Continuum wrote:never grown cactus, so any advice is welcome.
Hello, I admire your cacti... I tried to pm you this message (with some modifications) when I was a new member:
I have 1 medium size T. pachanoi with 2 pups attached to it; It's several feet tall. It's in a mixture of about 90% sand & about 10% soil; I suspect mine is retaining too much water, but mine looks (almost) asymptomatic. If I could re-do it, I'd put it in some form of small size clay pellets, or pea gravel, to increase drainage. Pictures of my cactus are included in my thread about Salvia light intensity, fertilization, and cloning.
[I have little other cacti growing experience]... My advice to you is acquire small-gravel type growing medium to transplant them into. In my experience, horticultural perlite will (over-time) come to the surface of the growing medium. This will make it where the medium holds more moisture than it had held previously. I have a decent amount of experience with growing other types of plants.
I use a light fixture that holds 8 T5 light bulbs (432 watts total), and at this point, my cactus is not directly under the light, it's about 9 inches to 1 foot to the side of the light, and the light is elevated about 4 inches above the cactus canopy elevation. It's my understanding that over-watering is the most common mistake made while growing any plant.
I echo the recommendation for a temperature/humidity monitoring device at canopy level; I also want to mention that it couldn't hurt to acquire a light intensity monitoring device such as a digital foot-candle meter (to ensure they are definitely getting enough light intensity).
I have not yet sprouted any of my
Lophophora williamsii seeds.
I wish you and your cacti the best.