>"it explains how Poa does NOT need light to germinate and will still grow under the canopy of other grasses. Is that true?" Absolutely. Want to have some fun? Google "poa annua + antarctic" You do not state where you live, but here in the Midwest, we can cheat mother nature a little sometimes. Most early to mid Augusts, day time temperature remain warm, but the nights are starting to get cooler. It is this time that here we can cheat and drop seeds. One needs to baby it very closely, to get germination and growth from the new seedlings with watering, but it can be done. Then 2 weeks after germination (around Labor Day +/-) drop Dimension, to prevent poa annua from germinating as soil temps drop into poa's preferred range. *Once again - cheating. Most say wait until 2 mows of the new seedlings before applying preM's, however Zach Reicher of Prudue / now Unv Of Neb studies shows cheating can be done. See link here http://www.jstor.org/discover/10.2307/3988908?uid=3739656&uid=2129&uid=2&uid=70&uid=4&uid=3739256&sid=55906481363 Tenacity can be used anytime during this period, including seed drop day, and should be applied regularly during the fall for best results. Then at last cut of the year, apply Dimension again when you winterize with nitrogen - to prevent that "poa annua + antarctic"

Certainty is no longer labelled for cool season grasses. Compared with Velocity, it is inferior but both leave much to be desired on poa triv control. It may be worth it to try if you are at your wits end and need something to try before a nuclear option is entertained. I personally think early spring selective roundup is the best way. But for poa triv that is young and intermingled with the desirable grasses... no way you can selectively apply roundup. My current experiment is to hit it with Tenacity until it bleaches, then spray primo maxx and follow up with Tenacity. We'll see. I would also urge you to NOT irrigate in the heat of summer. Poa triv is the least heat tolerant of your CRF, PRG, KBG mix. Hopefully much will bow out. Also be on the look out for seeding. If you don't frequently mow or let it grow too long, it will seed and then you have not just stolon spread but a seedbank to contend with.

Good article but actually it doesn't really dispute my observation. =) I love what alfalfa does for my roses, and it sounds from that article that hosta love it, too. I think my hydrangeas were happy with their feeding as well. I thought it was interesting (though likely anecdotal since this wasn't a controlled study) that dianthus (specifically desmond) in my garden might not be a fan. I know I won't test any other dianthus with alfalfa since I dare not mess with their flowering.

This was a chart before: Sorry it did not transmit correctly. Go to Nebraska site.