Dollarweed and Pennywort in Moist North Texas Flower Beds: Causes and Control

If you’ve got round, bright green lily-pad-shaped leaves spreading across your flower beds — especially in the wetter, shadier spots — you’re dealing with dollarweed, also known as pennywort (Hydrocotyle spp.). It’s one of the clearest indicators of overwatering or drainage problems in ornamental beds, and it’s one of the most tenacious warm-season weeds we deal with across DFW. The good news is that dollarweed is manageable with the right combination of cultural corrections and targeted herbicide use. Our flower-bed weed control program addresses dollarweed as part of a broader strategy that starts by identifying and correcting the moisture conditions that allow it to thrive.

What Dollarweed Is Telling You About Your Beds

Dollarweed is a moisture indicator weed. Its presence in your flower beds is a reliable signal that soil is staying wet too long between watering events. In North Texas, where we apply generous amounts of irrigation to keep ornamentals healthy through summer heat, overwatering is extremely common — and dollarweed moves in immediately when conditions are right. It prefers:

• Consistently moist or wet soil: Dollarweed thrives where drainage is poor or where irrigation frequency keeps the soil surface perpetually damp.
• Partial to full shade: It grows under shrubs, along fence lines, and in the north-facing sides of beds where sunlight is limited and evaporation is slower.
• Warm temperatures: DFW’s warm springs and summers (combined with irrigation) create ideal conditions from April through October.
• Compacted soil: Poorly structured North Texas clay that drains slowly keeps surface moisture high, which dollarweed exploits aggressively.

Identifying Dollarweed Correctly

Dollarweed is distinctive and relatively easy to identify once you’ve seen it:

• Leaves: Round, bright green, and shiny with a wavy or scalloped margin. The stem attaches at the center of the leaf (peltate attachment), not at the leaf edge — like a miniature lily pad. Individual leaves range from about the size of a quarter to 2 inches across.
• Stems: Long, slender, and creeping along the soil surface, rooting at the nodes. The plant spreads horizontally rather than growing tall.
• Rhizomes: Dollarweed has an underground rhizome system in addition to its surface stolon spread, which allows it to persist through light frost and dry periods and regrow from roots when top growth is removed.
• Smell: Crushed leaves have a faint parsley-like aroma, which can help distinguish dollarweed from similar-looking ornamental plants.

The Moisture Correction Must Come First

Applying herbicide to dollarweed without correcting the underlying moisture problem is fighting with one hand behind your back. New dollarweed from soil-stored rhizomes and seeds will continue germinating and establishing as long as conditions remain favorable. Before or alongside your herbicide program, take these steps:

• Audit your irrigation schedule: Are drip emitters or spray heads hitting the problem areas at a frequency that keeps soil surface wet? Reduce watering frequency and water more deeply instead — less often, more volume each time.
• Improve drainage: If water pools in bed areas after rain, consider improving bed grade, installing drainage paths, or amending heavily compacted soil with compost to improve permeability.
• Increase air circulation and sunlight: Trim overhanging shrub canopy where possible to allow more drying between watering events.
• Check for plumbing issues: In some cases, irrigation lines have small leaks that create persistently wet spots. Check emitters and lateral lines if a specific spot is always wet regardless of watering schedule.

Herbicide Control Options for Flower Beds

Once moisture conditions are addressed, targeted herbicide use accelerates the elimination of established dollarweed:

• Triclopyr: A post-emergent broadleaf herbicide with good activity on dollarweed. Products containing triclopyr labeled for ornamental use can be spot-applied to dollarweed patches while shielding surrounding ornamentals. Repeat applications are needed as new growth emerges from surviving rhizomes.
• Atrazine: Effective on dollarweed but has significant restrictions on ornamental use and soil leaching potential. More commonly used in turf; not ideal for bed applications near sensitive plants.
• Imazaquin: Has pre- and post-emergent activity on dollarweed and is labeled for some ornamental bed uses. Check the label carefully for ornamental compatibility before applying.
• Glyphosate spot treatment: A carefully directed glyphosate application to dollarweed mats — protecting all ornamental foliage with cardboard or sheeting — is effective and practical for dense infestations. It kills down to the rhizomes with thorough coverage. Multiple applications are needed as new growth emerges from deep rhizomes.

Why Pull-and-Done Never Works on Dollarweed

Pulling dollarweed is satisfying momentarily but almost never solves the problem. The rhizome network stays in the soil and regrows within two to three weeks. Without addressing moisture and applying chemistry that penetrates to the root system, you’re simply mowing off the top of an underground plant that will return immediately. Consistent, repeated herbicide applications combined with moisture correction is the only approach that delivers lasting results.

If dollarweed is your primary problem, there’s a good chance other moisture-loving weeds are sharing your beds. Read about yellow and purple nutsedge in DFW flower beds — nutsedge and dollarweed often co-occur in the same wet, poorly drained spots. Hamann has been managing these problem weeds in Arlington and DFW landscape beds since 2006. Call us at (682) 408-9013 and we’ll assess your beds, identify the moisture problem, and put a targeted treatment plan in place.