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What
do I do with my recommendations?
You
may click on any nutrient you are interested in, or simply scroll
down the page to review them all.
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Lime or Limestone
Lime
or limestone is applied to increase the soil's pH.
This may be necessary because of the native condition of the soil,
or due to the many things that happen over time to acidify the soil.
Just about everything we do in the yard or garden has a natural
tendency to reduce the soil pH. Anything from use of fertilizers,
manure, peat moss, compost, lawn clippings, and leaf mulch can acidify
the soil. If lime is needed, you will be given recommendations for
either limestone or pelletized lime. The amount of lime recommended
will be shown for several different soil depths for either material
used. For example, if you only intend to work the soil and attempt
to affect the top three inches, less lime would be needed than if
you wanted to affect the soil to a depth of nine inches.
You
may follow the recommendation for either pelletized lime
or limestone. Because limestone contains many different sizes of
material, from powdery fine to the size of small rocks, it reacts
at differing rates. The very fine particles will begin to change
the soil pH immediately, but the larger particles will not go to
work until they have been weathered or broken down over time. Pelletized
limestone is specially formulated to break down relatively quickly.
Therefore, less pelletized lime is needed than limestone, since
it will react more quickly.
It
is ideal to apply lime in the fall, since it then has all winter
to break down and begin changing the soil pH. If you apply lime
in the spring, it is best to do so at least two weeks before planting.
You should also avoid applying lime and phosphorus-containing fertilizers
at the same time. The lime and phosphorus can undergo a reaction
that will make both unavailable to your plants.
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Sulfur
Although
sulfur is a nutrient needed by all plants, the recommendation we
give you is for the purpose of lowering the soil pH. A high soil
pH makes it difficult for plants to take up other nutrients. For
example, even if your soil has adequate iron in it, at very high
pH levels your plants can show signs of iron deficiency.
We
make sulfur recommendations when the pH is over 7.0. These recommendations
are only to bring the soil pH to about 6.8. If you are trying to
grow truly acid loving plants like blueberries or azaleas, you may
need considerably more sulfur to lower the pH to an acceptable level.
Whenever making sulfur applications to lower the soil pH, it is
best to take soil samples annually to monitor the progress. Whenever
possible, it is best to work the sulfur into the soil being treated.
The sulfur recommendations you receive will be in terms of pounds
of sulfur per 1000 square feet per season. If possible, a split
application is preferred. Add one-half the recommended amount before
planting and one-half in the fall.
•
Nitrogen
Nitrogen
is recommended in terms of pounds of nitrogen per 1000 square feet
per season. It is a good idea to split up the total amount of nitrogen
into several applications throughout the growing season. However,
you should exercise caution with nitrogen applications during very
hot and/or very dry months. It is the nitrogen in fertilizers that
is most likely to cause "burning" of plant tissues. This is seen
as browning of leaves and is caused by the salt content of the fertilizer
"drying" the leaf tissue.
•
Phosphorus
Phosphorus
is recommended in terms of pounds of phosphorus per 1000 square
feet per season. Since phosphorus is essential to root development,
it is a good idea to apply at least some of the required phosphorus
before planting or transplanting. Phosphorus is also important for
flower/fruit development, so applying some later in the season is
also a good idea. Remember not to apply phosphorus and lime
at the same time.
•
Potassium
Potassium
is recommended in terms of pounds of potassium per 1000 square feet
per season. Since potassium is relatively mobile in the soil, additional
amounts should be applied if you are experiencing unusually heavy
rainfall, or if you are irrigating (watering) regularly.
•
What do the numbers mean?
In
any complete fertilizer, there will be at least three numbers in
the formulation. If the fertilizer contains any secondary or micronutrients,
there may be additional numbers given in the formulation. The first
three, however, will always be the same and given in the same order.
These will be nitrogen, phosphorus, and potassium. These numbers
indicate the percentage (by weight) of the nutrients the fertilizer
contains. For example, a fertilizer marked as "12-12-12" contains
12% each of nitrogen, phosphorus, and potassium. This means that
100 pounds of this fertilizer would supply 12 pounds each of nitrogen,
phosphorus, and potassium. Any fertilizer that is called "complete"
will contain all three of these major nutrients. Not all fertilizers
are complete, however. There are fertilizers which contain only
nitrogen, only phosphorus, only potassium, or perhaps two of the
three. When choosing a product to use, you should consider both
the needs of your soil and plants, as well as the cost of the materials
to deliver these nutrients. Even if your recommendation does not
call for any potassium, for example, it may be less expensive to
use a complete fertilizer than to buy one product with only nitrogen
and another with only phosphorus.
•
How do I choose a fertilizer?
It
is important when looking at your recommendations that you remember
that this is all they are - recommendations. Just as in human
nutrition, there are several ways to meet the desired end. While
it may be preferable to eat a certain number of fruits and vegetables
each day to supply all of the nutrients we need, it is often easier
to take a vitamin! Your plants are not particularly interested in
how they get their nutrients, but certain minimum amounts
must be there for healthy growth. Let's look at an example that
might help you to determine what fertilizer to use.
You
have been given a recommendation for your lawn that calls for 3.0
pounds of nitrogen per thousand square feet, 6.0 pounds of phosphorus
per thousand square feet, and 4.0 pounds of potassium per thousand
square feet. At the garden center, you have these products to choose
from:
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