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Orchid Fertilizing Schedule

So, you're starting to get serious about orchids. You've figured out the basics of light, heat, watering, humidity, and repotting. But with all of the orchid fertilizers and amendments out there, how do you keep it all straight?

Smart fertilizing leads to healthy orchids with multiple inflorescences and beautiful blooms.

In my beginner days, I messed around with all kinds of fertilizers. They were often found on sale, promised as an "all-in-one" fix, or otherwise from big-box stores and simply labeled "orchid fertilizer." I knew about NPK ratios from my Master Gardener training and reading orchid guides, but I didn't know what was current best practice for orchids. One winter, after noticing that some of the oldest and most reliable orchids in my collection had mottled and yellowing leaves, I researched the symptoms and found out that it was due to Calcium and Magnesium deficiency. I ran through all of my assorted fertilizers, only to find out that indeed NONE of them had these essential micronutrients. So I read further. Through the assistance of many books and American Orchid Society articles about orchid fertilizers (Sue Bottom has several wonderful essays on the subject), I began to make smarter choices for my orchids.


Double-headed Paph. delenatii exhibiting good culture.

The first step was to drop all fertilizers that didn't contain micronutrients. For my water quality, MSU Orchid Fertilizer (RO/Rain/Tap) was the best choice. (If you haven't checked the pH and TDS of the water you use for your orchids--and adjusted your fertilizer to suit--you probably should. I hope to post about this soon. Otherwise, look for knowledgable orchid growers' publications on the subject. Googling "orchid water quality" is a good start.)


Many orchid books and websites advise that we fertilize our orchids "weekly, weakly." I find that MSU is better used for most orchid species by following the directions on the package: 1 tsp/gallon during active growth, 3/4 tsp in rest season. Its 13-3-15-8-2 formula is safe to use at the recommended strength, especially when balanced with regular flushes of pure water.


Coelogyne mayeriana enjoys balanced fertilizer and warm temps year-round.

After years of experimentation, I've come down to using only the fertilizers and amendments listed below. To wit, Quantum Orchid and MaxSea have both shown beneficial effects across many orchid genera. I do utilize a bit of extra CalMag in periods of rapid growth, because I noticed my largest and fastest-growing phalaenopsis orchids this year needed a bit more than MSU was able to provide. SuperThrive's efficacy is widely debated, but many orchidists still utilize it on faith. (If this is you, keep using it! It's just not proven its mettle for me.) I use Mosquito Bits to make sure fungus gnats stay at bay. (Several places online say that fungus gnats do not harm orchid roots; I have strong proof to the contrary and am aggressive about fungus gnat larvae control.)


Oncidium Twinkle (Tsiku Marguerite) puts on a great show when well watered with the right nutrients.

What follows is my general guide for orchid fertilization and amendments. The picture below was my first attempt to map it out; lower down I list a month-by-month guide.


Orchid Fertilizer/Amendment Schedule


These guidelines assume that you water once per week. If you water more, flush pots with pure water every fourth watering.


MSU= MSU fertilizer; MB = MosquitoBits;

QO = QuantumOrchid; CM = CalMag; MaxSea=MaxSea


January

Week 1: MSU 3/4 t/gal, refresh MB

Week 2: MSU 3/4 t/gal

Week 3: MSU 3/4 t/gal, QO

Week 4: flush pots with water only


February

Week 1: MSU 3/4 t/gal, refresh MB

Week 2: MSU 3/4 t/gal

Week 3: MSU 3/4 t/gal, QO

Week 4: flush pots with water only


March

Week 1: MSU 1 t/gal, refresh MB

Week 2: MaxSea 2 t/gal

Week 3: MSU 1 t/gal, QO

Week 4: flush pots with water only


April

Week 1: MSU 1 t/gal, refresh MB

Week 2: MaxSea 2 t/gal

Week 3: MSU 1 t/gal, QO

Week 4: flush pots with water only


May

Week 1: MSU 1 t/gal, CM 1 t, refresh MB

Week 2: MaxSea 2 t/gal, CM 1 t

Week 3: MSU 1 t/gal, CM 1 t, QO

Week 4: flush pots with water only


June

Week 1: MSU 1 t/gal, CM 1 t, refresh MB

Week 2: MaxSea 2 t/gal, CM 1 t

Week 3: MSU 1 t/gal, CM 1 t, QO

Week 4: flush pots with water only


July

Week 1: MSU 1 t/gal, CM 1 t, refresh MB

Week 2: MaxSea 2 t/gal, CM 1 t

Week 3: MSU 1 t/gal, CM 1 t, QO

Week 4: flush pots with water only


August

Week 1: MSU 1 t/gal, CM 1 t, refresh MB

Week 2: MaxSea 2 t/gal, CM 1 t

Week 3: MSU 1 t/gal, CM 1 t, QO

Week 4: flush pots with water only


September

Week 1: MSU 1 t/gal, CM 1 t, refresh MB

Week 2: MaxSea 2 t/gal, CM 1 t

Week 3: MSU 1 t/gal, CM 1 t, QO

Week 4: flush pots with water only


October

Week 1: MSU 1 t/gal, CM 1 t, refresh MB

Week 2: MaxSea 2 t/gal, CM 1 t

Week 3: MSU 1 t/gal, CM 1 t, QO

Week 4: flush pots with water only


November

Week 1: MSU 3/4 t/gal, refresh MB

Week 2: MSU 3/4 t/gal

Week 3: MSU 3/4 t/gal, QO

Week 4: flush pots with water only


December

Week 1: MSU 3/4 t/gal, refresh MB

Week 2: MSU 3/4 t/gal

Week 3: MSU 3/4 t/gal, QO

Week 4: flush pots with water only


As a shorthand:

January, February, November and December (winter/resting months) have the same regimen.

March and April (slow growth months) have the same regimen.

May, June, July, August, September and October (robust growth months) have the same regimen.


I use this schedule for phalaenopsis, aerangis, angraecum, brassavola, bulbophyllm, cattleya, coelogyne, dendrobium, encyclia, epidendrum, laeilia, leptotes, masdevallia, maxillaria, neofinetia, paphiopedilum, psychopsis, vanda, and a few other orchid genera. Of course, some demand longer, non-fertilized winter rest than others. I mark those pots with a colored tag to remind me not to fertilize them, and always use pure water sparingly in the cold.

Miltassia Dark Star 'The Orchidworks' illustrates rich colors and healthy foliage, in part due to careful fertilizing.

I finally feel as though I've begun to crack the Rubik's Cube of orchid fertilizers and amendments. I remain open to new things, but for now, I like being able to trace my orchids' health through records of thoughtful care.


I'd love to hear what your fertilizing regimen and amendment habits are. (Please contact me through email, Facebook, or Instagram.) Happy growing!

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    Contact: orchidmuse1@gmail.com