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Plants that won’t stay in their lane

Peggy Singlemann
Once fennel is through blooming I remove the spent blossom heads to prevent reseeding. I allow only a few to go to seed for harvesting.

With the garden in the grip of the winter, I think these cold months are the best time to dream about the perfect garden. Whether surfing garden websites or flipping the pages of catalogs, it is easy to get mentally pulled into what is new and unusual! I love the colorful photos and alluring descriptions; they do their job and quickly make me think of lofty ideas for the coming season’s gardens.

While garden dreaming is a wonderful winter pastime, dreams are also easily shattered. This happens when I come upon a page with a beautiful flowering plant that I once blissfully added to a border — only to spend the next few years trying to eradicate it. The memory jars me back to reality, and I quickly move on to another page. I have a mental list of these plants and top of the list is sea oats (Uniola paniculata). This native grass is perfect for conserving sand dunes along the coast because of its tenacious roots, along with drought and salt tolerance.

However, while the aggressive reseeding nature of this native plant makes it perfect for conservation of dunes, it does not make it perfect for the border. Sea oats will take over the garden quickly. The problem is when weeding out the seedlings, each small plant easily snaps off at its crown. This means only the green upper portion of the plant is pulled off, leaving those tenacious roots to resprout. To remove the thousands of seedlings and their roots, I had to scrape the surface of the soil using the side of my hori hori knife. I then disposed of the scraped-off soil offsite for fear of a single root resprouting elsewhere. This is the type of memory gardening nightmares are made of!

Another perennial which quickly seeds itself throughout the border is common fennel (Foeniculum vulgaris). The seeds of this popular herb should be harvested each year unfailingly. Doing so will prevent the border from becoming a huge fennel bed due to rampant reseeding. Common fennel is a member of the carrot family and has long, deep growing roots. The exception is Florence fennel (Foeniculum vulgaris var. azoricum), which forms an edible bulb that I find delicious when roasted. Regardless, those seeds are perfect for flavoring, not so for the garden.

Some of the most beautiful annual bedding plants can also be self-seeders. These plants are often described as “readily self-seeding” and “proficient self-seeders.” When you read these phrases in a plant description quickly turn the page or scroll down the screen! In the past I ignored these phrases — and paid for that decision.

Plants that I have regretted growing years after the initial planting include the herb, borage (Borage officinalis). Other annuals I spent years removing from the border are spider flower (Cleome hassleriana), larkspur (Consolidago ajacis), butter daisy (Melampodium divaricatum) and four o’clock (Mirabilis jalapa). These sun-loving plants thrive in dry conditions, but don’t stay in their lanes because they reseed everywhere!

Peggy Singlemann
Melampodium will reseed in a border so I planted it in a large container.

There are a few perennial plants that don’t stay in their lanes either. While a few reseed themselves, most of the perennial herbaceous plants I avoid planting in a border spread rapidly by underground rhizomes. Top of the list is the yellow flowering, grass-leaved goldenrod (Euthamia graminifolia). This late summer blooming plant attracts numerous pollinators, and the tight growing cluster of stems create shelter for birds in the winter. However, it is difficult to keep under control, so I recently moved it to the meadow where the roots can run in any direction.

A plant restricted to a container in my garden is mint. The aggressively growing roots of Lemon mint (Mentha x piperita f. spicata), peppermint (Mentha piperita) and spearmint (Mentha spicata) wreak havoc when planted in the border. Other fast-spreading perennial plants that do the same are wormwood (Artemisia ludoviciana), and lilyturf or monkey grass (Liriope spicata). Both of these plants are easily confused with other species. Silver leaved wormwood is typically confused with mugwort (Artemisia vulgaris), which has a green leaf with a silver underside. Liriope spicata is often confused with Liriope muscari because these plants are often referred to by the same common name. The difference is L. spicata has white flowers and the grass-like foliaged plant rapidly forms colonies due to underground rhizomes, while the purple flowers of L. muscari are borne atop tight clumps of the grass-like foliage. To keep the differences straight it is wise to learn their botanical names, because gray vs. green leaves or running vs. clumping growth habits make a huge difference when planning a garden.

Aggressive plants can be forced to stay in their lane by placing them in a large container.

Another plant that runs across the garden is creeping jenny (Lysimachia nummularia). The golden leafed form, Lysimachia nummularia ‘Aurea’ is equally as aggressive. This plant doesn’t know what a lane is — never mind staying in one. I inherited a small piece of creeping jenny through a friend and thought it was worth keeping. Unfortunately, that little piece now covers most of my border and has choked out a few of the more delicate plants along the way. Like other plants that won’t stay in their lane, constantly removing the newly sprouted areas of creeping jenny becomes tiresome.

Creeping Jenny carpets a border to the extent it chokes out delicate plants.

The trick is not to introduce them into the garden to begin with.

Garden catalogs have been around since the 1700s and while informative, they are also sales tools. Using university-based websites, noted by .edu, to cross reference plants that sound too good to be true is a step I take before buying a new plant. Visiting public gardens during the growing season is another opportunity to learn about new plants. I encourage you to use these resources to fulfill your dreams of a perfect garden. While growing plants is the best way to learn, I hope my experiences will aid you in your plant choices.

Happy Gardening!