Sunflowers

When the sunflowers all tipped over what seemed like the same day a few weeks ago -I thought it was annoying, and that maybe their heads finally got too big for their roots.  I intended to tie them back upright with string.  It didn't occur to me that they were mature.And since I've been sadly neglecting my greenhouse, and never did get around to re-erecting them, by the time I hacked my way in there, now on a salvage mission since the stalks were dead and yellowing, the heads were on their way to mold (!).Totally mature, fat seeds and plump kernels inside.  So there I go.  The birds will enjoy this year (only a couple heads were lost).Sunflowers mature extremely quickly in the greenhouse, it appears, and I suppose I planted these early (beg May).  The ones I have outside are far from finished.I feel like I need to explain giving good GH space to sunflowers: for some reason I have very little luck growing them outside.  They are very attractive fodder for various munchers for far too long- until they're some feet high, I think.  And then, the wild birds empty the heads before the kernels even ripen.  I have more room in the GH than I know what to do with, so why not stick some squash and sunnies in there?