Organic dry amendment replacement for bottled cal-mag nutes? (Preferably off-the-shelf)

I use Gaia green basalt Rockdust. Great source of calmag and also good for water retention. Hope this helps!

Hello. I've been using a product I like. It's Wollammo at wollammo.com. It's a calcium-silicate mined in Quebec Canada. It's a powder that can be mixed with or put on any medium. It has in it SiO2 55% - CaO 29% - MgO 3.1% - K2O 1.4% - Fe2O3 0.65% - Mn2O3 0.60% This provides a source of plant-available silicate, carbon neutral calcium, magnesium, and other beneficial trace elements and micro-nutrients. Check it out. Chuck.

Fish bone meal or gypsum will work. Maybe water in some epsom salts early-mid flower.