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Choosing the right plant

Gardens with native plants are much more stable overall

By Carol Papas ©2012
Penn State Master Gardener


As spring approaches, gardeners will be inundated with slick advertisements promoting plants that may or may not live up to their hype.  We’ll see examples of picture-perfect annuals pumped up with water soluble fertilizer.  Finally, we’ll be encouraged to show off our golf-course worthy lawns--free of weeds and emerald green, after following a multi-step program to eliminate every insect and weed. 

There is a cost to heeding to the admonitions of companies selling plants and chemicals to enhance our landscapes and gardens, says Douglas W. Tallamy.  He has written an eye-opening book, Bringing Nature Home: How You Can Sustain Wildlife with Native Plants (Timber Press, $17.95). Encouraging gardeners to go native is nothing new.  Native plants have been promoted for their contributions to the landscape since Sara Stein wrote Noah’s Garden almost 20 years ago. 

Mr. Tallamy’s book focuses on the importance of planting to sustain insects critical to maintaining the food web. This is not to say that gardeners should rip every non-native plant from their gardens (imagine what you’d be left with), but to consider plants that supply native insects with a viable food source.  Whether you have an established garden and you’re making choices to complement ‘Endless Summer’ hydrangea, or if you are starting from scratch, introducing native species into the garden has many benefits. 

Sweet Bay Magnolia flower
Sweet Bay Magnolia flower has a sweet fragrance
Photo: Mike Masiuk

Mr. Tallamy reminds us that suburban sprawl, 4 million linear miles of public roads and our obsession with sterile lawns have all contributed to the reduction of habitat and loss of diversity impacting native insect populations.

 

Beyond the impact of habitat destruction, Mr. Tallamy also notes that native insects prefer native plants over alien species.  Insects choose to eat the leaves of plants based on leaf chemistry.  Native insects do not readily adapt to the chemical mixes contained within the leaves of introduced species.


Insects

Insects are specialists when it comes to choosing which plants to eat.  Mr. Tallamy retells a story of caterpillars eating the leaves of a black cherry tree.  After consuming the lower leaves on the tree, the caterpillars crawled over the leaves of a Japanese honeysuckle vine wound around the tree trunk to get to cherry leaves on the higher branches. 

Unrelated to the impact of alien species on the biomass of native insects, many of our imports have become invasive plants, including autumn olive, kudzu, purple loosestrife, Japanese barberry and Japanese knotweed.  When alien plants prevail, diseases and insects come with them and can cause collateral damage to habitats.


Fungus

American chestnut trees, flowering dogwood (Cornus florida) and California oaks have all been ravaged by fungi which did not affect their Asian counterparts yet destroyed our native trees. Japanese beetles and the hemlock wooly adelgid are just two of the insects let loose into our gardens after hitching rides on imported nursery stock.

The final nail in the coffin for upsetting a thriving ecosystem is the reliance on chemicals to create a beautiful garden. Mr. Tallamy puts it very well:

“In an effort to create gardens free of insect problems, most gardeners have used a recipe perfect for cooking up insect outbreaks: alien plants, lack of plant diversity and insecticides.  Would we not better achieve our goal of a pest free garden if we employed nature herself to look after things?  We have spent the last half-century proving beyond the shadow of a doubt that a sterile garden does not work. It is a high-input enterprise requiring more time and money than most of us would like, or are able, to devote or spend.” 

Studies suggest that gardens created from native plants are more stable and self-regulating than gardens predicated on alien plants.  Striving for a suburban ecosystem complex enough to keep itself thriving without micromanagement by the gardener is something to work for. 

Introducing native plants to your garden is as simple as doing a bit of research.  If you enjoy a wooded lot, resist the temptation to cut down “trash trees” such as black cherry.  The 456 species of Lepidoptera (moths and butterflies) supported by that tree, as well as the birds that eat their larvae, will applaud you! 


Planting for Future Generations

If you are debating which tree to plant for shade and generations of your grandchildren to enjoy, choose a white, red or scarlet oak, a favorite of 534 species.  Pass on the rows of ‘Bradford’ pears at the big box stores this spring.  They grow fast, are cheap to propagate (hence that great price) but their branches are so prone to ice and wind damage that they’re a poor landscape choice.  Instead choose a species of our native serviceberry. You’ll still have pretty white flowers in the spring, followed by fruits that the birds relish, and lovely fall color, too. 

If you are enjoying the ‘Knockout’ rose you purchased last year consider underplanting it with alum root or coral bells (Heuchera americana) or flowering spurge (Euphorbia corollata), native perennials which will dress up the base of the rose better than a sea of mulch. 

Knockout Rose
Knockout Rose

Locating these plants might require a bit of work, but native plant specialists and nurseries may have them, or could order them for you.  Many native perennials can go head to head with delphinium hybrids for beauty including: willowleaf bluestar (Amsonia tabernaemontana), blue prairie indigo (Baptisia australis), Culver’s root (Veronicastrum virginicum) and goatsbeard (Aruncus dioicus).  These perennials are available at nurseries with a broad selection of plants and won’t disappoint like the fancy delphiniums that never reach perfection in our area and rarely return for an encore performance.

There is an excellent appendix in Mr. Tallamy’s book.  Take a look at the extensive list of choices appropriate for our region.  Native plants may have to make do without publicists, but they’re great choices for your landscape.


Appendix

This spring, as you walk around your garden and think to yourself, “I could use something right here,” chose a native plant you won’t see in every yard in the neighborhood.  The birds and butterflies will thank you for it!

Below is a short list of native plants readily available at local nurseries.  Selected from the appendix of the book: Bringing Nature Home: How You Can Sustain Wildlife with Native Plants. Tallamy, Douglas W. (2007, expanded in 2009). London/Portland: Timber Press.

Shade and specimen trees

Betula nigra, river birch

Nyssa sylvatica, black gum

Shrubs and understory trees

Aronia arbutifolia, red chokeberry (moist sites)

Asimina triloba, pawpaw

Cephalanthus occidentalis,  buttonbush (moist sites)

Cercis canadensis, redbud

Chionanthus virginicus, fringe tree

White Fringe Tree
White Fringe Tree

Clethra alnifolia, sweet pepper bush

Cornus sericea, redtwig dogwood (moist sites)

Hamamelis virginiana, witch hazel

Magnolia virginiana, sweetbay magnolia (moist sites)

Rhododendron viscosum, swamp azalea

Vaccinium corymbosum, highbush blueberry

Viburnum nudum, smooth witherod

Herbaceous perennials

Actaea racemosa, black cohosh (dry sites)

Andropogon gerardii, big bluestem

Asarum canadense, wild ginger

Asclepias incarnata, swamp milkweed

Athyrium filix-femina, lady fern

Chrysogonum virginianum, green and gold

Dicentra eximia, fringed bleeding heart (moist sites)

Jeffersonia diphylla, twinleaf (moist sites)

Pachysandra procumbens, Allegheny spurge

Polygonatum commutatum, Solomon's seal (moist sites)

Polystichum acrostichoides, Christmas fern

Ratibida pinnata, pinnate prairie coneflower (dry sites)

Tiarella cordifolia, eastern foamflower


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