Wednesday, January 22, 2014

Native Plant Wish List for 2014

With a new planting season approaching I am planning on continuing my crusade to replace  the invasive species with native, mostly indigenous, plants.  I have another round of brush clearing to do this winter, especially the removal of some Autumn Olive tree/shrubs.  I am also looking to reduce the number of Butterfly bushes and Forsythia on the property and replace them with higher value native shrubs. 

Over Christmas I took the time to finish reading Designing Gardens with Flora of the American East, by Carolyn Summers.   The chapter on 'showy substitutes for invasive plants' was very inspirational in making up my plant list for this season.  This book is an excellent resource for anyone interested in designing native plant gardens.  There is sound reasoning behind each of the recommendations in this book.  I found this to be  much more useful than just a list of what should or should not be done when designing a garden or landscape.   To enhance the wildlife value of our property I am trying to  use a combination of plants that have something in bloom throughout the season for the pollinators as well as berries and fruits for the birds and small mammals.

Anyway, here's a list of my target plants for 2014:

Pussy Willow, Salix discolor.  I was surprised that this is a native species.  I is used so commonly in early spring decor that I figured it had to be imported.  The catkins swell in very early spring, first as white, silky buds, then opening to reveal either yellow (male) or greenish (female) flowers.  Pussy Willows are dioecous, male and female flowers are borne on separate plants.  My plan is to use the pussy willows as replacements for Forsythia.  The color intensity will be much less, but the wildlife value will be so much higher with the willow.  For all its flowers, I have seen very few bees visiting a forsythia in bloom.    Pussy Willows like full to part sun and prefer moist soils but will tolerate some dryness.  They are larval hosts for Viceroy and Mourning Cloak butterflies and they tolerate deer.  
I'm not sure of the exact species.  This photo is from the end of March in Boston.
I took this photo of a shrubby willow at the Arnold Arboretum about 5 years ago.  I did not record the name at the time.  As I was trying to find out more info about it, I went to the arboretum's web site and found that they have actually made an Internet accessible map of their plantings.  Using that map and my memory of where I took the photo, the willow in question is either the native Bebb's Willow, S. bebbiana, or an introduced Black Willow, S. gracilistyla 'Melanostachys'.  Based on the light color of the catkins, I guess that it's the former.

Another substitute for Forsythia is Spicebush, Lindera benzoin.  Its flowers impart a yellow haze to the forest understory about the same time as the Forsythia are in bloom.   It grows better in shadier situations than either Pussy Willow or Forsythia. 

For a partly shady area I would like to try replacing the Forsythia with Red Osier Dogwood, Cornus sericea.  This plant is in bloom from mid-late May and follows up with nutritious berries in mid-late summer.   Besides the flowers and fruits this dogwood also has purplish fall foliage and red-colored stems in winter, features definitely lacking in the one-trick pony, Forsythia.  Species plants can get large (6-10') but there are compact cultivars like 'Isanti' and 'Arctic Fire'.  A big problem with dogwood is that deer find most of the plant pretty tasty, but I have seen large plantings doing well along the roadsides.  This dogwood serves as the larval host for the Spring Azure butterfly.

This 'Isanti' cultivar is in full bloom at the end of May and should grow to about 6 feet.
Cutting back the older growth each year will keep the size down
and give more new red stems in the winter.

As far as replacing the Butterfly Bushes, Buddleia davidii, a multi-shrub approach may be needed.  Butterfly Bush has a long period of bloom and is very attractive to pollinators.  But it's like candy.  The plant does not act as a host for any native insects.  Thus, as it displaces native species, it excludes useful host plants, and degrades the habitat value of the garden.
The seed heads of Sumac make them easy to spot.  Not sure which species this is.
The stems of R. glabra are smooth, while those of R. typhina are hairy.
For the early part of the summer I am looking to Smooth Sumac, Rhus glabra.  This is also a common roadside plant, but not so common in the nursery trade.  It's chartreuse panicles do not stand out to humans, but they do to butterflies.  What is most noticeable in this shrub is the scarlet fall foliage and the deep red berries through the fall and winter.  It grows to about 15 feet, similar to many of the mature butterfly bushes around here. The larvae of the Hairstreak butterfly use Sumac as host plants.

For  the second part of the season I will put in some American Elder, Sambucas nigra ssp. canadensis (often S. canadensis).  American Elder likes medium to moist soils and part to full sunshine.  I have seen this growing in roadside ditches covered  with white umbels in the middle of summer.  Dark, palatable berries follow in early fall.   This shrub does not have a neat compact form, but neither do most forms of Butterfly Bush.  I am somewhat concerned about deer browsing on the young plants, so some protection will be needed. 

This native Spiraea blooms throughout the summer
and is a magnet for bees.

Other shrubs that provide mid and late summer flowers which  I put in last year include dense St. John's Wort, Hypericum densiflorum, and Meadowsweet, Spiraea alba var. latifolia (this one blooms all summer long).

In the areas where I have cut down the Autumn Olive, Elaeagnus umbellata, I am looking for native plants to provide lots of mid-summer  flowers, a large crop of fruits, and fairly dense branching to provide cover for birds.  Cockspur Hawthorn, Crataegus crus-galli, looks to be a good fit.  It blooms through mid-June and has lots of berries from late summer into winter.  It has dense horizontal branching and long thorn that provide a lot of protection for birds.  (For use closer to people there is a naturally thornless variety, var. inermis.

I would also consider Chokecherry, Prunus virginiana, while blooming earlier, it is faster growing and has fewer disease problems.  Chokecherry lacks the thorns of Hawthorn, but can form a thicket-like colony.  Looking in Douglas Tallamy's book Bringing Nature Home,  the cherries are near the top of the list as far as their ability to support butterfly species.  Hawthorns come in 12th, both way ahead of an invasive species like Elaeagnus. 

'Blue Muffin' is noted for it's sapphire berries,
as long as there is another Arrowwood around for pollination.
The other shrub that I will be putting in place of the olives is Arrowwood Viburnum, Viburnum dentatum.   These bloom in late May through mid-June and produce dark blue berries from late summer through autumn.  As I have mentioned before in this blog, Viburnums are self-sterile, so you need to have more than one genetic individual of each species to get berries.  Fortunately a local nursery is offering seed grown, wild-type plants so I won't have to worry about self incompatibility.  Wild-type Viburnums can get too large for many landscaping situations.  There are a number of more compact cultivars for garden use, such as the 'Blue Muffin' (aka 'Christom') shown here.  Together the Viburnums and the Hawthorn or Chokecherry will provide a nice edge habitat for with both food and shelter for wildlife.