Florida Betony

What is Florida betony?

Florida betony is a mint-family perennial that has become one of the toughest broadleaf weeds to clear out of lawns and beds across the South. It grows in the cool season, coming up in fall, peaking in late winter and spring and going quiet in summer, which catches many homeowners off guard. Florida betony identification is simple once you dig: the plant hangs from crisp, white, segmented tubers that look like a rattlesnake's rattle, which is where the nickname rattlesnake weed comes from.

Those tubers and the brittle rhizomes that carry them are the problem. They snap apart when you pull or hoe, and broken pieces can sprout new plants. Most preemergence herbicides do nothing, because new plants rise from tubers rather than seed. It moves into thin turf and mulched beds, tolerates sun or shade and wet or dry soil, and often hitches a ride in field soil or recycled potting mix.

Florida Betony identification: what to look for

Check the stem first: like other mint-family plants, Florida betony has square stems and leaves in opposite pairs. Then think about timing, since it shows up in fall and spring rather than midsummer. To confirm, dig down a few inches beside a plant. The white, ringed tubers set it apart from its close relatives, none of which make tubers.

• Stems: Square (four-sided) and upright, often hairy; whitish to light green on young plants and sometimes purplish on older ones.
• Leaves: Opposite, toothed along the edges, up to about 2 inches long and 1/2 to 1 inch wide, ranging from lance-shaped to broadly spade-shaped.
• Flowers: Clusters of 3 to 6 small, two-lipped flowers in the upper leaf joints, pink to white and spotted with purple, mostly in spring.
• Tubers: Crisp, pale white and segmented like a rattlesnake's rattle, attached to brittle, branching rhizomes. This is the key trait.
• Habit: Erect and dense, up to about 2 feet tall in unmowed areas, often forming thick stands.
• Seeds: Each flower can form four tiny nutlets, but seed matters far less than tubers in how it spreads.

Where it grows in the United States

Florida betony grows throughout the Southeast, from Florida north to Virginia and west to Texas, and USDA records also place it in California. USDA lists it as native, though UF/IFAS points out that its true origin is debated because it is not certain the plant grew in Florida before 1940. University of Georgia Extension describes it as a native invader that spread out of Florida in the 1940s and 1950s and became a problem weed from North Carolina to Texas.

Its favorite targets are bare or thin turf and mulched landscape beds, but it also infests gardens, farm fields and disturbed ground. Lawns usually thin first from mowing too low or too often, poor watering or feeding, a grass not suited to the area, or unchecked insects and disease, and betony fills the gaps. It has spread widely through landscapes and nurseries as tubers carried in field soil or recycled potting media, and it can grow up through weed barrier fabric.

Florida Betony look-alikes

A few plants get mixed up with it:

• Staggerweed (Stachys arvensis): A related hedgenettle with the same square stems, but it sprawls rather than standing upright, its leaf pairs are spaced closer together, and it makes no tubers.
• Mouse's ear and hyssop-leaf hedgenettle (Stachys crenata, Stachys lythroides): Close relatives that also have square stems and opposite leaves. Both have shorter gaps between leaf pairs than Florida betony, and neither produces the white, segmented tubers.
• Henbit (Lamium amplexicaule): Another square-stemmed mint that shows up in lawns in the cool season. Henbit is a winter annual with fibrous roots and no tubers; its rounded, coarsely toothed, hairy leaves lose their stalks toward the top of the stem, its flowers are purple, and the plant dies off as late spring warms up. Florida betony is a perennial that returns from white, segmented tubers and has pink to white, purple-spotted flowers.

How to get rid of Florida betony

Pulling, digging and mowing: Hand-pulling only works on small patches, and only if you dig deep and remove every tuber and rhizome piece, because anything left behind regrows. Hoeing tends to chop the brittle rhizomes into more pieces instead of killing the plant. In beds, a 2 to 4 inch layer of coarse mulch such as pine bark, pine straw or wood chips smothers many emerging shoots, and landscape fabric under the mulch helps further, though shoots can push through gaps. Large infestations generally need herbicide.

Cultural control matters most, because the right conditions keep it from coming back.

• Keep turf thick with the right mowing height and frequency, proper watering and fertilizing, and a grass suited to your area.
• Deal with lawn insects and diseases promptly so the turf does not thin out and open space for betony.
• Mulch beds 2 to 4 inches deep with coarse material, with landscape fabric underneath where practical.
• Use clean soil and potting mix, and avoid field soil or recycled media from places where betony grows.

Herbicides: Common lawn preemergents such as oryzalin, benefin, pendimethalin and bensulide do not control Florida betony, because it returns from tubers. For lawns, University of Georgia Extension lists 2,4-D, dicamba, three-way combinations of 2,4-D, MCPP and dicamba, and atrazine, and reports good to excellent results in its trials with trifloxysulfuron, metsulfuron and foramsulfuron. Apply 2,4-D and dicamba products in the cool months while betony is actively growing; summer and hard-winter treatments fail. Atrazine works best in mid- to late October, with a second treatment in mid- to late February on warm-season lawns; it suits centipedegrass, St. Augustinegrass, zoysiagrass and dormant bermudagrass but not tall fescue. Centipedegrass and St. Augustinegrass tolerate 2,4-D and dicamba less well than other lawn grasses, so choose products labeled for them. In beds, a directed glyphosate spray that stays off ornamentals works best when betony is flowering and needs repeat treatments; dichlobenil, applied between early November and mid-February, controls it around established woody shrubs, trees and roses but is not for flower beds. Contact products only burn back the tops. Use products labeled for the site, and follow the label, which is the law. If you hire someone to spray, make sure they hold your state’s pesticide applicator license; the rules for each state are in our pesticide applicator license guide.

Keeping it from coming back

Because it travels as tubers, the best prevention is keeping infested soil out. Use clean topsoil and potting mix, look over the root balls of new plants, and be cautious with field soil or recycled growing media. Dig out any single plant you find, tubers and all, before it spreads.

In lawns, thick, healthy turf is the main defense, since betony takes hold in bare and thin areas. Note where it showed up and check those spots each fall, when new shoots emerge and are easiest to treat.

Questions we get about Florida betony

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