Question

1. Provide three reasons why you would not recommend mixing nitrogen fertilizer into the backfill when planting a 3-inch caliper dormant tree in March.

Answer 1

Newly planted trees and shrubs lack the ability to absorb nutrients until
they grow an adequate root system. Fertilizing at planting with quickly-
available nutrient sources is not recommended and may actually inhibit root
growth. However, a soil test is useful to determine the need for adjusting pH
before planting. If the soil test indicates a need for phosphorus or potassium,
incorporate these nutrients into the bed or backfill at planting time as
directed.
For established plants, apply fertilizer in spring before growth starts, or
wait until mid-summer after shoot growth ceases, as root growth and
maximum nutrient uptake occurs during these periods. Plants generally take
in few nutrients during periods of active shoot growth or flowering. Avoid
fertilizing with high nitrogen sources during late summer (late August to
mid-September), because it may cause certain plants to put out a new flush
of leaves that could be susceptible to early frost damage. Fall fertilization
(mid-September through mid-October) can be beneficial, however,
providing plants with nutrients that are stored in roots and stems, ready to
use for the next spring’s growth.
Do not fertilize plants showing symptoms of drought stress. Do not
fertilize a tree or shrub during a drought unless plants are irrigated
regularly. Plants cannot use the fertilizer without adequate water. Some
fertilizers may damage the roots and scorch the leaves if water is lacking.

Do not apply fertilizer indiscriminately. Lawn and landscape
fertilizers, if not managed properly, are a contributing source
of nutrients associated with water quality degradation. Excess
nitrogen can leach through soil and pollute ground water; it is also
of high concern in estuarine systems. Phosphorus carried by runoff
water into freshwater lakes, ponds, rivers or streams can result in
algae blooms and have other biological effects. In addition, the
effects of diseases, insects or environmental stresses may be more
severe on heavily-fertilized plants.