Michigan Gardener - Your guide Great Lakes gardening: Garden Event Calendar / Expert Advice / Plant Profiles / Tree Care

PLEASE NOTE: In the autumn of 1995, we hatched the idea for a free, local gardening publication. The following spring, we published the first issue of Michigan Gardener magazine. Advertisers, readers, and distribution sites embraced our vision. Thus began an exciting journey of helping our local gardening community grow and prosper.
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Norway Maple doesn’t look healthy

July 16, 2009 •

by Steve Turner

Over the last couple of years, my Norway maple seems to be getting thinner, getting its fall color early, and some limbs are dying on one side of the tree. What’s wrong?

Unfortunately, the situation does not look good. From what you have described, it sounds as if your tree has girdling roots, which is a major problem of Norway maples and ‘Crimson King’ maples, a cultivar of the Norway maple. Many of these trees develop the problem between 25 and 40 years of age, which is also when the tree starts to mature and become the picture perfect tree we all admire. If you look closely at the base of the tree, you will see that instead of your tree having “root flare” as it goes into the ground, it looks more like a telephone pole going straight into the ground or it has a flat side instead of being round. These are sure signs that the roots below are wrapped around the trunk and are causing a slow, but certain death by strangulation for your otherwise perfect maple.

The reasons for this are a little more complicated. The problems begin in the nursery when the trees are dug for transplanting. The process of digging severs tree roots, which in most trees is no big problem. But with Norway maples, this causes a major change in the way the root system develops. In the tips of the roots is a growth regulator that causes all the roots behind the tip to remain smaller than the main root which extends away from the tree. When this root tip is severed, the tree loses its ability to control the size of the lateral roots, and that is where the trouble begins. The lateral roots become dominant and cross the trunk of the tree causing the restriction that eventually brings the demise of the tree. It’s no coincidence that the size of the trunk at the time of decline is usually the size of the original root ball at the time of planting, which is why it takes so long to discover the problem.

Unfortunately, there is no cure. Fertilization will only speed up the growth of the tree and cause it to die sooner. Cutting the roots is expensive and is not a permanent solution; they will grow back in time and then you are back to square one. Keeping the tree well watered will help prolong its life, but it is not a cure.

Steve Turner, Certified Arborist, is from Arboricultural Services in Ferndale, MI.

Garden Snapshots: Ninebark ‘Monlo’

July 15, 2009 •

Jonathon Hofley / Michigan Gardener
Physocarpus opulifolius “Monlo”

Proper planting instructions for trees and shrubs

July 14, 2009 •

by Steve Turner

I know you have all read the pamphlets and have probably done it a few times, but it never hurts for a little review. If I had a dollar for all the improperly planted trees I have seen over the years, I would be rich!

First, dig the hole as deep as the root ball and at least twice as wide. Be sure to not dig too deep; a good way to prevent this is to measure the root ball against the shovel handle and check it often when digging. If you do dig too deep, remember to pack the soil firmly under the ball to prevent settling once the plant is in place. This is more important for trees than shrubs. On the other hand, if the hole is not deep enough, keep digging. Don’t make the mistake of planting high and then mounding soil up around the root ball, even in clay soils. One exception is a compacted clay subsoil, which can be found in new subdivisions. If you can’t dig deep enough, then add a lot of topsoil around the top of the root ball to make a gradual decline down to the grade level.

After the tree is in the hole, cut and remove as much of the wire cage (if present) as possible. Any part that you can’t remove should be cut and bent down. Untie the twine around the trunk and pull down the burlap. If the burlap is in good condition, push it to the bottom or cut it out. If it is old and roots are growing through, then leave it and make several vertical slices instead. If you are planting potted shrubs, carefully remove them from their pots and make several vertical slices down the root ball. Grab the bottom of the roots and pull them back up like peeling a banana and set them in the hole with the cut sections pointing out. Next, begin to backfill using the same soil that came out of the hole, making sure to break up any large chunks of soil. There should be no large air spaces left behind as you fill. Stop about 6 inches from the top and add fertilizer to the remaining fill, preferably either slow release or organic fertilizer that is low in nitrogen. Complete backfilling to grade level.

When planting trees or large shrubs, do not mix soil amendments such as sand, peat, or topsoil to the fill. These work better as top dressings. They actually create a false environment within the planting hole and do not encourage outward growth of the roots. Instead, the roots tend to wind around in the hole, which can eventually lead to girdling roots. Also, drainage can be a problem with dissimilar soils. Water will not move from one soil type to another until the first is completely saturated. This is why it is important to check the soil of the root ball before you buy the plant. Ideally, you should not plant trees grown in sand in clay soils and vice versa. It can only cause problems in the future.

Now that the plant is in the ground, water well and keep the soil moist for several weeks, but do not overwater. Before watering, move aside the mulch and feel the soil to verify it isn’t too wet before adding more water. Keep the mulch away from the trunk of the plant and do not add too much mulch — 3 to 4 inches is plenty.

Steve Turner, Certified Arborist, is from Arboricultural Services in Fenton, MI.

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