The ubiquitous black-eyed Susan, Rubeckia hirta, can bloom in its first season from seed but may persist for up to 3 years. |
A little over 10 years ago I kicked off this blog with an introduction to the idea of using native annuals in the home landscape. I thought it was time to revisit this theme and add a little more detail with a focus on native annuals and biennials that can be used in the Mid-Atlantic garden.
While there is a growing interest in native trees, shrubs and herbaceous perennials there are very few native annuals promoted for landscape use in native landscape designs. This lack of focus is due in large part because the longer-lived species can be counted on year after year to uphold the integrity of the design. When included in a design, conventional annuals are often used as temporary accent pieces, just to add interest or fill a gap in the permanent landscape.
In general, many of the annuals used in designed landscapes and home gardening are of exotic origin and have been further improved horticulturally for maximum visual affect. These plants and methods are not bad or evil; they are just a several steps away from what would be considered natural to a given area. While beautiful, these plants lack local character, certainly on a regional, if not continental scale. To the extent that they are different from the local flora, they may not provide the same ecological value, such as food and shelter for wildlife in the area, as native species do.
In
contrast, native annuals may function more as perennials. Those that are
adapted to the local environment will die back after a season or two, but they
will maintain a presence in the garden, by reseeding, though not necessarily in
the same location. For some people, this may be a problem since the
plants will move around, disrupting the design. Others would consider
this as a natural phenomenon and appreciate how plants are able to find their
proper niche. The ideal native annual could be considered as a plant that
develops quickly with more flowers, a longer flowering cycle than perennials,
and that reseeds but is not invasive.
Plant Selection for the Mid-Atlantic
To generate my initial
list of Mid-Atlantic annuals and biennials I used the USDA Plants
database. This database contains a listing of all plants identified as
growing wild in the United States. It does not, however, distinguish
whether the plants in a location are indigenous or have escaped cultivation.
Using the 'Advanced Search' function I first selected North American native
species. Then I selected NJ, PA, MD, WV and VA as my Mid-Atlantic States.
For duration I selected annual and biennial and I selected 'forb' for plant
type. This resulted in a list of over 700 taxa. This list of plant
names included some duplication since varieties and sub-species are listed in
addition to the species. This database
has since been revised but you can get similar results for your region using
its new “Characteristics
Search” feature. Alternatively you
can use the Wildflower Center’s combination
plant search function on their database, but there you would be doing one
state at a time.
Here are three short-lived Mid-Atlantic natives, spotted beebalm over growing a patch of American pennyroyal and backed up with black-eyed Susans. |
Next, I scanned the list
for species that I was familiar with that, in my opinion, had some garden
value. The attributes I considered included form, appearance of foliage
or flower, scent of flower or foliage, or value to wildlife. I came up
with a list of over 40 species that I have or would like to have in my
gardens. These criteria are of course
arbitrary in the sense that I am looking at features from a human
perspective. In reality each of these
species has evolved to fill an ecological niche and, as such, has a real value in
their natural home. Most gardens, however, are created and curated by humans, and
are not complete, natural ecosystems. This is especially the case in
urban and suburban settings where soils, water courses and wildlife corridors
have been disrupted; although, we can aspire to create naturalistic areas where
some semblance of a natural ecosystem can catch hold, particularly with the use of native plant species.
The Plants
Here’s a partial listing
of the native annuals and biennials grouped according to their garden function.
Big Plants
Bearded beggarticks (Bidens
aristosa), American bellflower (Campanulastrum
americanum), tall thistle (Cirsium
altissimum), biennial gaura (Oenothera
gaura, formerly Gaura biennis), jewelweed
(Impatiens capensis), and evening
primrose (Oenothera biennis).
Showy Plants
These species are of
more manageable size and have good sized and/or showy flowers.
Climbing fumitory (Adlumia fungosa), partridge pea (Chamaecrista fasciculata and C. nictitans), plains coreopsis (Coreopsis tinctoria), Corydalis sempervirens, fleabanes (Erigeron annuus and E. philadelphicus), firewheel (Gaillardia pulchella), annual sunflower (Helianthus annus), cucmberleaf sunflower (Helianthus debilis), sneezeweed (Helenium amarum), standing cypress (Ipomosis rubra), spotted beebalm (Monarda punctata), sweet everlasting (Pseudognaphalium obtussifolium), black-eyed Susan (Rudbeckia hirta), clasping Venus looking glass (Triodanis perfoliata), and blue vervain (Verbena hastata).
Partridge pea returns reliably from seed each year if open soil is available |
Philadelphia fleabane is a prolific reseeder and can grow anywhere there is an opening, such as a thin lawn. Commonly grows as a biennial in my yard. |
Fillers
These plants will fill in space and while
each has some interesting features, will not steal the show.
Hog peanut (Amphicarpaea bracteata), yellow
corydalis (Corydalis flavula), American
pennyroyal (Hedeoma pulegioides), Indian tobacco (Lobelia inflata), clearweed (Pilea
pumila), red-whisker clammyweed (Polanisia
dodecandra), Pennsylvania smartweed (Polygonum
pensylvanicum), field pansy (Viola
bicolor), and common blue violet (V.
sororia).
American pennyroyal has very small flowers but produces a strong minty scent when disturbed. Its tiny seeds can find their way into the smallest cracks. |
Special Requirements.
Most native annuals owe their long-term success
to being adapted to some form of disturbance which makes it difficult for long-lived
plants to get established. Some species
are adapted to very special conditions.
One common example is jewelweed (Impatens
capensis). This annual can grow
quite large and sports distinctive orange flowers but it needs very wet soils
to survive.
Some interesting native
annuals are hemiparasitic, their roots tap into nearby plants to help them
develop fully. Two examples are the
False foxgloves, such as fernleaf false foxglove (Aureolaria pedicularia), which are parasitic on oaks, and Scarlet
Indian paintbrush, (Castilleja coccinea),
which grows with assistance from the roots of grasses.
Spring blue-eyed Mary germinates in the fall and blooms in early spring. It is often found growing under deciduous trees. |
Some winter annuals found in the Mid-Atlantic include: Spring blue-eyed Mary, (Collinsia verna), Yellow fumewort (Corydalis flavula), Old field Toadflax (Nuttallanthus canadensis), Fernleaf phacelia (Phacelia bipinnatifida), Miami mist (Phacelia purshii), and Field pansy (Viola bicolor).
One trick with growing winter annuals is that you need to avoid pulling them out while you are cleaning up flower beds in the early spring.
A few of these species
are commercially available as potted plants right now. Others may be had by getting seed from native
plant suppliers. For others, these
plants may occur naturally on your site and one just needs to be observant when
they show up and then to take care that they are able to develop and set seed
to create a new generation.