Leaching Your Plants, HUH ??
One of the questions I get frequently is, "What the heck are you talking about ..."leaching"??? Well, 40+ years ago when I started growing orchids, my mentor told me I had to "leach" the plants. I asked the same question!! It means if you have hard water, ours is around 850 to 1150 ppm of various minerals, that stuff will build up in the planter mix and on the outside of the pots. You can see it cake up around the drain holes of the pots after awhile. So "leaching" will keep that from happening.
Several 'acids' can be used to leach, it just depends which is easiest for you to obtain. Epsom Salts (Magnesium Sulfate) even Costco has this in small packages. Citric Acid - probably you would have to get this from your local chemical supply place. Phosphoric Acid - Again the chemical company is probably where you might find this. White Vinegar - I have never used this material, but I hear it works good. And there are probably other acids that will do the same that I'm not familiar with, you chemical engineers out there can probably add to this list. The two that I use are the first two on the list.
Epsom Salts is easy to use. I was told to use one teaspoon per gallon of water and I have been doing that for 40 years. I still got a slight white powder buildup on the clay pots, and I was told later that if I used Citric Acid at 1/4 teaspoon to a gallon, that would even take off the magnesium dust I was seeing from the Epsom Salts, and it does.
Here's how I use the stuff. I mix up two tanks, one of fertilizer, one of acid. Both hold 20 gallons of concentrate fed into my proportioner will make 2000 gallons of either fertilizer or acid. So I put 2000 teaspoons of fertilizer in one and 2000 teaspoons of Epsom Salts in the other. I drop the injector line into the fertilizer tank, and when the tank is empty I have put 2000 gallons of fertilizer out on the plants. In the summer that's about a weeks watering for me, in the winter it's about a months watering for me. Then I switch the line to the acid tank and water with that until it is gone. That means an equal amount of leach material went thru the plants pots, washed the leaves, etc. and I am ready to switch back to the fertilizer again. Easy enough eh? That's all there is to it.
I had one water expert come by and say, "850 ppm? You can't grow orchids in that!!" "Well, look around you!" I said. Another thing I learned where the acid helps. I use this acid to lower the pH of the fertilizer mix. I am told around 6.5 is the pH I should need, so after I put in the fertilizer I check and add Epsom Salts to the fertilizer tank until it's output is around 6.5 with the fertilizer and all. If you even use fertilizer from an injector and you have fertilizer sludge at the bottom of the tank when it is empty, this will cure it. All the fertilizer will dissolve if the pH is right, if not there will be a mess of gooey stuff to clean out of the tank later. So that's about all I know about "leaching". Anyone else want to add to this? Write me !!