Has anyone used this fert?
 

Hi all,


I cant remember whose interview but remember it was on Youtube. Has anyone use Jack's Water Soluble fert 15-5-15 Ca-Mg? If anyone has experience about it, please give me some inputs. I appreciate it.

Thanks,

Tony

I have seen it recommended by some orchid vendors (cannot remember which ones).

It's fine.

Fertilizers are NOT all that important. More specifically, the formula isn't that important - just manage it by nitrogen concentration.

1/2 teaspoon/gallon applied weekly is fine.

It looks as good as any other recommended fertilizer for orchids but you should still remember like with all other fertilizers too it was originally designed for garden plants.
Why does this matter?
Well garden plants can require 5 times higher concentrations of macro nutrients and orchids are sensitive to the macro nutrients so we use 5 times less, no problem there, same as with all the others inclucing the MSU fertilizer but orchids like the same amount of micro nutrients as other plants so using 5 times less of an all purpose garden plant fertilizer means you will be using 5 times less micro nutrients too.
I would recommend to think about supplementing this one with micronutrients for best results as you will end up feeding 5 times less micronutrients if you feed 5 times less than the recommended amount this was originally designed for.
It is also low in Calcium and magnesium which is fine for garden plants but again using 5 times less if you use rain water it will contain too little calcium and magnesium using it on orchids.
If you use it with tap water it will only need added magnesium as tap water contains more calcium than rain water. Magnesium is easiest added with epsom salts. I would recommend half the amount of epsom salt to the amount of this fertilizer you add to your water. Working out how much micronutrients to add is a bit trickier but generally 1/5 of what is recommended for garden plants added on top of any micronutrient mix should be good. You just want to supplement it a bit - that is for the best results.

As far as I’m aware, K-Lite is the only fertilizer that was developed specifically for use on orchids and other epiphytes. It also has the highest Mg and Ca content. Despite objections I’ve heard, practical experience has shown that it also works well on tomatoes, herbs, figs and annuals.

That’s said, the MSU RO formula and the Jack’s product also have plenty for orchids, even when used with pure water.

As far as the micro’s are concerned, they are considered “micro”nutrients or “trace elements” for a reason; the demand is low, they are primarily used in catalysts and transfer phases in the various phytochemical processes within the plant, so aren’t consumed very much, so don’t need to be supplemented as often. It is common in some large (non orchid) nurseries to feed cheap NPK fertilizers most of the year, and only add trace elements once or twice a year.