Feeding Potless Vanda

[Ray]

If you do the calculations of the chemical processes going on within a plant to fix carbon (i.e., to grow), pretty much any plant must consume and process about 5g of NPK and about 200 lb of water,

For bare-root plants, that uptake occurs ONLY with the saturation of the velamen at the instant of feeding. Let's try a theoretical example:

A vanda in a slat basket with no medium, with its roots wetted, can only absorb what hits the roots and is immediately absorbed by the velamen. If those roots are 3/8” in diameter and the velamen is 1/8” thick, each inch of root length has 0.01943 in3 of velamen (let’s call it 0.02 in3 for convenience) which is about 0.32cc. Let’s also assume it can absorb 100% of that volume (it’s bound to be a bit less in reality).

A 25 ppm N solution of K-Lite requires 0.1925g fertilizer per liter, meaning there is 0.0001925g in a cc. That means that each inch of the vanda root can absorb 0.0001925 x 0.32 = 0.00006g of fertilizer. A mature vanda might have what? 20 feet of roots? If that’s correct, at each watering, it can absorb 240 x 0.00006 = 0.015g of fertilizer. (That assumes 100% of the liquid is absorbed with no evaporation.) If growing a pound requires 5g of fertilizer, that would mean that this vanda should do that in about 333 waterings. Double the fertilizer concentration and you, theoretically, halve the time.

However, let's not forget that fertilizer is only ONE parameter that affect growth, and it is a minor one at that. My greenhouse in PA and Motes' in FL have drastically different annual light, heat and humidity profiles, so while Motes' plants might be able to use a lot of fertilizer, mine probably cannot, due to other limitations.

[WaterWitchin]

Just a question here amongst the sci-guys... what's a tsuke?

[estación seca]

Originally Posted by WaterWitchin

Just a question here amongst the sci-guys... what's a tsuke?

Is that a trick question... like "How do you like my new hairstyle?"

[K-Sci]

Originally Posted by WaterWitchin

Just a question here amongst the sci-guys... what's a tsuke?

It is the Japanese word meaning 'attachment.' It's the joint where the part of the leaf that eventually drops off attaches to the part that doesn't.
Neo collector term.

[WaterWitchin]

Originally Posted by K-Sci

It is the Japanese word meaning 'attachment.' It's the joint where the part of the leaf that eventually drops off attaches to the part that doesn't.
Orchid collector term.

Gracias K-Sci!

[Ben_in_North_FLA]

"What led you to this conclusion?
K-Sci"
actual growing experience....'I built a 12x18 ft
shadehouse strictly for vandas and a few mounted cattleya alliance plants. plants were hanging on pipes at 8ft above ground. Used 50 percent shade cloth and was covered with clear 6 mil poly. I controlled watering with overhead misting system (on twice each morning 15 minutes each cycles)and dosmatic fertlizer injector all controlled by a battery timer and shade house was pretty much on autopilot, except for fertilization once a week.
I got tremendous growth on all vandas with 3 ft plus of uninterrupted full size foliage and roots that extended to 4-5 feet below first leaf and many plants had to have the rootball coiled up like a hose to keep them off the ground. initially all plants were on baskets but they wound up with roots interlocking each other and I had to literally use a machete to separate the plants and then removed the baskets and just hung them with a wire hook.
When fed at 1 tsp rate they grew normal and hardly bloomed, bumped up 1 TBSP and things changed substantially, more blooms.

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[Clawhammer]

Originally Posted by Ben_in_North_FLA

"What led you to this conclusion?
K-Sci"
actual growing experience....'I built a 12x18 ft
shadehouse strictly for vandas and a few mounted cattleya alliance plants. plants were hanging on pipes at 8ft above ground. Used 50 percent shade cloth and was covered with clear 6 mil poly. I controlled watering with overhead misting system (on twice each morning 15 minutes each cycles)and dosmatic fertlizer injector all controlled by a battery timer and shade house was pretty much on autopilot, except for fertilization once a week.
I got tremendous growth on all vandas with 3 ft plus of uninterrupted full size foliage and roots that extended to 4-5 feet below first leaf and many plants had to have the rootball coiled up like a hose to keep them off the ground. initially all plants were on baskets but they wound up with roots interlocking each other and I had to literally use a machete to separate the plants and then removed the baskets and just hung them with a wire hook.
When fed at 1 tsp rate they grew normal and hardly bloomed, bumped up 1 TBSP and things changed substantially, more blooms.

My growing experience says different. I fertilize (mostly) every watering with a very low ppm fert solution and my three vandas are almost constantly in bloom. Two of them recently just put a second spike out of the same node they are so happy.

I am not doubting your experience, I just caution any grower in making such definitive statements about what one HAS to do in order to get blooms. I mean, obviously vandas don't get a tbsp / gallon in nature...

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[K-Sci]

Originally Posted by Clawhammer

My growing experience says different.
I just caution any grower in making such definitive statements about what one HAS to do in order to get blooms. I mean, obviously vandas don't get a tbsp / gallon in nature...

Good advice. By this same reasoning I chose to fertilize at 1/4 tsp/gal rather than jump to 1 Tbs/gallon more often, an increase of 3.5 times.



I recently bought a TDS meter on Amazon that tests accurate in a reference solution and will find out what the PPM is next time I water (if I remember).

[K-Sci]

Thank you estación seca and Ben in Florida!

Okay, after upping my fertilizer from 1/4 tsp every other week to 1/4 tsp ever other day, my Vanda (pictured with copious roots earlier in this thread, boomed. What's remarkable (to me at least), is that it just finished blooming last month. It has never bloomed twice in a season before. Here's a picture of my reward, though it isn't really quite as blue as the picture (on my screen).

K-Sci

[Ben_in_North_FLA]

Originally Posted by Clawhammer

My growing experience says different. I fertilize (mostly) every watering with a very low ppm fert solution and my three vandas are almost constantly in bloom. Two of them recently just put a second spike out of the same node they are so happy.

I am not doubting your experience, I just caution any grower in making such definitive statements about what one HAS to do in order to get blooms. I mean, obviously vandas don't get a tbsp / gallon in nature...

I am just relating my results growing hundreds of vandas , ascocendas, ascocentrum, aerides, and various vandaceous hybrids and also the culture details provided by RF orchids and Motes orchids as well.
Not all my orchids are heavy feeders and the rest usually get 1 TSP per gallon dilution.
Obviously no one should change their culture at another grower's suggestion without trying a test plant first and confirming results. At some of my orchid culture presentations I expand that aspect substantially.

I have never tried the weakly/weekly method or weak feeding at every watering as I want my plants to enjoy the clean water rinse several time between feedings to avoid root burn. My vanda shadehouse was covered and protected from rain.

Sounds like you're satisfied with the three vanda sample that you mentioned.

Next time that you are attending any Major orchid show that RF orchids attends, pls take a good look at their plants display and inquire about their vanda feeding. Always good to have useful information from one of the world's premier growers.