Hi gle-

The target soil temp for putting down pre em is 55.

How does pre em work? Wouldn't it prevent new growth of bulb pants, or new canes of fruit rubes? Just wondering...

As with all herbicides keep it away from non target plants.

Even if you're late, don't despair. Late is better than never, and you'll catch any plants that sprout a bit later than their friends. And plants aren't like clockwork!

Plus the fact that you really aren't late anyway. :-)

" How does pre em work? Wouldn't it prevent new growth of bulb pants, or new canes of fruit rubes? Just wondering.. "

Pre-em works by dessicating the newest and most delicate roots of sprouting seeds, so it's generally only effective on those. Bulb plants, canes, and so on would be unaffected since they're being fueled by the parent plant far more than by their own new growth. It might help...but for the most part, observation indicates that they simply pause until the pre-em degrades and then continue on their merry way. If they even pause at all, since the parent plant can power root growth right past the pre-em layer.

Fortunately, that does make pre-em one of the safest things to apply. While avoiding non-target plants is always a good idea...well, I tend to simply overspray the entire lawn and garden without any consideration of that. :-) Experience has taught me that nothing I have is susceptible to the Prodiamine I use, and won't have any reaction to it.