Tips for Keeping Trees and Shrubs Healthy

By Melinda Myers - horticulturist and gardening expert
September 18, 2020

Proper watering, mulching, pruning with a purpose and fertilizing when needed are key to keeping your trees and shrubs healthy and promote longevity. Follow these four keys to keeping your trees and shrubs healthy.

1) Watering Trees and Shrubs

Water new tree and shrub plantings thoroughly and often enough to keep the root ball and soil beyond moist.  Check newly planted trees growing in well-drained soils twice a week and those in heavy clay soils once a week.  Potted trees and shrubs are often grown in soilless potting mix. This often dries out more quickly than the surrounding soil. You may need to water the root ball more often than the surrounding soil to compensate. Even established trees benefit from proper watering during dry periods.  Water thoroughly whenever the top 4 to 6 inches of soil are crumbly and slightly moist.

Soak the area under and six feet beyond the branch spread as tree roots go 2 to 5 times the height of the tree away from its trunk. Water the area under and several feet beyond the area covered by the shrubs.

Here are a few ways to make the job easier for you; because if it is easy you are more likely to do it.

  • Use a soaker hose to place water directly on the soil and above the root zone of the tree or shrub where it is needed. You’ll spend less time dragging hoses and sprinklers and waste less water.
  • Or convert discarded 5 gallon buckets into slow-release watering devices. Drill holes in the bottom of the bucket. Place several buckets beneath the tree canopy. You’ll need to apply 10 gallons of water for each diameter inch of the tree. Fill the buckets with water and let gravity do the work. 

2) Mulching Trees and Shrubs

Mulch the soil surface around trees and shrubs to conserve moisture, reduce competition from grass, suppress weeds and prevent weed whips and mowers from damaging the plants. This means less work for you and a better growing environment for the plants

Create as large a mulch area under your trees and surrounding your shrubs as you can tolerate.  Spread a 2 to 3-inch layer of shredded bark or woodchips over the soil surface. Pull the mulch away from the trunk and off the shrub stems. Piling mulch against the plants can lead to rot and other problems.

3) Pruning Trees and Shrubs

Prune plants with a purpose. Wait a year to do major pruning on newly planted trees and shrubs. Just remove broken and damaged branches. Once established, prune to create a strong structure. Continue to remove broken, crossing, inward-facing and rubbing branches. Make cuts above an outward-facing healthy bud or branch or flush with the branch bark collar, swollen area where branch adjoins the trunk.

Excessive pruning can stimulate unwanted growth that will need to be managed in the future. When major pruning is needed spread it over several years for better results.

pruning a dead tree branch

4) Fertilizing Trees and Shrubs

Fertilize only as needed. Trees and shrubs get most of their nutrients from fertilizer applied to surrounding lawns and gardens. But there are times we may want to lend a helping hand. The best time to fertilize is early spring before growth begins or fall once plants are dormant.

Give plants growing in sandy soils or areas with limited soil nutrients a fertilizer boost if needed.  These plants tend to grow slower and have smaller or paler leaves than normal, but are otherwise healthy. Use a low nitrogen slow release fertilizer like Milorganite that promotes equal top and root growth. Plus it contains organic matter that helps improve the soil.

Fertilize with Milorganite to help promote flowering on established plants that fail to bloom.  Research found when microorganisms release nutrients from Milorganite pellets it also releases some of the phosphorous and potassium bound to soil. The phosphorous promotes root growth, flowering and fruiting and potassium increases disease resistance and hardiness.

Follow the recommended rates on the Milorganite bag or website. Just spread the Milorganite over the mulch area and lightly rake it in. Let nature move it down through the soil and to the plant roots.

Milorganite Fertilizer | Tree Application Rates
Planting Type Application Rate Suggested Application
Established Tree 5 lbs per inch of trunk diameter Pour into holes (1” wide x 12” deep) spaced 2 feet apart along drip line. The second best option is to broadcast Milorganite in a circular band around the drip line of the tree.
Transplanted Tree ½ lb per foot of tree height Mix with soil at the bottom of the planting hole prior to inserting the transplanted tree. 3 months later, hand spread an equal amount of Milorganite slightly past the drip line.
Milorganite Fertilizer | Shrub Fertilizer Application Rates
Planting Type Application Rate Suggested Application
Established shrub beds 5 lbs per 100 sq ft Scatter uniformly over the soil surface and work in with a hoe or rake. For individual shrubs, apply 1 lb of Milorganite per shrub in the root area.
Transplanting shrubs ½ lb per feet of shrub height Loosely mix with soil at the bottom of the hole prior to inserting shrub. 3 months later, hand spread 2 lbs of Milorganite under the plant and lightly rake into the soil.

You’ll need a different approach for trees growing in the lawn.  Apply small amounts of the recommended amount of fertilizer throughout the area under and six feet beyond the branch spread.  Start two feet away from the trunk and every two feet along concentric circles around the tree. Use a dandelion digger or similar tool to apply the fertilizer 6 to 12 inches below the grass roots for the tree to absorb.

Investing a bit of time in the proper care of your trees and shrubs will result in years of enjoyment and beauty.

Changing some habits or maybe it’s just fine tuning the way you maintain your trees and shrubs, can greatly improve your results.  Take a look at this list of Don’ts and Do’s then make needed adjustments in your tree and shrub planting and maintenance.