Feeding your plants

[Ray]

Over the years, I have focused a great deal on the science behind feeding my plants, and more recently done a lot of studying related to nutrition in epiphytes, which, it turns out, is a lot different than that in terrestrial plants.

There are lots of debates concerning formulas, the sources of the nutrients, and the like, but I have come to the conclusion that fertilizer is very low on the orchids' "Maslow Hierarchy". How many times have we heard "My grandmother NEVER feeds her plants, and they bloom beautifully."?

The plants are approximately 90%-95% water, so maybe that should be the primary focus.

I think that the best thing we can do for our plants is grow them in a manner that permits VERY frequent watering (mounting, therefore is #1, closely followed by basket culture with minimal or very open media; it explains one of the benefits of semi-hydroponic culture, too, if you must use a pot), and the use of pure water with only a trace of nutrient added.

With no exception, people switching from mineral-laden tap water to pure water always remark at the improvement in their plants. "They just look brighter and perkier" (if that's possible). At the Alamo OS speaker's day last Fall, Harry Phillips (Andy's [of Andy's Orchids] brother) made it a point to stress that RO water is the best thing you can do for your plants.

Then, if you add a tiny amount of a complete fertilizer - orchids in nature see something on the order of 15-25 ppm TDS, roughly equivalent to about 1/4 teaspoon of MSU fertilizer in 400 gallons - and water very frequently, you're probably going to see the best growth.

For the record, I am not advocating that little fertilizer - I now use about 35 ppm N, which is about 1/4 tsp (of K-Lite) per gallon, yielding a TDS of about 250-300 ppm, but I am unable to water every day. If I was, I'd probably lower my concentration by another 50%-67%.

Back when I was first developing the S/H culture technique, I purchased 300 each of Oncidium Sharry Baby and Phalaenopsis Lemforde White Beauty in flats, and they all went into S/H culture. Half of each were fed and watered twice a week, the other half DAILY for 6 months. The "daily" group were significantly bigger at the end of the experiment. I attributed it to them getting more food, but in retrospect, maybe the "more watering" part was more important.

I have also had discussion with folks who claim that even if you only feed infrequently (as opposed to the "every time" mode I employ) the rate of plant growth is directly related to the frequency of watering.

[tucker85]

Excellent information, Ray.

[Andrew]

Originally Posted by Ray

There are lots of debates concerning formulas, the sources of the nutrients, and the like, but I have come to the conclusion that fertilizer is very low on the orchids' "Maslow Hierarchy".

I completely agree with you here, Ray. I suspect the reason why fertilizer gets such a disproportionately large share the discussion topics is because it's one of the few cultural factors that we truly have control over. For the most part, more important factors, such as light, temperature, water, humidity, etc, are largely dependent on the conditions we have available to us and are not as easy to modify.

[Leafmite]

Ray, I really appreciate all the information you provide on fertilizers. Thanks!
I agree that orchids probably do have variations in what they need, nutrient-wise. My other plants certainly do. Growing plants is definitely science and our growing areas are labs, whether we wish it or not. :|

[orchidsarefun]

Ray - a couple of questions
1) with RO does the filter used need to be exchanged based on time ( eg months in use ) or gallons of water that pass through ?.......or hopefully never
2) some fridges have filtered water capability. What is the main difference between this water and RO water ?
3) if you live in an area where the water is fairly "pure", is a RO system still useful ? or maybe 2) + 3) would suffice ?
Thanks

[tucker85]

If you use rainwater or RO water, make sure you use a fertilizer that contains calcium and magnesium. Some orchid formulas don't include those two elements because many water supplies have adequate amounts of calcium and magnesium already in them. If you prefer to use a fertilizer that doesn't have calcium and magnesium, you can use a cal/mag supplement a couple of times a month.

[Ray]

Originally Posted by orchidsarefun

Ray - a couple of questions
1) with RO does the filter used need to be exchanged based on time ( eg months in use ) or gallons of water that pass through ?.......or hopefully never
2) some fridges have filtered water capability. What is the main difference between this water and RO water ?
3) if you live in an area where the water is fairly "pure", is a RO system still useful ? or maybe 2) + 3) would suffice ?
Thanks

With RO systems, the sediment, carbon filters, and membrane do need to be changed periodically.

The real factor is volume - about 3000 gallons for the sediment filter, 6000 for the carbon, and 12,000 or more for the membrane - but lacking a way to measure the throughput, folks often resort to time, being 6-, 12-, and 24 months, respectively.

Refrigerators and Brita filters work about the same, only removing dissolved organic substances via carbon, and having no effect whatsoever on dissolved inorganic solids.

NYC has some of the purest tap water around, but that's about 50 ppm TDS. Personally, I wouldn't bother with an RO system there. Some "purists" might disagree.

[hcastil3]

Great info Ray, thanks

[RosieC]

Really interesting Ray.

I do find my daily watered mounts doing substantially better than plants even on a 3-4 day cycle.

I have several Den kingianum plants that are keikis from the same parent (and the parent). I purposefully grew them differently to see what did best, although as I wasn't doing this scientifically there are too many variables changing between each to give a scientific analysis of the results. I have one mounted, some in bark, some in leca (not S/H), some in the greenhouse, some in the house.

However what I see, is the mounted one that gets daily rain water is doing far better than any of the others. It's still not the biggest (the parent still is) but it's far bigger than the keikis it started out with and it's new canes are much fatter than any of them, and fatter than the parent's new canes.

I fertilize a bit randomly I'm afraid, but the mounted one get's a low strength fertiliser, and get's it every few days. The parent get's the same strength about once a week, while the others get your old recommended strength about once a week.

So while what I see it far to random too be much proof of anything, it also leans towards what you are saying... more water, pure water, low fertiliser.

Hmm, if I had time I should do more detailed experimentation, I have tonnes of these kingianum keikis... but I'm afraid I'm unlike to find the time

It does make me think though, probably not coincidence my mounts are my best growers... just a shame I can't viably handle more of them.

[NYCorchidman]

I live in NYC. I water everything with tap water. All my plants grow and flower well as they should.
I never really kept up with fertilizing until this year, but honestly, I do not see any difference or benefit.

I do think good watering is the most important. After all, most of plants body is made up of water anyway, and orchids get plenty of water everyday in nature.