Garden phlox (Phlox paniculata) is a popular perennial plant grown for its summer-blooming flowers that come in a variety of colors. But you may spot some lookalike weeds invading your garden or landscape that resemble phlox. Chances are it’s an invasive plant called dame’s rocket.
Dame’s rocket (Hesperis matronalis) is a biennial or short-lived perennial that has become highly invasive throughout parts of North America. Though it resembles phlox with its purple to white flowers, dame’s rocket can aggressively take over gardens and natural areas.
Read on to learn how to identify dame’s rocket weed, how it spreads, and tips for controlling it.
How to Identify Dame’s Rocket Weed
At first glance, dame’s rocket looks a lot like phlox. But there are a few key differences
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Flowers – Dame’s rocket has 4-petaled flowers, while phlox has 5-petaled flowers.
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Bloom time – Dame’s rocket blooms in late spring, while phlox blooms in summer to early fall.
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Color – Dame’s rocket flowers can be white, pink, or purple. Garden phlox is typically purple, pink, red, or white.
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Height – Dame’s rocket grows 2-4 feet tall. Garden phlox is shorter, reaching 1-2 feet.
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Leaves – Dame’s rocket leaves are alternate, lance-shaped and toothed. Phlox leaves are opposite, oval, and smooth edged.
Once you know what to look for, it’s easy to distinguish these aggressive weeds from garden phlox.
Where Does Dame’s Rocket Weed Come From?
Dame’s rocket is native to Europe and parts of Asia. It was introduced to North America as an ornamental garden plant and is still sold in some areas as an ornamental.
It has escaped backyards and now grows aggressively across much of the United States and Canada. Dame’s rocket grows in a variety of conditions and habitats, including:
- Gardens, fields, and landscaped areas
- Roadsides and ditches
- Open woodlands, forests, and prairies
The plant is classified as invasive in some areas including the Midwestern and Northeastern US. It’s illegal to buy, sell, or propagate dame’s rocket in some states.
How Does Dame’s Rocket Spread?
This aggressive weed spreads easily and grows rapidly under the right conditions. Here’s how it proliferates:
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Prolific reseeding – Each plant produces thousands of seeds that scatter up to 16 feet away. Seeds remain viable in soil for many years.
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Self-sowing – Dame’s rocket drops seeds as the plant dies back in summer, leading to new plants sprouting the following spring.
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Root fragmentation – Broken root segments left in soil can resprout into new plants.
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Wind dispersal – Seeds float on the wind and spread to new areas.
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Animal dispersal – Seeds cling to animal fur and are carried to new locations.
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Human dispersal – Humans spread dame’s rocket by planting it or inadvertently dispersing seeds.
Tips for Removing and Controlling Dame’s Rocket Weed
Eradicating dame’s rocket takes patience and persistence. Here are some effective control methods:
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Hand pull – Pull plants in early spring before seed set. Remove as much root as possible. Dispose of plants in trash, not compost.
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Mow/cut – Mowing can prevent seed production but must be repeated multiple times per season. Don’t mow when seeds are present.
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Cultural methods – Maintaining healthy native vegetation can help prevent dame’s rocket invasion.
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Herbicides – Apply systemic herbicides like glyphosate to foliage in spring and fall. Use caution around desirable plants.
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Burning – Prescribed burns in spring may control infestations. Follow up with herbicide.
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Replant with natives – Replant areas where dame’s rocket was removed with competitive native grasses and wildflowers.
Controlling dame’s rocket requires a multi-year effort. Monitoring areas and quickly removing new sprouts is key to preventing reinfestation.
How to Tell Dame’s Rocket Apart From Native Phlox Species
In addition to garden phlox, dame’s rocket is sometimes confused with similar native phlox species like:
Wild Blue Phlox
Wild blue phlox (Phlox divaricata) is native to eastern North America. Here’s how it differs from dame’s rocket:
- Native wildflower that blooms April-May
- Flowers have 5 petals (not 4 like dame’s rocket)
- Grows to 1 ft. tall (shorter than dame’s rocket)
- Naturalizes in open woodlands (not aggressive)
Garden Phlox
Garden phlox (Phlox paniculata) is another popular garden perennial native to the eastern US. It differs from dame’s rocket in:
- Blooms July-September (not early summer like dame’s rocket)
- 5-petaled flowers (not 4 petals)
- Grows 1-2 ft. tall
- Doesn’t spread aggressively
Once you learn how to spot the differences, it’s easy to distinguish between dame’s rocket weed and similar native phlox species. Keep an eye out for 4-petaled flowers blooming early summer to identify infestations of this invasive plant.
How to Keep Dame’s Rocket Out of Your Garden
Here are some tips to prevent dame’s rocket from invading your garden in the first place:
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Learn to identify dame’s rocket weed so you can recognize it if it appears.
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Inspect new plants thoroughly before bringing home. Dame’s rocket is still sold by some nurseries.
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Ask for native plant alternatives to dame’s rocket at garden centers.
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Monitor your property boundaries for invasion from nearby infestations.
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Remove dame’s rocket immediately if spotted and dispose of properly.
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Maintain healthy soil and plant mostly native species, which compete better against invasives.
Keeping a lookout for the early signs of dame’s rocket weed will help you nip invasion in the bud. Protect your gardens and native landscapes by identifying and swiftly removing this aggressive plant.
Weed or Wildflower? Spring Weeds that Look Like Native Plants
Not everything that pops up in the yard is a weed. Native wildflowers and other desired plants also can readily spread and sprout. And because some of them look like common weeds, you should know the difference between them before you pull them out.
Killing native look-alikes by mistaking them for weeds can be detrimental to the ecosystem. Many native plants provide pollen for pollinators that are in short supply, food for native butterfly caterpillars, and natural, free soil coverings that keep the soil from washing away.
Also, getting rid of the wrong plants wastes time, money, effort, and herbicides without a reason.
How to tell the difference?
People often mix up weeds and nice plants because their flowers look the same, bloom at the same time, or bloom in the same color. A closer look usually fleshes out the difference.
For example, a weed flower might be a little different in shape from a wildflower that looks like it, or it might have a different number of petals, or the flowers on the stems might be set up in a different way. The flowers on some plants are so different that they can be told apart right away, even if the leaves and plant habit look very much the same. Just be sure to eliminate a weed before its seeds have a chance to mature and drop.
A second identifier is plant leaves. One plant may have larger, wider leaves while the other may have narrower or even needle-like foliage. Or, one plant’s stems might have leaves that face each other, while the other plant’s stems might have leaves that go up and down in a different order. Or one plant’s leaf edges might be smooth while the other’s might be “toothy” or jagged.
Other determining clues include the plant’s growth habit (spreading, bushy, upright), where the plant is growing (sun vs. shade, wet vs. dry, disturbed vs. soil that hasn’t been disturbed), how quickly or aggressively a plant is growing, and what the plant looks like below ground (roots, runners, or bulblets).
Here are six common spring weeds and how to tell them apart from similar native plants:
Creeping charlie (Glechoma hederacea) vs. golden ragwort (Packera aurea). These two ground-huggers have similar heart-shaped foliage, but the flowers quickly differentiate them.
The weedy creeping charlie produces close-to-the-stem lavender flowers while the native golden ragwort produces golden daisy-like flowers.
The edges of creeping charlie leaves are scalloped, and the plant smells like mint when you crush it. The leaves of golden ragwort are toothed.
Lesser celandine (Ranunculus ficaria) vs. marsh marigold (Caltha palustris). Both of these flower yellow in early spring, grow in moist habitats, and have similar heart-shaped leaves.
The tell-tale difference is that when you dig up lesser celandine (an invasive in more than 20 U. S. states) you’ll find cream-colored bulblets and roots with finger-like tubers. Native marsh marigolds have no bulblets and fibrous roots.
Lesser celandine also is sometimes confused with native wood poppies. The distinction is the yellowish-orange sap that comes out of wood-poppy stems.
Garlic mustard (Alliaria petiolata) vs. cut-leaved toothwort (Cardamine concatenata). Both of these produce clusters of small white flowers in spring. The weedy garlic mustard has triangular, wrinkled leaves that smell like garlic when they are crushed. Native cut-leaved toothwort has narrower leaves and no garlic odor.
Giant hogweed (Heracleum mantegazzianum) vs. cow parsnip (Heracleum maximum). These are both big carrot-like plants with toothy leaves that bloom with umbrella-shaped white flowers in the middle to late spring. The native cow parsnip doesn’t have purple spots on its stems like the weedy giant hogweed does. The giant hogweed is also much bigger and has fuller flower clusters than the cow parsnip. The leaves of giant hogweed can be five feet long and have deeply cut lobes. It can grow to be 14 feet tall. Its leaves are half the size of giant hogweed’s and have more rounded lobes. Cow parsnip grows to be about 7 feet tall.
Giant hogweed is a hazardous, federally listed noxious weed. Its sap contains phototoxic chemicals. If the sap touches your skin and then is exposed to sunlight, it can irritate your skin badly, leaving behind painful, burning blisters and scars that last a long time. If you get the plant on your skin, wash it with soap and water right away and keep it out of the sun for 48 hours. This plant can also displace native plants. Native cow parsnip is less toxic, but it can still cause a rash or burn. Use caution around either plant.
Star of Bethlehem (Ornithogalum umbellatum) vs. wood anemone (Anemone quinquefolia). Both of these produce star-shaped white flowers in early to mid-spring. One big difference is that native wood anemones have wider leaves with toothy edges than weedy star of Bethlehem, whose leaves are narrow and grass-like.
Creeping speedwell (Veronica filiformis) vs. woodland phlox (Phlox divaricata). Both of these are short, spreading perennials with blue flowers in April and May. Weedy creeping speedwell grows in a creeping way and has round leaves that alternate up its stems. On the other hand, native woodland phlox (also called creeping phlox and blue phlox) grows in a clump-like way and has narrower leaves that are opposite each other on the stems.
Read how to control and prevent different kinds of weeds.
Confusing Garden Look-alike: Dame’s Rocket | Outdoor Elements
FAQ
What is the invasive flower that looks like phlox?
What plant is similar to phlox?
How to tell dame’s rocket from phlox?
What is the difference between phlox and Hesperis?
Is Phlox a weed?
Unfortunately, it’s easy to mistake phlox for a deceiving invasive weed called dame’s rocket (Hesperis matronalis). Still, there’s a good reason gardeners are so enthusiastic about phlox — it’s not just beautiful and fragrant; it’s also, with few exceptions, native to North America.
Do creeping phlox weed?
Once established, ground covers like creeping phlox begin suppressing weeds by giving them no space to grow – essentially crowding them out. Try weeding before planting your creeping phlox during the spring or fall – this should help with suppression and keep weeds at bay next bloom.
What do Phlox leaves look like?
The leaves are lance-shaped with pointed tips. Prairie phlox leaves are hairy (Figure 7) while wild blue phlox has smooth leaves (Figure 8). In contrast, dame’s rocket has alternate leaves (Figure 9), which means that the leaves grow singly along the stem, alternating sides.
Is there a Phlox look-a-like?
There is, however, a non-native look-a-like that people often confuse with phlox. This look-alike, called dame’s rocket ( Hesperis matronalis, Figure 3) is a mustard native to Eurasia and was introduced to North America during European settlement in the 1600s, and it has now become established in many parts of the northern United States and Canada.
How many petals does a Phlox have?
While the flowers have similar colors and shapes, phlox always has five petals, as opposed to dame’s rocket, which has only four. What time of year the flowers appear can also offer a clue, as dame’s rocket flowers usually bloom in early summer, as opposed to phlox, which generally blooms later. Additionally, you can check the plant’s leaves.
How do you identify a phlox plant?
To identify phlox ( Phlox spp.), look for tight bunches of five-petaled flowers that come in almost every color. Some varieties have hairy leaves, while others are smooth. Those lance-shaped leaves grow opposite each other in pairs on the stem. Phlox grows in Zone 3 or Zone 4 to 9, depending on the specific variety.