Why not
Cal-Mag? The ratio's wrong, wrong wrong wrong. Once I began separating Ca from Mg, I saw, for example, that The White isn't a '
Cal-Mag whore' as she's been labeled for so many years, she needs CALCIUM, lots of it, lots more than Mg, like a ratio closer to 6:1 Ca:Mg, instead of the typical 3:1 we see in so many products (can't remember
Botanicare's ratios). Push the ratio of Ca:Mg up, and no more chasing of the tail trying to correct an immobile nutrient problem that, once noted 3-4 weeks in, is too far along to really correct before harvest.
My method of precharging has been to make a mild vegging solution, lower in K, using liquid guanos that smell like gack (seriously, horrid stuff) and teas/extracts. Since I use organics, I can't really measure EC accurately. It's been a
while since I've charged a batch of coir, but if you go with any vegging feed at about... say 250-350ppm (what's that, around... .3-.5 EC? @.5 conversion?), and then on top of that add the Ca and Mg (ratio of 6:1, using 20-30mls/gal of combination product won't be too much, and adding more Ca to that could be helpful) you'd be hitting pretty close to what I was doing. Super easy would be to mix up some PBP (or similar, I don't think it really matters all that much) along with the
Cal-Mag, assuming you have a mixed product, get the vegging to that 250ppm range and then add in the
Cal-Mag at about 20mls/gal, I think you'd be doing alright.
This is specifically for coir that needs to be charged. Again, if you're going with a brand like Canna that doesn't require charging, then you should be ok skipping this step. However, I REALLY encourage people to find and use a Ca-only product in conjunction with either Epsom salt (MgSO4, just had to argue this one w/my doc the other day) or a Mg-only product, I think you'll find that it's better overall. Unless someone's put out a
Cal-Mag product that's got about a 6:1 ratio, like I was discussing before.
And as noted, Ca and Mg can indeed be given via foliar feeds. I find it's fine to correct a Mg- this way, it's easy, but if I've gotten to the point of having to deal with a Ca- this way then it's too far along.