Invasives

My Least-Favorite Plants

One of my regular blog readers asked if there were any plants that I DON’T like. Well, yes, there are a few.

 

Cortaderia selloana - Pampas Grass

Pretty from a distance. Up close, the razor-sharp leaf edges slice one to shreds. When it is time for the fall cutback, get out the meat-handlers metal mesh gloves and protect all skin.

Pampas Grass

Houttuynia cordata ‘Tricolor’ - Chamaeleon Plant

This spawn of Satan will spread out of control almost immediately upon touching soil. The crushed leaves smell awful (other common names include Dog’s Breath). I volunteered to help a friend remove this from her garden. It involved lots of digging and multiple applications of herbicide. After three months of vigilance, we thought the battle was won. A few months later, we found a piece that has snaked its way under a nine-foot width of concrete to encroach on her lawn.

Chameleon Plant has another common name, “Dog’s Breath” to describe the odor of its crushed foliage.

 

Oenothera ‘Siskyou’ - Pink Evening Primrose

Impossible to eradicate. No matter how many times you pull it out, seedling pop up everywhere. When I worked in a garden center, customers would describe themselves as Plant Killers and ask for something un-killable. I blush to think of the number of times I placed one of these in their hands and assured them, “This plant will grow on a concrete block.” I hereby apologize to all you victims.

 

Pink Evening Primrose magically appears in unlikely places — like this roadside ditch alongside a highway.

Yucca

Needle-like points at the ends of the leaves draw blood when you swear you were at least ten feet away. I have mowed over these, dug out roots, sprayed herbicide, and done everything else in my gardener’s Box of Tricks to remove several of these that were planted by my husband’s grandmother. We finally moved. I expect to see a news item any day now where one popped through the concrete foundation of an apartment building that was erected above.

A flowering patch of Yucca, just waiting to draw blood.

 

Equisetum - Horsetail Rush

Prehistoric plant that should have died along with the dinosaurs. It is scratchy and coarse. Some gardeners find it attractive. To those, I say “keep it in a container” or you will be grubbing it out of your garden for the remainder of your life. It did not survive by being delicate.

Horsetail rush, a prehistoric survivor.

Vinca

Not an evil plant, but it spreads enthusiastically. Stems root wherever nodes touch soil. At my former home, a previous owner planted it against the foundation. At first, it concealed the brick under a lovely green screen, populated with blue flowers. It soon became a snake haven with the need for almost weekly trimming. This was one of the very few occasions in which I resorted to herbicide to eradicate a plant. I pulled all the dead stems and tossed them into the woods…where they came back to life and took over a half-acre while I was not watching. It is deer resistant.

"Perennial Ageratum" - Invasive Alert

When I moved into my first home, I begged for a start of “Perennial Ageratum” from my mother’s garden. She warned me to “be careful what you ask for” and said that the plants spread “like wildfire.” I assumed that the plant could not be THAT bad, since she had acquired her start from her own mother’s yard. Mistaken assumption.

Perennial Ageratum or Blue Mist Flower (Eupatorium colestinum or Conoclinium colestinum) resembles Ageratum, a well-behaved annual with fuzzy blue powder-puff blooms. Blue Mist is a hardy perennial that spreads aggressively via underground rhizomes and self-seeds. I. When driving through the countryside in September, I often spot it growing in ditches and near old home sites. It can be considered a weed because of its spreading tendencies.

The 24” tall plants will thrive in sun or shade (more blooms in sun), wet or dry, and any type of soil. They will tolerate either drought and soggy wet soils. They are not bothered by insects, disease or deer. Pollinators love them.

In late summer or early autumn, they erupt into a haze of soft blue flowers that look like asters from a distance. I cope with their invasive nature by planting them with other aggressive growers and allowing them to duke it out for ground space. A great combination is Blue Mist and Goldenrod (Solidago). These two bloom at the same time. Add ‘Autumn Joy’ sedum and accent with Mexican Salvia (Salvia leucantha) for a pretty fall combination.

Control the root spread of both Blue Mist and Goldenrod by planting them in plastic nursery pots with the bottoms removed, then sinking those pots into flower beds. Be sure that the top rim of the pots extend slightly above soil surface. This will prevent spreading via roots. Deadheading as soon a blooms fade will help control reseeding.

The photo shows that a tiny seedling can have an impressive root network underground.

Ageratum roots.jpg
Perennial Ageratum flower