Since trees should be planted in the fall, and since fall coincides with Halloween, I thought it might be appropriate to mention some of the horrors brought on by incorrect tree planting decisions and procedures.
Unfortunately, there are many widely accepted tree planting practices that nearly always result in headaches and disappointments, but such practices continue nevertheless.
There is a notion in the minds of many that every front and back yard, regardless of size, needs at least one large shade tree in the center of the yard. Recognize that in a yard of 1,000 square feet or less, a shade tree such as a fruitless mulberry, a Chinese elm, a Shamel ash, a Brazilian pepper, a California sycamore, or a Valley oak will dominate the landscape or garden at the expense of sun seeking plants growing close by. Shade trees should be planted on the side or at the back of a yard or they will block out the sun so effectively that, in a span of a few years, the only plants able to grow will be shade loving species. Of course, trees planted on the side or at the back of a yard may also cause complaints when they begin to lean over and take away the sun from a neighbor’s yard.
In truth, Valley gardens that are most pleasing to their proprietors – and support the greatest diversity of plant species – usually receive at least half of the day’s sun. With less than half-day sun, you will see few flowers on roses and perennials and gather a meager harvest from vegetable plants and fruit trees.
To satisfy a craving for cool shadows without compromising the complete horticultural experience, plant medium-sized fruit trees that produce a modest amount of shade. Most fruit trees – apples, plums, peaches, apricots, citrus, mango – lend themselves to pruning and can be kept at a manageable height and girth, sharing the sun with the rest of the yard without compromising their own productivity. These days, most popular varieties of fruit trees are also available as semidwarfs. As a rule, semidwarf trees do not grow taller than 15 or feet.
When selecting a tree in the nursery, trunk thickness or trunk diameter – known as “caliper size” in arborist lingo – is the best indicator of tree strength. A tree that is 6 feet tall with a 1-1/2-inch caliper is a better buy than a 7-foot tree with a 1-inch caliper. A tree with a proper-size caliper should stand on its own immediately after planting and not need to be staked.
From my experience, it is often difficult – if not impossible – to wean a tree from a stake support. If a tree is so spindly that it requires stakes to stand up straight after it is planted, it should probably not be planted at all. It would be better to plant a much smaller tree which, despite its inferior size, can at least stand on its own.
After planting, do not prune off any small stems growing out of the trunk. The leaves on these small stems will produce food that will go directly into the trunk, increasing its thickness and wind resistance. After a year or two, when the trunk has been strengthened, these side stems may be removed.
A tree may flounder if too much soil amendment is placed in its planting hole. Soil amendments encourage roots to grow in a circular fashion; roots stay where the soft amendments are found and have no inclination to grow into the harder soil beyond. Trees growing in 1- to 7-gallon containers should be planted in holes where soil amendments make up no more than a quarter of the soil volume. Trees growing in 15-gallon or larger containers should not need any soil amendments in their planting holes. California native trees, regardless of size, should not be planted with soil amendments.
Lastly, there are a few trees that should not be planted in the fall. Tropical trees, such as citrus, avocado, guava and mango, are more wisely planted in late spring or summer. Aloe and cactus trees, as well as palms, will also benefit from warm-season planting.