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Without High Phosphorus
A New Fertilizer Proves Itself with Orchids

By Jan Szyren

The past two years have been the most exciting of my horticultural career. Imagine my delight at receiving a Certificate of Cultural Excellence as my first-ever AOS award for Coelia bella ‘Anastasia’, CCE/AOS, which scored 91 points. Since that joyful event, the Michigan State University collection is, to quote a local judge, “creating quite a stir in the local orchid community …” with nine more cultural awards, an Award of Merit and a Highly Commended Certificate, 28 show trophies and countless blue ribbons since. The secret to my success: a new fertilizer developed at Michigan State University. And the great news is you can use this fertilizer at home, too.

The nutritional program at Michigan State University is vastly different from the majority of recommendations circulating within the horticultural world about the fertilization of orchids. This fertilizer is now being referred to as “Michigan State University’s Magic Fertilizer.” In fact, there were two formulas originally produced for the university that have been shown to work well for orchids. The first, called RO Water Special or 13-3-15, was designed for a pure water source like rainwater or reverse-osmosis (RO) purified water. Due to the extreme variability of well-water mineral content, the RO Water Special formula is the preferred choice for the home grower. The second formula, called Well Water Special or 19-4-23 was designed to complement the well water found at Michigan State University.

John Biernbaum, PhD, of the Horticulture Department at MSU, along with Bill Argo, PhD, of the Blackmore Company and Larry Metcoff of GreenCare Fertilizers, designed and formulated these two fertilizers for use in the MSU research and teaching greenhouse ranges on a broad range of horticultural crops: Easter lilies, poinsettias, annual bedding flowers, perennials — just about everything but orchids. Several years ago, I sought Biernbaum’s advice and he suggested I give the Well Water Special a try on the orchids. I have been using it for the past six or seven years and I also use it for everything grown in the teaching collection: ferns, conifers, annuals and perennials, hundreds, even thousands of tropical plants, cacti and succulents, from mundane coleus to the unusual Welwitschia mirabilis.

The results obtained with the Well Water Special on the 400-plus species in our orchid collection were absolutely unbelievable after just one season. Five years later, we have specimens of Bulbophyllum, Coelogyne, Dendrobium, Laelia, Cattleya and Cymbidium that are almost too big to carry.

In response to my puzzlement about our spectacular flowering and the folklore that high levels of phosphorus are required for flowering, Biernbaum told me that “it’s not the high doses of phosphorus that boost the flowering, but the lack of excess nitrogen.” (Excess nitrogen will cause excessive foliar growth at the expense of flowers.) Additionally, these two fertilizers complement or balance the two types of water that are found at Michigan State.

Photograph: John H. Lewis

HOW I USE IT††For the MSU orchid collection, I use the Well Water Special at a concentration of 125 ppm nitrogen. I first make a concentrate of the fertilizer by dissolving 27 pounds (12.2 kg) of the Special fertilizer in 50 gallons (190 l) of water, and then add one gallon (3.8 l) of an organic acid (Seplex organic acid by GreenCare Fertilizers) to counteract the horrific alkalinity levels and high pH of MSU water. The concentrate is diluted with well water through an injector at a 1:100 ratio, yielding the solution of 125 ppm nitrogen. For those without injectors, this is equivalent to about 2 teaspoons (12 gms) of fertilizer added to 5 gallons (23 l) of water. I give two to three applications of the fertilizer followed by a generous RO drench, with less fertilizer and more RO for the lady’s-slipper orchids and pleurothallids. In essence, this means the plants are fertilized with a low concentration of nutrients at almost every watering. This practice, called Constant Liquid Feed, reduces wastes due to unassimilated nutrients and also greatly reduces potential groundwater contamination from high-concentration runoff.

Because I love to water the plants, I prefer clay pots and wooden baskets. In the spring and summer, when new growths are developing, I often water many plants daily, Monday through Friday. But I do treat each plant as an individual. A dose of fish emulsion given in the spring is the only supplement.

On sunny days, the greenhouse warms up, causing the evaporative coolers or fans to run constantly, circulating such a volume of air that those plants in clay pots or baskets dry rapidly. Also, because the goal is big, beefy new growths, I choose to err on the moist side during periods of active growth. In the warmer months, I also like to go through the entire collection after watering (fertigating) and spray a fine mist of RO, just enough to wash the leaves off and trickle down into the pots. This helps keep excessive build-up from forming (we jokingly call our well water here “liquid rock”) and besides, it just makes me plain happy — the earthy smell, the humidity, the glistening leaves and flowers. This is joyful work.

Of course, in the winter, this becomes problematic. I try to avoid at all costs the slightest amount of water stress, keeping each plant as hydrated as possible. Due to security issues, the orchid houses are locked on the weekends and the collection is left alone for two days. So the plants do dry out fully every weekend. I delight in those occasional dreary rainy summer days, when it’s safer to skip watering entirely, those being my best days for repotting, grooming, weeding, sweeping or doing library research.

Jan Szyren is greenhouse coordinator and orchid grower in the Plant Biology Teaching Greenhouses at Michigan State University. She received her degree in horticulture from MSU in 1999. Michigan State University, East Lansing, Michigan, 48824 (e-mail szyrenja@msu.edu).

MSU Fertilizer Background



   Well Water Special  RO Water Special
   (19-4-23)  (13-3-15)
 Nitrate Nitrogen  13.6%  12.5%
 Ammoniacal Nitrogen  5.7%  0.5%
 Urea Nitrogen  0.0%  0.0%
 Phosphorus as P2O5  4.0%  3.0%
 Potassium as K2O  23.0% 15.0%
 Calcium  2.0%  8.0%
 Magnesium  0.0%  2.0%
 Iron  0.16%  0.17%
 Manganese  0.08%  0.08%
 Zinc  0.08%  0.04%
 Copper  0.08%  0.04%
 Boron  0.01%  0.01%
 Molybdenum  0.01%  0.01%











Source: GreenCare Fertilizer, Inc., Kankakee, Illinois 60901 (tel 815-936-0096)

Analysis of MSU well water, which is pH 7.9, is approximately as follows (ppm = parts per million or- milligrams per liter):
Calcium = 104 ppm elemental
Magnesium + 34 ppm elemental
Sodium + 8.5 ppm elemental
Potassium = 1.4 ppm elemental
Iron + 0.84 ppm elemental
Manganese + 0.04 ppm elemental
Copper + 0.70 ppm elemental
Zinc = 0.17 ppm
Sulfate (as SO4) = 91 ppm
Bicarbonate + 383 ppm

Multiply 125 by the number of gallons of fertilizer you want. Divide that result by the (“number value” of Nitrogen in your fertilizer times 1,200)
Example:  using 20-20-20 to mix up 100 gallons of fertilizer solution:
125 _ 100 = 12,500 
20 _ 1,500 = 30,000
12,500 divided by 24,000 = .52 pounds (8.3 ounces) of fertilizer needed.

Anyone can get a full analysis of a water supply from your local agriculture extension service. There are also a number of commercial laboratories that specifically work with greenhouses and will test water for about $30 to $40 per sample plus shipping. These include J.R. Peters Laboratory, Pennsylvania (tel 800-743-4769), Micro-Macro International, Georgia (tel 706-548-4557),

Quality Analytical Laboratories, Florida (tel 850-872-9595), Soil and Plant Laboratory, California (tel 408-727-0330). Culligan can also test your water for around $60.

If you would like to try the fertilizer formulas mentioned in this article contact: Hilltop Orchids (tel 765-795-6016), Porter’s Orchids (tel 517-8622-4188), Green Acres Orchids (tel 517-543-5670) and rePotme.com (tel 302-855-5859). It is also available in 25 pound (159 kg) packages from Blackmore Company (toll free 800-874-8660).