Fertilizing & Mulching

Fertilizing - Get a Soil Sample Test First
Fertilization is another aspect of tree maintenance and tree health. A soil sample test should be done in order to determine what if any nutrients are deficient. North Carolina Cooperative Extension offices in your area can assist you with the soil sample. Knowing what is deficient or ample in your soil will help you decide what type of fertilizer, if any, should be applied. Run-off and build-up of excess nutrients may have detrimental effects on plant, animal and human life around you and downstream from you.

Fertilizer is best applied in the spring or fall. Active root growth occurs mostly in the early spring or late fall when soil temperatures are cool and little competition from leaves for water and nutrients is present.

Nitrogen (N) is possibly the most critical in the growth of the tree and is the element most deficient in most soils. Nitrogen is responsible for the green color in leaves and twig growth. It is easily depleted from the soil. Treatments of nitrogen between July and September should be avoided since they promote late flushes of growth that are too succulent and easily damaged by the freezing temperatures of early autumn.

Phosphorous (P) aids in the maturing of tissues and stimulates root growth. It is important in flower, fruit and seed production.

Potassium (K), also known as potash, assists in the manufacturing of sugar and starches, helps tissues mature and heightens the color of flowers.

Arborists frequently apply liquid fertilizer through a probe into the soil which results in faster uptake by the trees, and a more visible response. Injecting or implanting fertilizer into the trunk is useful for specific nutrient deficiencies or where root area is limited. Since injection and implants require holes to be drilled into the tree, their use should be limited to special applications.

Mulching
Mulch can be your tree's best friend. Proper placement of mulch around your trees helps to keep the tree healthy. Mulch helps to conserve moisture for the tree's roots and in the current drought situation in North Carolina a little extra moisture will help the trees greatly.

The rule of 3's for mulch:

• Maximum of 3 inches deep
• Minimum of 3 foot diameter around tree
• Keep it about 3 inches away from the trunk

Watering
Just like other living organisms, trees need water. Water is essential not only for a tree's survival, but it is also the source of oxygen that is released during the process of photosynthesis. The most limiting factor for newly planted tree growth and survival is lack of adequate water. Newly planted trees should be regularly watered for the first three growing seasons. Water newly planted trees every few days initially, then once a week depending on soil conditions and rainfall. Weekly to monthly watering should continue until the tree is established in the landscape. Do follow all applicable local watering restrictions during times of drought.

A good slow soaking over several hours is best, and may be done with an oscillating sprinkler, a soaker hose, a tree irrigation bag, or slow drip bucket. Watering should be focused on the root ball, the planting area, or in mature trees, under the canopy. Don't over water. Too much water can kill a tree by eliminating the air from the soil and suffocating the roots. The soil should not stay saturated, but have time to dry out between each watering. Again, do follow all applicable local watering restrictions during times of drought.

As a general rule, 2 gallons of water should be applied for every 1" of tree diameter.