Dollarweed, also known as pennywort (Hydrocotyle spp.), is one of the most frustrating and persistent weeds for homeowners, particularly in warmer, humid climates like many parts of Kenya. Its distinctive round, coin-shaped leaves, which give it its common name, can quickly spread through lawns, flowerbeds, and even gravel paths, forming dense mats that choke out desirable plants. This aggressive perennial thrives in moist conditions, making it a common sight in irrigated lawns or areas with poor drainage.

Dealing with dollarweed requires a multi-pronged approach that combines proper identification, cultural practices, and targeted control methods. Simply pulling it often isn’t enough, as its extensive root system and ability to spread via rhizomes and tubers allow it to quickly re-establish. This guide will provide you with the knowledge and strategies needed to identify, manage, and ultimately reclaim your lawn from the tenacious grip of dollarweed.

Your Guide To Dollarweed

Dollarweed (Hydrocotyle spp.) is a group of low-growing, perennial weeds that are part of the Araliaceae (ginseng) family. While there are several species, they share similar characteristics and growing preferences.

Key characteristics that make dollarweed a formidable foe:

  • Rhizomatous Spread: It spreads aggressively via underground rhizomes (horizontal stems), allowing it to colonize large areas rapidly.
  • Tubers: Some species also produce small, potato-like tubers along their rhizomes, which can sprout new plants even if the main plant is removed.
  • Wet-loving: Its primary identifying characteristic is its preference for consistently moist or even waterlogged soil conditions. You’ll often find it thriving in poorly drained areas, near leaky sprinklers, or in low spots in the lawn.
  • Prostrate Growth: It grows very low to the ground, making it difficult for lawnmowers to effectively cut.

Understanding these traits is crucial for developing an effective control strategy.

How To Identify Dollarweed in Your Lawn

Accurate identification is the first step in effective weed control. Dollarweed has several distinguishing features:

  1. Leaf Shape: This is the most obvious characteristic. The leaves are nearly perfectly round, resembling small coins or miniature lily pads. They range in size from about 2.5 cm (1 inch) to 7.5 cm (3 inches) in diameter.
  2. Petiole Attachment: Unlike many other round-leafed plants, the leaf stem (petiole) of dollarweed attaches to the center of the leaf, rather than at the edge. This “umbrella-like” attachment is a key identifier.
  3. Growth Habit: Dollarweed typically grows very low and forms dense mats or patches. It often creeps along the ground, sending out roots from its nodes as it spreads.
  4. Flowers: While small and inconspicuous, dollarweed does produce tiny, whitish-green flowers in clusters, often appearing in late spring through summer. They emerge from the point where the petiole attaches to the leaf stem.
  5. Location: You’ll most commonly find dollarweed in areas of your lawn or garden that are consistently wet, poorly drained, or frequently irrigated. This includes low spots, near downspouts, or around frequently watered flowerbeds.

Common Look-Alikes (and how to distinguish them):

  • Creeping Charlie (Ground Ivy): Leaves are also rounded and scalloped, but the petiole attaches at the edge of the leaf, not the center. Creeping Charlie also has square stems and a minty odor when crushed.
  • Clover: Clover leaves are compound, meaning they are made up of three (or sometimes four) separate leaflets, not a single round leaf.
  • Wild Violet: Wild violet leaves are heart-shaped, not perfectly round, and the petiole attaches at the indented base of the heart, not the center.

How To Get Rid of Dollarweed

Controlling dollarweed requires a combination of cultural practices, manual removal, and, if necessary, chemical treatments.

Cultural Methods (Prevention and Long-Term Control)

The most effective long-term strategy for dollarweed control involves addressing the underlying conditions that allow it to thrive: excess moisture.

  1. Improve Drainage:
    • Aeration: Compacted soil prevents water from draining properly. Aerate your lawn regularly (especially in spring or fall) to improve soil structure and allow water to penetrate deeper.
    • Amending Soil: For areas with heavy clay, incorporate organic matter (like compost) to improve soil structure and drainage.
    • Address Low Spots: If your lawn has depressions where water pools, consider filling them with topsoil or installing a French drain to divert water.
  2. Adjust Watering Practices:
    • Water Deeply, Less Frequently: Dollarweed thrives on constant shallow moisture. Water your lawn deeply and less frequently to encourage deeper root growth in your turfgrass, while allowing the topsoil to dry out between waterings. This makes the environment less hospitable for dollarweed.
    • Check Irrigation: Ensure sprinklers are not leaking or over-spraying specific areas. Adjust run times based on actual needs, not just a schedule.
  3. Proper Mowing Height:
    • Raise Mower Blade: Mow your lawn at the highest recommended height for your turfgrass type. Taller grass shades the soil, keeping it cooler and suppressing weed seed germination. It also makes it harder for low-growing weeds like dollarweed to get enough sunlight.
  4. Fertilize Appropriately:
    • A healthy, dense lawn is the best defense against weeds. Fertilize your turfgrass according to its specific needs to promote vigorous growth that can outcompete dollarweed. A soil test can help determine nutrient deficiencies.

Manual Removal

For small infestations or as a follow-up to other methods, manual removal can be effective, but requires persistence.

  • Digging: Due to its rhizomatous nature, simply pulling dollarweed will often leave behind roots or tubers that can re-sprout. For best results, use a weeding fork or trowel to dig out the entire plant, making sure to remove as much of the root system and any associated tubers as possible.
  • Consistency: Be diligent. Revisit the area regularly and remove any new growth as soon as it appears.

Chemical Control

For widespread or stubborn infestations, herbicides may be necessary. Always read and follow product labels carefully, including safety precautions and application rates.

  • Pre-Emergent Herbicides: These prevent weed seeds from germinating. While effective for some weeds, dollarweed primarily spreads by rhizomes and tubers, so pre-emergents are less effective against existing infestations. They can help with new plants from seed.
  • Post-Emergent Herbicides: These kill existing weeds.
    • Selective Herbicides: Choose a broadleaf weed killer that is safe for your specific type of lawn grass (e.g., those containing 2,4-D, MCPP, and dicamba). These chemicals are designed to kill broadleaf weeds without harming turfgrass.
    • Application: Apply when dollarweed is actively growing (usually spring or fall, when temperatures are moderate), and when no rain is expected for at least 24 hours. Multiple applications may be necessary, spaced according to product instructions.
    • Targeted Application: For small patches, spot treat with a ready-to-use spray. For larger areas, a hose-end sprayer or pump sprayer can be used.
    • Systemic vs. Contact: Systemic herbicides (like glyphosate in non-selective products) are absorbed by the plant and translocated to the roots, killing the entire plant. Contact herbicides only kill the parts they touch. For dollarweed, a systemic broadleaf herbicide is usually more effective due to its extensive root system.
    • Glyphosate (Non-selective): For areas where you want to kill all vegetation (e.g., bare patches, gravel areas), glyphosate can be used. Caution: It will kill your lawn grass and any other plant it touches. Use with extreme care.

Natural Methods for Dollarweed Control

For those who prefer to avoid synthetic chemicals, several natural approaches can aid in dollarweed control. These often work best as part of a comprehensive strategy that includes cultural practices.

  1. Boiling Water: For small, isolated patches in hardscapes (like cracks in driveways) or where you don’t mind killing surrounding plants, carefully pouring boiling water directly onto the dollarweed can scald and kill it. Repeat applications may be needed.
  2. Horticultural Vinegar (Acetic Acid): Concentrated horticultural vinegar (20% acetic acid or higher, much stronger than household vinegar) can act as a non-selective contact herbicide. It will burn the foliage on contact.
    • Caution: This is corrosive and can cause skin/eye irritation. Wear protective gear. It will kill any plant it touches, including turfgrass. It does not typically kill the roots, so re-applications will be necessary.
  3. Salt Spray: A solution of table salt and water can desiccate dollarweed. However, like horticultural vinegar, it’s non-selective and can harm turf. Moreover, excessive salt can build up in the soil and render it unsuitable for future plant growth for extended periods. Use with extreme caution and sparingly.
  4. Heavy Mulch/Smothering: In garden beds, a thick layer of cardboard followed by 10-15 cm (4-6 inches) of wood chips or other organic mulch can suppress dollarweed by blocking sunlight. This is a long-term strategy for garden beds, not typically for lawns.

Final Thoughts on Dollarweed

Dollarweed is a tenacious weed, but it’s not invincible. The key to successful control lies in understanding its preference for moisture and implementing a comprehensive strategy. Prioritizing improved drainage and adjusting watering habits are fundamental steps that will create an environment less appealing to dollarweed. Coupled with consistent manual removal and, if necessary, judicious use of appropriate herbicides, you can effectively manage and eventually eliminate this stubborn invader, allowing your desired turfgrass to flourish and your lawn to look its best. Patience and persistence are your greatest allies in the battle against dollarweed.