Native Annuals revisited

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 can grow from seed to about
5' tall in a season.  Bloom time is in late summer.

Despite their short life times some native annuals and particularly biennials can grow quite large, 4-6 feet tall.  These plants are best located in the background or in a larger format setting.

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. 

Winter annuals are a group of plants that have adapted their life cycles to avoid the heat and dryness of summer, or competition for sun light in a wooded setting, by doing most of their growth from fall into springtime, when light and moisture are more plentiful.

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. 

This clasping Venus looking glass came up on its
 own and bloomed in early June.  To encourage its
 return I avoided mowing the area so that it could
 set seed, but it will need open soil the following
 year so that it can grow.

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.

 

Picking the Right Ferns

When I think of planting ferns I usually think of shady, moist conditions.  But that’s not all.  There are ferns that do well in dry conditions and some that can handle a fair amount of sun.  One aspect of fern selection I had not thought of much was soil pH (or acidity).  My only knowledge here was that maidenhair fern, Adiantum capillus-veneris, needed alkaline conditions, but that was about it.  (However, Northern maidenhair fern, A. pedatum, is less demanding, preferring neutral conditions.)  My eyes were opened a bit further when I read an article in Fine Gardening by C. Colston Burell on Hardy Native Ferns.  In it is a table listing light and soil tolerance of about 25 native ferns.   I thought that I now had a definitive decision making tool.  However, as I did some more research for this blog post I started finding conflicting information on what conditions particular species preferred.  One reason for the confusion may be the difference between ‘preferred conditions’ and ‘conditions tolerated.’  While some species are very particular about what they need to grow, others are more tolerant of variation.  Lacking a full understanding how growing conditions were measured and of what truly unacceptable conditions are, I am inclined to treat published growing conditions as more what you’d call guidelines than actual rules. 

With that in mind, the table got me to thinking about the ferns I had planted that were not doing very well.  Three particular ferns that are not excelling in my plantings are royal fern, cinnamon fern and hay-scented fern.  The soil in my area is neutral to alkaline and these struggling ferns are listed in Burell’s table as preferring acidic soils. 

The royal fern, Osmunda regalis, is in a moist shady spot.  I was hoping that this taller fern would form a diffuse back ground to highlight smaller plants planted in the foreground.  After three years it has not grown more than 6 inches tall and has only put out a few stems.  This year I will try transplanting over some ostrich ferns, Matteuccia struthiopteris, into that area.  These are listed as growing in alkaline conditions and they have a very strong vase shape, though they are visually more dense than royal ferns.

Ostrich fern grows to about 3' tall with a strong vase-shaped
habit, reaching full size by mid-spring.  Its preference
for neutral to alkaline conditions makes it a good choice
for foundation plantings.

The cinnamon fern, Osmunda cinnamomea, is doing somewhat better.  It’s planted in part sun with similar moist soil.  I was hoping that the light green fronds of the vise-shaped fern would stand out on the edge of a shrub border.  So far the plants are just holding on.  Perhaps here I could add some sulfur to make the soil just a bit more acid.  (That would also benefit the nearby hollies.)

These 2 cinnamon ferns were chosen for there bright green color and
vase-shaped form which contrasts with the darker green of the
hollies behind.  All of these plants would benefit from a bit more soil acidity.

The third fern that is under-performing my expectations is hay-scented fern, Dennstaedtia punctiloba.  My understanding was that this aggressive fern would grow just about anywhere.  That’s why I am using it in my vinca replacement project where the conditions are dry shade.  Three years in and only one clump has spread a little, and two others have died. 

These hay-scented ferns, growing in a gravel bed, are just unfurling
in mid-April in the Boston area.  They will grow to be about 2' tall.

Considering that my soil is pretty much neutral (6.8-7.2) I should avoid ferns that need acidic conditions and focus more on those that are happy with neutral conditions. 

Ferns suited to neutral to alkaline conditions include: ostrich fern, Matteuccia struthiopteris, marginal wood fern, Dryopteris marginalis, lady fern, Athyrium  filix-femina and sensitive fern, Onoclea sensibilis.  One uncommon fern I found growing in the woods was blunt-lobed cliff fern, Woodsia obtusa, which prefers alkaline conditions.

This cliff fern is growing on a east facing rocky slope.

Ferns that I have found noted as indifferent to soil pH are Christmas fern, Polystichum acrostichoides, and ebony spleenwort, Asplenium platyneuron.  These are both very common ferns on my property.

Christmas fern is evergreen and has a more relaxed upright habit. 
Even in January this fern looks pretty good.  

Ebony spleenwort is a smaller fern more useful as a ground
cover component than as a feature plant.  This specimen was
growing in full shade and was about 8" tall.  In sunnier locations
it stays closer to the ground.  Ebony spleenwort will grow on a
variety of soils whereas other species of spleenworts prefer
neutral to alkaline conditions.

Maybe it's best to proceed cautiously when there is a question.  If you’re uncertain, rather than doing a massive planting, put in one or two and see how they do. 

Getting Ready for Stiltgrass 2021

My battle against Japanese stiltgrass, Microstegium vimineum, is a nearly year round effort.  To help me focus my efforts I’ve prepared the following table to remind me of where I will get the most for each hour of work in each season.

Japanese Stiltgrass Control

Season	Actions	Pros	Cons	Comments
Late Winter Early Spring	Pre-emergent treatment	Effective in lawns and smoother (even) surfaces with access to soil surface.  Allows lawns and perennials to get a head start.	Will affect all germinating seeds for several months.  Uneven coverage on rough surfaces.  Application needs to be at the right time.	Takes at least 2 years to knock down seed bank to see significant progress.  More time to complete elimination, if ever.
Late spring-Summer	Herbicide	Grass selective herbicide leaves broad leaf plants and some sedges intact. Try products containing Fluazifop-p-butyl	Difficult to control collateral damage, especially with non-selective herbicides	Targeted application and use of selective materials may limit side effects.
Late spring-Summer	Pulling	Non-toxic and selective.  Opens space for other species.	Labor intensive; left over stilt grass will expand to fill gaps.	If removal is not complete this will need to be repeated at the end of summer
Late summer/Early fall	Cutting/ pulling/ burning	All methods to reduce the amount of seed	Need to complete actions before seed begins to ripen.	Copious amounts of seed being produced, need to be thorough and avoid spreading any ripened seed.

 Because Japanese stiltgrass is an annual there are two points of vulnerability based on its life cycle.  As an annual all plants start new from seed each spring.  If you can disrupt germination you can make a significant dent in how much stiltgrass you will have to deal with.  This is where I have found preemergent herbicides to be very useful.  Products labeled for control of crabgrass have proven effective.  The other weak spot is seed production in early fall.  More on that below.

On the left you can see the effect of a single treatment with
a preemergent crabgrass herbicide.  The right side is thick with
bright green Japanese stiltgrass.  Photo taken in early July.

Springtime

An important part of using a preemergent is getting it applied at the proper time, neither too early or too late in the spring.  There are tools on the internet that track growing degree days, such as GDD Tracker 4.0.  The idea is that plants will develop at a rate controlled by how much heat they receive over time.  For germination, the soil temperature is particularly important.  It is important to realize with a preemergent it is critical to have the material well distributed on the soil prior to the onset of germination.  That’s why I like a really like the calculator, it builds in the time when you should actually apply the product.  Another way to time the application is to watch for when forsythia are in bloom.  In my limited experience just before peak bloom is a good time to do the preemergent application.

I have found that preemergent use on the lawn is very effective.  There was a significant reduction in stiltgrass in the lawn after treatment for two consecutive years.  Also the red fescue that I overseeded is really starting to knit together.  I should do a test this year to see if I can skip treating a portion of the lawn for a year without a resurgence of stiltgrass?  Maybe for a small area.  I'd hate to lose the progress I've made so far.

I have also experimented with preemergent treatments in a meadow area.  Here the ground is much coarser and there is a lot of debris on the ground.  It is very difficult to get an even application of the granular herbicide.  I have seen a decrease in the amount of stiltgrass seedlings in areas where the preemergent was applied.  But there are also patches where the stiltgrass still comes in densely.  I assume that these are due to uneven application.    

Another concern I have with this meadow area is that the preemergent treatments will inhibit the germination of other desirable plants.  The meadow area I have is dominated by wingstem (Verbesina alternifolia), wild blackberry, smartweed and a variety of sedges.  In addition there are the usual invasives: Wineberry (Rubus phoenicolasius), Oriental bittersweet, Japanese honeysuckle and multiflora rose.  Besides reducing the amount of Japanese stiltgrass I have also noticed a significant reduction in the amount of bull thistle, Cirsium vulgare, a non-native species.  (Of course having a thick layer of JSG will also inhibit or kill anything that is not well established, so one needs to balance the effects of the herbicide with not doing anything.)  Last spring I transplanted in a number of black- and brown-eyed Susans (Rudbeckia hirta and R. triloba) and some wild bergamot (Monarda fistulosa) in the gaps that opened up.  It is particularly important for the ‘Susans’ that they be allowed to reseed.  For this year (2021) I will not do the preemergent treatment in the areas with these reseeding perennials.  Instead I will focus on some areas that have not been treated before.

Last year I did experiment with surface burning of stiltgrass seedlings.  While it did provide some temporary control, more seedlings appeared a week or two later.  For me burning with a torch is a maintenance activity and it’s easier than bending over to pick out seedlings.  Spring fire does not work as a one-time treatment in my hands.

Mid-Season

I have been reading more about grass specific herbicides and how they would fit into a plan for eliminating Japanese stiltgrass.  I can see using them as a tool in maintaining a perennial bed or in a well defined, designed landscape.  For me I don’t expect to be using them because most of my landscape is more like managed wildlands.  I generally welcome any native species that pops up annual, perennial, shrub or grass.  So I don't want to run the risk of killing something new and unexpected.

This patch of unmown grass has benefited from both regular pulling
of stiltgrass and a single treatment with a preemergent. 
As I've opened spaces I've planted in natives such as switch grass
and wild bergamot (taller plants to the back right).  The yellow flowers
are wingstem and goldenrods that have come in naturally.

Most of my mid-season activity is focused on pulling and back-filling with desirable, native species.  This year I will be moving many of my excess plants from the vegetable garden, Rudbeckias and Monarda, as well as some overgrown New England asters and goldenrods into spots where I will have weeded out the stiltgrass.  Native species that are competing well against stiltgrass include golden ragwort, mayapple, wild bergamot and grasses and sedges such as river oats, deertongue grass, Virginia wild oats, and rosey and sallow sedges (Carex rosea and C. lurida).

 

This patch of golden ragwort, seen here in mid-April, started from a
single clump planted 2 years earlier.  This species is very effective
at excluding both Japanese stiltgrass and garlic mustard.

6 years ago I seeded in Virginia wild rye.  It is particularly evident
in unmown, shady areas around trees.  This cool season grass gets
started early in the season, well before stiltgrass, and grows 2-4 feet tall.

If pulling is not complete, the remaining stiltgrass will refill newly created voids.  One thing I learned last year was that it can put down roots anywhere a node comes in contact with the soil.  I will try to limit my efforts on mid-season pulling and burning to when I have something to fill back into the open space or where there are new natives trying to get established.  I will store up my energy for late summer when there is less time for the stiltgrass to regenerate and have enough energy to produce flowers and seeds.

Late Summer and Fall

This is a time when you can make a significant dent in the amount of seed that is produced for next year with the least effort.  Pulling stiltgrass that is 3+ feet tall in late summer will remove a huge amount of potential seed.  It’s also easier on the back than pulling shorter plants.  Timing is important.  It should be done early enough that any seed present on the plants will not be able to mature and late enough that and remaining fragments of plants won’t have time to recover and put up additional flowers.  Here in the mid-Atlantic August is about the right time for that. 

If you find yourself pulling stiltgrass later in the season after seeds have started to form you will need to be more careful about disposing the pulled grass.  You don’t want to risk spreading any seed around.  While I knew that stiltgrass has flowers hidden within the stem, I had not realized until last year that there may be flower stalks buried in nearly every leaf node of a healthy stiltgrass stem.  That is a lot of potential seed!

By my index finger you can see one of the flower spikes
 that was hidden within the stem.  These are able to
self pollinate and produce seed without ever opening up.

Cutting or mowing close to ground level is most effective at this time, too.  Burning with a torch at ground level (when safe and where allowed) is also effective.  I’m not certain, but there is a possibility that some cuttings or unburned stem parts may reroot if they contact the soil under favorable conditions.  I will often rake up the cuttings and put them in a separate pile where they can decompose without mixing in with other materials.

In years past I have spent a lot of time in the late summer and early fall raking stiltgrass out of the lawn.  This was probably of little use since much of the stiltgrass had probably developed seed by then.  Last year I combined raking with overseeding with cool season turf grasses.  The hope was that the cool season grasses would germinate quickly and fill in the gaps left from the stiltgrass.  That should work, in theory, but I can't comment on the results.

So the plans are in place and it's almost time to get started!

Plans for 2021

The New Year brings new opportunities for trying new things in the garden as well as continuing projects from last year. 

One project that I will be continuing from last year is removing and replacing vinca from a wooded area.   I will be expanding that to begin removing yellow archangel, Lamiastrum galeobdolon, from an adjacent area.  While this species is not currently on any official state invasive plant lists in the Mid-Atlantic, it is a species of concern.  (It is a state listed invasive in Washington State.  More locally it is on the Arlington County Virginia invasive plant list.)  It does spread aggressively by runners and root fragments.  Pulling is effective as long as all of the plant is removed.  I sprayed some of it with glyphosate last fall when doing garlic mustard treatments, but I don’t know if that will be effective.  Triclopyr is reported to be effective.

I really love the round leaflets of the trefoil and the way winds
its way along to ground, finding openings. 

 In addition to the plants added last year to replace the vinca, this year there will be some white wood aster, Eurybia divaricata, and round-leaved ticktrefoil, Desmodium rotundifolium.  Both of the species are well adapted for growing in dry, partly shady locations.  While the aster is fairly easy to come by I have been searching for the ticktrefoil ever since I first saw it in the wild back in 2005.  I’ve got a lead on it at a not-too-far-away nursery and hope to secure a few plants for this year.  The name trefoil refers to its having three leaves.  This particular species is notable for its distinctly round leaves.  An other common name is prostrate ticktrefoil, for its ground-hugging habit.  This makes a good partner in a matrix planting.  I can see using it around upright perennials like Solomon's seals and clumping ferns.

Virginia waterleaf has deeply incised leaves with whitish splotches
 that resemble water spots.  The plants shown here are in a moist
shady area near the Potomac River.  Other plants in this area include
Virginia bluebells, trilliums and bedstraw.  Photo taken early late April.

Another invasive that I have been fighting for a while and making some headway is Japanese stiltgrass, Microstegium vimineum.  I will continue fighting it with a multipronged assault, including preemergent herbicides and lots of pulling.  As I’m opening up space I’m backfilling with native species.  In addition to more of the Obedient Plant, Physostegia virginiana, that I put in last fall I‘ll be adding some Virginia waterleaf, Hydrophyllum virginianium, to a moist shady area.  This area is already populated by Virginia bluebells, Mertensia virginiana, lady fern, Athyrium filix-femina, and a variety of grasses and sedges.  (In writing this I wonder if I should look into creating a display garden of plants with only the specific epithet of virgini--.  Talk about being a plant nerd.)

The foliage on this NJ tea looks an awful lot like many Japanese spireas. 
Its compact size and tight clusters of white flowers in mid-summer
makes an excellent replacement for exotic Spireas.

While looking over the property it dawned on me that I have a number of exotic spireas that I have been ignoring, but now I’ve decided it’s time to explore some native replacements.  In the past I’ve worked on properties that have had hundreds of spirea seedlings popping up in mulched beds.  I’ve been fortunate here that I have not seen many seedlings at all.  This may be because of the half dozen plants I have all are the same cultivar, and that cultivar is less fertile.  Or the areas where the spireas are do not see much soil disturbance so seeds are less likely to get a foothold.  In any case I set about looking for a compact native shrub that grows to about 3’ and is relatively low maintenance.  Shrubby St. John’s wort, Hypericum prolificum, and the smaller cultivars of summersweet, Clethra alnifolia cv., are two candidates that I already have.  I instead am going for something new, New Jersey tea, Ceanothus americanus.  These are readily available as small plants by mail order but are not very common in larger sizes at area nurseries.  I have some seedlings on order.  Some of these I will plant out directly and some I will bring along in pots for a season.  According to Missouri Botanical Garden website, these will make good container plants that I can grow on my deck.

Prairie dropseed is notable for its dense mounds of fine foliage. 
In late summer it sends up panicles of pink-tinged flowers. 
I see it as a native alternative to exotic fountain grasses.

Another focus for this year will be to relocate the plants I have into the right place.  High on my list is to move my swamp mallow, Hibiscus moscheutos, to a sunnier location.  I put it on the edge of a swale but over the years it has gone light to heavy shade and is now barely surviving.  Another plant that I’ve allowed to get overshadowed is prairie dropseed, Sporobolus heterolepis.  This beautiful fine bladed grass can grow into 2-3’ mounds, topped by wispy flower plumes in late summer.  While primarily a plant of the Mid-West it is also found on a few sites in the East, possibly prairie remnants.  I allowed mine to get swallowed up and shaded over by some exceptionally healthy coral honeysuckle, Lonicera sempervirens.  I will be getting some new plants and put them into more open locations where they can reach full size.  These are also good candidate for container gardening, so I may set 1 or 2 aside for that purpose.

While I had planted tomatoes here, there was also a crop of black-
and brown-eyed Susans coming in.  These were all first year
rosettes so they did not compete much with the tomatoes for air-space,
but I imagine there was a lot of root competition.

In the vegetable garden I have the opposite problem.  The surrounding wildflowers, particularly the black- and brown-eyed Susans, Rudbeckia hirta and R. triloba, have invaded the beds.  Rather than throw them out I will move them to an area where I am battling Japanese stiltgrass.  The timing should work out where I can use a torch to burn off the first crop of stiltgrass seedlings at the beginning of May and then transplant in the Rudbeckias as the veggie garden is getting prepped.

Speaking of fire, last year I used the garden torch to control weeds in the vegetable garden.  Areas that were cultivated followed by flaming seemed to have fewer weeds than areas that were only cultivated.  However weeds did continue to germinate through the spring so burning is not a one-time thing.  A couple of weeks ago I went out to find a garden bed covered in hairy cress, a winter annual weed.  I got out the torch to see if I could kill these weeds without disturbing the soil.  I checked the bed about 10 days later and most of the cress was dried up.  Aside from keeping the fire under control, my biggest concern is damaging any in-ground irrigation lines.  A quick pass of a torch is enough to melt a soaker hose.   I find the use a the torch most effect at clearing areas where the fencing is buried beneath the soil.  The fire is able to reach between the holes in the chicken wire that would be otherwise inaccessible with a hoe. 

The upper image is immediately after flaming the bed on the right. 
The cress has taken on a darker green color.  10 days later most
of the cress is brown, but a few cress evaded the flame. 
Note that I pulled the soaker hose out of the bed before burning.

2020 Year in Review

Seems like so many of my blog posts are about removing invasive species.  That is a big part of gardening and landscaping, editing out the things that don’t belong.  That said, the more exciting aspect of gardening is putting in new plants and features and celebrating new milestones.  With that in mind let’s take a look back on new things that I’ve encountered/undertaken in my landscape.

This past year I have been trying to be smarter about where I placed plants.  I’m trying to make the hard choice not to buy something if I don’t have the right conditions, or enough space, for it.  An example is wavy hair grass, Deschampsia flexulosa.  While tolerant of shade I placed on the edge of a shrub border along with some mountain mint.  I was quickly overgrown and did not make it through the season.  This year I planted it in open shade in a dry location where there won’t be much competition.    

I did start some native perennials from seed this past year.  I had good results with downy woodmint, Blephilia ciliata, both in terms of germination and potting up and planting out.  It seems to be doing better in open shade in average to dry soils. This is another candidate as a vinca replacement.  I also had good results germinating and potting up both fireweed, Chamaenerion angustifolium, and pearly everlasting, Anaphalis margaritacea.  Neither of these did well after being potted up or when planted in the garden.  They seemed to have a problem with the soil being too moist, or not draining fast enough. 

A few years back I planted a ring of red osier dogwoods, Cornus sericea, around an existing clump of forsythias with the goal of eventually removing the forsythias as the dogwood got established. The dogwoods on the sunnier, drier side of the forsythias have died off.  I replaced one of these with a gray dogwood, C. racemosa, which is more tolerant of dry soils. Other woody plants added were a shadbush, Amelanchier canadensis, and a choke cherry, Prunus virginiana.  I had planted some these bare root in the past and had limited success.  This time I got larger, potted specimens and I planted them where they would get better light.

I got an American beautyberry, Callicarpa americana, and put it in the same area as some of the Asian species, purple beautyberry, C. dichotoma, which are starting to spread more than I’d like.  As the native shrub matures I’ll pull out the exotic species.  We are located just north of its native range, but with global warming, it will probably do all right here.

American beautyberry, at the top, has larger, more
oval leaves than purple beautyberry (below).

In the spring I removed a sourwood tree that never developed due to being pot bound, even after over 7 years in the ground.  I replaced it with a ‘Wintered’ winterberry holly.  I think the medium-sized shrub will be in better scale for the location, the access path between our house and garage.  I already have a couple of male winterberries in the area, so I should be getting berries to benefit our overwintering birds.

I got a pair of Hydrangea arborescens ‘Haas Halo’, a lacecap form of smooth hydrangea having many more fertile flowers than the very popular mophead cultivar ‘Annabelle’.  I expect these to be better for the pollinators.  They arrived late in the year and I put them in the ground as soon as I could.  I will need to mulch them soon to help them survive their first winter here.

I would like to get all the vinca out of this area and replace
 it with suitable Mid-Atlantic native species.  The new plantings
went in on the right edge.  The foreground is mostly established
Heuchera and Tiarella.

My big ‘new’ project for 2020 was to get busy removing a large bed of Vinca minor from under some evergreens.  I am taking a matrix approach of adding a variety of native plants, compatible with dry shade and seeing what is successful.  Here’s a list everything in the mix: Aquilegia canadense, Eurybia macrophylla (seed grown), Geranium maculatum, Heuchera villosa, Heuchera ‘Palace Purple’, Solidago flexicalis, Tiarella cv., and Viola labradorica.  Two fine bladed evergreen grass-like species are also included: Carex eburnea and Deschampsia flexicaulis.  The violet is looking particularly good in the open right now in December.  We’ll see this spring how suited these are to this dry, partly shady location.

This past spring I planted a number of small trees in the woods, particularly red maples, which I had potted up and held over the winter. I put them in areas where I had killed some mature tree of heaven, Ailanthus altissima, to get a head start on reforestation.   Being somewhat remote these trees did not get a lot of aftercare.  Not surprisingly, most did not survive.  Recently I saw this story about success of natural succession.  They observed that trees that came up from the existing seed bank performed better than ones that were planted.  Maybe adding trees to the already forested areas is more work than it’s worth, especially when there are already naturally occurring seedlings present.  On my last survey of the area I noticed a number of seedlings of hackberries, maples, oaks and tulip trees.

I’m starting to get fruits on some of the native trees that I planted.  I got my first persimmons this year.  I planted this tree about 7 years ago.  I also got some berries formed on the fringetrees, Chionanthus virginicus, but these didn’t stay on the tree long enough to ripen.  I also go some fruit on my 4 year old sassafras.

My first crop of persimmons.  Persimmons are not ready
to be picked until they are soft and starting to wrinkle.  These are ready!

The dark blue sassafras berry has already fallen away leaving
the bright red pedicel.  This effect should be more striking
when the tree has more than two berries.

Freshly planted obedient plant. 
I hope that it will spread here
and help displace the
Japanese stiltgrass.

On the invasive species front I’m making good progress against Japanese stiltgrass using a variety of methods.  The use of pre-emergent herbicides in early spring has been particularly helpful.  I also saw less hairy cress, Arabis hirsuta, in the lawn.  This reduction was probably a combination of pre-emergent treatments and early season mowing to remove flowers before seeds ripen.  By reducing the amount of annual weeds, the lawn is able to knit together more tightly.  This makes it harder for new weeds to get established.  I’ve also planted some obedient plant, Physostegia virginiana, an aggressive native species see how it does against stiltgrass in a shrub border.

For garlic mustard I am including a fall treatment with glyphosate, after most other plants have lost their leaves.  I did this in mid-winter 2020 and it seemed to help reduce the number of mature plants in the spring.

So now that the 2020 growing season is about to close, it’s time to start thinking about what to do in 2021.