This is going to sound rather flip but when it needs it :-) And that is determined by both the plant, the size container and your weather. It is difficult to be more precise than that. Knowing your plants and what they need in the way of water should be your first concern, as well as monitoring how they look.

btw, you do not need to repost your entire question if not responded to immediately. Just add on to the original post to bring it up to the top of the list. Multiple postings of the exact same question just get confusing.

Thanks.

My OP contained too much info so I thought a new post (with just the pertinent info) would elicit responses.

Gary correct me if I am wrong, but I think what Gary wants to know (and what I want to know) is How can I tell when plants in 'gritty mix' need to be watered? Not how often they need to be watered. I do not want to wait until they wilt because that damages the plant. I have tried shoving a dowel into the mix but, unlike 5-1-1, no particles adhere to indicate dampness and it is difficult to tell if the dowel is moist. A moisture meter is useless.

It seems that the best way to tell is to dig down about four inches to see if it feels moist.

About 10 days ago, I re-potted all of my plants (in 50 containers) in gritty mix and I've been thoroughly watering the plants every day.

Most of the plants are doing OK but some are still in repot-shock (wilted, dropped or yellowed leaves).

Get them out of direct sun. Do not fertilize.

It seems there should be a better way to determine the gritty-mix's moisture than digging down about four inches in the containers,

The re-potted plants are under a lattice patio-cover until they recover from being re-potted. No fertilizer.

physicall inspecting the medium is a very good way of determining when to water ANY medium.