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.

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????