Hi,
Helping a friend with his garden and he has a visible calcium deficiency. Starting to get tiny brown spots. So far we have done the following:
He has been using
CalMG @ 5 ml/Gallon every feed.
Nutrients @ 5.8
His coco ph test came back to 6.4
We flushed with more volume @ 0.5 EC (Ro water + Canna A+B) @ 5.6
No sign of improvement, but it hasn't gotten worse. I was thinking a
CalMG foiler to help them out? They are about 14 days into flower.
Thoughts?
First thought is that it's really refreshing to see someone who actually knows what a Ca- looks like. That's my first thought.
Second thoughts are as follows: Get a separate Ca and Mg product. I like BioLink's 6% Ca, it's certified organic and doesn't give you extra N. Once I separated out Ca and Mg, I found everything went that much easier. Incorporating worm castings into the mix, as teas, top-dressings or part of your coir mix are quite helpful here as well, as can be good old molasses (it's part of my feeding regimen from start til end).
Allow pH to range a little more broadly, I feel that 5.8 is a bit tight and you'll see better uptake if you allow a range, easily up to 6.2, and ranges outside both ends, high and low, are also acceptable.
You will not observe any improvement in the already-affected areas. All you will observe is cessation of progression of symptoms. Know that Ca can be given via foliar application, too, which further allows you to push the EC of root feedings. With me so far?
You can do the same thing with Mg using MgSO4 at the rate of 1/4tsp/gal+surfactant (dish soap, JMS Stylet, aloe juice all work here).
What I do is alternate the supplements offered at feedings, one feed they'll get Ca (from the get-go, they're always getting it because it's immobile and is difficult to correct once onset is observed), the next they'll get their Mg.
Keep your Ca:Mg ratios at 3:1 or above.
As to using tap water to resolve any Ca or Mg problems, I personally was unable to do that because my (well) water, though very high in both Ca and Mg, had both minerals locked onto carbonates (the CO3 molecule). Carbonates affect pH, and they're difficult to break apart to make Ca and Mg available. It's
available Ca and Mg that you're after here.
Was the coir charged with Ca or
Cal-Mag, possibly + a light vegging solution, prior to planting? Obviously, this is brand-dependent, but I learned both by bein' tol' by a grownup and by making the mistake of not doing it well enough that it's rather important.
What else..? I've gotta think about it to get at what else, but right now you've got to resolve the Ca-. If you're late in flower (looking at around 2 weeks prior to choppy-chop) then it's a done deal, no need to spend time, money or energy on trying to resolve a problem that won't.