Tree Care


Sufficiently watering a newly planted tree for the first three years is most crucial to the trees establishment. In addition to rain showers and turf watering, deep, periodic watering of the tree will ensure proper root development.

Check the soil moisture every three days during hot weather and once a week during mild weather. Dig down four inches next to the base of the tree and feel the soil. The soil should be moist, but not wet. Water often enough and deep enough to maintain moist soil four inches below ground level. If the soil content is sandy you will need to water frequently. Clay soils and soils with high organic matter need less water. A mulched waterwell constructed around the base of the tree will increase water retention and also protect the tree from being struck by lawn mowers and weed trimmers.


Mulch should be spread all over the excavated area at the base of the tree to a depth of 3 to 5 inches. However, the mulch must be kept away from the trunk to prevent injury to the tree bark.


A tree can be fertilized three to five years after planting. Trees showing loss of vigor indicated by: light green or off color leaves, dead twigs or slowed growth may need fertilizing. Use a balanced formula such as a 10-8-8 (Nitrogen-phosphate-potassium) fertilizer which also contains sulphur, magnesium and zinc.

Beware of lawn fertilizers containing weed killers that may enter the soil at the tree’s dripline (the circumference of outermost branches) which may seriously injure or kill the tree.


The main purpose of pruning during the first few years is to develop a balanced, well-spaced distribution of branches while maintaining the typical form of the species. Branches on the lower half of the tree that may interfere with pedestrians or traffic should be removed before they reach a diameter of ½" to 1".

Little, if any, pruning is needed at the time of planting. The top of the tree should never be pruned except to remove a fork. During the first decade or two, as the main structural branches of young trees develop, pruning to promote a strong framework is a sound investment. It will reduce the need for more expensive pruning later, and the smaller cut surfaces will be exposed to infection for a much shorter time.

Pruning cuts that remove entire branches should be positioned just beyond the branch collar and slanted slightly away from the trunk at the bottom. Do not cut the swollen collar at the base of the branch, as this would delay closure of the wound. Use sharp tools that leave smooth surfaces, to promote rapid closure of wounds and lessen the chance of infection.

A permit must be obtained from the Urban Forestry Department prior to any pruning of trees in the right of way. There is no charge for a permit.  For pruning work in the right of way a certified arborist with a licensed tree care company is required by Nampa City Code.  Click here for a current list of approved licensed companies.  

Helpful Links

  • How to Prune Trees - USDA Forest Service bulletin. The objective of pruning is to produce strong, healthy, attractive plants. By understanding how, when and why to prune, and by following a few simple principles, this objective can be achieved.
  • Tree Decay, an Expanded Concept - USDA Forest Service bulletin.
  • Rx For Wounded Trees -This USDA Forest Service web page offers guidelines on how to care for trees to keep them healthy and to protect them from wounds. It also prescribes ways to prevent, recognize, and minimize damage by decay that most often sets in after tree wounding.
  • American National Standard for Tree Care Operations Tree, Shrub and Other Woody Plant Maintenance