Some Like it Hot: Invasive Species to Focus on in the Summer

As the year marches on and we begin to move on from the Spring rainy season in Hamilton County to the hotter and drier Summer many of our invasive species have been hard at work growing and preparing to release seed for the next year.  May and June are incredibly important for managing these invasives, especially our invasive grasses and other herbaceous plants. The good news is that targeted action now can dramatically reduce their spread and make long-term management achievable.
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One of the primary groups to focus on this time of year is invasive grasses. Species like Cattail, Common Reed, and Reed Canarygrass thrive in the warm, humid conditions of early and mid – summer. These grasses all thrive in aquatic areas and can easily be found ringing our retention ponds, in drainage ditches, along rivers and creeks, around Geist and Morse Reservoir, and a wide variety of other aquatic environments. 

Cattail: More Info

Common Reed: More info

Reed Canarygrass: More info

Other herbaceous invasive species (herbaceous refers to anything that does not have woody stems.) to look out for in the summer include Poison Hemlock, Canada Thistle, and Teasel. These plants are aggressive and sweep through prairies, wood lines, and even our lawns and neighborhood common areas. Left unmanaged, they can quickly form dense stands that crowd out native vegetation, reducing habitat quality for pollinators and wildlife. Many of these species also produce abundant seed or spread through underground root systems, making early detection and control especially important to prevent long-term infestations. 

Canada Thistle: More Info

Poison Hemlock: More Info

Teasel: More Info

For HOAs, homeowners, and land managers timing and technique are essential. Mechanical control methods such as mowing before flower and seed production can help keep these infestations from spreading. Over time, repetitive mowing throughout the season may even exhaust the plant’s root system and kill it. For larger infestations, areas where mowers cannot go, or for more aggressive control, herbicide application may be the most practical option.  As always, follow the label requirements – an important thing to look for with many of these species is an herbicide that is rated for aquatic purposes to reduce the likelihood of negative effects on our ponds, rivers, and streams.
 
With any invasive species control, but especially grasses and herbaceous plants, consistency is key. A single season of control will not eliminate the plants, but repeated efforts year after year will steadily reduce their presence and provide space for our native plants to take hold. Monitoring treated areas later in the summer and into the fall can help catch regrowth or late bloomers and aid in strategizing for next year’s maintenance.

And finally, don’t overlook the importance of restoration. Many of these herbaceous plants grow in thick stands that, once removed, will leave a bare spot that may need to be filled with beneficial plants or else invasive species will move right back in. Healthy, diverse plant communities are one of the best defenses against future invasions. 

A healthy and diverse native planting is the best defense against invasive species!