One of the surest indicators that spring has arrived is the appearance of two purple-colored plants along Tri-State roadsides: purple dead-nettle and henbit. Every year I get dozens of questions on these two attractive plants, which can either be considered wildflowers or weeds, depending on whose yard they are in.
Both of these plants have purplish flowers, and are in the mint family. Both plants are commonly found along roadsides and waste ground, although they are often seen in farm fields and gardens, creating immense carpets of purplish-red. Both plants are also cool-season annuals, meaning that they will germinate, bloom, produce seed and die during the late winter and early spring.
If you look closely at the plants, you can easily tell them apart. Henbit can be 4 to 16 inches tall. The leaves, as with all mints, are opposite each other on the stem. The leaves are bright green, scalloped and rounded, and clasp the stem without petioles. Pink to purple flowers are produced in the leaf axils along the upper several inches of stem.
Purple dead-nettle has crowded, heart-shaped leaves that tend to overlap. The upper leaves tend to be dark purplish in color, and are attached in an opposite pattern. The red or purplish flowers form a spike at the top of the plant. Purple dead-nettle can get about 4 to 12 inches tall.
Most folks are merely curious about the identity of these plants. However, every year I receive many calls from gardeners (and even farmers) who want to know how to get rid of these plants. Generally, I see no reason to label these early harbingers of spring as “weeds.” They aren’t hurting anything that I can see.
In order for a plant to be classified as a “pest,” we generally expect it to be causing some sort of problem in the garden. Maybe it’s competing with your garden plants for water, nutrients, or sunlight; maybe it’s physically injuring your plant (like honeysuckle strangling a young tree); or maybe the plant itself is dangerous (poison ivy).
Henbit and purple dead-nettle come under none of these categories. We generally have no crops in the garden when these plants appear, so they’re not competing for anything. They don’t physically injure the garden crops, nor are they themselves harmful to people or livestock. In fact, due to their need for cool weather, they usually dry up and die by the time the soil warms up enough to plant our crops.
I see no reason to spray or mow them. They will all too soon disappear for the season. My recommendation is to sit back and enjoy their beauty.
Speaking of recommendations: Starting this year, all retail stores that sell pesticides (including insecticides, herbicides, fungicides, and other products) may have to do things a little differently. If the store has employees that are expected to answer specific questions from customers on what product to use for a pest, or how much to use, then these employees must be registered pesticide consultants.
Stores that have registered pesticide consultants have registered with the Office of the Indiana State Chemist, and have provided training to their employees on the proper and safe usage of pesticides. The store will post a sign saying that they have registered pesticide consultants on staff to answer your pesticide questions.
If you have basic questions while you’re shopping, be sure to look for a registered pesticide consultant. If you have more detailed questions about pesticide usage and alternatives, contact the Purdue Extension Service at (812) 435-5287, or by e-mailing me at Larry.Caplan@ces.purdue.edu .
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