The Pink Cloud

Asters (Aster occidentalis) in the foreground, Tall willow herb (Epilobium brachycarpum) in the distance...that's the pink cloud.

I am facing a dilemma. The pink cloud of epilobium is even more substantial than last year's, on which I posted exactly one year ago today. Here is the standard view, taken today, of the northern part of the prairie--
Beneath this pink cloud is a good spread of Idaho fescue, quite a few geraniums, some lupine...all sorts of young prairie plants. I have been going through and digging out individual weeds (some sow thistle, China lettuce, mustard, a few salsify, but not too bad) and wondering whether this epilobium will put down too much seed or if this is the kind of biomass that is going to help create the mulch that makes a prairie. My dilemma is whether to mow it down before it goes to seed or to leave it. At the moment I am thinking I should mow. Even now I will still get some epilobium seed, but not the awesome onslaught I (or my neighbor Jerry) would get if I don't, and the clarkia has already gone to seed, so that seed will be planted anyway. At some point I need to let things go but I'm not sure this is the time; while perennials are still pretty young and small, mowing doesn't upset them too much at this point and it might even the playing field.