Keeping Trees Healthy in Stressful Conditions

Keeping trees healthy can be one of the most challenging things for gardeners. I once heard a colleague from Kansas State University say that trees in Kansas cannot be healthy, because our environment is too tough on them. But there are ways in which you can keep a tree as healthy as possible. There are several factors which help in keeping trees healthy in the landscape.

Here in the Central Great Plains, we have a unique set of growing conditions. Our cold hardiness zones seem to flip-flop every year or so, depending on the winter. We get southwest winds in spring and summer, northwest winds in winter, and temperatures ranging from negative 25 to 110 degrees F every year. And rain? Who knows what kinds of moisture we will get.

So what do we need to know when keeping trees healthy? There are several factors. These include picking the right tree, planting and watering, fertilizing, insect and disease control/monitoring, and winter care.

Picking the Right Tree

When keeping trees healthy, the most important step is picking the right tree for the location. When I sell trees, I ask questions about the location where the customer wants to put a tree. The following list of locations need to be known.

  • Is it a place where water sits or collects after a rain? Or where a sump pump drains out? Or do the downspouts dump nearby?
  • Is the landscape and house new construction where the topsoil has been removed?
  • Did you build a house in the middle of a crop field?
  • Are you on a hill? Or in a valley?
  • Are there mature trees already growing nearby?

These first questions will help in picking the right tree for the right place. For example, if you are wanting a large shade tree to grow in a spot where water collects when it rains, but is otherwise dry, then I would recommend a baldcypress. If you lived in the middle or side of a crop field, with fairly new construction, I might say an American elm, Osage orange, or Kentucky coffeetree. Pick the right tree for the right spot.

Keeping Trees Healthy in Wet Areas

keeping trees healthy in wet soils
Baldcypress growing along a waterway

What kind of trees grow best where it is wet? Or where water collects then drains away? I mentioned the baldcypress above. And there is not a lot of places in our region where the ground stays wet or gets wet but does not flood. Flooding is a whole other situation, where even the baldcypress may have some problems. But there are a variety of trees which will grow in semi-wet areas.

  • Baldcypress
  • Black gum or tupelo
  • Cottonwood
  • Swamp white oak
  • Weeping willow
  • Black willow
  • River birch
  • Sycamore
  • Sassafras
  • Sweetgum

Keeping Trees Healthy in Dry or Poor Soils

Kentucky coffeetree
Kentucky coffeetree can grow in tough sites

Picking a tree for these soil conditions may be harder than picking for a wet one. We live in an area where the soil is regularly degraded via farming practices, soil stripping for housing, or overgrazing. Wind and water erosion is common. When you hear your customer ay that they recently built their home, it should make you cringe inside. It works for me. I know that their yard is likely subsoil with 6 inches of added back topsoil. Or it was heavily farmed crop land. Either way, the soil life is poor or nonexistent. This means that there is no or little soil life to help trees maintain their health.

But by starting with the right tree for the space can be a big help. Some trees do well, if not thrive in poor sites and situations.

  • American elm
  • Kentucky coffeetree
  • Osage orange
  • Hackberry
  • Bur oak
  • Chinkapin oak
  • Catalpa
  • Post oak
  • Sugar Maple
  • Apple
  • Horsechestnut
  • Honeylocust
  • Willow Oak
  • Dwarf chinkapin oak
  • Ginkgo

Trees for Established Landscapes

Perhaps the easiest place to grow healthy trees is in landscapes which are established. These are usually urban or suburban type landscapes, with mature or aging trees already on site. Lots of customers look for ornamental trees to add to the landscape, or to fill in where a large trees was removed. In these cases, choosing a tree is a lot easier, and all of the above options can be used, along with these below.

  • Redbud
  • Magnolia
  • Crabapple
  • Red maple
  • Hybrid Maple
  • Scarlet Oak
  • Shumard Oak
  • Serviceberry
  • Dogwood
  • Beech
  • Tuliptree
  • Cherry
  • Japanese tree lilac
  • Seven Sons
Keeping trees healthy with proper placement - redbud
Redbuds are good trees for established landscapes

Keeping Trees Healthy in Special Places

Some trees are even harder to keep healthy, because they are hardly suited for our area. But people still want to grow them. And I do not blame them a bit. Such trees as Japanese maples. Some of our most interesting trees take the most work to keep healthy. They need to be situated in exactly the right location, often where neither southwest nor northwest winds can bother them. And no late afternoon sunlight!

  • Japanese maples
  • Korean maple
  • Weeping redbud
  • Variegated maples and redbuds
  • Japanese snowbell
  • Katsuratree
  • Some dogwoods
  • Tricolor beech
  • Weeping cherry

Keeping Trees Healthy by Planting and Watering

The second most important thing to keeping trees healthy is planting. Even more so than watering. If a tree is picked correctly, but planted too deep, it will die very quickly. And planting too high can also be a problem. The best thing to do is plant slightly above ground level, so the root ball sticks out at least an inch. Soil is easy to add up around the edge of a root ball above the soil. But it is difficult to remove excess soil from around the trunk in a hole.

The old standby of digging your hole twice as wide and deep as the root ball results in poor root development and a greater risk of settling of the tree after planting. And settling results in soil getting around the trunk and “choking” the tree to death. The same results you would get from planting a tree with girdling roots.

Watering Trees

What do I do in my own landscape? How I water trees has always worked for me, so it stands to reason that it would work for you too. I recently was reminded of this method by a colleague at a major nursery operation. When watering newly planted trees, soak it. Put water on until it is running out of the hole and the ground around it is muddy. Then mulch with 4 to 6 inches of organic mulch.

After doing this, wait 4 to 7 days, and check by sticking your finger or hand into the planting hole. If it is still wet, then wait until it is feeling cool by not dried out. Then repeat the process. How long do you wait to check? Well, that depends on your personality. I would likely wait the whole 7 days, while I know lots of people who would get nervous before 4 days is over. Keep watering newly planted trees (less than 3 years in the ground) in this manner for 2 to 3 years. Sometimes you will be able to go weeks without watering.

watering trees
When watering trees, soak it until it is muddy all around

Should We Fertilize Trees?

More and more, I am realizing the value of fertilizing trees. Keeping trees healthy relies heavily on picking, planting, and watering. But is also is important to think about the site it is being planted into. Many of the landscapes in which trees are going in the Central Great Plains were once farms. Some have been out of crops for 4 plus years, and others just recently.

What does that have to do with fertilization? A lot more than we realize. What do native prairies, woods, savannahs, and untilled pastures have in common? Living soil. What is living soil? Living soil is a soil that contains life made up of micro-organisms, worms, bacteria, fungi, protozoa, nematodes (good and bad), and much more. These things work together in symbiosis with plant roots in a mutual exchange of foods (carbohydrates, micronutrients, macronutrients, and water).

Until our soils start to become living again, the trees we plant in them will need fertilizer. But organic is always best because it helps feed the micro-organisms which start to take up residence as soon as you quit the synthetic pesticides, herbicides, and fertilizers,

Organic fertilizers include compost, seaweed extract or meal, compost tea, fish emulsion, composted manures (chicken, pig, cow, horse), manures (rabbit, goat, sheep), and leaf molds (partially composted leaf matter). Even in depleted soils, there are nutrients waiting to be used. But the trees cannot use them without the help of mycorrhizal fungi which partner with them for nutrient and water exchange. So build the soil and bring it back to life!

Keeping Trees Healthy in the Face of Insects and Diseases

It seems that every season we hear of some new insect or disease facing our trees. But if we had healthy trees would these things be a problem? For some pests, yes. Others, no. By keeping trees as healthy as possible, we eliminate many, but not all, of the pest problems. For example, if you were able to maintain a landscape with living soil, healthy, well-watered and cared for trees, you would rarely risk diseases such as bur oak blight, bacterial leaf spot, fireblight, and scorch. But other diseases are more likely to be a problem based on your tree selection; cedar-apple rust, apple scab, oak wilt, anthracnose, and powdery mildew.

I love insects on trees. At least, as long as they are native insects and not invasive ones. Because it is the invasive insects which cause all the problems. But there ways of keeping them at bay too. As for leaf feeding insects, such as Japanese beetles, the best remedy is to plant species they do not like. Although, that is challenge enough. Japanese beetles do rarely feed on Kentucky coffeetree, hackberry, baldcypress, willow and Shumard oak, and maples. But there are much worse insects. The tree killing kinds.

Invasive Tree Killing Pests

The following list comprises insects which kill trees either within a few weeks, months, or years, depending on their nature of feeding or destruction. Some methods of prevention include systemic pesticides (yuck), soaping the bark with Irish spring soap, or spraying with chemicals (some organics work well here).

Keeping Trees Healthy in Winter

Winters in the Central Great Plains are a challenge. We never know what it will be like. Sometimes, like in 2023-24, we may get a little snow and a lot of warmth. Or it could be a direct opposite. If you go by superstitions, such as the cutting of a persimmon seed, winters could be full of snow, dry and cold, or mild. But it is a guessing game for most of us.

So we need to get our trees ready before winter sets in. I like to mulch trees in the fall because a good think layer of mulch will protect the root ball and roots of newly planted or young trees. By using 4 to 6 inches of organic mulch, in at least a 3 foot radius around the tree, we insure the roots from drying out in warm winter. If the ground does not freeze up right away, then water! Watering is still critical even in winter when trees are dormant on top.

Another thing to do is to protect the bark of young trees from rabbits, deer, and sunscald. Many of our young trees have smooth bark for the first 1 to 10 years, and need to be wrapped in the winter to prevent sunscald or sunburn. Trees that have a big problem with sunscald are maples, tuliptree, elm, and fruit trees. Some trees do not need to be protected from sunscald. These include most oaks, hackberry, Kentucky coffeetree, and birch. But all of them should be wrapped away from rabbit and deer damage.

wrapping tree trunks
Wrapping tree trunks with paper wrap to protect from sunscald

Conclusion

If you have done all these things, you might be able to keep your trees healthy. But it is a gambling game in a climate that is constantly cycling. We may get unexpected weather events such as hail storms, drought, flooding, lightning, wind gusts, early or late freezes, and ice. So it can be difficult no matter what you do. But I prefer to go for the gold and aim to keep my trees as healthy as possible.

Happy planting!

author of keeping trees healthy

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