Vinca Replacement

Ever since we moved here 7 years ago I’ve wanted to replace the Vinca (V. minor) from our shady driveway turn-around.  Because I was new to the Mid-Atlantic area I didn’t want to do a wholesale replacement with something I wasn’t sure would work in this mostly shady, dry environment.  So I took a piecemeal approach, trying a little of this and a little of that, leaving most of the vinca in place.  This year I’ve decided to get more aggressive with the replacement, adding some successful species and trying some more new ones.

This was the next area for vinca removal.  It gets morning sun and open shade later in the day. 
It is framed on the right and left with test plantings of Heuchera and foam flower.

My primary reason for getting rid of the vinca is that it is an invasive species.  It is able to creep out of managed landscapes and run rampant in forested areas forming a dense ground cover that excludes native species.  From an aesthetic standpoint, while verdant, it can be rather boring and lack personality. Because of its ability to form thick foliage mats it tends to block out other less competitive species and creating a monoculture, at least on the ground plane.  

Most of the plants I have tried have survived the dry shade, but only a few have competed strongly against the viney invasive.  In all, I have tried nearly 25 native species in this area.  Strong competitors include Jack-in-the-pulpit (Arisaema triphyllum), green and gold (Chrysogonum virginianum), hayscented fern (Dennestadtia puntiloba), bigleaf aster (Eurybia macrophylla), Heucheras (I’ve had success with H. villosa and the cultivars ‘Citonelle’ and ‘Palace Purple’), twinleaf (Jeffersonia diphylla), Virginia creeper (Parthenocissus quinquifolia), zig-zag goldenrod (Solidago flexicaulis), merrybells (Uvularia sessilifolia), golden Alexanders (Zizia aurea), and the low-growing shrub sweetfern (Comptonia peregrina).  Also the non-native variegated Solomon’s seal (Polygonatum odoratum variagatum) is doing well (I imagine the larger native P. commutatum would also do well).  These are able to grow and spread without much help from me.  

Species that survive the conditions but need some help to keep from being overrun include wild bleeding hearts (Dicentra eximia), Alleghany spurge (Pachysandra procumbens), hoary mountain mint (Pycnanthemum incanum), smooth aster (Symphiotricum laevae), foam flower (Tiarella cordifolia), sedges (white-tinged sedge Carex albicans and pensylvanica, and there are some more robust wild ones like loose flowered sedge, C. laxiflora, that do very well).  Barren strawberry (Geum fragarioides, formerly in the genus Waldsteinia) should work well under these conditions, but in my case it seems to struggle.

Species that would be overrun without intervention include Meehan’s mint (Mehania cordata), woodland phlox (Phlox divaricata), and Labrador violet (Viola labradorica).  The only total failure was partridgeberry (Mitchella repens).  This tough little plant does not like to be covered, so between the vinca and the pine needles piling up it didn’t stand much of a chance. 

In this year’s planting I’m adding another sedge, ivory sedge (Carex eburnea), also wild geranium (Geranium maculatum) and, though I’m doubtful about this one, wild columbine (Aquilegia canadense).  I also have some downy wood mint, Bleiphila ciliata, which I started from seed that should do well in dry shade.

On the west end of this planting which gets a little afternoon sun, you can see the
ground hugging green and gold (now in bloom) and the much taller golden Alexanders (to the right).
Other plants include wild black raspberry, which appeared on its own, and several
volunteer trees that need to be pulled out.  

One of the features of vinca that is hard to copy with many native species is that it looks good (that is, pretty much the same) throughout the year with relatively little maintenance.  This is a great attribute from a design standpoint, but that does not make up for its invasive tendencies and relatively low ecological value.  Of the native species mentioned here green and gold and the sedges are evergreen (or nearly so) and the heucheras and foam flowers look good for most of the year.  Where there is sufficient moisture golden ragwort (Packera aurea) would be a very good evergreen choice.  

In the foreground you can see how Pennsylvania sedge pokes through gaps
 in the Virginia creeper (5-leaflets).  The sedge remains green throughout the year,
but looks a little ratty come January.  Another strong presence here is the zig-zag goldenrod,
with its ovate leaves, in the left and center of this image. 

Clearing this area took about 45 minutes.  Much of the time was consumed 
separating the vinca from the good soil after it had been pulled.  The pulled vinca 
was segregated to dry out and die before being put onto the debris pile.

Clearing the new planting space was surprisingly easy.  Since the area was thick layers of decomposed pine needles, the soil was very loose and most of the vinca could be removed with a 4-tine garden cultivator.  What didn’t come out with the cultivator was hand pulled.  I’m sure some bits of vinca remain and these will be addressed as they pop back up through the mulch.  I like using the fork because it hooked on the vines and it minimized damage to the deeper tree roots. 

Most of the new plants are in.  The most obvious are the heuchera and foam flowers. 
In addition to the wild geranium, columbine and ivory sedge are more
zig-zag goldenrod at the back of the planting and Labrador violets to the front edge. 
You can see the garden cultivator I used lying to the left.

Another means of vinca removal is cutting it back low then covering with a layer of cardboard, then mulch or clean soil.  This method would be better where the vinca is more firmly rooted.  I’ve tried spraying it with glyphosate, but the kill rate seemed rater low.

Here's the completed planting from another angle.  The new plants are mostly on the right edge
(see the little white tags?)  In the center of this view are established heuchera and foam flowers.

Using a variety of plant species in this area allowed me to tailor the planting to fit the variations in the site conditions: deeper vs. partial shade, arid vs. average moisture, etc.  Using plants with a tendency to spread both above ground, like foam flower and green and gold, or below the surface, like hay-scented fern helps cover the ground more quickly and allows the plants to migrate through the site to find their best conditions.  The variety also increases the biodiversity, extends the periods of bloom and provides more variation in form and color. 

I think for the next phase of vinca removal I will move to the middle of bed and try some taller species like the great Solomon's seal, white wood aster and more hay-scented fern.

New Additions for 2020

Every spring (and sometimes in the fall) I make plans on what new or additional regionally native plants I want to add to the garden/landscape.  Here's what I am planning for 2020.

I’m trying big leaf aster, Eurybia macrophylla, from home grown seed again this year.  Last year I harvested seed from an isolated plant.  This year I got it from an area that had several distinct individuals.  Many asters are self-incompatable, so the seeds that I am using this year are more likely to be fertile.  (Though tiny, they did seem to be thicker this year).  I’m still waiting for them to germinate; it’s been 14 days, so far.  Over the years I've had a hard time getting good levels of germination from asters and goldenrods.  Fortunately, in nature, they do just fine on their own.  (I’m also comparing unstratified to 30 days cold moist stratification.  We’ll see.)

There bigleaf aster are doing quite well in the dry shade under
the eaves along the foundation of a house.

I’m also stating some more switch grass, Panicum virgatum, from seed that I bought 3 years ago and kept in a refrigerator.  I was pleased to see that they are still viable, germinating beginning in less than a week.  They were planted in seed starting mix, under lights and bottom heat to warm them to 65-72 F (no stratification). I've been planting these out in a meadow area as plugs where I am trying to displace the very invasive Japanese stiltgrass, Microstegium vimineum. 

Here's an American lady butterfly on its host plant, pearly everlasting.

The tiny seeds of pearly everlasting give way to tiny sprouts (little green spots in this photo). 
After 30 days of cold, moist stratification, these germinated on the soil surface after only 3 days.

The bright pink flowers of fireweed should
stand out through mid-summer in the meadow.

Some new seeds that I am starting now are downy wood mint, Blephilia ciliata, pearly everlasting, Anaphalis margaritacea, and fireweed, Chamaenerion  angustifolium (formerly an Epilobium).  In the past I’ve tried the latter two before from seed with little luck.  This time I’m stratifying at lower temperatures, 37 vs 45 F.  Again, we’ll see.  Of these plants, fireweed can be pretty aggressive, once established.  My plan is to put it into a mown meadow that is home to other tough plants like wingstem, Verbesina alternifolia, Panicled tick trefoil, Desmodium paniculatum, and a variety of thistles.

When we first moved here one of my goals was to rip out all the vinca that was growing along our shady driveway and replace it with native species.  Before going whole hog I wanted to test some species to see which ones were strong competitors in this dry, shady location.  Seven years later and I haven’t made a lot of progress.  Plants that are doing well and slowly expanding are Green and Gold, Chrysogonum virginianum, and Pennsylvania sedge, Carex pensylvanica.  Alum root, Heuchera villosa and cultivars, and foamflower, Tiarella cordifolia, are surviving but not expanding rapidly, I have high hopes for the hay scented fern, Dennstaedtia punctiloba, but it has not expanded much in its first 3 years.   This year I decided to get moving again on this project.  I’ve ordered a number of dry shade tolerant plants:  Red columbine, Aquilegia canadense, ivory sedge, Carex erburnea, wild geranium, Geranium maculatum, Zigzag goldenrod, Solidago flexicaulis, and Labrador violet, Viola labradorica.  Also some of my big-leaf aster will go in, if/when they are successful from seed. 

These Green and Gold, are doing well in an area that was covered in vinca. 
They are continuing to spread but they have not out-competed the vinca.

Last year I potted up some of the red maples that were coming from seed.  I have killed a number of invasive Ailanthus that were dominating the canopy in one area of my woods.  I wanted to give the newly opened up woods a jump start with some native trees.  Red maples, being more shade tolerant, seem to be a good choice (and they’re free).  Since we have sugar, red, and silver maples here it is possible that these seedlings could be any of these or even a cross between red and silver, Acer x freemanii.  When they were young they looked like red or sugar maples.  But as they developed it became harder to tell from the leaf shape, they weren’t as deeply divided as a sliver maple, but not all simply 3-lobed like the ideal red maple.  They all seemed to have overwintered successfully under some shrubs along the garage foundation.  Later this spring I will start putting them in.

Here's my collection of maple seedling after I potted them up last spring. 
Most of them had the 3-lobed leaves indicative of red maple.  As they grew on
it became less clear that these were all red maples.

Planting Plans for spring 2015

Every year brings another opportunity to grow my native plant collection.  This year I'm focusing on 4 areas:  Clean up and replanting around the swimming pool, clean up and expansion of the meadow, replacing the vinca along the driveway and build up a privacy hedge with the neighbor.  After learning a bit about the current conditions, what is already here and what might be expected to grow here naturally, I've put together a shopping list of natives to get this year.

This moss phlox is pretty happy growing along the pool deck,
A good portion of it is on the concrete slab.
The colors can be intense, so I use mostly one color at a time.

The area around the swimming pool is infested with common evening primrose (Oenothera biennis).  While native, there is just too much of it and it is not that attractive close up.  The soil is mostly a fast draining fill with a moderately high pH (ca. 7.5).  Since this is far from native soil I put a greater focus on what would look good growing in this setting.  Since I had already started using this area for plants native to Texas (my wife's home state) I will be adding two of my favorites, Wine Cups (Callirhoe involucrata) and Indian Blanket (Gaillardia pulchella).   I got some seed on a recent visit to the Wildflower Center.  These will be great for the full sun areas and they tolerate alkaline soils.  The moss phlox could use some bolstering up as well.  I am attempting to remove the English ivy from the enclosure and this phlox seems to be a good candidate to fill back in.

This species of wine cups grows close to the ground, filling gaps around taller plants.
Seed requires a hot water treatment and  30  days cold stratification for germination. 

This is the annual species of Indian blanket, Gaillardia pulchella.

Small's Penstemon is long blooming in shady locations.
The contrasting lavender and white blossoms show up at a distance.

In the shadier areas I will be trying out Greek Valerain (Polemonium reptans aka Jacob's Ladder) and Small's Penstemon (Penstemon smallii).  Despite its common name the valerain is actually a native to the of the US.  This had confused me for a while.  Looks like the name Greek valerain is used for a number of species in the Polemonium genus.  One of them with particularly showy flowers, P. caeruleum, is a European native.  P. reptans grows more like a ground cover

I've ordered some more Indian Pink (Spigelia marilandica) for an area in the pool enclosure with more moisture and organic soils.

This cottonwood seedling appeared in the vegetable garden.
I'll transplant it this spring to a moist part of the new meadow.

I have an area that has been overrun with invasives that I am trying to convert to a meadow.  I cleared half of it last year and hope to finish this spring.  After removing the bad guys I am backfilling with native species.  I realize that I'm making more work for myself by trying to kill off invasivies at the same time as introducing new plantings.  By planting mostly shrubs I think I can more easily manage the area with an annual mowing/whacking of the undesirable plants.  For the right way to convert a weedy area to a meadow or prairie check out this link.

Last year I planted an American plum (Prunus americana) and several elderberries (Sambucus canadensis).  This year I will add some chokecherries (Prunus virginiana) and smooth sumac (Rhus glabra).  I also have a Cottonwood (Populus deltoides) seedling to put on the edge.

The pawpaw blooms in early May,
just before the leaves open up.  

Way in the back I have a large grove of Pawpaw (Asimina triloba) trees.  I've been watching them for 2 years and I have yet to see any fruit.  Since pawpaws produce better with cross-pollination, I will be adding a couple of new individuals to the area,  It is possible that my entire grove is really just one clone.  We'll see if this helps, in a couple of years.

These goldenstar have more than doubled in size after a year in the ground.
I'll get some more to speed up coverage.

In the shady area around the driveway I have been ripping out the vinca and replacing it with shade tolerant natives.  I started with foamflower (Tiarella cordifolia) and Heucheras and these are taking hold.  In addition to these I've seen some really good results with Goldenstar (Chrysogonum virginianum, aka Green and Gold) in open shade areas.  These are relatively easy to find in a regular nursery, sometimes marketed with the plants that you can walk on.  Another plant that I've used in dry shade is big-leaf aster (Eurybia macrophylla), It has dense foliage and spreads by rhizomes so it should do a good job competing with the vinca.

This shiny summer foliage pf aromatic sumac turns red and orange in the fall.
We'll see how it performs in a shadier location.

The boundary between our nearest neighbor is defined with a double row of white pines.  At 40+ years old they are now limbed up fairly high and not providing much screening.  We have already put in a juneberry (Amelanchier canadensis), hazelnut (Corylus americana) and Hoptree (Ptelea trilfoliata).  There was also a pawpaw already there, doing a pretty good job despite the drier conditions.  We are looking to add some additional shrubs to fill in this gap and obscure the view.  A local native plant nursery has listed maple-leaf viburnum (Viburnum acerifolium) for sale this year.  I've been told that this is a very difficult shrub to propagate.  It does well in shady woods so I'm looking forward to trying it here.  I should get two since they don't self pollinate.  I am also looking to get some aromatic sumac (Rhus aromatica).  The wild form grows 5-12 feet, just the right size for our area.  I already have some of the 'Gro-low' cultivar.  At about 3 feet it is a great ground cover shrub for many difficult locations.

Now with may list in hand, I can hardly wait until spring!