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 (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
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 cannot
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 zigzag 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.
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 its
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 homeowners. 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. The caliper of the tree is 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
signs of stress and better yet you should strive to never
have a plant of yours go wanting.
Bulletin (Provided by Plant Products Co. Ltd.)
30-8-8 Tree Fertilizer -
Suspendible Fertilizer With
Slow Release Nitrogen
Insoluble Nitrogen from urea formaldehyde
Phosphoric Acid (P2O5)
Copper (Cu) (actual)
Iron (Fe) (actual)
Manganese (Mn) (actual)
Zinc (Zn) (actual)
(Ethylene diamine tetraacetate) (Chelating