Cinquefoil in Pennsylvania Gardens

To weed or not to weed—that is the question. It is often difficult to determine what a weed is and what is a desirable plant or flower. When I began gardening, an experienced neighbor told me that a weed is only a plant growing in a spot where you don't want it. Although homey advice, some plants interfere with the garden and the ecosystem to such an extent they become invasive and need to be controlled or eradicated. Some varieties of cinquefoil fall into this category.

There are over 300 species of cinquefoil (Potentilla spp.), and they are primarily perennials, although some are annuals or shrubs. As a genus, they belong to the rose (Rosaceae) family. Most species' leaves have five to seven leaflets. Interestingly, the common name, cinquefoil, is derived from the Old French word, cinqfoil, meaning five (cinq) and leaf (foil).

Common Cinquefoil

Common cinquefoil (Potentilla simplex) is a native North American perennial with numerous yellow flowers and medium to light green leaves that blooms from May to July and grows to a height of 4 to 6 inches. It prefers sun to part shade and thrives in low-fertility soil. Besides your flower beds, they can be found in open woods, fields, and meadows.

It is often initially difficult to recognize it as a weed because it resembles several varieties of strawberry, including wild and mock strawberries. The plants are differentiated by looking at their leaf structure. Common cinquefoil has five palmately compound leaflets, while strawberry plants have a three-leaflet structure.

Common cinquefoil has a long, persistent tap root and spreads through stolons (runners), which re-root and create new plants. This results in densely matted patches, which may create a problem in the garden as they easily overrun and displace the more desirable plants.

Sulfur Cinquefoil

Sulfur cinquefoil (Potentilla recta) is a perennial native to Eurasia and was accidentally introduced to North America in the late 1800s. Sulfur yellow flowers bloom in clusters on the ends of rough and hairy stems from May to August. Its leaves are also rough and hairy with five to seven palmate leaflets. Growing in full sun to part shade, it reaches a height of 1–2.5 feet with a 1- to 2-foot spread.

It can be mistaken for the native slender cinquefoil (Potentilla gracilis). Slender cinquefoil can be distinguished by darker yellow flower petals, a silver tint to the leaves' underside, and hairs perpendicular to the stem.

Because sulfur cinquefoil thrives in low-fertility soil conditions and is drought-tolerant, it is robust, and its seeds spread quickly. Its habitat includes fields, meadows, rangelands, and any disturbed open areas. Since it is unpalatable to livestock and wildlife, it spreads unchecked and is considered invasive as it can displace both native and non-native plants. It is of considerable concern to farmers and ranchers because it damages valuable pasture land.

Control and Eradication

Small clusters of cinquefoil plants can be effectively pulled by hand or dug with a hand tool, taking care to remove the whole root system. Clasp the base of the stem close to the ground when pulling to provide greater leverage. It is often helpful to do this when the soil is damp and loose, making accessing the plant's root system easier. Its long, persistent tap roots can make common cinquefoil a challenge to remove, so care must be taken to remove all the tap roots, or the plant will re-establish. Larger clusters may require the use of a garden spade or fork to effectively clear the area and multiple sessions to ensure total eradication.

An herbicide can be used, but care must be taken to avoid spray drift that will kill nearby plants. Always carefully follow the label directions when using any type of herbicide. Keep in mind that some herbicides cannot be used near vegetables or edible plants. For additional information regarding herbicide use, contact your local extension office.

It is always best to get control of invasives in the garden before they have a chance to take hold and take over. Be vigilant in reviewing your gardens and nipping small problems in the bud.