep the zone of equilibrium within reach. On fruit trees, “upright growth is never fruitful,” she said. The zone of equilibrium is the fruit-producing area of the tree. Ralph enthusiastically promotes the idea of growing backyard fruit trees that are kept small with strategic pruning. The goal is to keep the tree small enough so you don't need a ladder to maintain it. She prunes twice a year. The primary pruning is on June 21, “even if the tree has fruit on it.” Since trees store nutrients in their leaves in the summer, this summer pruning helps stunt the tree by removing resources before they are stored in the roots. Winter pruning might seem easier because the leaves are gone, but it's less effective if you want to keep a tree small, and it's not good for trees such as apricot that are particularly sensitive to waterborne diseases. In January, Ralph's touchup winter pruning takes 15 minutes total for the 7 small trees in her garden. It pays to keep fruit trees small. Even a fruit tree that's 12 ft. high “will have lots of wormy and inferior fruit” because you can't get in there to thin the fruit, she said.
Rule 3. Make aesthetic decisions. Aesthetics is “more important than thinking about thinning cuts or apical dominance or fruiting spurs,” Ralph said. “Different pruners make different decisions.” A pruner she knows who specializes in Japanese maples opens the canopy so that “a bird could fly through the tree” without its wings hitting the branches. An open canopy reduces the chance of disease.
Rule 4. Pruners learn by pruning. “The tree will teach you more than the internet can, than I can, than my book can,” Ralph said. Her book is entitled Grow a Little Fruit Tree: Simple Pruning Techniques for Small-Space, Easy-Harvest Fruit Trees (Storey, 2014, 168 p.). She also offers workshops in the East Bay.
Thinning cuts are made to reduce the size of main branches and redirect growth. Cut back to a branch no smaller than one-third the diameter, and make a clean cut so that it can heal properly. Never leave stubs.
This young deciduous fruit tree is developing a strong scaffold. The all-important knee-high heading cut was made at the proper time, and then 3-4 strong branches were selected. Each summer, this tree will be pruned so it will stay small.
The place where a tree was grafted onto a rootstock shows a color change or a knob. Be careful to prune away any suckers that originate below the graft union as soon as you see them. If you let suckers grow, they will eventually take over, since they will be more vigorous than the part of the tree above the graft.
© 2016 Tanya Kucak