Fertilization should be done in early spring with an 18-5-9 fertilizer at 1/2 pound of nitrogen per 1,000 sq. ft. In September, October and November, one pound of nitrogen per 1,000 sq. ft. should be applied. The fertilizer should be watered in thoroughly after each application. Slow release fertilizers should be used whenever feasible and don’t forget the off-season feeding in late fall.
A deep rooted feeding, using a soil auger, will mean shallow rooted plants will not be overfed in order to feed the tree and will not rob the tree’s deeper roots of nutrients. The best time for feeding is mid-October and should be applied at the rate of 1/2 pound for each foot of tree height on young trees and two pounds for each inch of trunk diameter.
The optimum period for fertilizing deciduous shrubs is early spring and should be applied at a rate of 2-3 pounds of actual nitrogen per 1,000 sq. ft. of shrub beds. Use a 2:1:1 ratio fertilizer, being careful to prevent fertilizer drifting into turf areas.
Coniferous Evergreen Trees & Shrubs
Like deciduous trees, coniferous evergreen trees and shrubs are best fed in mid-October. Conifers are slow constant feeders and prefer slow-release type fertilizers. Feed coniferous evergreen trees at the same rate as you would deciduous trees. Coniferous evergreen shrubs are best fed about August 1st. Rake existing mulch up and pile close at hand. Spread a well composted steer manure as follows:
One inch deep under young coniferous evergreen shrubs, which are three feet, and under.
One and 1/2 inches deep for evergreen shrubs up to ten feet tall.
CAUTION: Most conifers prefer a soil that is neither strongly alkaline nor acidic. Test soil once a year to maintain a neutral pH of 7.0.
Broadleaved Evergreen Shrubs
Broad-leafed evergreens, like the conifers, prefer a slow release fertilizer and should be applied in spring (never after early June). Fertilizers should be watered in well after each application.
Broad-leafed evergreens preferring an acidic soil should be spread in mid-March at a rate of 1/2 cup of azalea food for a 5-year-old hybrid. Spread it over the root area under the shrub and repeat this process three weeks and six weeks later.
Broad-leafed evergreens preferring a more alkaline soil should be fertilized by spreading an organic 10-3/5 fertilizer at the rate of one pound for every 20 sq. ft. of shrub bed. This should be done in mid-February and repeated in the third week of April and first week of June.
Groundcover plants respond best to an annual spring application of a 5-10-5 fertilizer at the rate of 3 pounds per 100 sq. ft of bed. Be sure to wash the foliage thoroughly with a strong spray after application to prevent burning and to flush the nutrients into the soil.