Mike,

90% of the time it's weekly for me using MSU for tap water and I use Epsom salts a couple times a year. Every month or so, I use plain water heavily to wash minerals/build-up out of the pots. The other 10% of the time I use whatever is available. Miracle Grow when it happens to be handy, diluted fish emulsion sometimes, just whatever is handy. If it isn't specifically for orchids, I use it a 1/2 strength. I think it is good to mix up the fert. routine occasionally.

For mounties and bareroots, I use a pump sprayer during winter and will put leftover fert in it when it's there, usually every other week or so. I try not to fert the mounties more than 1 week straight. During summer when they are outside, they get fertilized once a week with the rest of the 'kids and plain water the rest of the week.

I generally get new growth and roots through out the year, although some struggle being indoors over winter. Very few brown leaf tips (sometimes a sign of fert issues, probably the issue with a couple of my phrags) and I'm satisfied with the blooms the orchids provide. I currently have 14 in bloom (phals, catts, dens, an epi, an equitant, a dendrochillum), and @12 more of different types in spike. During 'winter' I generally get something new blooming every week or so. I'm happy, happy, happy.

All that said, I don't think fert is as important as culture/conditions, but it does play a factor in my opinion and experience.

Bob

With regards to fertilizing orchids, my impression is that success is measured more with what you don’t see, than what you do. So a picture that represents proper feeding of an orchid would be far less convincing and instructive than a picture of an orchid that has been over-fed. The variety of approaches that have been employed by various orchid-growers and touted by experts is mind-boggling. But the common thread among the cognoscenti seems to err towards “gently.”

In the several decades that I’ve been growing orchids (much of which has been spent with no firm concept of what orchids actually need to support their growth) there seems to have been only one major “breakthrough” which has soared above most other approaches, and which has lasted in its renown to this day. That of course would be the MSU approach of utilizing relatively low phosphorus in its overall balance, together with employing mostly nitrate-sourced nitrogen and avoiding Urea nitrogen altogether. The other guiding concept in fertilizing would be summarized by the recommendation that a steady, consistent and relatively weak fertilizing regime is more supportive to orchids than strong periodic fertilizing. There are several approaches to this process, according to how scientifically-minded one happens to be. One would be to determine optimal PPM nitrogen over a prescribed period of time based on the type of water you happen to be using. The other, simpler approach (after ensuring that your water source is acceptably conducive to orchid-growing to begin with) is to feed weakly weekly at ¼ strength of the monthly recommendation, assuming a 20-20-20 or equivalent formula. Or using that same strength as a constant feed with periodic flushing, depending on genus and its tolerance to added “salts.” For example, I don’t hesitate to constant feed my cattleyas and phalaenopsis with a monthly flushing. But I wouldn’t feed my paphs with that strength more frequently than once a week, so at least one, of not two plain water applications fall between feeding. In addition, good general feeding practice frequently advises pre-watering before applying fertilizer to buffer sensitive roots. Given the application of a ¼ strength solution I feel this is less important for some genera that others. Finally, as some readily available fertilizers are balanced for acid-loving plants, it would be inadvisable to assume that any fertilizer that happens to be on hand would be helpful to orchids. The below link accesses an article on MSU fertilizing and a table that sets out two formulas. It is important to remember that orchids do most of what they do by virture of the light and supportive moisture that they receive. The picture below represents an overfertilized, and arguably over-lit paph from an overly-eager grower, i.e., me.

MSU Fertilizer Formulas

John,

I agree with everything you said except mixing ferts. An occasional shot of Epsom salts has been advised for the @20 years I've been growing orchids, if not Epsom salts use a high cal-mag type every now and then. Different orchids like different things, they are from different environments and thus what provides and how they get fertilized is also different. In my mind, if you mix it up just a little you may hit upon things that a few of your orchid like that they don't get in the MSU.

I don't put any real scientific process into my orchid growing (unless something I read or heard makes sense) as I do it as a fun hobby and it's just one of several hobbies I have currently. I try to use common sense and experience, as in learn from your mistakes. I've learned what works for me in my conditions, but someone else's mileage may vary. I'm also lazy and try not to have to spend a terrible amount of time dealing with the 'kids, an hour or so every Saturday morning and a few minutes a couple times a day works well for me as far as watering and care.

Again, all that said I don't think fertilizer (unless extremely overdone) is that important. For me, Conditions/Culture/Good light are more important to successful growing and blooming of orchids

Bob

Thanks, Bob. I don’t want to be scientific about it either, because I’m not a scientist. Lots of stuff in there that I just don’t care about. However, the subject of fertilizing is filled with absolute BUNK. So there’s something to be said for doing some of your own digging, paying attention to scholarly, respectable studies, in addition to finding out what people are using and why (especially the “and why.”). If a person wants to be a good grower, he/she should learn some basics, and maybe even some “not-so-basics” if they don’t want to be overly-dependent on hear-say from others. Forums are amazing and I love them, but a person is asking for trouble by taking someone else’s advice off the cuff without having a personal store of knowledge to evaluate their claims. Example: On another forum a person responded to an LED newbie (not me) who was looking for a certain type of setup for his space. The responder praised her lights high and low, citing all the plants that grew amazingly for her and in repeated posts insisted that these were the proper lights for the OP to invest in, providing links, etc. Turns out the OP bought these lights, they were completely insufficient for him. After he had posted his results, the responder said something like, Oh, well, I use those lights in a sunroom that also receives a fair amount of natural light. Seriously!!! And this was “senior member” of that forum. Back to fertilizing - there is a widely prevalent myth which is been around for decades that if you grow your orchids in bark, you need to use a higher nitrogen content than you ordinarily would to compensate for the nitrogen being consumed by organisms responsible for the decomposition of the bark. It is now believed that using this higher level of nitrogen is actually hastening the decomposition of the bark by increasing the organisms responsible for it, as opposed to benefitting the plant. Maybe you want broken-down bark, but that’s not dumping something on your plant because you read it or heard it somewhere. There’s another tale that sphagnum bonds with “salts” in fertilizers so that you can’t flush them away. I still have to check on that one, although, if you’re fertilizing modestly, using good water and repotting every year, is this a problem? Good questions. Is this being “scientific,” or just informed?