The arborists at Pewaukee Tree Care are often asked questions about tree health and diseases:
“How do I make this tree very resistant?”
“My branches are dying? What do I do?”
“I want this pine to live old enough for my grandchildren…”
So… what’s the best way to care for your tree? That depends on the tree’s species and your climate. But there are general tips professional arborists follow to keep trees vigorous and healthy. We share them here:
- Select the right trees for your location
- Use the right soil
- Plant properly
- Water at the right time
- Mulch
- Fertilize
- Prune and trim
- Manage pests and diseases
- Protect young trees in the winter
- Confide in your local arborists
9 Ways to Grow Healthy Trees and Keep Them Thriving
The biggest secret to keeping healthy trees is growing them the right way. Once properly established, trees generally don’t need pampering unless they’re super susceptible to certain pests and diseases.
If you suspect your tree has been affected, contact your local arborist right away.
But if you’re dealing with a growing tree and want it to thrive, then do the following:
Select the right trees for your location
Some trees simply wouldn’t survive in certain climates. Others might, but would struggle.
Sugar maples thrive in Wisconsin.
To save yourself a lot of headaches, choose tree species that are fit for your climate and soil conditions.
Wisconsin has a few native species, like the Sugar Maple or the White Pine, that thrive effortlessly. Palm trees, on the other hand, aren’t hardy enough for the Midwest’s harsh winters.
It’s a good idea to check the USDA hardiness zones to know what trees would thrive in your location.
Source: United States National Arboretum
Consider sunlight
Some trees require six hours of sunlight daily to grow well, while others are perfectly fine with less than four hours. Know what works for the species you’re planting, and plant them in an appropriate location.
Consult your local arborist if you don’t know the sunlight requirements of your seedling or plant.
Assess the planting site
Before planting, thoroughly assess the site. Consider the available space, soil quality, drainage, and surrounding structures. Ensure there’s enough room for the tree to grow to full maturity without crowding or interfering with structures.
Use the right soil
Test your soil composition
Soil quality varies across Wisconsin, and understanding your soil composition is essential.
Testing your soil can reveal its pH, nutrient content, and texture, which can help you make informed decisions about tree care. For instance, soils rich in clay or sand may require different treatments to be made suitable for planting.
Of course, this depends on what tree species you’re planting. Some popular Wisconsin species, like American Sycamore and Hackberry, are suited for clay.
Consult your local arborist to know the soil requirements for your trees.
Ensure drainage
Trees do not tolerate waterlogged soil well. In areas with poor drainage, you may need to install drainage systems to prevent root rot and other issues. Your type of soil might determine if you need drainage.
Clay retains water and causes waterlogging, so it typically needs drainage. Sandy soil, on the other hand, drains water quickly, so your plants will need more frequent watering.
Test your soil’s drainage by digging a 12-inch deep hole and filling it with water. If the water drains in an hour, then it’s good. Four hours and longer, then you need drainage.
Plant properly
If you’re planting seedlings, understand that they are fragile. They won’t survive if you don’t handle them properly before planting. Keep them moist right until the time they’re planted.
The Wisconsin Department of Natural Resources recommends a temperature of 34-36 degrees Fahrenheit.
If you’re planting a young tree (or sapling), dig a hole of the appropriate depth and width, typically two to three times the width of the root ball or container.
Carefully place the tree, backfill with soil, and water thoroughly. Avoid planting too deep, as this can suffocate the tree’s roots.
How to not plant too deep? Measure from the beginning of the tree’s root flare to beneath the root ball. Then, dig a hole for that exact measurement. Put your root ball in the hole, making sure the root ball is at or slightly above the ground.
Water at the right time
Water newly planted trees about once a day for the first 2 weeks. If your new tree is a big one, then water it daily for 4-6 weeks. After that, water every 3-4 days for the rest of the season.
Avoid over-watering. Generally, 2-4 gallons per inch of trunk diameter is ideal. You can also gauge the soil moisture by digging down a few inches and checking with your hands. The soil should be moist, not soggy.
Mature trees (more than 3 years old) generally don’t need as much tender, loving care. They will be fine with an inch of water per week during dry periods.
Recognize tree thirst fast
Wilting, yellowing leaves, and drooping branches are telltale signs of drought stress. When you observe these symptoms, it’s time to water.
Spot overwatering too
On the flip side, signs of overwatering include water pooling around the tree’s base, mold growth, and leaf drops.
All growing plants will require attention. But if you want mature trees that will thrive even if you never remember to water them, then consider hardy Wisconsin natives like the Bitternut Hickory and Thornless Honey Locust. Don’t worry, they are good-looking trees.
Thornless Honey Locust on the sidewalk.
Mulch
Mulching does more than give your tree base a manicured look.
Mulching at the base of a young tree
Proper mulching conserves moisture, regulates soil temperature, suppresses weeds, and even improves soil quality as it decomposes.
Just remember not to mound mulch against the tree trunk, which can cause rot. Your mulch doesn’t need to be tall. It shouldn’t exceed 4 inches.
Fertilize
The trees in your yard don’t usually get the nutrients they’re naturally exposed to in the wild, so you may need to fertilize.
A soil test will help determine your tree’s specific nutrient requirements. You should consult a certified arborist to know what works for your tree species and soil composition.
The essential fertilizers typically contain nutrients like nitrogen, phosphorus, potassium, and iron.
Best time to fertilize
Apply your fertilizers in late fall or early spring when the soil is moist. If you fertilize later than this, the weather will be too warm, and there will be more rain to wash the nutrients away.
Avoid fertilizing in the summer. Your trees will be stressed by heat and drought during this period.
How to fertilize
One popular method is to insert a slow-release fertilizer tablet into the soil near the tree’s root system. You can also make 12-inch deep holes around the tree’s drip line and place your fertilizer there.
Note that you don’t need to remove mulch to fertilize. You should also avoid touching the tree trunk with the material.
Prune and Trim
Pruning involves removing dead, loose, or infected branches while trimming cuts overgrown trees to improve their appearance.
Pruning dry branches
Both terms are sometimes used interchangeably, but here, we’ll focus on pruning since we’re discussing tree health.
The truth is, you might not necessarily have to bother with pruning, especially if your trees are mature or nearing maturity. Trees can fend for themselves, especially if their branches are in good condition.
What to prune
Don’t prune newly planted trees unless a branch is diseased, dead, or broken. They need the foliage to produce sugar that aids the growth of new roots.
2 to 5-year-old trees can be pruned to remove crossing branches, water sprouts, and root suckers.
When to prune
Pruning is best done during a tree’s dormant season. For deciduous trees in Wisconsin, this is usually late fall to winter.
Pruning during dormancy helps prevent infestation since most insects and disease carriers won’t be active during this period. For example, picnic beetles responsible for spreading oak wilt are not active in the winter. So this is the best time to prune oak trees.
It’s also easier to see your tree’s overall branch structure during its dormant season. This way, you can avoid making mistakes and cutting the wrong branches.
How to prune
You’re only pruning where there is a problem, so avoid perfectly fine branches.
Things to prune include:
- Crossing branches: branches that cross or rub against each other.
- Double leaders: two major growing points at the top of the tree.
- Root suckers: vertical shoots arising from buds at the base of the tree
- Water sprouts: vertical shoots arising from the trunk or branches that are several years old.
Crossing branches in a magnolia tree
A few more guidelines:
- Always maintain the tree’s central leader, its main upward stem.
- Cuts should be just outside the branch collar. Never leave stubs or take off the branch collar
- Always use the right tools: pruning shears and saws.
Prioritize your safety when pruning or trimming. Some trees may have branches that are hard to reach or that overhang structures. Generally, it’s wise to leave mature tree pruning to a professional tree service.
Manage pests and diseases
Wisconsin trees contend with several adversaries, from the notorious oak wilt to the invasive emerald ash borer.
To avoid dealing with infestations, you have to know how to identify the culprits. Some of the most popular Wisconsin tree diseases and infestations include:
Emerald ash borers: These shiny green beetles not only dig into the bark of your ash trees; they also attract woodpeckers and other destructive animals.
The deadly emerald ash borer.
Downy leaf spot: This fungal disease causes yellow spots and white patches on the leaves. It won’t kill the tree, but it will weaken and make it more susceptible to pests and diseases. It typically affects walnuts, hickory, and pecan trees.
Oak wilt: This particularly lethal disease targets oak trees. The leaves on affected branches often turn bronze or dull green. They may also droop or curl.
Rhizosphaera Needle Cast: This fungal disease ruins the appearance of Wisconsin’s conifers, especially the Colorado Blue Spruce. To identify, look for browning and a loss of innermost needles on the lower branches of the conifer.
Learn more about Wisconsin’s tree diseases and pests to identify which particular one is damaging your tree.
Prevention and treatment
Prevention and early detection are your best bet to deal with infestations. Inspect your trees regularly for signs of trouble. Browning leaves, cankers, strange growths, or unusual leaf drops may indicate a problem.
Treatment (preventive or post-infestation) is best left to professional arborists, as this varies largely depending on the disease and tree species.
Protect young trees in the winter
Wisconsin’s winters can be severe, and your trees need extra care to withstand the cold.
A few ways to do this:
- Insulate young trees with mulch. Put a layer of mulch on the soil around their root system.
- Wrap growing trees with tree guards. This deters hungry critters from munching on the tree bark.
Tree guards, used to protect young trees against animals. Simple burlap sacks would do.
- Thoroughly water your trees in the fall before the ground freezes. Trees dehydrate in winter as their roots can’t absorb moisture in the frozen ground. Water enough to make the ground moist but not soggy.
How much fertilizer?
Your soil test results will give you an idea of how much fertilizer to apply.
Your tree’s age is also an important factor. Slow-release fertilizers are best for newly planted trees. Liquid and compost fertilizers can burn the tree’s roots on contact.
Slow release fertilizers.
Luckily, most fertilizers come with a recommended rate label to guide your application.
Generally, you shouldn’t fertilize new trees in their first growing season until their roots have been established.
Confide In Your Local Arborists
If you’ve noticed something strange about your trees, your best bet is to ask your local certified arborists—you know, the tree nerds in your area.
They’ll have the right answers and recommendations for your specific plant.
If you need tree care advice within Milwaukee and surrounding cities, reach out to the professional arborists at Pewaukee Tree Care today. We’ll be glad to help.
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