Gene, Those are good ideas re: indicator plants. The trick is finding the right plants. I use Sedum coeruleum and Mimulus latifolius, which are attractive to boot. I also tolerate infusions of Crassula connata, which can generate a dense cover of small plants after 4-5 years but is easily controlled. When they become dense it is time to repot! There is also a small-flowered Cryptantha sp. and-- big mistake-- Muhlenbergia microsperma. The latter is cute with its plumes of purplish flowers but it soon becomes a prolific menace. Another work around for the common problems you cite is sowing more than one desirable plant in with another. For example, a tuberous Othonna generates "weed-like" roots (like Sonchus oleraceus in fact) and can hold the mix together where small bulbs are not up to the job. Dylan