When I started growing orchids I bought a
few books to learn about their culture.
What I understood about fertilizing was :
- fertilize with high nitrogen plants that
are potted in bark,
- fertilize with a balance fertilizer
plants that are potted in other media.
- use a high phosphorous fertilizer to
promote flowering & root formation.
Recommended dosage was 200 PPM nitrogen
(for plants in bark).
Some of the questions that came to mind
were :
- what PPM nitrogen for plants in media
other than bark ?
- should the fertilizer dosage be the same
year round ?
Then as I read more and more about orchids
and fertilizing I started being confronted with more issues :
- TDS (total dissolved solids)
- PH.
And I heard that some growers recommended
the use of Epsom salts, the occasional use of a fertilizer
called Mag Pro, the application in the summer of another
fertilizer, Peter’s Cal Nitrate, and yet another
fertilizer, Peter’s Plant Starter during potting,...
At times I got thoroughly confused.
All fertilizers contain as principal
ingredients Nitrogen, Phosphorous and Potassium, which are
commonly referred to as N-P-K.
The percent of these elements are shown on
the fertilizer container as 3 numbers separated by dashes,
always in the order N-P-K. For example: 30-10-10, 3-12-6.
In a 30-10-10 formulation, 30 % of the
contents are Nitrogen, 10 % are Phosphorous and 10 % are
Potassium.
In a 3-12-6 fertilizer, 3% of the contents
are Nitrogen, 12% are Phosphorous and 6 % are Potassium.
Nitrogen fertilizer is derived either from
urea, ammonia or from nitrates. Nitrogen derived from urea is not readily available to orchid
plants, therefore the Nitrogen in
the fertilizers we use must be derived from ammonia or
nitrates, not from urea.
Fertilizers are basically made of minerals
which are an essential ingredient of proteins. All living
things need minerals. We, humans, find many of the
minerals we need in fruits and vegetables, in meat, fish,
vitamins...
Plants also need minerals and that’s
what fertilizers will provide.
Nitrogen
Is an essential element for the
chlorophyllian function, that is for the leaves to convert
light and nutrients into carbohydrates.
Nitrogen is necessary for the plant to
grow. But excess nitrogen will cause plants to grow
excessively in size and may delay flowering ( think of those
Vandas ! ).
On the other hand nitrogen deficiency will
result in stunted plants.
A recent study by Dr. Yin-Tung Wand of
Texas A & M University suggests that “under severe
nitrogen deficiency, the proteins in the lower leaves are
digested and the nitrogen is transferred out of the older
leaves into the younger upper leaves (note : of Phalaenopsis).
As a result some of the lower leaves start turning yellow and
eventually fall off”.
Phosphorous
Is believed to regulate many activities.
It is necessary for the formation of cells,
it promotes root growth, it induces and stimulates flowering.
Deficiency is phosphorous will also result
in stunted plants, with dark green leaves.
Potassium
Is necessary for healthy growth. Deficiency
may result in dwarfness.
Micronutrients
Besides the essential elements (Nitrogen,
Phosphorous and Potassium), plants need other minerals such as
calcium, magnesium, iron, manganese,...usually referred to as
“trace elements” or “micronutrients”
because plants need them in much lower concentrations than
Nitrogen, Phosphorous or Potassium.
An ideal fertilizer is one than contains
the essential elements and all the micronutrients plants need.
Organic fertilizers such as guano and cow
manure must be decomposed by bacteria before the nutrients they
contain can be absorbed by plants (the same applies to nitrogen
from urea).
Decomposition does not occur readily in the
type of potting materials used for growing orchids, therefore
organic fertilizers are not suited for orchids.
Also, unprocessed organic fertilizers can
host diseases that will affect our plants.
For these reasons, we use, as our basic
fertilizers, inorganic fertilizers.
They may be benefits in an occasional
application of organic fertilizers such as fish emulsion, but
we are not experienced in their use or effects, therefore we
have not included them in our regular fertilizer program.
I don’t know how many different
formulas of fertilizers there are, but there are a lot.
So which fertilizer(s) should we use ?
Fertilizer chart 1
Here is a chart of the fertilizers we are
using in 2002.
As you can see we basically alternate
between high nitrogen (10 - 5 -5 ), high phosphorous ( 3 - 12 -
6 ) and balanced ( 7 - 7 - 7 ) fertilizers.
In the beginning of the summer we make 2
applications of 15 - 0 - 0 for additional calcium, and in the
summer time we use more frequently the high nitrogen.
But this is only part of the story.
Fertilizer chart 2
Because one of the other questions in our
mind was should we give our plants the same amount of
fertilizer year round ? Do they need the same amount when
they get 14 hours of strong light as when they get 8 hours of
low light ?
I do not remember getting or finding a
clear answer to this question, but it seems logical to me that
orchids (and all plants) could not possibly use the same amount
of nutrients on a short winter day as on a long, sunny, summer
day.
We found in the August 1998 issue of the
magazine Greenhouse Product News a table of illumination, by
month, for the Northeast. We adjusted this table to a
weekly schedule and used it to determine the amounts of
fertilizer we should give our plants. This is what Fertilizer
chart 2 shows.
We can not talk about fertilizers without
mentioning some other useful additives.
Superthrive
Makers of Superthrive claim their product
achieves miracles. We do not know from first hand experience
but we hear from a lot of people that it is very beneficial.
Robert Fuchs, a commercial grower in
Florida, claims that continuous use can cause mutations, so he
limits it’s use to once a month application.
Pro-Tekt
Consists of 3.7 % soluble potash and 7.8 %
silicon derived from potassium silicate.
Field tests have evidenced silicon improves
heat & drought tolerance.
In addition Dyna Grow (manufacturer of
Pro-Tekt) claims it increases resistance to environmental
stress, enhances healthier, stronger growth, and produces
hardier plants.
Considering several field tests confirm the
better results achieved when adding silicon, we made it part of
our fertilizer program.
KLN
A rooting hormone that was developed by
Dyna Grow to promote root formation on cuttings.
Dave Neil of Dyna Grow recommends to use it
for 3 waterings after repotting plants.
He also recommends to use it monthly as a
maintenance to promote stronger root growth.
But how much fertilizer should we put in a
gallon of water.
This depends on what kind of nitrogen PPM we
want to achieve.
Here is how to calculate the amount of
fertilizer to add to 1 gallon of
water in a watering can:
Of course an easy way is just to follow the
instructions on the fertilizer container.
If you decide to follow the instructions on
the fertilizer and if they give you a range, such as 1/4
teaspoon to 1/2 a teaspon per gallon, then use the higher
dosage in the summer and the lower one in the winter.
A Comprehensive Guide to orchid Culture
Venamy Orchids
1460 Route 22
Brewster, New York10509
1460 Route 22
Brewster, New York10509
Toll Free
1-800-362-3612
1-800-362-3612
Fax
(845) 279-2682
(845) 279-2682
venamy@orchidsusa.com
Copyright 2002
Venamy Orchids
Venamy Orchids