Fertilizing Your Trees and Shrubs

We have all over the last few years seen the effects of very dry weather on our plants. Our trees have shown a general lack of vigour. The symptoms of this lack of vigour are smaller foliage oven stunted, twisted or cupped and sometimes there is a summer shedding of these effected leaves. In autumn these plants may also develop their autumn colours earlier than normal. It should also be noted that plants under stress will usually produce an over abundance of fruit. The cause of these symptoms is a drying up of their root systems. The environmental stress on these plants can be further aggravated by a wet season which then encourages the dried up root system to rot. In short the consistent and timely applications of water and fertilizer avoiding the feast and famine approach will produce stronger, healthier and hardier plants.

It is always good to start out with a soil test before you begin fertilizing your plants. This will allow you to see what is missing, what is present and in what amounts. For example, too much phosphorus (P in (N P K)) will tie up the Iron (Fe) and Zinc (Zn) in the soil. The lack of Iron will cause a yellowing of the leaves called chlorosis. Iron is also a catalyst for the plants ability to use Nitrogen (N) and produce chlorophyll.

The first method of fertilizing trees and shrubs is broadcasting. It is quick and easy just broadcast the fertilizer over the ground around the perimeter of the plant. The fertilizer is not incorporated into the soil so much of the nitrogen is lost in a gaseous form into the air. This also encourages shallow rooting. This is a serious problem with tree roots in turf areas. Shallow rooting makes a plant susceptible to drought, cold, heat, compaction and physical injury. If you do use this method then water well but not excessively afterwards. If there is turf under these plants then the entire turf area must be fertilized to provide a consistent colour and rate of growth. The fertilizer is also not applied within two to three feet of the trunk of a tree. This method is not used on slopes where runoff is a problem.

Subsurface fertilizing is used where runoff is a problem or where the turf or groundcover under a tree can not tolerated the heavy load of fertilizer required by the tree. The first method of subsurface fertilization is the application of granular fertilizer in drilled or punched holes situated in a zig zag pattern evenly spaced around the drip line of the tree (perimeter of the branches). The holes must be made deep enough that the turf in the immediate area is not burned or receive more fertilizer than the rest of the turf. If it is not you will have circles of excessive growth or dead patches. Using the liquid injection method for subsurface fertilization allows you to water deeply at the same time. The liquid injection method of subsurface fertilizing is evenly distributed in the area starting two to three feet out from the trunk and extending out to the drip line of the tree. Do not over water to feed the plant and never fertilize a plant in moisture stress. You must water well but not excessively at least one day before you fertilize. In both of these methods the fertilizer should be applied to a depth of at least eight to eighteen inches.

Newly planted trees and shrubs have some special needs. First ask the nursery person when and what they were fertilized with. If it can be seen and removed do so. Do not throw it away reserve it. Good examples of these are pills, tablets and prills. Use a transplant fertilizer with a rooting hormone after planting. The reserved fertilizer is evenly distributed in the soil mix going back into the planting hole. The reason is if a plant is to establish itself into the native ground there has to be a reason to leave the rich comfy home of the original container mix and continue to move ever outward.

Rates and Timing

Dormant feeding of established trees and shrubs with a granular fertilizer is a good idea as it allows time for the fertilizer to start to work. Using a recommended fertilizer that suits the needs of both the plant and the soil fertilize according to the label directions. Generally for shrubs you will broadcast a granular fertilizer in early Spring at a rate of half to two pounds per hundred square feet. Obviously this is a guesstimate and will vary with the numerous different parameters. Trees in an area where there is turf you will apply a spring application when the turf can utilize it. If the tree requires more than the turf can handle then split your applications with the second one occurring some five to six weeks later. Generally you will broadcast a granular fertilizer at a rate of six to ten pounds per thousand square feet. Always apply the fertilizer your plant needs following the label directions. Deep root fertilization with liquid fertilizers is done in Spring ensuring that you do not over water. The liquids are applied to a depth of eight to twelve inches for trees and four to six inches for shrubs and flower gardens. Remember to always follow the label directions.

Another method of fertilizing a plant is through it's leaves. Foliar feeding is used when a quick fix is necessary. You maybe applying a single nutrient or a full compliment of them directly to the leaves. This is quite quick and fairly efficient. The liquid fertilizer can be applied after the foliage is hardened off in the Spring and up until August in this area. Precautions should be taken to prevent burning especially during periods of drought or high temperatures. Always follow the label directions.

The last way of fertilizing your trees and shrubs is the tree stake method. This is the easiest and hence the most popular method with home owners. The fertilizer spikes are driven into the ground with a plastic cap and a hammer. This is usually done in Spring or in very late Autumn. The spikes are driven into the ground evenly spaced at the drip line of the tree. The number of spikes used is determined by the caliper of the tree usually taken at eighteen inches up from the ground. Since the manufacturers instructions do vary always follow the label directions.

Plants are like people they do better under good growing conditions. It is important that you recognize the the signs of stress and better yet you should strive to never have a plant of yours go wanting.

Plant-Prod 30-8-8 Tree Fertilizer

The following table provided by Plant Products Co. Ltd. shows the breakdown of elements and compounds in Plant-Prod 30-8-8 Tree Fertilizer.

Plant-Prod 30-8-8 Tree Fertilizer - Guaranteed Minimum Analysis
Component Percentage
Total Nitrogen 30%
Water Insoluble Nitrogen from urea formaldehyde 16.7%
Available Phosphoric Acid (P2O5) 8%
Soluble Potash (K2O) 8%
Boron (B) (actual) 0.02%
Chelated Copper (Cu) (actual) 0.05%
Chelated Iron (Fe) (actual) 0.1%
Chelated Manganese (Mn) (actual) 0.05%
Molybdenum (Mo) (actual) 0.0005%
Chelated Zinc (Zn) (actual) 0.05%
EDTA (Ethylene diamine tetraacetate) (Chelating Agent) 1.0%

Directions for Use

Because of the high percentage of slow release nitrogen, Plant-Prod 30-8-8 Tree Fertilizer can be applied at any time of the year without harm to the tree.

Application Rates

Mix Plant-Prod 30-8-8 at a rate 15 kg of fertilizer in 490 L of water.


Apply 200 L of Plant-Prod 30-8-8 suspension per 100 square meters. For injecting, apply 2 L per injection at a depth of 20-25 cm, spaced 1 meter apart, within the drip-line.


Apply 0.5 L of Plant-Prod 30-8-8 suspension per injection. Space injections 60 cm apart at a depth of 10-15 cm. For small shrubs drench the soil with Plant-Prod 30-8-8 using a standard spray gun with the disc removed. Apply 1 L per square meter of root area.

Because this is suspendible (not soluble) fertilizer it requires constant agitation. Plant-Prod 30-8-8 is formulated to the same high standards as all other Plant Product fertilizers.


  • Plant-Prod 30-8-8 Tree Fertilizer has 78% of its nitrogen coming from Nitroform. This allows for 55% of the nitrogen to be slow release. This very low salt fertilizer guarantees safety for tree roots and a long term supply of nitrogen.
  • Plant-Prod 30-8-8 Tree Fertilizer contains more micronutrients than any other injectable tree fertilizer.
  • Plant-Prod 30-8-8 Tree Fertilizer contains only the highest grade ingredients. Therefore there are no contaminants that are harmful to plants.
  • Plant-Prod 30-8-8 Tree Fertilizer is produced in Brampton Ontario and packaged in strong plastic bags that are weather resistant and tough enough to withstand any field conditions.
  • Plant-Prod 30-8-8 Tree Fertilizer has a salt index of only 21, making it one of the safest tree fertilizers available.
  • Plant-Prod 30-8-8 Tree Fertilizer can be used in many Phases of tree growth.

For more information please contact Plant Products Co. Ltd.

Related Posts

View More Articles