'Dawn' dish soap works great. I don't know how "natural" it is, but I figure, if it's safe enough to wash dishes in, it's safe enough to spray on plants. However, I always use the dust form of BT, with a 'Dustin' Mizer' dust applicator -- it is a really efficient way to do it, and the 'Dustin Mizer' makes a little go a long way.

I have to agree with Rina, sounds like peat. I've never encountered your problem using a gritty mix. I've seen and rescued a lot of plants with that type of brick or concrete-like soil. It's very hard to hydrate. The first part of the rescue is to soak the entire plant...sometimes while it's still in the pot, in warm water and even then it's a real chore. The roots may be quite brittle so the warm soak helps with removing the dried soil from it.

I've had the same problem, especially with fabric pots (not so much with plastic). Last year I tried adding some Therm-X 70 wetting agent (70% yucca) to my irrigation water, but I'm not sure that it made much difference. Did you use the Earth Juice Assist product? I've considered trying it, but I read somewhere that it, too, uses yucca. Otherwise, I'm not sure that there's much of anything out there that's more effective or that I'd consider using on edibles. Last year, I also decided to try to remedy the problem by approaching from the other direction and began experimenting with alterations to the mix as a way to increase water holding capacity. For my tomatoes in Root Pouches, I went with a 60% bark, 25% peat, 15% DE (Napa Oil Dry) blend and still had problems. This year, I've shifted to bigger pots and a couple of experimental mix variations that include both coir (which is supposed to by hydrophilic rather than phobic) and DE: 50% bark (25% screened to 1/4" to increased water holding capacity), 25% coir (Botanicare CocoGro), 10% peat, 15% DE 60% bark (10% screened to 1/4%), 25% coir, 15% DE My hope is that the combination of the coir and DE will help overcome the hydrophobic tendency of bark and peat, but that's just speculation. The first variation might be too water retentive, but I decided to try out with a few plants and see how it goes.

I agree with Karen's post. Have you considered having bulk bins of components available at the garden center rather than selling your own pre-bagged mix? You could post graphics by the bins showing pictures of and explaining recommended mixes and why they work while still allowing people to customize for their specific conditions. Also, train the employees so they have at least a basic understanding of the components you're selling.