September is synonymous with school. So, this week we are
getting back to basics with a post that defines foundational gardening terms.
The better you understand these terms and phrases, the easier it will be to
identify, select and care for plants in your landscape.
Growing season: The period between the beginning of growth in
the spring and the cessation of growth in the fall.
Hardiness zone: Expressed as a number and letter combination
from 1a to 13b, the US Department of Agriculture has assigned a zone to every geographic
area of the United States based on the average annual minimum winter
temperature. Tags on plants sold commercially often identify the zone(s) in
which the plant will grow.
affected by landscape, structures, or other unique factors in a particular
for the three major plant nutrients contained in manure, compost, and
fertilizers. N stands for nitrogen, P for phosphorus, and K for potassium.
started from seed that grow, mature, flower, produce seed, and die in the same
Biennial: Plants that take two years, or a part of two years, to complete their life cycle. By freely reseeding, a biennial plant may seem to come back year after year, but you are actually seeing new plants.
Perennial: A plant that lives more than two years and produces new foliage, flowers, and seeds each growing season. Tenderperennial: A perennial that is not tolerant of frost and cold temperatures. Applying a winter mulch can help it survive It may die off above ground and regrow from the roots.
Woody perennial: A plant that goes dormant in winter and begins growth in spring from above-ground stems. Herbaceousperennial: A plant that dies back in the winter and regrows from the crown in spring.
Exotic: A plant of foreign origin or character; not native; introduced from abroad, but not fully naturalized. Naturalize: The process whereby plants spread and fill in naturally.
Native plant: A plant indigenous to a specific habitat or area. Nativar: A plant that is a cultivar of a native plant. Cultivar: A cultivated variety of a species. Propagation of cultivars results in little or no genetic change in the offspring, which preserves desirable characteristics.
Integrated pest management.
A method of managing pests that combines cultural, biological, mechanical, and
chemical controls, while taking into account the impact of control methods on
Invasive. Growing vigorously and outcompeting other plants in the same area; difficult to control.
Noxious weed. Weeds that have been declared by law to be a species having the potential to cause injury to public health, crops, livestock, land, or other property. Noxious weeds are very invasive. There are 124 plants in NC that meet the legal criteria.
When a gardening term has you stumped, refer to the glossary chapter of the Master Gardeners Handbook for a definition – there are hundreds of entries — and a small dose of continuing education.
Typically I don’t get riled
up about weeds that are easy to pull up by hand, but Japanese stiltgrass (Microstegium vimineum) is a HUGE
exception. Despite its fibrous, shallow root system, in just three to five
years this invasive species can overtake a natural area, pushing out natives
and non-natives alike. It is also detrimental to ground-nesting birds and can
contribute to fueling forest fires. I’ve observed more and more of it in local
forests and parks where I hike as well as the roadsides in my woodsy Durham County
neighborhood. It’s a sad sight, especially on conservation lands.
This spring was the first time I noticed stiltgrass at a friend’s home in the Piedmont region of Virginia. Normally when I‘m there I’m grousing about periwinkle (Vinca minor) and winged burning bush (Euonymous alata), two other invasive species which I have previously blogged about. I admit to feeling a bit of poetic justice at the sight of the one invasive (periwinkle) being overtaken by another (stiltgrass). But the feeling was fleeting. Every subsequent feeling has been more along battle lines – how can I fight this?
Before attempting to eradicate any weed, you want to be sure you have identified it correctly. When I first noticed stiltgrass, its structure and wispiness reminded me of bamboo, albeit a tiny version.
In plant ID lingo stiltgrass is a “prostrate to erect, sprawling and freely branched summer annual with spreading stems that root at the nodes … Leaves are rolled in the bud; ligules are short membranous with hairs …”1 If you’re thinking, hey what IS a ligule? Don’t despair! Stiltgrass does have one distinguishing characteristic that you need not be a botanist to recognize: Each leaf on stiltgrass has a silvery midvein that divides the leaf unevenly.
Note in the accompanying photo gallery how this feature is absent from other plants (some weedy, some not) that are often mistaken for stiltgrass.
The root structure of stiltgrass is also distinct from other weeds often mistaken for stiltgrass as noted in these photos. (Stiltgrass is the photo with the brown background.)
Growth habit and lifecycle Japanese stiltgrass seeds germinate in early spring. The plants grow and strengthen through the summer. In June the Virginia patch was about six inches high; At the beginning of August, the plants were two to three feet tall. In NC it flowers from mid-September through October and soon after flowering the seeds are dispersed – 1000 seeds per one wispy plant! Seeds stay viable in the soil for four years.
I consulted a lot of sources before writing this post and it seems that there is not one “right place” for stiltgrass to thrive. Some sources advised sun, others shade. Some moist woodland, others dry roadsides. Apparently, it is adaptable to a variety of conditions. It will even tolerate a mild frost. And, it really makes its presence known in areas where the soil has been disturbed. This may have been a factor for the Virginia property I referred to earlier as several very large trees were felled, cut up, and carted away from the land over the last year. That kind of activity definitely disturbs soil and surrounding environment.
Understanding the lifecycle of a weed or any unwanted plant is important because in order to stop it from spreading you need to stop it before it seeds. The flowerhead on stiltgrass though is quite small as are the seeds, so best to act based on the time of year than on a visual. From now through September is a good time for those of us in Durham County to act.
Tactical solutions Here are three ways to combat a stiltgrass invasion. Which tactic you choose will depend upon how much stiltgrass you have, where it is growing, and your comfort level with chemicals.
Hand-pulling or digging While this tactic is typically my go-to for weeding, it only makes sense with small infestations and even then, there are some caveats. When we pull weeds by hand, we disturb the soil which is often enough to bring previously dormant seeds to the surface where they will receive the sunlight they need to germinate. “Hand-pulling of stiltgrass plants needs to be repeated and continued for many seasons until the seed bank is exhausted.“2
Mowing If stiltgrass is growing in your lawn (or what passes as your lawn) then mowing seems like an obvious tactic. But when stiltgrass is mowed too early in its lifecycle, the roots re-energize and send new shoots above ground more quickly than the first time and it may flower and seed earlier, too.3 If possible, delay mowing stiltgrass until the end of August to deter regrowth or seeding.
The best way to prevent stiltgrass in a lawn is to follow best practices for lawn seeding and care. To learn how to properly maintain your lawn consult Carolina Lawns: A Guide to Maintaining Quality Turf in the Landscape
Herbicide My friend has given me complete freedom to attack the burning bush and the stiltgrass around his home, but not the periwinkle which he likes very much. After three decades it is as much a part of his mountain retreat as the cabin it surrounds. Knowing I needed to save the periwinkle, I turned to the one-percent solution. This is a tip I received from a weed control expert at a local botanical garden during an educational class. (We master gardeners need to complete at least eight hours of education each year.) Extension programs also endorse this solution.
A half to one-percent solution of glyphosate will kill Japanese stiltgrass without harming the other plants around it. Ready to spray containers of glyphosate I have purchased held an 8% solution. Concentrated varieties were 18%. I share this information to drive home the point that more IS NOT better. I suited up (long pants, long-sleeved shirt, tall rubber boots, nitrile gloves) before mixing up a much diluted version of the herbicide and I sprayed the stiltgrass.
Do not use glyphosate on your lawn. Pre-emergent herbicides for crabgrass are recommended for preventing stiltgrass from growing in a lawn. These are best applied in late spring or early summer so that the lawn has time to recover.
Weeding is a commitment Whichever method you choose, plan on at least a five-year commitment. Since I don’t live on or near the property I treated, I won’t know the outcome of my effort until the fall. But I already understand that my work is not finished. I was working in a natural area on a mountain side. I could not reach all the stiltgrass. Hopefully, the patch of stiltgrass growing on your land is smaller, more easily accessible and responds to your chosen method of treatment.
A fellow Extension master gardener recently brought this cheerful-looking plant to my attention. Its common names are lesser celandine or fig buttercup. (Scientific name is Ficaria verna and was formerly Ranunculus ficaria.) She spotted it blooming in March on the Ellerbe Creek and also beside the Eno River at Penny’s Bend, an area known for extraordinary native flora. However, this plant is not native to the the Southeast nor even to North America. It is an aggressive, exotic, invasive species that threatens to displace our beloved native spring ephemerals.
Lesser celandine is a herbaceous perennial that emerges earlier than most native species. Additional identifying characteristics are:
A basal rosette of dark kidney- or heart-shaped leaves;
A bright yellow flower blooms on a single stalk that rises eight to nine inches above the leaves;
Small bulbets borne in the leaf axis.
Abundant fig-shaped tubers form along the roots; Even when separated from the parent plant, the tubers can produce a new plant.
An overall tight low-growing mat that rapidly chokes out neighboring seedlings.
It grows best in moist, shady soils like those in a river’s floodplain.
Supporting its rapid growth are three ways the plant can reproduce: by the tubers/root fragments, by seeds, or by the bulbets. Any of these methods can form a new plant in the vicinity of the parent or be carried downstream to begin colonizing in a new location.
Complicating matters of identification is that lesser celandine looks very much like marsh marigold (Caltha palustris) which is native in North Carolina and enjoys similar growing conditions. The two can be distinguished by the number of petals on the flower (typically eight for lesser celandine and five for marsh marigold) and the appearance of the leaf margin (smooth for lesser celandine and serrated for marsh marigold).
Like many invasive plants, this one was introduced commercially as an ornamental plant. It became popular in the Northeast, but its status is in transition. It appears on the The North Carolina Native Plant Society invasive plants list as a “significant threat.” Yet it is absent from the USDA Natural Resources Conservation Service’s list of noxious weeds in North Carolina. That list reports that it is absent/unreported in N.C. and S.C., however according to the South Carolina Native Plant Society, it is banned in S.C.
Exotic plant species that essentially grow too well in an area negatively impact a local ecosystem by crowding out the native plants. Insects, birds and animals native to the area depend upon native plants for nutritional sustenance and preferred habitat.
If your property offers the ideal growing conditions for lesser celandine or marsh marigold and you appreciate diversity in your landscape, keep an eye out for an expanding patch of low-growing plants with bright yellow flowers. If it turns out to be lesser celandine, feel free to remove it. If you locate it on land you do not own, say while you are enjoying a public park or private nature preserve, you may bring it to the property owner’s attention, but you do not have the right to remove it. The patch recently found at Penny’s Bend Nature Preserve has been removed, and the patch on Ellerbe Creek was sprayed by a licensed herbicide applicator. It was linked to a larger patch growing behind a house just a couple blocks upstream on a feeder creek.