Tree & Shrub Care in St. Louis

Step 1: Deep Root Fertilization (February through March)

The program starts before most people are even thinking about their yard. In late winter, we apply a liquid fertilizer directly to the root zone of your trees and shrubs. Unlike surface applications that have to work their way down through the soil, deep root fertilization gets nutrients where they need to go right away, directly into the root system.

This timing is intentional. As trees and shrubs come out of dormancy in late winter and early spring, they’re actively pulling energy and nutrients from the soil to fuel new growth. Feeding the roots at this stage gives plants a strong head start, helping them push out healthy new leaves and branches as the growing season begins. Trees and shrubs that go into spring well-nourished are also more resilient against pests and disease later in the year.

Step 2: Dormant Oil (March through May)

Next, we apply dormant oil, a natural pesticide that works by smothering overwintering insects and their eggs before they have a chance to hatch and cause damage. Many common pests, like scale insects, aphids, and mites, spend the winter clinging to the bark and branches of trees and shrubs, waiting for warmer temperatures to become active. Dormant oil eliminates them during that window, before the season even gets started.

The timing here is critical. Dormant oil is most effective when applied while plants are still dormant or just beginning to wake up. Once leaves are fully out, the oil can cause damage to new foliage, so this step has to happen within the right window each spring. Because it’s a natural, low-impact treatment rather than a synthetic pesticide, it’s also a gentler way to control pests without unnecessary chemicals during a season when beneficial insects are also starting to emerge.

Step 3: Spring Slow-Release Fertilizer (May through July)

As your trees and shrubs head into their main growing period, we apply a slow-release nitrogen fertilizer. Nitrogen is the primary driver of green, leafy growth and plays a key role in photosynthesis, the process plants use to convert sunlight into energy. A well-fed tree or shrub is a healthier one, with stronger leaves, better color, and more resistance to stress.

Slow-release fertilizer is the right choice at this stage because it feeds plants gradually over time rather than all at once. A fast-release fertilizer can push too much growth too quickly, which can actually stress plants or make them more vulnerable to pests. Slow-release keeps things steady, giving trees and shrubs consistent nutrition through the spring and into summer without overwhelming them during one of their most active growth periods.

Step 4: Summer Insect Control (July through August)

St. Louis summers bring more than just heat. Japanese beetles, bagworms, and spider mites are especially active this time of year, and they can do serious damage to trees and shrubs if left unchecked.

Japanese beetles are one of the most recognizable summer pests in St. Louis. They skeletonize leaves by eating the tissue between the veins, leaving behind a lacy, shredded appearance. They’re especially damaging to roses, birch, linden, and fruit trees, and they tend to feed in groups, which means damage can escalate quickly.

Bagworms are caterpillars that build small, cocoon-like bags out of silk and plant material, hanging from branches while they feed. They’re particularly destructive to evergreens like arborvitae and juniper, and a heavy infestation can defoliate a plant badly enough to kill it. Catching them early in the season before they mature and lay eggs is key to keeping them under control.

Spider mites thrive in hot, dry summer conditions, which makes St. Louis summers a prime environment for them. They feed by piercing plant tissue and sucking out moisture, which causes leaves to look stippled, dusty, or bronzed. Heavy infestations can weaken plants significantly and leave them vulnerable to other stress heading into fall.

We also spot treat for fungus during this step. Heat and humidity create ideal conditions for fungal issues on trees and shrubs, and catching early signs of disease before they spread can mean the difference between a minor setback and lasting damage to your plants.

Step 5: Fall Slow-Release Fertilizer (September through October)

As temperatures start to cool, the focus shifts from above-ground growth to what’s happening underground. Trees and shrubs naturally redirect their energy toward root development in the fall, storing nutrients and building root mass ahead of winter dormancy. A slow-release nitrogen fertilizer applied during this window supports that process and helps plants go into winter in the strongest possible condition.

This is one of the most underappreciated steps in the program. A lot of people assume that fall means the growing season is over and feeding plants isn’t necessary. But what happens below the soil this time of year has a direct impact on how well trees and shrubs come back in spring. Plants that go into dormancy with strong, well-fed root systems are more resilient against cold damage and bounce back faster and healthier the following season.

Step 6: Fall Insect & Disease Control (October through December)

The final treatment of the year is all about protecting what you’ve built. As temperatures drop and trees and shrubs head into dormancy, many insects and diseases are looking for places to overwinter on your plants. Left untreated, they’ll be right there waiting when spring arrives, ready to cause damage before you even realize there’s a problem.

This step targets those overwintering threats before they settle in. Scale insects, for example, are a common problem on ornamental trees and shrubs and are notorious for being difficult to control once established. Treating in the fall disrupts their cycle before they can hunker down for winter. Fungal diseases can also persist on bark, stems, and fallen leaves through the cold months, so this final treatment helps reduce the chance of reinfection the following spring.

Winterizing your trees and shrubs isn’t just about surviving the cold. It’s about going into winter healthy and coming out of it the same way.

Why Timing Matters for St. Louis Trees & Shrubs

St. Louis’s climate sits at a crossroads between the Midwest and the South, which means local trees and shrubs face a wider range of stress than plants in more predictable climates. Late freezes in spring can damage new growth right after plants have broken dormancy. Summer heat and humidity create the perfect environment for insects and fungal disease. And early fall cold snaps can catch plants off guard if they haven’t had the nutrition they need to prepare.

Each step in this program is timed to work with the natural growth cycle of your plants, not around a generic calendar. Deep root fertilization happens when roots are ready to absorb it. Dormant oil goes down before insects become active. Summer insect control targets pests at their most damaging. Fall fertilizer feeds roots during the window when they need it most. And the final insect and disease treatment closes out the season before threats can overwinter and carry over into spring.

Miss a step and you’re not just skipping a treatment. You’re leaving a gap that pests, disease, or stress will find eventually.