Mountain Mints

Mountain mints are members of the genus Pycnanthemum.  This translates from Greek as dense flower, an appropriate name for these pollinator favorites.  There are 19 species of mountain mints, all native to North America, found primarily the eastern half of the continent.  These plants have tight clusters of small white to purple tubular flowers that are very attractive to pollinating insects.  Many of these species have pleasantly mint-scented foliage.  The leaves can be used to make a mint flavored tea, although one species, short-toothed mountain mint, contains higher levels of a toxic terpenoid, pulegone, than the others.  They are also resistant to deer browsing, at least in part due to these terpenoid compounds.

This hoary mountain mint was growing along
a trail near the Potomac River.

Over the past couple of years I have added three species of mountain mints native to the Mid-Atlantic region.  The first one that I put in was hoary mountain mint, P. incanum.  (Incanum means gray.)  Its native habitat is listed as upland woods, which I interpreted as dappled shade with average moisture soil (mesic).  I have observed this species growing happily along some nearby trails.  

At home I planted it in a woodland edge, but it failed after about a year, probably due to too much shade and competition.    Where it has been successful is in open shade with dryish soil and less competition.  I expect it would be happier with a little more moisture and a little less shade. 

Note the grayish blush on the leaves and stems.  Also,
 the teeth on the leaf edge are small and widely separated.

Short-toothed mountain mint (P. muticum) is a species that I’ve had more success growing at home.  It seems happy growing in dappled shade in average well drained soils.  It needs more moisture than hoary mountain mint to excel.  Like hoary mountain mint it has a pleasant minty scent when disturbed and is very attractive to pollinators.  It is a more upright growing plant than hoary mountain mint.  On one site where I have it growing it is leaning over as it is reaching for the sun. 

Short-toothed mountain mint has white flowers and there are many short teeth along the leaf margins. 
Also the the leaves are broader in the center and thy are nearly sessile (no petiole).

The third species I have planted is slender mountain mint (P. tenuifolium).  This species, with its very narrow leaves, is well adapted for sunnier, drier locations.  Unlike the other two species discussed here, its foliage lacks a strong minty scent.  Even so I have not noticed any deer browsing on its foliage or flowers.  On the plus side it has relatively over-sized pink-tinged flowers that bloom from late spring to mid to late summer.  

The flowers of slender mountain mint come in dense clusters
making them look much larger than they are individually.

I got the slender mountain mint to plant opposite a threadleaf coreopsis (Coreopsis verticillata ‘Zagreb’) with the idea that the similar foliage would create a symmetrical design.  While the foliage of the two plants is similar, the laxer habit and bluer foliage of the mint gives a different impression than the tighter, upright form of the coreopsis.  This combination has worked out well for the pollinators. The coreopsis reach peak bloom in mid-June and the mountain mint took over in late June and is still going strong into mid-summer.

Coreopsis 'Zagreb' is on the left of the walk, slender mountain mint is on the right, behind the post. 
This combo doesn't look bad, but they are definitely different looking plants.

Overall I have been well pleased with my mountain mints: long-lasting minty foliage for me and lots of nectar-rich flowers for the pollinators.

Designing with Native Plants

Designing with native plants is not that different from designing with any other plant palette.  You still use basic design concepts, using the shapes, colors and textures of plants to create rhythm and flow in the landscape.  What is different is that your selection of plants is more focused on native species, ideally ones that are regionally or locally native.

Advantages

What you gain from using native species in your landscape is greater benefit to the nearby wildlife, better fit with the local ecology and character of the region, and, if your plant selection was right lower maintenance and increased sustainability.

There are North American native plants species that will grow under just about any landscape situation imaginable.  That doesn't mean that any North American plant will grow anywhere in North America.  Beyond the many geographic climate zones there are also differences in soil chemistry, texture, moisture, exposure to sunlight and competition both from other plants as well as animals.

By looking at nearby native plant communities you can get some inspiration about what to combine in your landscape.  At Mount Auburn Cemetery in Cambridge MA they created a meadow using many species of grasses and wildflowers native to the Northeast. 

This constructed 'Northeast Meadow' features showy goldenrod (Solidago speciosa),
little bluestem (Schizachyrium scoparium), New England blazing star (Liatric scariosa), hyssopleaf thoroughwort (Eupatorium hyssopifolium) and brown-eyed Susan (Rudbeckia triloba).

When I was designing a planting for a sloping path I selected some species that I observed along a nearby hiking trail in Maryland Heights.

Bottlebrush grass (Elymus hystrix) and clustered mountain mint
(Pycnanthemum muticum) are major components of this hillside garden.

While I stress about how you need to match plants to their ideal conditions, there are often surprising exceptions.  Test their adaptability by trying a plant or two in unusual locations, they just might catch hold.  This is why I like to use natives that produce a lot of seed, particularly native annuals.  The seed is able to spread around and find new places to grow, some of which will be a good fit.

This pink tickseed was originally planted in a near-by bed but found a better home when seed fell into a crack in the driveway.

Challenges

Some natives are generalists and are able to grow well under a wide variety of conditions.   Others are more specialized, having adapted to some very specific growing conditions.  Some of the frustration of working with natives is that while it is implied that they are adapted to grow in North America, a given native will not necessarily do well everywhere on the continent. 

Another factor to realize is that residential landscapes often have very different soil conditions than near-by natural areas.  Depending on where they are located around a building, light exposure and moisture levels can also be very different from undisturbed areas.  Newer construction areas often have compacted soils.  Many times the native top soil has been removed and replaced with soil from another location.

Reasons for failure of new plantings include competition from other plants, incorrect soil chemistry, texture or drainage, or missing  companion plants.  Also consider age of plants and the original conditions when they were planted.  Many shrubs growing in shade were planted when there was less competition both for light and root space.  Planting new specimens into an established wooded area is more challenging now than when the area was originally planted.  I have been fooled into planting new rhododendrons under established shade trees based on seeing mature shrubs in woodland settings.  In many cases, there is too much competition in the root zone for water and nutrients and too much shade cover for the new plants to get established.  Options here include opening up or raising the tree canopy, clearing a wider root zone (without damaging the existing trees), or  opting for more shade tolerant species.

Sometimes when I see native species dominating some harsh environmental conditions and I think, wow that could grow anywhere.  That is often faulty reasoning.  In many cases these plants excel because they have adapted to those conditions in specific ways to use those harsh conditions to their advantage to out compete other species.  

Rock harlequin will excel in thin rocky soils but does
 not compete well in normal soils against other plants.

One example is rock harlequin (Corydalis sempervirens) a short lived perennial that needs to reseed itself to maintain a garden presence. It's native to rocky slopes in the Northeast where there are shallow pockets of soil and exposure to full sun for a good portion of the day.  When planted in richer soil or 'better' conditions it often fails due to competition from other plants. 

Almost all plants in nature grow in a community of some sort.  There are a few  species that require a host plant to help them grow and develop.  Indian paint brush (Castilleja sp.) tap into the roots of neighboring plants, such as little bluestem or penstemons, for nourishment.  False foxgloves (Aureolaria sp.) are partially parasitic on the roots of oak trees.  And , like many members of the pea family, Texas bluebonnets (Lupinus texensis and sp.) do better when there are specific soil bacteria present to help them fix nitrogen. 

Texas bluebonnets are winter annuals that blanket open fields with their iconic blue and white flowers in early spring.  They are well adapted to the calcareous soils with the assistance of a soil bacteria.  Performance in other regions is erratic. 

Plant Selection and Sources

The nature of native plants are that they are native to particular areas of the country based on climate, soil chemistry and evolutionary history. As such there are very few 'nationally native' plants, nor should there be.  If you search the garden centers you can often find sections devoted to native plants.  The nice thing about many commercially available native plants, though there may not be many of them, is that most have been selected to be commercially viable, that is they work in many residential situations and are fairly robust.  We need to expand the offerings by asking for more of these plants.  American Beauties is one program based in the Northeast that is supplying a variety of native species.  There are also a number of native plant suppliers that you can find on the web.   Izel Plants is a clearing house for a number of native plant nurseries primarily in the Eastern US and has an extensive catalog of native species.  The Plant Native link below also has listings of native plant nurseries by state.   You can also search the web for nurseries in your region that specialize in native plants. 

To help with the selection of which species to use there are a number of websites that allow you to search for plants based on the site conditions.  You can find plant search websites for a given area by using search terms like 'Native Plant Database for  '  My favorite site to search is from the Wildflower Center.  It allow you to search by where a plant is native as well as specific growing conditions and plant attributes such as size and bloom color.  Plant Native is another good site.  While the plant lists are smaller, the plants listed are mostly commercially available.  Missouri Botanical Garden has an excellent search platform, but it is not solely native species.

Strategies for Designing with Native Species

• Try to match the preferred conditions/habitats of a new plant to your local conditions (much easier than trying to match your conditions to those of a given plant).
• Start small, when in doubt.  Before doing a massive planting put in a couple of plants as a test to see if they survive.
• Try a new species in a couple of different locations to see where it grows well. 
• Don't just drop a new plant into an established bed.  Clear some area to allow for roots to get established without competition.  Also open up the canopy to let in some light.  Water well, but don't feed perennials, shrubs or trees until the roots are established (about one growing season).
• Build a plant community by learning about which plants grow together in nature.
• When starting perennials from seedlings, like you get with liners or sizes one quart or smaller, it will take as many as three seasons for them to reach their full glory.  The adage 'sleep, creep, then leap' really does hold true when start from small specimens.

What worked in 2016

Looking back on how my plans for incorporating the new native plants worked this past year revealed more successes than failures.  Here's a rundown on what worked, what didn't and what I learned.

Plants from seed
Probably my best result came from seed for rose verbena, Glandularia canadensis.  After about 6 weeks of cold stratification I had very good rates germination after a week under lights.  I didn't see any plants from direct seeding outside done at the end of February.  Either that wasn't long enough or the conditions just were not right.  Surpizingly the plants are still leafy green outside (we are on the border of zones 6 and 7).

I also had good results with the annual Texas sage, Salvia coccinea, after a month of cold moist stratification.  We also had a lot of these coming up in pots that had been stored in an unheated garage, but none from seed that was left outdoors.

 The failure here was with Indian blanket, Gaillardia pulchella.  This one germinated during stratification.  I planted the sprouted seeds, but they were weak and didn't amount to much, even after being potted up.

Rose verbena was blooming by mid-July
and continued through the summer.  

This American bellflower is a favorite of native miner bees. 

A biennial that is really happy here is American bellflower, Campanulastrum americanum.  I started a few from seed in 2013 and now have volunteers scattered around the flower beds.  Another name for this species is tall bellflower; mine typically reach 4-5 feet when in bloom.  The deer browse on this a little early in the season, but tend to leave it alone after July.  It can get rather lanky, so it is best toward the back of a border or in the shade where it does not get so tall.





New Perennials

The white flowers of wild strawberry are another way
to distinguish it from mock strawberry, which has yellow flowers.

Since I was seeing good results from a hardy cultivated strawberry from the local master gardeners I thought I would try out some of the native species, wild strawberry, Fragaria virginiana.  Planted in mid-spring, these small plants settled in enough to put out runners to start new plants a foot or two away.  Got some flowers but no fruit this first year.  Looks promising as a fruit-bearing ground cover for next year.

These white woodland phlox, growing in my woodlands
are similar to ones I transplanted to under the pines.

I also planted both woodland and creeping phlox, Phlox divaricata and P. stolonifera, in open shade under some pines.  This is an area where I am trying to replace a mass of vinca.  These species do well in the shade of deciduous trees, we'll see how they handle the consistent dry shade of evergreens.  The woodland phlox that I planted in the spring disappeared in the middle of summer but put forth new growth in the fall.  The creeping phlox, which is more tolerant of dry soils, was planted in the fall.  We'll see which of these two species is more successful here.

In this same pine-rich area I added more Foamflower, Tiarella cordifolia, and hairy alumroot, Heuchera villosa, as seedlings.  In general the Heuchera survive these conditions much better than the Tiarella.  It was probably too dry for the young plants to get established.  While the Heuchera grow better, they are also more subject to browsing by critters, deer or rabbits of both.  Next time I get some Tiarella I'll try it in a moister location, perhaps under a walnut tree.

The flowers of blunt mountain mint are very attractive to pollinators.

A new native I added to the garden was blunt mountainmint, Pycnanthemum muticum.  I had been trying out hoary mountainmint, P. incanum, for a couple of years.  Planted in a partly sunny location, it has been rather slow to grow.  I planted the blunt mountainmint in a slightly sunnier location nearby and it grew to about 2' and was covered with dense pinkish flowers.  As showy as the flowers are the silvery bracts at the base of each flower.

I have been trying to get some blazing star, Liatris sp., to grow for several years.  It seems they get started, then disappear.  I'm pretty sure I'm losing them to some small mammals, ground hogs or rabbits.  This year I tried plains blazing star, L. squarrosa, with mixed success.  The ones planted in the open disappeared, while the ones surrounded by other plants were able to survive.  We'll see if these can get established.

Plains blazing star in bloom.  This species has
button-like flowers rather than spikes

Another regionally native plant that didn't bloom but seems to be getting established is vasevine, Clematis virona.  I didn't notice them much during the growing season, but when I cheked for them this past week I did find that the wiry vines had grown several feet.  I hope I can share some photos of its bell-shaped flowers next summer.


New Shrubs

This gray dogwood managed to bloom before it got pruned back by deer.

My main 'reclaimation' project last season was to displace invasive wineberry, Rubus phoenicolasius, and Japanese honeysuckle, Lonicera japonica, from a steeply sloping hedgerow.  I don't want to destabilize the slope, so I have been cutting back the invasives and treating the stumps with herbicide.  In 2014-15 I put in some smooth sumac, Rhus glabra.  This year I added gray dogwood, Cornus racemosa to the top and middle slopes and American hazelnut, Corylus americana, to the shadier lower slope.  Most of these were planted bare root in the spring and they seem to have survived their first year.  The biggest challenge for the dogwood is deer browsing.  This was also a problem the first year I planted red osier dogwood, C. sericea, but after a year the deer seemed to lose interest.  I have read that deer will browse more on new plants, especially those from a nursery, because their leaves are more tender and they are higher in nitrogen.  After the plants settle in, the leaves toughen up and become less appealing.  I hope it will be the case here.

On a disappointing note, only one of the five bare root red cedars, Juniperus virginiana, survived.  I have my lone survivor surrounded by chicken wire to protect it from deer.  I'll probably need to keep it caged up for a few more years, especially during rutting season.

Now its time to start planning for next year.  Let's see, what should I get????