Pretty but Problematic: Flowers That Resemble Phlox

Phlox are iconic flowering perennials loved for their dense, colorful blooms However, some look-alike flowers actually aren’t phlox at all One in particular is an invasive plant that can threaten natural habitats. Learning to identify key differences helps avoid mistakes.

The Issue of Look-Alike Flowers

Garden phlox (Phlox paniculata) is a popular border plant grown for its fragrant clusters of flowers in white, pink, red, purple and more Its low-growing cousin, creeping phlox (P subulata), carpets the spring landscape in blue, purple, pink and bi-colored hues.

These garden favorites have long grown wild as well. Wild blue phlox (P. divaricata) can be found across eastern North America in shady forests and woodlands. Prairie phlox (P. pilosa) or wild sweet william displays fuzzy foliage and five-petaled blooms on the prairie.

Given phlox’s beauty, it’s no wonder similar flowers are welcomed by gardeners. But some phlox look-alikes aren’t as benign.

Dame’s Rocket – A Problematic Imposter

One of the most common phlox imposters is dame’s rocket (Hesperis matronalis). This plant may be less familiar by name but recognizable to many from its clusters of showy blooms in white, pink, and purple.

While visibly similar to phlox at first glance, dame’s rocket is not a phlox at all. It is actually a mustard native to Eurasia and was brought to North America as an ornamental garden plant.

This has proven problematic, as dame’s rocket readily escapes cultivated areas. It spreads aggressively and has naturalized across much of the U.S. and Canada. For this reason, many jurisdictions prohibit its sale and urge removal.

Identifying Dame’s Rocket vs Phlox Flowers

It’s easy to mistake dame’s rocket for phlox from a distance. A closer look reveals key differences to tell them apart:

• Petals – Phlox have 5 petals, dame’s rocket has 4
• Flower shape – Phlox are tubular, dame’s rocket are flatter
• Flower clusters – Phlox has open, loose arrangement, dame’s rocket has a dense spike
• Fragrance – Dame’s rocket has a sweet, strong scent unlike phlox
• Bloom time – Dame’s rocket peaks in late spring, phlox peaks in summer
• Plant shape – Dame’s rocket has alternate leaves on erect stems, phlox has opposite leaves

Learning these subtleties helps identify dame’s rocket properly. It’s much less welcome than phlox in natural areas, where it can overwhelm native wildflowers.

How Dame’s Rocket Spreads

Once established, dame’s rocket spreads readily by seeds. A single plant can produce thousands of seeds annually. These seeds germinate in disturbed areas, including gardens.

Wildlife, waterways, mowing, and other forces easily spread seeds beyond intended boundaries. Large monoculture stands often appear along roadways, ditches, and woodland edges.

Vigorous growth shades out and outcompetes native plants. Dame’s rocket grows rapidly in spring and early summer to overtake slower natives. It also releases allelopathic chemicals that suppress neighboring plants.

Controlling and Removing Dame’s Rocket

Eradicating dame’s rocket requires persistence. Hand pulling plants before seed set helps prevent spreading. However, removing root fragments left behind may lead to regrowth.

Mowing or string trimming won’t kill the plant but can prevent seeding if timed right before flowering. Always bag and dispose of cut material rather than composting.

For larger infestations, applying specific herbicides may be necessary. Glyphosate products can be effective when applied in early spring or fall. Follow directions carefully to avoid harming nearby native plants.

Repeating control measures for several years is key to getting dame’s rocket under control. The payoff is preserving habitat for valued native wildflowers like phlox species.

Enjoy Phlox – Avoid Dame’s Rocket

Garden phlox offers plenty of safe options to enjoy these summer-blooming perennials. Seek out native wild blue phlox and prairie phlox to appreciate in wild areas.

But resist the urge to plant dame’s rocket. Its aggressive nature creates issues down the road. By avoiding look-alikes and removing existing stands, gardeners can protect the habitat phlox naturally thrives within.