Hairy bittercress (Cardamine hirsuta) is a one-of-a-kind lawn weed that is unmistakable once you know how to spot it in your lawn. This broadleaf weed spreads unique flowers and leaves across your landscape that harm your grass and plants by stealing nutrients from the soil, but that is not where the dangers stop. Come learn how dangerous hairy bittercress can be to your landscape and what you can do to stop it!
Hairy bittercress is a small and distinctive-looking weed that is commonly found in various habitats, including woodlands, gardens, and lawns. It is easily recognized by its basal rosette of leaves and upright stems that branch off in multiple places. The leaves are round or oval, and they alternate along the length of the stems. The leaflets are typically roundish and hairy, and the stalk may be somewhat hairy, but not always.
The plant is most easily recognized by its tiny white flowers that are about 2.5 to 5 mm long, with four petals that bloom in clusters near the top of the stems. These types of flowers are characteristic of the mustard family (Brassicaceae), to which hairy bittercress belongs. The plant also produces seed pods along the upper stems that are known to occasionally “shoot” out seeds in a flicking manner, which will spread the invasion across your property.
Key Characteristics
The life cycle of hairy bittercress is a testament to its adaptability and resilience. As a true winter annual, it germinates in the fall, establishing rosettes that persist through the colder months. With the arrival of spring, these plants grow rapidly and produce slender stems and their characteristic white flowers. The flowers give way to elongated seed pods that burst open, propelling seeds into the surrounding environment and starting the life cycle all over again. The breakdown below will provide a bit more information on each step in the life cycle of hairy bittercress.
Explosive seed dispersal is the best way to describe the method through which hairy bittercress spreads. The process is facilitated by the tension buildup within its elongated seed pods. Upon reaching maturity, these pods rupture at the slightest touch or disturbance, launching seeds up to several feet away from the original plant. A single plant can produce between 600 and 1,000 seeds, with each silique containing about 30 seeds.
Though seed dispersal is the main way hairy bittercress spreads, this weed is also capable of regenerating from broken stems or uprooted fragments. Hairy bittercress has fibrous, shallow roots that can be difficult to remove by hand. Attempting to pull up one of these plants often results in tiny bits of roots being left in the soil to regenerate.
Despite its small size (no more than 12 inches tall), hairy bittercress poses a significant threat to the health and aesthetics of landscapes. Dense infestations can outcompete desirable vegetation for essential resources, such as nutrients, water, and sunlight, resulting in thin, patchy lawns or garden beds. As mentioned above, the unique and explosive seed dispersal means that a single plant emerging on your property can quickly turn into a widespread infestation.
Hairy bittercress is also known to form dense mats in turfgrass as more and more plants begin to germinate and overtake the soil. For these reasons, timely and proper control of hairy bittercress is vital to the health of your lawn and landscape.
As we have discussed, controlling hairy bittercress can be difficult for a number of reasons. This tenacious weed grows quickly, bursts seeds across your property, and can remain viable in the soil with even the tiniest bit of plant matter or seeds. The best approach is to cultivate a lush and healthy lawn that can choke out bittercress seedlings, but this is easier said than done. Herbicides can be used to both prevent and control hairy bittercress after all options have been explored. The tips below will help ensure that your property stays free of hairy bittercress this season.
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