|
Fertilizer
By Marie McKinsey, CPH
When you visit your local hardware or garden
supply store, you will find lots of fertilizer products. How
do you choose the right one for your situation? Here's some
basic information that will make the decision a little easier.
 |
|
Image
courtesy of the
West Virginia University Extension Service
|
The main nutrients contained in most fertilizers
are nitrogen, phosphorus and potassium. On the front of fertilizer
packages, you will see three numbers that will tell you the
percentage of each contained in that particular product. A 20-20-20,
for example, is one that contains 20% of each nutrient; a 30-10-10
contains 30% nitrogen, 10% phosphorus and 10% potassium. To
decide on the fertilizer you need, you need to know what each
of these nutrients do for a plant.
- Nitrogen
promotes leafy, vegetative growth.
- Phosphorus
promotes flowering, and therefore fruit production, and
stimulates root growth.
- Potassium
promotes root growth and benefits the general health of
the plant, making it more resistant to disease.
In general, evergreens and lawns need fertilizers
with a higher percentage of nitrogen. Blooming plants need more
phosphorus and potassium. Good nutrient ratios to look for are:
3-1-2 for lawns and 1-2-2 for flowering plants. NOTE: fertilizers
with a high percentage of nitrogen will suppress blooming, so
don't use lawn fertilizer in your perennial beds!It isn't necessary
to buy different fertilizers for different plants, so don't
be taken in by the myriad of products on the shelf. You don't
need rose food and tomato food and bloom "boosters".
A single, all-purpose fertilizer will take care of all your
vegetables and blooming plants. You will also need a separate
formulation for your lawn. (Try to use a fertilizer for turf
that has less than 30% nitrogen; otherwise you will spend most
of your free time mowing grass.)There are a few specialty nutrients
you should know about. Some evergreens, most notably rhododendrons,
suffer from an iron deficiency which causes their leaves to
turn yellow. This is quite common and can be solved by using
a chelated (pronounced KEY-lated) iron product or using Miracid
fertilizer. A good dousing once a year should take care of the
problem. Bulbs are heavy users of calcium and like a top-dressing
of it after blooming and a bit of it worked into the soil when
they are planted. Roses and tomatoes need extra magnesium -
check the package when you buy bags of all purpose fertilizer
to be sure magnesium is included as a trace element. As you
probably know, there are lots of forms a fertilizer can take.
There are granular forms, liquids, spikes, etc. Here are some
thoughts to keep in mind as you decide which to use.
- The
granular types that you mix with water and pour around the
base of the plant are quickly and easily taken up by the
roots. The disadvantage is that the nutrients can leach
through the soil quickly in a rainy spell, moving them out
of reach of your plant's root system.
- Foliar
sprays are also quickly taken up by plants, but their effects
are not long lasting. (And the spray apparatus can drive
you crazy - they clog too easily.)
- Granular
products that you sprinkle on the soil do a good job of
slowly releasing nutrients. They are especially useful in
wet weather. If you apply them in dry weather, water them
in.
- Time-release
fertilizers, such as Osmocote, come in round pellet form
(they look like off-white caviar). These are expensive,
but do a good job of slowly releasing nutrients over several
months. This type of fertilizer is often used in the nursery
trade.
- Avoid
using fertilizer spikes. As water dissolves them, they create
a concentrated pool of fertilizer which can burn the roots
adjacent to the spikes yet provide little or no benefit
to other areas of the root system. Stick with the dry fertilizers
and liquid mixes that you can spread evenly over the soil.
Think you have over-fertilized? Water, water,
water. This will dilute the fertilizer and wash it down below
the root zone.
|
 |
|
