Friday, July 30, 2021

It's Stiltgrass Time Again

As summer is peaking so is the time to focus on removing Japanese stiltgrass, Microstegium vimineumAt this time (beginning of August) in the Mid-Atlantic region this invasive grass is putting on a growth spurt, but has not yet begun to develop viable flowers. In one of my previous blog posts on this subject I prepared this table to help keep track what to do to combat stiltgrass at each point in the season.

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.

While it is too late to count on herbicides cutting close to the ground level and pulling at very effective methods to employ at this time in order to prevent Japanese stiltgrass from reproducing.  Because this is an annual grass, keeping it from reseeding goes a long way to eliminating from your environment.  In wooded areas and existing beds where there are many desirable plants intermixed with the stiltgrass I opt for pulling as my preferred approach.  Since it has grown fairly tall by this time, I usually pull it by the handfuls then leave it out in the sun to dry.  If you are weed whacking it you could leave the cut grass in place to dry; however, I’ve read that doing this can generate a thick layer of thatch that can be difficult for other plants to grow through.  Whenever possible I will rake out the cut grass and leave it in the sun.  If I’m confident that there is no viable seed in the stiltgrass I will mow over the dried grass to help return that organic material to the soil.

For several years I have been removing stiltgrass manually from this
shady mossy lawn.  This year I treated it with a preemergent herbicide
 in late April and am seeing only a few instances of stiltgrass.  In addition
to the moss and some fine fescue and sedges there are patches of selfheal,
Virginia jumpseed and white avens. 

I’ve noticed that this year that the stiltgrass is more brittle and harder to pull cleanly out of the ground.  This may be due to the drier weather that I am experiencing at this time.  I’m afraid that I may be leaving more rooted fragments that may be able to regenerate.  I will try to time my next pulling campaign to be after a significant rainfall to soften the soil. 

Another thing I’ve noticed this year is that the plants that I am pulling up have multiple rooting points along the stem.  I’m thinking that as I am reducing the number of stiltgrass plants, year by year, there is more room for them to spread laterally.  So a partial success, but it means that there is still more work to be done.


I've treated this woodland path for two consecutive years with a
preemergent as indicated by the white line.  You can see the
bright green stiltgrass to the back and on the right. In the treated area
are a variety of grasses and sedges.  Deer tongue grass is the
largest species here.  In late March this area is covered with spring beauties.

Looking over my property I see that the most significant reduction in Japanese stiltgrass is where I have applied a preemergent herbicide in early spring.  This year I applied Dimension™ (dithiopyr) at the higher recommended rate.  This is expected to be effective for 3-4 months.  It was applied at the time recommended for crabgrass control (380 GDD(32°F)), or about the time when the forsythia were coming into full bloom.  I am seeing next to no stiltgrass in many parts of the lawn as well as in the treated parts of my ‘mown meadows’.  Better results are seen where I have treated for at least two consecutive years.  In these meadows and in the more natural areas I try to avoid treating the same area with a preemergent two years in a row.  This is to allow the seeds of the many desirable plants to germinate on the off-years. 

As far as native plants that compete well against Japanese stiltgrass, golden ragwort, Packera aurea, seems to actually suppress the growth of stiltgrass.  Virginia wild oats, Elymus virginicus, and bottlebrush grass, E. hystrix,  compete well.  What I believe to be fowl manna grass, Glyceria striata, has been able to out compete Japanese stiltgrass in shady moist areas.  This grass develops early in the year with tall, thick growth that shades the ground.  The downside of this grass is that it dies back to the ground after going to seed in late June.  

This photo, taken at the end of May, shows thick growth of
a grass that I believe to be fowl manna grass.  The area inside
the white circle has been free of stiltgrass for the past two years.

 I have been posting blogs about my battle with Japanese stiltgrass since 2014, probably 3-4 times a year.  Following are links to several of the more informative posts.  Getting Ready for Stiltgrass 2021, July 2020 What to do about Stiltgrass Now, The Forsythia are in bloom, Now is the Time, and Making a Plan to manage Japanese Stiltgrass.

Friday, July 16, 2021

I Planted ...What???

For a long time I’ve wondered why the great interest in exotic barberries and no mention of our native species, American barberry, Berberis canadensis.  From the design standpoint, Japanese barberry offers a wide variety of foliage colors and forms while, as it stands today, there is only the native form of B. canadensis available.  Of course the Japanese barberry, B. thunbergii, we see today is the result of much work in the horticultural field to develop all those unique forms.  This widespread use of Japanese barberry in the landscape has led to its spread into the wild.  Birds do like the red berries and deposit them throughout the landscape through their droppings.  Once established in the wild it is able to out-compete native vegetation as it is rarely browsed by deer.  Instead the deer turn to native vegetation, in many cases severely decimating the native plant populations.  Japanese barberry has also been associated with the spread of Lyme disease due to its tendency to harbor ticks.

This American barberry was planted in early spring
and has more than doubled in size since then.
 

Identifying features of American barberry are the
 three-pronged thorns and the teeth or bristles
on the leaf margins as indicted by the arrows.


American barberry, B. canadensis, is a mounding shrub growing from 2 to 6’ tall that can spread via underground stems.  It has 1-2 inch long spatulate leaves with widely toothed margins.  Its thorns are three pronged, which differentiates it from the single pronged Japanese barberry.  In the spring it bears drooping clusters of yellow flowers.  The flowers give way to red, edible fruits in late summer to early fall.  One concern with American barberry is that it is an alternate host for black stem fungus (rust) in wheat.  (European barberry, B. vulgaris, is the major offender which led to its near total eradication in wheat farming areas.  Japanese barberry does not act as a host for this disease.)  However this is not as significant of a problem within its native range south from PA to GA.  Native habitats include savannah and open woodlands, but these areas are decreasing due, in part, to fire suppression leading to increases in shade.  Some gardening sources indicate that American barberry will grow under a variety of conditions, in the wild it favors shallow, neutral to basic soils.


The reason I wanted to try now American barberry is as a replacement for Asian spireas.  In particular I’m looking for a mounding shrub that blooms in the summer and grows 3-4’ tall.  I would also expect that this barberry would be resistant to browsing by deer, but that is not confirmed.  I'm also looking at NJ Tea, Ceonanthus americana, as possible spirea substitutes.  More on that later.



I found this Eastern Wahoo growing in Beaver Brook Reservation
 in Belmont, MA.  The inset shows the deeply furrowed bark which
 appeared to take on a diamond-like pattern
.

 The other new plant that I got this spring is Eastern Wahoo, Euonymus atropurpureus. It is a small tree or large shrub native to the eastern U.S.  I have generally been in the business of ripping out Euonymus species whenever I saw them.  This has applied particularly to burning bush, E. alatus, and wintercreeper, E. fortunii, both invasive species.  A number of years ago I came across an Eastern wahoo growing in an unmanaged suburban woodland in the Boston area.  The bright colored seed pods in fall and the diamond patterned bark were two attributes that sparked my interest.  What I found may have been a garden escapee since it is not native to the New England states. Its native range is primarily in the Mid-West; however, it does extend into parts of Maryland, as well as Pennsylvania, Virginia and West Virginia.  So when I saw that it was available at a regional native plant nursery I decided to give them a go.  It is quite shade tolerant so I put them in an area where I have been removing established tree of heaven, Ailanthus altissima, as well as seedlings of burning bush.


This photo, taken in early November, shows that Wahoo holds onto its leaves
fairly late into the year.  Most of the red arils have fallen from the flowers. 

One of the tricky aspects of planting eastern wahoo, while actively removing winged euonymus seedlings is that I will need to tell them apart, lest I remove a desirable plant.  The obvious thing is to make sure that I keep a recognizable tag on the wahoo and remember where they are planted.  Comparing young wahoo to burning bush seedlings show both to have some corkiness, but the Wahoo has it in straight lines and it is not as pronounced as on burning bush.  Also, the leaves of burning bush are stiffer and more narrow and pointed than those on a young wahoo. 

Here's a comparison of an existing burning bush (left) with
 an Eastern Wahoo seedling (right).


Tuesday, May 25, 2021

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.

 












Friday, April 2, 2021

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. 


Friday, February 19, 2021

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!