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Carolina Geranium

Carolina geranium (Geranium carolinianum) is a branching winter annual or biennial with long hairy stems that range from green to red. Leaves are hairy on both surfaces with various divided sections and bluntly toothed margins. The fibrous root system has a shallow taproot, and the plant usually has a maximum height under 12 inches. The flowers of Carolina geranium are found at the tips of stems and vary from white to pink with five petals. The seeds have a distinctive elongated beak which gives the plant its nickname, cranesbill.

Carolina geranium is found throughout South Carolina and commonly occurs in lawns, landscape beds, fields, and roadsides that receive minimal maintenance, as well as areas with poor, dry soils.

Carolina geranium (Geranium carolinianum) stems range from red to green, and the plant has a shallow taproot. Adam Gore, ©2019, Clemson Extension

Carolina geranium (Geranium carolinianum) stems range from red to green, and the plant has a shallow taproot.
Adam Gore, ©2019, Clemson Extension

The heavily dissected leaves of Carolina geranium (Geranium carolinianum) make it easy to recognize from other plant species. Adam Gore, ©2019, Clemson Extension

The heavily dissected leaves of Carolina geranium (Geranium carolinianum) make it easy to recognize from other plant species.
Adam Gore, ©2019, Clemson Extension

Cultural Control

To reduce the occurrence of Carolina geranium in lawns, maintain a healthy stand of turfgrass with proper fertilization, irrigation, and mowing practices. Due to the shallow taproot, Carolina geranium is easily pulled out. For more information on turfgrass maintenance, refer to HGIC 1216, Bermudagrass Yearly Maintenance Program; HGIC 1215, Centipedegrass Yearly Maintenance Program; HGIC 1217, Zoysiagrass Yearly Maintenance Program; HGIC 1218, St. Augustinegrass Yearly Maintenance Program; and HGIC 1219, Tall Fescue Maintenance Calendar.

Chemical Control in Lawns

Before using any pesticide, be sure to read and follow all label directions. The label will specify any protective clothing, if necessary, which should be worn during herbicide mixing and application.

Several 3-way herbicides containing 2,4-D, mecoprop (MCPP), and dicamba are available to homeowners for post-emergent control of Carolina geranium. These products may also contain carfentrazone or sulfentrazone. Applications can be made at any time throughout the life cycle, but for best control, applications should be made at the seedling or immature stage to prevent seed development.

These products can be used to spot treat Carolina geranium in tall fescue, bermudagrass, and zoysiagrass lawns. Lawns containing centipedegrass or St. Augustinegrass may need reduced herbicide rates, which will be stated on the product label. Injury to centipedegrass and St. Augustinegrass may occur if these products are applied during the turfgrass spring green-up, i.e., the transition period between dormancy and active growth in spring, or if applied during excessively hot (>90 F) and dry weather during the summer. See Table 1 below for products.

Herbicide products containing atrazine can be used on centipedegrass and St. Augustinegrass for both pre-and post-emergent control. Rainfall or irrigation within 2 or 3 days following application may decrease the effectiveness on existing weeds. However, to prevent weed seed germination, rainfall or watering is necessary within 7-10 days of treatment to carry the herbicide into the soil, as atrazine products are absorbed by seedling roots. Do not apply atrazine in areas with a high water table or within two times the width of the drip line of desirable hardwood trees and shrubs. See Table 1 below for products.

The use of various pre-emergent herbicides can prevent the germination and emergence of Carolina geranium in lawns. To prevent seed germination, pre-emergent herbicides are applied in early fall and repeated 8 to 10 weeks later. Granular pre-emergent herbicides must be watered into the soil with ½ inch of irrigation or rainfall. Choose a pre-emergent herbicide that containing isoxaben or dithiopyr to prevent seed germination of Carolina geranium. See Table 2 below.

Note that broadleaf, post-emergent herbicides have the potential to harm desirable landscape plants. To avoid damage do not allow spray to contact desirable plants or their root zones. Avoid applications during windy conditions. Keep the sprayer nozzle close to the ground, adjust the nozzle tip for a coarse spray, and use a nozzle hood to prevent off-target damage. For more information on avoiding and identifying herbicide damage to landscape plants, please see HGIC 2349, Herbicide Damage to Landscape Plants.

Table 1. Examples of Post-emergent Herbicides for Control of Carolina Geranium in Turfgrass.

Product Brands Active Ingredient % Active Ingredient Labeled for Use on Listed Turfgrass Species
Southern Ag Lawn Weed Killer with Trimec Concentrate 2,4-D 3.05 Bermudagrass
Centipedegrass
St. Augustinegrass
Tall Fescue
ZoysiagrassLowered label rate for use on:
Centipedegrass
St. Augustinegrass
Mecoprop 5.30
Dicamba 1.29
Ferti-lome Weed-Out Lawn Weed Killer with Trimec Concentrate 2,4-D 5.88
Mecoprop 5.45
Dicamba 1.21
Bayer BioAdvanced Southern Weed Killer for Lawns Conc.; & RTS1 2,4-D 7.59
Mecoprop 1.83
Dicamba 0.84
Bayer BioAdvanced Southern Weed Killer for Lawns RTU2 2,4-D

Mecoprop

Dicamba

0.311
0.075
0.034
Ferti-lome Weed Free Zone Concentrate; & RTS1 2,4-D 10.49
Mecoprop 2.66
Dicamba 0.67
Carfentrazone 0.54
Gordon’s Trimec Ready to Spray Lawn Weed Killer Concentrate; & RTS1 2,4-D 5.56
Mecoprop 1.34
Dicamba 0.62
Ortho Weed-B-Gon Lawn Weed Killer Conc.; & RTS1 2,4-D 8.658
Mecoprop 2.127
Dicamba 0.371
Ortho WeedClear Weed Killer for Lawns Concentrate 2,4-D 8.658
MCPP 2.217
Dicamba 0.371
Spectracide Weed Stop for Lawns Concentrate; & RTS1 2,4-D 7.59
Mecoprop 1.83
Dicamba 0.84
Spectracide Weed Stop for Lawns RTU2 2,4-D 0.593
Mecoprop 0.144
Dicamba 0.066
Bonide Weed Beater Plus RTS1 2,4-D 6.42 Bermudagrass4
Ryegrass
Tall Fescue
Zoysiagrass
Quinclorac 2.13
Dicamba 0.60
Bonide Weed Beater Plus RTU2 3 2,4-D 0.313
Quinclorac 0.104
Dicamba 0.029
Ortho Weed-B-Gon Lawn Weed Killer Plus Crabgrass Control Conc.; & RTS1 2,4-D 6.42
Quinclorac 2.13
Dicamba 0.60
Hi-Yield Atrazine Weed Killer Atrazine 4.00 Centipedegrass
St. Augustinegrass
Southern Ag Atrazine St Augustine Weed Killer Atrazine 4.00
1RTS= Ready to Spray; hose-end spray bottle
2RTU= Ready to Use; pre-mixed spray bottle
3Labeled for spot treatments
4Products containing quinclorac may temporarily yellow bermudagrass lawns.

Table 2. Examples of Pre-emergent Herbicides for Control of Carolina Geranium in Turfgrass.

Product Brands Active Ingredient % Active Ingredient Labeled for Use on Listed Turfgrass Species
Ferti-lome Broadleaf Weed Control with Gallery Isoxaben 0.38 Bermudagrass
Centipedegrass
St. Augustinegrass
Tall Fescue
Zoysiagrass
Vigoro Crabgrass & Weed Preventer Dithiopyr 0.17
Hi-Yield Turf & Ornamental Weed & Grass Stopper containing Dimension Granules Dithiopyr 0.125
Sta-Green Crab-Ex Crabgrass & Weed Preventer Granules Dithiopyr 0.17
Bonide DuraTurf Crabgrass & Weed preventer Dithiopyr 0.27

Control in Landscape Beds

In landscape beds, a 2- to 3-inch mulch layer can suppress many weeds from germinating, including Carolina geranium. Mulch also greatly benefits landscape beds. For more information about the benefits of mulching, see HGIC 1604, Mulch. A pre-emergent herbicide containing dithiopyr (Dimension) or isoxaben (Gallery) can be used in landscape beds; however, the application of a pre-emergent may affect the rooting of landscape plants and subsequent plantings, so it is important to read the label for its use around specific landscape plants. See Table 3 below for products labeled for use in landscape beds.

Hand-pulling of Carolina geranium is effective due to its shallow taproot; however, be sure to remove the plant before it goes to seed to prevent further spread. If necessary, the use of an herbicide containing glyphosate is effective and will have less soil activity to affect nearby landscape plants, as compared to 3-way herbicides and atrazine.

Table 3. Examples of Pre-emergent Herbicides for Control of Carolina Geranium in Landscape Beds.

Product Brands Active Ingredient % Active Ingredient
Ferti-lome Broadleaf Weed Control with Gallery Isoxaben 0.38
Snapshot 2.5TG Isoxaben
Trifluralin
2.0
0.5
Bonide DuraTurf Crabgrass & Weed Preventer for Lawns & Ornamental Beds Dithiopyr 0.27
Vigoro Crabgrass & Weed Preventer Dithiopyr 0.17
Hi-Yield Turf & Ornamental Weed & Grass Stopper containing Dimension Granules Dithiopyr 0.125
Pre-emergent herbicides are for use around established landscape plants.

They may inhibit the rooting of newly installed plants, especially bedding plants and perennials. Do not incorporate herbicide into the soil. Check the product label for tolerant landscape species. Hose off any herbicide granules from landscape plants after application, and then water the herbicide into the soil.

If this document didn’t answer your questions, please contact HGIC at hgic@clemson.edu or 1-888-656-9988.

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