RO water

[Ray]

Steve,

About 10 or so years ago I adopted the philosophy that in nature, a plant may not have a lot of food, but what's there is always there (I've since learned that's not strictly true, but...), so I started feeding at 50 ppm N at every single watering.

After reading the MSU article and having lots of discussions with Bill Argo, the formula's inventor and a PhD plant nutritionist, I increased that to about 125 ppm N, and have been doing that for about 5 years now with no problems.

As to the steady feeding in nature, while I may have been correct about the low-but-steady nutrient supply, what I didn't realize was the degree of nutrition pouring out of the forest canopy whenever it rains, suggesting a low background nutritional level with interspersed spikes.

[Spider]

Dendrobium anosmum is a very hungry plant, but doing fine in my window, and all my orchid friends want a keiki.
I guess I have to be a little careful with the spraying, maybe i should buy bottled water for that.
Eva

[Ross]

Originally Posted by Spider

Dendrobium anosmum is a very hungry plant, but doing fine in my window, and all my orchid friends want a keiki.
I guess I have to be a little careful with the spraying, maybe i should buy bottled water for that.
Eva

Did you notice the exceptional root growth when provided with all the nutrients it was seeking? I was amazed!

[Spider]

Yes I have seen the difference of the root thicknes and mass. Some Phal roots are nearly as thick as my little finger.

[smweaver]

Okay, I'm going to start giving everything between 100 and 125 ppm with each watering. I think most of the plants accepted my humble apology yesterday, as nothing keeled over and died during the night. And I think that the greedy Vandas were quite excited to hear about the increased feedings they'll now be getting.

[quiltergal]

I think you'll be amazed at the change in your plants in a very short period of time. I know I was.

[FinnBar]

i wasn't aware of all that. thank you all who helped bring it up.

[Ray]

By the way, for those of you who "summer" your plants outdoors where they get a lot of rain - you're probably going to want to feed them extra then, as the rain is essentially pure water that's flushing the pot quite thoroughly.

An observation on that, though: if you've built-up a lot of fertilizer residue in your potting media, it can adversely affect root growth. If you allow the rain to thoroughly flush your pots, that will be reversed, and you're likely to see a lot of root growth - that's good, but it is temporary. If you continue to follow a "foodless" watering regimen, your plants will decline.

A similar root-growth burst can sometimes be seen if the medium stays wetter for a longer time than you normally allow it. If you see that, it is likely an indicator that the plant could do better if watered more, so you just have to adjust your medium to allow for it.

[Spider]

What is ppm? I measure my fertelizer in a ml measure spoon. I ml to 1½ l water.

[Ray]

Read this:
http://www.orchidboard.com/community/68526-post8.html