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There are many other aspects to tree care besides pruning.  In addition, the needs of a tree change as it matures.  In the early stages after transplanting, the development of a new root system is the most important factor determining successful establishment.  For this reason, watering, mulching and protecting the tree from injury are paramount.  As the tree ages, monitor it for signs of stress.

Follow-Up Tree Care After Planting

Water

Ideally, you should water a newly transplanted trees twice weekly (in the absence of rain) with a deep soaking that saturates the first 6 inches of soil.  If possible, water the tree for the first three growing seasons.  The water should seep slowly into the soil.  Trickle hoses, drip irrigation bags (gators), or other slow-release methods should be used.

Remove Stakes, Wires and Wrap

Stakes and wires should be removed 1 - 2 years after planting.  Removing tree wrap is important.  Most wrap is on the tree to protect it during transport.  When left on the tree, moisture will become trapped between the wrap and the trunk, providing a good environment for fungi to grow and bark to rot.

Mulching

Mulches can divided into organic and inorganic materials.  Organic materials, such as shredded leaves, breakdown and become part of the soil.  Inorganic materials, such as gravel, do not.  There are many benefits to mulching.

• Protect trunk from mowers

• conserves soil moisture

• reduces soil erosion

• impedes weed growth

• restricts soil cracking

• limits salt build-up

Most organic mulches add further features.

• protects the roots from traffic

• cuts down soil compaction

• improves soil fertility and structure

• moderates soil temperatures

Mulch Management

Replenish organic mulches annually.  Avoid fresh organic mulches, i.e., those that have not been leaches or composted.  They often 1) deplete soil nitrogen, especially if small in size and thickly applied, and 2) can be toxic, especially mulch made of conifer (cedar, for example) sawdust and bark.

Apply 2 - 4 inches of mulch to the tree's drip line if possible.  Remember, the drip line moves out as the tree grows.  Keep the mulch 3 - 5 inches away from the base of the trunk.  The mulch should look like a donut when you are through.  (See Correct Use Of Mulch for an illustrated example of mulching.)

When applied too thickly or against the trunk, mulch will increase the possibility of disease and insect troubles, especially on poorly drained clay soils.  Piled too deep, mulch will prevent the penetration of oxygen into the soil and suffocate the root systems.  Piled against the trunk, mulch prevents gas exchange through the lenticels.  Do not kill your tree with the kindness of a mulch volcano.

Fertilizing

Fertilizing trees refers to the practice of supplementing soil nutrients with some of the 17 chemical elements required for growth and development.  Trees are autotrophs: they use nutrients to feed themselves by making sugar in the leaves that can be used right away, or stored as starch for future needs.

Most of the time, trees do not need fertilizer.  Trees adjust their growth and development rates to the level of nutrients available in the soil, and usually make out all right as long as the roots can continue to grow.  In nature, trees get nutrients from air, organic matter and soil minerals.  Organic matter can be restored for urban trees by keeping composted leaves and twigs under the crown.

Fertilizer should be considered a prescription drug - prescribed only when the problem with the tree is identified.  It is not tree food.  If your tree is showing symptoms of stress, determine the tree's needs by doing a soil test.  Is it getting adequate sunlight or water?  Is it suffering from an insect or disease outbreak?  Did someone dump motor oil onto the soil around the tree?  Each type of symptom represents a different need.  Lack of water and compacted soil have been shown to be much more limiting to the growth of urban trees than low nutrient levels in most cases.

Unusual yellowing, especially between the leaf veins, may indicate a specific nutrient deficiency.  If you suspect a nutrient deficiency, have the soils tested and follow test result recommendations for adding fertilizers.  Here is what research says about tree fertilization:

• Never fertilize newly planted trees.  Wait a year for the tree to become established and then evaluate the leaves for symptoms.

• Young deciduous trees benefit from some additional nitrogen (e.g., 10-6-4).  Since plant growth is irregular and nitrogen is mobile in the soil, use a slow-release fertilizer.

• Conifers rarely need fertilization at all, since most are adapted to low-nutrient soils.

• Serious pest and structural problems result on trees that are over fertilized.  Highly fertilized trees often attract more diseases and insects.  Their shoots are weaker as well.

• Surface application is the easiest, cheapest and most effective method of fertilizing ornamental trees on most soils.  Other methods also work, but are rarely necessary.

• Aeration and watering of urban trees often produce the same growth response as fertilization.  They facilitate root growth and nutrient mobility through the soil.

• Trees surrounded by grass benefit from the application of a complete fertilizer every few years.  If you apply winterizing fertilizer to the grass, this is unnecessary.

• Slow-release low-nitrogen fertilizers should be applied in early fall or early spring.  They will be used by the roots in the fall, and by the roots and shoots in the spring.

• Standard fertilizers should be applied in late May or early June.

For more information read "Fertilizing Trees and Shrubs" (Cornell University, 1989, rev. 1997), available from your local office of Cooperative Extension or the DEC.

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