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.

Building a Container Water Garden

One of the challenges to creating a pollinator friendly garden is to include a water source.  We have a few static birdbaths, but ours are out of the way and often ignored.  To prevent mosquito breeding in these still ponds we throw in a 'mosquito dunk' which kill their larvae.  Having visited a few gardens with elaborate water gardens I was inspired to bring those home, in a scaled down version.

The finished product 2 days after completion.

What I have assembled is a container water garden that sits on our deck in easy view of the front door.  While I really wanted to include a lotus, they require a lot more space (min. 6 sq.ft.) to do well.  Instead I found a miniature water lily with 3" leaves that are in good scale with my container.  For a vertical element I chose squarestem spikerush, a native species that grows to 2' tall.  Anything taller would be out of scale.

Let me run you through the features of this container garden and the steps to build it.  The tub itself is a plastic planter bought from Costco for under $20.  The top is 2' in diameter and it holds about 20 gal. of water.  The depth is 15-18" which allow for the lily to be about a foot under water.  The bluestone rocks are partly for decoration but some are porous enough to be a butterfly watering station.  The rocks are stacked to create a small waterfall, powered by a small fountain pump.  For this sized tub, 20 ghp is sufficient. Since waterlilies do not like moving water the waterfall is directed to the side and into the rushes to slow the flow to a ripple.  The reason for the waterfall is to add a sound element to the garden and to create enough flow to keep mosquitoes from breeding in the otherwise still water.

The steps for constructing this garden are pretty easy.  Here the parts I used are shown.  They include the container, this one is plastic but a galvanized metal tub would work as well. There are also a small submersible pump, a timer, and about 3' of flexible hose to route water for the waterfall.  The concrete blocks create a flat base for the plant pots and the decorative stones.  Since I wanted a waterfall, at least one of these stones is concave to channel the water.

The 'hardware' for the water garden.

Next there are the plants.  We are fortunate to live not too far from Lilypons Water Gardens in Adamstown, MD.  They have been in business for a 100 years supplying water garden plants, fish and supplies.  There I was able to get some advice and select plants appropriate to my needs.  Since my container only has about 3 sq. ft. of surface I needed to look at smaller sized plants.  I selected the 'Helvola' hardy waterlily, with its smaller leaves and flowers it would not look at all crowed in my small container.

Here I measured the length of the stems so that
 I could place the pot at the proper depth in the container.
Turned out the setting directly on the bottom
 was the perfect spot.

Here's the square-stemmed spikerush.  The stems have a
flat membrane at each corner that catches the light.

Here I used the concrete blocks to elevate
 the spikerush so that it would not be too deep.

After placing the plants I added a couple of more concrete blocks to create a base for the decorative rocks and waterfall.  I put the pump behind the rocks to hide the cord and minimize turbulence.  The pump hose was was positioned on top of the waterfall rock and additional stones were used to press the hose in place.

Now with everything in place I filled the tub with water until the leaves of the waterlily were floating loosely on the surface.  The water was hazy for a couple of hours, but by the next day it was clear as seen above.  

Most water lilies like full sun, some like 'Helvola' tolerate part sun.  In its present location this container gets about 4 hours of direct sunlight.  Since the flowers open in response to sun (and close up in the evening) a sunnier site will keep the flowers open longer.