Florida betony a tenacious weed

By Audrey Post
MS. GROW-IT-ALL®

Q: I have a healthy growth of Florida betony in part of my lawn. It is growing in about a 20-foot by 30-foot isolated area. I wish to eliminate it, before it spreads further. I am willing to kill the grass in that place, if that's what it takes. I am up in years and not really able to remove it by digging out all the roots. Please advise me on the best way to kill it.

A: Stachys floridana, also known as Florida betony and rattlesnake weed, is a perennial weed that flourishes in cool weather and goes dormant in the heat of summer. It is spread by stringy white roots that end in a sectioned tuber that looks somewhat like the rattles on a rattlesnake – hence the nickname. Its flowers form seeds that drop and germinate in any kind of soil, further spreading it.

Bad manners are what give it a bad reputation, because it’s not really an ugly plant. It just tends to show up where it’s not wanted and then take over. To say that Florida betony is tenacious is not giving it enough credit. It ranks right up there with kudzu and smilax in the “difficult to eradicate” department. It usually is introduced into the home landscape hidden among the roots of other plants, particularly sod.

Is there any chance you could grow to love it? It’s sort of pretty, it’s native and it’s relatively maintenance- free, although it does disappear on you in summer. No way, eh?

You said digging it out isn’t really an option for you, although that is the best way to eradicate it. However, you could work on beefing up your grass to choke it out. This isn’t the right time of year to fertilize your lawn, but if you can wait until April when soil warms, that’s one possibility.

Since you’re willing to sacrifice the turfgrass, smothering the betony with mulch is one possibility. Use a weed-whacker to cut the betony to the ground before you apply the mulch; the rhizome will still be underground, but the mulch will deprive it of the opportunity to emerge. Any strays that pop through the mulch can be plucked out if the soil is moist.

If you want it dead, you’re going to have to apply herbicide, probably more than once. The most effective time to spray Florida betony is in October, with a repeat application in February, which coincides with the fall and spring flushes of growth. As cool as it has been this fall, it’s probably too late to apply it now. Wait until early February. A product containing atrazine, which is found in most lawn weed-killer formulas including Hi-Yield Atrazien, has been effective. Don’t use a weed and feed product, because you don’t want to encourage the grass to grow until April, when the soil has warmed.

The University of Georgia has tested various herbicides on Florida betony, and reported good results with Monument, which contains trifloxysulfuron; Manor, which contains metsulfuron; and Revolver, which contains foramsulfuron. Timing was key to the effectiveness of each product. As with any herbicide, follow the directions on the label.

Herbicides containing glyphosate, such as Roundup, weaken Florida betony but you’ll have to make multiple applications to kill it. You could start with Roundup now, but it will kill everything. Do you really want a 20- by-30-foot bare spot in your lawn?