Tag: green mulch

Bringing Plants of the Piedmont back to Downtown Durham

On By durhammastergardenersIn bees, beneficial insects, birds, cover crops, CPTED, crime prevention through environmental design, Downtown Durham, NC, drought tolerant plants, Durham NC, garden design, gardening, Gardening calendar, Gardening information, gardening NC, green mulch, ground covers, ground covers for living mulch, how to improve soil, insects, landscaping for wildlife, living mulch, native plant list, native plant list for Piedmont NC, native plants, Natives, NC Native Plants, Perennial, phenology calendar, Piedmont Prairie Garden at Rotary Plaza, pollinator gardening, polyculture, renewable gardening, soil, soil health, sustainability, sustainable garden design, sustainable watering, sustanability, Uncategorized, urban challenges in landscaping, urban garden, urban gardening, urban heat islands, urban planning, urban prairie garden, urban wildlife, uuban service benefits in landscapes, water wise plants, wildlife

By Eric Wiebe, NC State Extension Master GardenerSM volunteer of Durham County

A once neglected site, Rotary Plaza in downtown Durham comes alive in July 2021 with sunflowers that produce seeds for wildlife. Millet, a grain used here in the design and novel to many urban dwellers, also serves as a great food source for gold finches and other birds. (Image credit: Ben Bergmann)

Have you noticed changes to the plantings in downtown Durham over the past few years? If not, you need to head on down, walk around, and appreciate the transformation of the many of the city-owned green spaces. This transformation, and the strategies behind it, point to a new way of thinking about our relationship to the landscape, both in urban settings like downtown, but also in our own yards. 

I had the pleasure of both walking around downtown Durham with and then sitting down and talking to Ben Bergmann, the architect of this transformation. Ben was hired by City of Durham in September 2020 and charged with re-envisioning and elevating horticulture in downtown Durham, including creating a Downtown Horticulture Crew within Landscape Services. Ben brought a widely varied background to this position, trained with BS, MS, and PhD degrees in plant sciences, and working as everything from small business owner and farmer to tropical agroecologist and research scientist. One thing all this work has in common is plants and his great love of them. Ben feels this broad range of experiences has helped prepare him for a job that has him applying both the art and science horticulture to a municipal government position with its many constraints and opportunities and multitude of stakeholders. 

“When I started, I realized I needed a mission statement to clearly and concisely communicate to my supervisors and the public what I and my unit in government is doing.” He stated that his landscape design and management are guided by the goal of enhancing

  • Environmental sustainability
  • Programmatic stability
  • Aesthetic appeal
  • Service benefits

He notes that it is important to recognize that these categories are not mutually exclusive, but each has a role to play in his horticultural work supporting the living landscape in downtown Durham. 

Designing Sustainably

Ben explains that a crucial re-orientation is to start planning a landscape by thinking about how it can best align with the ecosystem, and that means starting with native plants that can be used. “For urban contexts some people would say that there is nothing native to these downtown spaces, and they will use this as an ‘out’ to plant whatever they want. I don’t embrace this–something was native, originally, in these spots. Many times these native plants can and will grow and thrive in these spaces.”

When Ben thinks about which native species to use, he first looks for plants native to the North Carolina Piedmont and secondarily to the larger Piedmont of eastern U.S. He notes, however, that it is very important to select plants with a long-range vision. That is, when accounting for global climate change, plants that are going to be here in 20 years may very well be in an environment that looks more like the southern Piedmont, our coastal plains, or South Carolina.

(Left to right) By selecting plants that can cope with a warming environment, Bergmann installed dwarf palmetto (Sabal minor), a plant typically associated with climates in the native ranges east and south of Durham, NC, and shown in green on the USDA’s zone map. (Image credit: Ben Bergmann; https://plants.usda.gov)

While native species take the lead when planning bed renovations, Ben states that non-native plants can still play a role. Returning to his guiding principles, non-natives can help fill functional gaps that might be hard to resolve in the short run with native species. Similarly, there are times that a spot planting of a non-native will help achieve a particular aesthetic goal by providing highlight color, texture, or architecture.

(Left to right) Before, a non-imaginative flag pole bed at Durham Parks and Recreation building included a highly invasive and exotic species: Nandina domestica. After a re-imagining, the same bed demonstrates there is a place for non-native plants alongside natives, especially during transition phases. (Image credit: Ben Bergmann1

Because the legacy plantings downtown were almost 100% non-native, it means that during a bed’s transition period, some non-natives may be left to help visually and functionally stabilize the bed until new, native plants can get established and then take over. Among other things, the non-native plants retained just for the transition can provide shelter from the sun and wind during establishment.

(Left) The process of establishing an urban prairie at the Rotary Plaza began in September 2020 with beds filled with weeds and remnants of long past garden attempts. (Middle) In March 2020, the the beds are full of cover crops: crimson clover, a nitrogen fixer that is great for pollinators in early spring, and winter rye, which has high biomass production and deeply penetrating roots. The intricate planting pattern reflects intentionality and provides visual interest. (Right) By July 2022 the Piedmont Prairie Garden at Rotary Plaza is realized and chock-full of sustainable native plants. (Image credit: Ben Bergmann)2

Even given how much he has achieved is such a short time, Ben still takes the long view when planning and planting. For example, cover crops have been used in very purposeful ways in areas such as the Rotary Garden. During the initial transition of this space, cover crops were planted and maintained in ways that not only helped build the soil, but created visual interest. Over time, the cover crops matured and eventually replaced with native perennials, creating an evolving horticultural narrative in this space. As Ben said, “Some [landscape] designers shy away from transitions–they want to ‘put a tarp over it’ until it has reached its final phase. I don’t shy away from transitions; they are an important part of my plans.”

Ben notes that using select non-native plants, cover crops, and other annuals allows him to more easily use seeds, plugs, and small plants in the beds. In the case of herbaceous perennials and woody plants, besides being less expensive, younger, smaller plants will typically develop more robust root systems and quickly outgrow their bigger counterparts.

Addressing Urban Challenges

Ben was quick to remind me of the many contextual limitations and challenges the Downtown Horticulture Crew faces daily that home suburban gardeners rarely have to contend with. For example, CPTED (Crime Prevention Through Environmental Design), is an important set of guiding heuristics that often preempts other design considerations. In addition to making sure plantings do not screen illicit activities, it also disallows designs that interfere with security cameras or impair pedestrian safety, including driver site lines at street crossings. 

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The center of the Chapel Hill Street parking lot is a perfect example of an urban heat island with even hotter microclimates where landscapes are needed. (1) In January of 2022, the lot was cleared of weeds and other unhealthy, dated, and non-native landscape plants. (2-5) The view in 2024, after Bergmann and his team revitalized the area with an assortment of heat-tolerant natives. (Image credit: Ben Bergmann)3

Most of the beds Ben and his crew manage are surrounded by heat absorbing asphalt and concrete and buildings with glass that intensify solar radiation by reflecting light onto them. This creates heat islands much hotter than in surrounding communities. In addition, tall buildings funnel wind through these spaces and block rain, further desiccating plants. 

Humans also are unhelpful, by walking on, driving over, or otherwise physically challenging plantings. Some soils are more like landfill or construction sites, and many have the negative impact of overuse by dogs on their walks. Even with these challenges, Ben has identified quite a few native species that are up for environmental extremes while still fulfilling functional and aesthetic goals. Not surprisingly, he is currently exploring the possibility of a demonstration xeriscape-inspired bed. This one may very well include some non-native plants more typically found in desert environments.

Educating the Community

Ben understands that an important part of his job is educating not only the workers and residents of downtown Durham but all city residents and visitors as to a new way of envisioning landscapes. Landscapes that, while they exist in a human-built environment, much more clearly reflect real ecosystems of the NC Piedmont. This means not only planting predominantly native species but planting them in soil nourished by natural mulches created by the plants themselves rather than imported, dyed wood chips. He also allows the plants to go through full cycles, creating visual landscapes that sometimes predominate in browns, grays, and blacks, as much as greens, yellows, and reds. 

(Left to right) The Piedmont Prairie Garden at Rotary Plaza in early January with the last vibrant colors and in late February, when the remaining plants still create an almost black-and-white picture. (Image credit: Ben Bergmann)4 (Below) By designing a phenology calendar for his plantings, Bergmann pays careful attention to nature’s timing. This tool helps gardeners know when to plant, specific bloom times, and when colors, textures, and other elements are present throughout the seasons. For a closer view, click on the link for an electronic version of the calendar in our Resources and Additional Information section below.

He is heartened that there is a growing critical mass of professionals helping him in this educational work. The City of Raleigh and Wake County has been hard at work creating plantings that reflect this same vision. He also has strong allies at Duke Gardens, where Annabel Renwick, has provided both inspiration and plants for some of the bed designs. Ben recognizes that it will take a while both for his beds to reach the final stages of their design vision and for Durham residents to embrace this new look, but he has already received lots of positive feedback for his renovated beds. It will also be up to Durham Master Gardeners, and committed gardeners everywhere, to help continue to educate the public and support this work.

Plant lists for featured Downtown Durham Sites

1–The planting design at the Parks and Recreation administration site include a mix of natives (*) and non-native plants: threadleaf coreopsis* (Coreopsis verticillata), creeping phlox* (Phlox subulata), eastern ninebark* (Physocarpus opulifolius), panicle hydrangea (Hydrangea paniculata), lantana (Lantana camara), coleus (Solenostemon scutellarioides).

2–Plants in the Piedmont Prairie Garden at Rotary Plaza include swamp milkweed (Asclepias incarnata), blue mistflower (Conoclinium coelestinum), purple coneflower (Echinacea purpurea), Joe-Pye weed (Eutrochium fistulosum), Spotted Joe-Pye weed (Eutrochium maculatum), common sunflower (Helianthus annuus), scarlet rosemallow (Hibiscus coccineus), larger blue flag iris (Iris versicolor), cardinal flower (Lobelia cardinalis), switch grass (Panicum virgatum), garden phlox (Phlox paniculata), hoary mountain mint (Pycnanthemum incanum), brown-eyed Susan (Rudbeckia triloba).

3–Center of Chapel Hill Street parking lot showcases the following native plants: sedge (Carex bicknellii), purple love grass (Eragrostis spectabilis), Elliott’s lovegrass (Eragrostis elliottii), scarlet rosemallow (Hibiscus coccineus), swamp rosemallow (Hibiscus moscheutos), Virginia sweetspire (Itea virginica), tulip poplar (Liriodendron tulipifera), black-eyed Susan (Rudbeckia hirta).

4–The Piedmont Prairie Garden at Rotary Plaza in late February still offers color, texture, and winter interest. They include climbing aster (Ampleaster carolinianus), scarlet rosemallow (Hibiscus coccineus), switch grass (Panicum virgatum), hoary mountain mint (Pycnanthemum incanum), white goldenrod (Solidago bicolor), showy goldenrod (Solidago speciosa)–with touches of hopeful green, beardtounge (Penstemon digitalis), eastern beardtounge (Penstemon laevigatus), stoke’s aster (Stokesia laevis), adam’s needle yucca (Yucca filamentosa).

5– See below for Bergmann’s list of natives that are tried-and-true performers for Durham and central North Carolina.

Resources and Additional Information

Piedmont Prairie Garden at Rotary Plaza Bloom Time / Color Calendar (electronic version)

https://go.ncsu.edu/piedmontprairiecalendar

NC State Extension on landscaping for wildlife with native plants in urban environments

https://content.ces.ncsu.edu/landscaping-for-wildlife-with-native-plants

North Carolina Native Plant Society’s list of recommended native species

Recommended Native Species

NC State Extension on all things native plants

Article Short Link https://wp.me/p2nIr1-4Ku

Sustainable Summer Gardening: Irrigation and Soil Coverage Tips

On By durhammastergardenersIn irrigation, Uncategorized

By Melinda Heigel, NC State Extension Master GardenerSM volunteer of Durham County

(Image credit: Pixabay)

With temperatures increasing and perennials waking up from their long seasonal slumber, summer will be quickly upon us. Summer gardening in Durham County presents both challenges and opportunities in the home landscape. Our summer brings the challenges of high heat and humidity, strong sun, and dry weather.

The good news is we live in a region (USDA hardiness Zone 8a) that allows us to grow a wide variety of ornamental plants and vegetables. And despite our constant bemoaning about clay soils, they are often quite rich in nutrients and retain needed moisture.

Probably one of the toughest things gardeners face when the mercury rises is ensuring plants have adequate moisture. As we all know, water is an important resource, so how can you maintain landscapes by using water wisely and keep plants healthy? Here are some strategies you can employ to ensure proper moisture and sustainability.1

Proper Irrigation (There really are better ways to water)

Know When to Water

First, newly-installed plants need more consistent water, sometimes daily, during their establishment period, usually during the first year. Once plants develop root systems, they are better able to tap into moisture already in the surrounding soil. With established plants, did you know that watering more thoroughly (deeper and longer) but less often is best? This method encourages deeper root growth. If you have our typical clay soils in your landscape, one benefit they provide is holding onto moisture longer, so make any supplemental irrigation you are providing count.

Practice sustainable gardening by watering only when needed. Simple tools like a rain gauge can help you determine if a summertime afternoon shower provided enough rain to meet your plants’ needs. (Image credit: Melinda Heigel)

Another important factor in sustainable irrigation is to water only when plants need it. You do this by simply paying careful attention to your landscape, containers, and plants. Look for signs like slightly drooping or wilting leaves; poke into the soil about ¾ of an inch with your fingers to see if the soil is dry. Consider installing an inexpensive rain gauge in your garden. On average, established plants need approximately 1 inch of water per week, which often can be met by rainfall and enhanced with additional irrigation as needed.

Although this seems like a no-brainer, water your plants at the right time of day. I can’t tell you how often I see sprinklers in yards and gardens running in hot mid-day summer sun — a less than optimal plan. Instead, watering in the early morning means better water absorption and less evaporation in the heat of the day. Day and evening watering might be necessary given your schedule, but you also might have unintended results due to wet leaves (see below).

Choose the Best Watering Techniques

Watering techniques can also be important to success.  Whether you are watering with a hand-held watering can or hose, get the water down to the plant’s base where it touches the soil.  Getting the plant leaves wet with overhead watering doesn’t get water to the roots where it is most needed, and prolonged wetness on the leaves can contribute to fungal diseases like powdery mildew or leaf spot especially during hot months.  Overhead watering during the heat of the day can also be ineffective due to water evaporation. Using sprinkler irrigation on a windy day may mean you are watering your sidewalk instead of plants. For these reasons, sprinklers are not always the best solution.

While overhead watering alone doesn’t cause plant diseases like cerospora leaf spot and powdery mildew seen here, prolonged wet foliage combined with hot and humid weather provide perfect conditions for fungal pathogens to infect susceptible plants. (Image credit: Melinda Heigel)

Other irrigation methods like soaker hoses or permanent drip irrigation efficiently provide the moisture where plants need it the most. These methods deliver water slowly and deeply. Likewise precious water is less likely to runoff and water your concrete. You can use these direct watering methods virtually any time of the day without increasing disease pressure as foliage stays dry. Placing a soaker hose on a timer attached to your hose connection means you don’t have to remember when to water.

Examples of a watering device that dates back to ancient times known as an olla. (Image credit: University of California Master Gardener Program of Contra Costa County)

Innovative ways exist to provide supplemental irrigation that are low tech and effective. Collapsible bags filled with water around trees and shrubs slowly release water to ensure these newly-installed plants are receiving proper moisture. Just remember to keep them filled, of course. Even placing something as simple as a recycled milk jug, drilled through with small holes and filled with water in your garden bed can provide slow, steady moisture.  An ancient technique by a pot called an olla (pronounced oy-ya) utilizes an unglazed clay vessel buried in the ground to deliver water. An unglazed, water-filled terracotta pot with a plugged drain hole buried in the ground next to plants and covered with a terracotta saucer suffices. Water slowly seeps out of the container to irrigate nearby plants.  Again, you must remember to refill the pot and be careful not to damage existing roots when installing. Consider burying an olla as you initially install plants. These vessels take up room in the garden, so some people only use them near high-value plants. You can also try this system in containers.

Soil Coverage (Mulch is more than aesthetics)

Use Organic Mulch to Increase Drought Tolerance

Generally, uncovered soil around plants equals drier, poorer soils and potentially stressed plants. Using a couple of inches (typically 2-3 inches) of the traditional organic-based wood mulch (shredded bark, bark chips), pine needles, or compost is a great strategy to reduce plants’ water needs by keeping the root zone cooler. Mulch also keeps soil from crusting over, thus allowing better water penetration.  Just make sure you keep the mulch off leaves and stems of the plants to prevent decay, disease pressure, and even rodent damage.  This is true for tree trunks, too: no volcano mulching!

Incorporate Living Mulch

Using living plants in place of more traditional wood mulch leads to healthier plants, better soils, and less watering.  (Left to right) A homeowner has replaced wood chips in their garden bed with bugleweed. A late fall view and a spring shot when the living mulch is blooming with purple flowers, which makes it an even better feature in the garden. (Image credit: Melinda Heigel)

Have you ever heard of green or living mulch? A new way of thinking about mulch is using living, growing plants to cover the ground in the place of “traditional” mulch. Farmers have incorporated cover crops like crimson clover and hairy vetch in their crop rotation schedules for a long time, and home gardeners are getting in on the action. By installing low-growing plants that act as ground covers in place of traditional mulch, these plants grow as an understory layer to your larger plants. The goal is to gain complete soil coverage once these plants reach maturity. Benefits to a living mulch include cost savings (they don’t have to be replaced annually like traditional mulch); healthier soils and plants (green mulch provides additional nutrients back into the soil, boosting soil health, and making plants in your garden grow deeper roots); and increased water holding capacity for the soil.

(Left to right) Note the creeping jenny (Lysimachia nummularia) ground cover used as an underplanting in a spring-blooming flower bed. If choosing creeping jenny, gardeners must keep a close watch on this ground cover, which can be overly enthusiastic around other plants in the garden.2 Here a gardener is establishing a living mulch of creeping moss phlox (Phlox sublata) in their planting bed. In early spring, profuse blooms brighten the landscape.  (Image credit: Melinda Heigel)

When it comes to living mulches, look for spreading ground covers that are not overly aggressive or known invasive species.

Some Suggested Ground Covers for Living Mulch

For sunnier areas

-Prostrate blue violet (Viola walteri ‘Silver Gem’) Native, silvery heart-shaped foliage, with blue to lavender flowers, herbaceous perennial

-Plantain-leaved pussy toes (Antennaria plantaginifolia) Native, semi-evergreen, attracts pollinators

-Creeping thyme (Thymus serpyllum) Fragrant leaves, attractive pink to purple flowers, drought resistant

-Golden groundsel (Packera aurea) Native perennial, naturalizes rapidly, yellow flower

-Moss phlox (Phlox subulata) Spring blooming, attractive flowers, semi-evergreen

For shadier areas

-Bugleweed (Ajuga reptans) Dense creeper, semi-evergreen to evergreen, blue-to-lavender flowers

-Wild ginger (Asarum spp.) Prefers moist soil, so some shade is a must, semi-evergreen to evergreen foliage depending on species, heart-shaped leaves

-Sedge (Carex spp.) Native and non-native species, perennial, can be evergreen, grass-like, highly ornamental

-Bloody cranesbill (Geranium sanguineum) Clump-forming perennial plant, lobed leaves and small pink-to-violet flowers

-Foamflower (Tiarella cordifolia) Herbaceous perennial, lobed leaves, delicate pink-to-white flowering spikes

-Green and gold (Chrysogonum virginianum) Native plant, 1-2 inches in height, semi-evergreen, showy yellow flowers

-Creeping jenny (Lysimachia nummularia) Herbaceous perennial, semi-evergreen, can be overly vigorous grower, use where spread is not a concern

Watering plants in the summertime seems like such a simple concept, but it is often vexing to home gardeners. Doing it correctly and sustainably is vital to your plants’ success. Enjoy your summer in the garden and use these simple tips to make sure your plants do too!

Notes

A version of this article appeared in DCo Life, the Durham County Employee Magazine, summer 2024.

1—Of course, choosing water-wise plants for your garden or containers that are zone appropriate is also a great way to ensure summer success.   Check out these online resources for more information and plant lists.

NC Botanical Garden’s “Gardening for a Drought: North Carolina Native Plants to the Rescue.”

Gardening for a Drought: North Carolina Native Plants to the Rescue

Extension Master GardenerSM volunteers of Durham County blog post “Ten Plants that Can Take the Heat”

https://wp.me/p2nIr1-1vS

2–In some parts of the US, creeping jenny is considered invasive and some experts suggest its best use is in container plantings. Some advise to use as a ground cover only where invasive spread is not a problem. See NC State Extension’s Plant Tool Box link below for more.

https://plants.ces.ncsu.edu/plants/lysimachia-nummularia

Resources and Additional Information

Read about one Texas Master GardenerSM volunteer’s quest to install living mulch in her landscape.

https://www.startribune.com/a-master-gardener-makes-the-case-for-living-mulch/510676132

While this post doesn’t address proper lawn irrigation, it’s a hot topic during the summer. The EPA estimates that landscape water use counts for one third of all residential water use. Read here for best practices and sustainability tips for watering lawns.

Watering Lawns

NCSU’s Office of Sustainability’s link offers ideas for saving water in the garden this summer when irrigating.

Save Water in the Garden this Summer

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