Street plantings of sweet gums here appear to have a solid mat of roots beneath them, that it wouldn't be very easy to dig planting holes among. And wouldn't allow new plantings of smaller plants to thrive. Likewise areas beneath anything other than quite old and tall, high branching conifers (including pines) are often mostly bare of anything other than needles and cones because of the conditions these trees create. There are reasons gardeners often want to plant places beneath comparatively young trees, these zones don't have a lot of spontaneous or previously planted plants there already because conditions are too tough for this. You will have to choose specific kinds of plants known to tolerate such planting locations in order to have a good chance of satisfactory outcomes. Look around for matching sets of circumstances elsewhere in the area and see what looks good in them. And never plant in small pockets or zones of replaced or modified soils. Instead plant in loosened, existing soil with mulching applied and maintained afterward. If a site appears to need fertilization - a soil test is the best way to check - apply suitable products starting from the time of planting, unless the plants chosen come home from the sales yard with obvious fresh fertilizer pellets on them. And these make it into or around the planting holes. Something with a triple 10 ratio I would wonder about being suitable for azaleas. Sounds a bit strong for these and also you have to be careful about using a product with an alkaline pH on these plants - products chosen should always have labeling that says something like Evergreen Food or Rhododendron, Azalea and Camellia Fertilizer. Finally you want to minimize applications of phosphorus (the third 10 in this instance) to soils that are not known to be chronically deficient in P to a significant degree. Phosphorus leaches extremely slowly so if you keep applying it there is a buildup of it and like any soil mineral too much becomes toxic (one expert writing on the subject said many American properties had become "low grade phosphate mines" due to the chronic heavy use of high phosphorus fertilizers).

'Bill, I guess we are both beginners in propagating conifers. My god I didn't know it was this hard to grow conifers...' We all have to start somewhere. Don't give up. I think the methods Dave O. gave to us really simplifies things. Next time, I'm going to do mine that way. It will cut down on a lot of the work. This time, I spent a lot of time checking temperatures and that's because I didn't have a thermostat on my mat, so I used a timer and had to continually check and change the on/off cycles to coincide with what ambient temps were doing. The colder it got outside, the more heat it took to keep 70d bottom heat (remember I'm zone 3 brrr) :) . Next year I definitely will have a thermostat. I also spent time buying/configuring lighting, next year, I won't have to fool with that. Built myself an insulated rooting chamber, should work just fine 'as is' next year. And the reading. I must've read certain articles 10x before it totally sunk in, then you have to sort through all the contradictory and incorrect information found on the internet. So yeah, first time around is always the hardest. Keep us posted on what you do next time, I find it interesting. I still don't know how my stuff will turn out but I'll keep posting on my "Rooting Tsuga Canadensis" thread as things develop. Good Luck! :-) Hey Dave! When you finally set your tank outside in the shade, is it still sealed? Or do you have it vented by then?

No, just caulking the edges.

Photos of the actual space would help... Skip the casing or build out the one side enough to allow casing. Don't do just one side, it will always look unfinished