Weedy Grasses
Simply put, weeds are just “plants in the wrong place.” Whether they are welcome in the landscape depends on individual perspective. On the other hand, invasive plants are harmful to Florida’s ecology and should be managed accordingly. When maintaining your lawn, certain weedy grasses might pop up that don’t belong or even interfere with your target species. Below are a few grasses to be aware of.
Cogongrass
Cogongrass (Imperata cylindrica) is a prolific invasive grass prohibited in Florida. It has spread to every county in the state since its introduction in the 1930s. Cogongrass has even become a monoculture in some pastures, dominating the landscape as the sole occupant. This species will quickly displace desirable plants and is difficult to control. It spreads using its extensive creeping rhizome root system that can conserve water during long periods of drought. It also has wind-dispersed seed production that allows it to spread long distances. The seed head is fluffy and white, while the leaf blades tend to be yellow to green. Infestations often occur in circular patches. Cogongrass is easier to treat when caught early on. Certain herbicides used in addition to integrated management techniques can prevent spreading.
Wavyleaf Basketgrass
Wavyleaf basketgrass (Oplismenus undulatifolius) is a perennial grass that has become a problem species in the Southeast. It grows along the ground in shady areas, outcompeting many turfgrass species. It requires very little water and nutrients, which allows it to spread to areas where other plants may not be able to survive. Wavyleaf basketgrass forms dense mats that prevent the growth of native trees and understory species. It can be identified by its wavy leaves and sticky seeds. The seeds adhere to clothes, boots, and animals, establishing themselves in other areas where they fall. The sticky parts of the plant can even become irritants for pets if they come into contact with their skin, paws, or eyes. The best method of control is prevention; keeping a thick, healthy lawn and planting shade-tolerant turfgrass can keep wavyleaf basketgrass at bay. You can also manually pull up the plants with their roots, which are shallow and easy to remove.
Torpedograss
Torpedograss (Panicum repens) is an incredibly invasive species in Florida and is documented as such by the UF/IFAS Assessment of Non-Native Plants. It negatively alters native plant communities, outcompeting other species with its prolific growth. Its creeping rhizomes spread into gardens, lawns, and landscape planting beds, growing upwards of 20 feet long. The rhizomes are so strong that they can even penetrate wood and asphalt. Torpedograss can also expand its range via stem fragments, which form new plants. This makes management difficult—manual removal often leads to cuttings being distributed in the soil, leading to more new growth. But in smaller areas where the infestation is confined, turning and breaking up the soil might be successful. Prevention is key, and maintaining a healthy ecosystem with native species can help. Lawns that are affected by disease or pests are more at risk of weed establishment.
Crabgrass
There are many species of crabgrass in Florida, including India crabgrass (Digitaria longiflora), blanket crabgrass (Digitaria serotina), southern crabgrass (Digitaria ciliaris), and large crabgrass (Digitaria sanguinalis). These grasses all act as weedy, intrusive plants. Crabgrass is difficult to manage because of its ability to produce thousands of seeds from a single plant. This grass is a summer annual that can’t take the cold, leaving an infested lawn with brown patches during winter. But unfortunately for you, it comes back in the spring from leftover seed. In southern regions, crabgrass can sometimes persist as a short-lived perennial. It’s important to choose the right plant for the right place and maintain thick, healthy turfgrass through proper maintenance. This will keep the lawn relatively resistant to crabgrass and other weeds. Pre-emergent herbicides are recommended as well.
Southern Sandbur
Southern sandbur (Cenchrus echinatus) is known for its spiny seedheads that become a nuisance when hitching a ride on clothes, shoes or skin. Each bur contains 1-3 seeds, and their ability to cling to surfaces allows them to disperse easily. Southern sandbur is a grass that thrives in warm areas of the South and is well adapted to dry, sandy soils. While native, it is considered a weed in pastures and gardens. The key to prevent establishment is to keep your lawn healthy with proper fertilization, irrigation and mowing (at the correct height and frequency). As an annual, it will die off in winter, but to prevent reemergence in spring from seeds, you can drag a carpet, cloth or blanket through the contaminated area to capture the burs. Pre-emergence herbicide can also be used.