Mounds, not the candy

I like to plant trees and shrubs on constructed
soil mounds as opposed to planting them in
flat ground. If you’re working with slightly
heavy clay/loam soils, the mounding is
especially critical to preventing root or crown
rot (Phytophthora spp.—a fungal disease of the
upper portion of the roots, near the soil surface).
Many ornamental and fruiting tree and shrubs die
of crown rot without the gardener ever suspecting
the culprit. The fungus damages the sapwood,
either killing individual limbs or the entire plant.
Once the symptoms (pale-yellow, wilted leaves)
appear, it’s too late to do anything about it.

So, mounds help stave off root rot.

In areas where the summers are dry, make your
planting mounds in the fall; then all you have
to do in early spring after bare root roses, fruiting
and ornamental trees, and berries arrive is open
the winter wet soil enough to place the roots and
cover it with native soil. In areas where it rains in
the summer, wait until the soil drains after a rain
so that it’s moist, not wet.

Here you can see the cross section of a mound made
of composting chips and leaves from a tree service.
The mound is capped with six to ten inches of soil and immediately
planted. All plants are still planted on small mounds on the composting mound.

Based on my book Roots Demystified.

Visit my web site to learn about my new book on drip irrigation and other gardening books.

NOTE: The comments section at the bottom of the post has disappeared. Click on the "___ Comments" button or the title under the "Blog Archives". Thanks, Robert

Don't let roots circle when planting trees & shrubs

Spring is tree-planting time for many gardeners. It's also the time to make big mistakes when planting. Alas, this tree popped out of it's planting hole due to poorly-trained landscape contractors after being struck by a car. This poor tree needed to get its roots away from the planting hole. (You can see the circling roots just the way they were in the planting container.) Planting on a mound will help "drive" roots away from the tree's base as it drys out faster, making the roots seek moisture further from the trunk. So will fracturing the sides of the hole. (This tree may have been "planted" by auguring a hole in the ground and just plopping the tree into the hole.) The roots responsible for absorbing water and nutrients are the very young and tiny root hairs found near the tips of new roots. Older roots, much like older branches, have a bark-like covering that protects the root but doesn’t produce root hairs. In one study done with radioactive isotopes in England, the roots 4.5 feet away from the trunk of a 10-year-old apple tree absorbed less than 10% of the water and nutrients absorbed by the entire root system. The study showed that proportionately, many more feeding roots are found at, or beyond, the drip line of a tree’s foliage. Because of this, I prefer to place a ring of in-line emitter tubing at or beyond the tree’s drip line. This produces a “doughnut” of moisture, and far more of the root zone is adequately irrigated than with a single line of hose down a row of trees. As the tree grows, extra lengths are added to this circle of moisture to correspond with the new growth in the canopy. By setting the circle of emitters farther out every few years, you’re encouraging the tree’s roots to explore more soil volume and gather more nutrients for superior growth. Such trees would stand a better chance against wayward cars.

Note: I somehow lost the usual section "Post a comment". To leave a comment, simply click on the area/button that says "___ Comments" below. Or, clicking on the title of a Post under "Blog Archive" also gets you to a view that gives the option of leaving a comment. Robert

Visit Robert Kourik's web site to learn about his great gardening books.

Pop goes the weasel (tree)

As written in my book Roots Demystified, Change Your Gardening Habits to Help Roots Thrive, amendments are materials such as sand, peat moss, compost, and rice hulls have been added to the planting holes to supposedly improve drainage and keep the soil loose and friable. Fertilizers, such as blood meal, cottonseed meal, greensand, and wood ashes, are those ingredients added to provide mostly nutrients. Some amendments, such as compost, are thought to do both improve drainage and act as mild fertilizers.

One of the best studies of the effect of amendments for fertility was done at Oklahoma State University at Stillwater by Joseph Schulte and Carl Whitcomb. They planted 108 silver maple trees with 11 different soil treatments and a control (untreated planting hole). One conclusion was: "no benefit was derived from the use of soil amendments either with a good clay loam soil or a very poor silt loam subsoil." They found that the control plantings with no additional amendments generally outperformed the plantings with amendments for drainage and fertility.

The loose soil of the amendments in a traditional planting hole makes something like an underground swimming pool full of water when it rains hard, drowning important root hairs. Adding a lot of amendments only leaves the roots unprepared for the shock of what lies beyond the amended area. (And nobody can amend the area of the mature root system seeing as how much wider it is than the foliage.) Often the roots fail to make it out of the well-amended hole and merely circle around in the loose planting medium, rendering the trees likely to blow over during a storm. The trees most tolerant to wind are those with the widest root systems. Or, as the photo shows, not spreading the roots when planting can allow the tree to simply pop out of the ground when hit by a car or pulled out by hand.

Please post a comment - I want to know what you think.

Visit my web site to learn about my gardening books.

NOTE: The comments section at the bottom of the post has disappeared. Click on the "___ Comments" button or the title under the "Blog Archives". Thanks, Robert