Ask a Question forum: Fertilizers

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Name: Glen Barfield
Mountain View, Hawaii 19 degre
May 6, 2016 9:59 PM CST
Aloha Gardeners,

I'm wondering what the effects would be on orchids using different types of fertilizers. I'm faced with the choices of high nitrate, ammoniacle or urea nitrogen sources. I want to grow show quality flowers on plants that will be in a greenhouse in Hawaii. I've also her mixed reviews on high phosphorus and high potassium fertilizers. what do you think would serve me best? Aloha, Glen
Name: Sue
Ontario, Canada (Zone 4a)
Daylilies Birds Enjoys or suffers cold winters Native Plants and Wildflowers Butterflies Annuals
Region: Canadian Keeps Horses Dog Lover Plant Identifier Garden Sages
May 7, 2016 5:44 AM CST
Welcome! Glen. I'm no expert with orchids so I would suggest posting this question on the orchid forum. I had heard that urea was not a good form of nitrogen for orchids but according to this article I just found from the St. Augustine Orchid Society, that's a myth:
Name: Glen Barfield
Mountain View, Hawaii 19 degre
May 7, 2016 1:25 PM CST
Mahalo and aloha Sooby.
Name: Greene
Savannah, GA (Sunset 28) (Zone 8b)
Rabbit Keeper Critters Allowed Celebrating Gardening: 2015 Plant Identifier Garden Ideas: Master Level Garden Sages
Herbs Region: Georgia Region: United States of America Native Plants and Wildflowers Dog Lover Composter
May 7, 2016 6:26 PM CST
@drdawg grows orchids; he may be able to answer...
Sunset Zone 28, AHS Heat Zone 9, USDA zone 8b~~"Leaf of Faith"
Name: Ken Ramsey
Starkville, MS (Zone 8a)

Orchids Greenhouse Vegetable Grower Ferns Region: United States of America Hummingbirder
Composter Bromeliad Master Gardener: Mississippi Cat Lover Tropicals Plumerias
May 7, 2016 8:26 PM CST
I honestly don't know, Glen/Greene. I use four different formulations, but they are standard to the industry. Generally speaking, those formulae high in nitrogen aid more in vegetative growth than flower production.
drdawg (Ken Ramsey) - Tropical Plants & More
If God wanted me to touch my toes, he would have put them on my knees.
Name: Elaine
South Sarasota, Florida (Zone 9b)
The one constant in life is change
Cat Lover Master Gardener: Florida Tropicals Multi-Region Gardener Vegetable Grower Region: Florida
Herbs Orchids Birds Garden Ideas: Level 2 Garden Sages Celebrating Gardening: 2015
May 7, 2016 8:52 PM CST
Hi Glen and welcome. I think almost everyone who grows orchids will have a different answer for you as far as fertilizers go. But I have also read that the urea issue has been disproven.

I have a couple of orchid books written by very knowledgeable people here in Florida. One is a professor emeritus in Env. Hort. at UF, Thomas Sheehan, who has been growing orchids in a greenhouse for 50 years, and he uses regular old Miracle Gro in a hose-end sprayer every two weeks. He says he has great results doing this. He varies the strength of the fert according to the seasons, because of course we get more temperature variations here than you do in Hawaii. Very dilute fert in winter when we get nights down into the 40's, and much more in summer when the nights never get below 80.

The second "authority" is Dr. Martin Motes who grows orchids commercially in South Florida. (his doctorate is in literature, not anything plant related, but he still has been growing orchids for many years). He got into much more in-depth analysis of fertilizing than Tom Sheehan. Our first issue here (and you might have it there, too) is phosphorus in the water. Our water, both tap and well water, has high levels of naturally occurring phosphorus, and it reacts with metallic elements in fertilizer like magnesium, potassium, and other trace metals making them unavailable to the plants. This is especially critical to foliar feeders like orchids. So he recommends using formulations with a very low phosphorus component (the middle number of the big 3) for regular feeding of orchids, and only in springtime to use a high phosphorus formula to stimulate root growth and flower formation. He also advises to correct the pH of any water you use on orchids to a neutral 7.0 or even a bit lower, to again make all the nutrients readily available to the plants. Or, use nothing but rain water. His other important advice is to boost the magnesium in your fertilizer by adding Epsom Salts to the sprayers regularly.

Even though you aren't in Florida, I'd recommend you get a copy of his book "Florida Orchid Growing, Month by Month" for his detailed recommendations. I've adopted a much better regimen for my orchids since reading it, (both fert, and pest and disease issues) and everybody's growing SO much better now. The book's available from Amazon.

"Success is stumbling from failure to failure with no loss of enthusiasm." –Winston Churchill
Name: Glen Barfield
Mountain View, Hawaii 19 degre
May 7, 2016 9:28 PM CST
Thank you all. A wealth of information. Mahalo and aloha, Glen

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