Tag Archives: Mt. Cuba Center

Carex: The Wondercover

Carex woodii blooming

A few years ago, I had the opportunity to create a new garden bed toward the front of the property. It was a little too far away from the spigot so watering was going to be an issue and quite possibly deer. I wanted native shrubs but my saplings were going to take time to mature, thus leaving bare space for a few years. Having a new bed as a blank canvas is great but you have a lot of “blank” until the saplings mature.

I thought I would cover the soil with groundcovers and had heard great things about the genus Carex. I visited the local nursery and selected several Carex “Evergold” plants. In fact, this well-known local garden center only had the brightly variegated cultivars of Carex. But I liked the fact that its graceful arching leaves added color to the garden and stayed evergreen in the winter. True to form, the plants performed well despite the lack of watering. Deer have not bothered them (although they did enjoy the oakleaf hydrangea). In fact nothing has bothered the plants – they are work horses in my Virginia garden.

So when I saw the new Mt. Cuba Center Research Report on Carex for the mid-Atlantic region at a nursery trade show this past week, I picked up a copy. The 24-page publication is great. There are many detailed photos illustrating the botanical structure of the plant, photos of the top performers, and charts. The report can be downloaded from Mt. Cuba Center.

Top performer: Carex woodii

In 2017, Mt. Cuba Center’s Trial Garden staff planted 70 different types of Carex, 65 species and five cultivars (no, not my ‘Evergold’). Carex are grass-like perennials that are found in diverse habitats from wetlands to coastal sand dunes. A member of the Cyperaceae plant family, Carex is a sedge. Its stems are triangular with three edges and a solid interior. Usually their flowers are grass-like and insignificant but there are a few with larger, more pronounced flowers. The plants can be clumping or spreading. They are evergreen, semi evergreen, or deciduous in the winter. Most gardeners use them as groundcovers or as a “spiller” in a large container. They also can be used to stabilize soil, prevent erosion, and serve as a turf alternative.

Carex plants under shade at Trial Garden

For four years, the Trial Garden staff evaluated the plants for their horticultural qualities, vigor, and adaptability. They were planted in the fall of 2017 and given supplemental water for the first year to get established. From then on, they did not get supplemental water, they were not fertilized, and they only received a late winter cutback. Each plant was assessed in both full sun and shade and in average soil. The plants were rated on a scale of 1 to 5 with 1 being very poor and 5 being excellent. Top performers are in the 4.2 range or higher, but the report does caution that those plants with lower scores are not necessarily inferior. They may be useful or good performers in other conditions (more wet or more dry soils).

Top performers are listed below. The report provides a full paragraph and one to two photos for each.

  • C. woodii (Wood’s sedge): 4.7 shade rating, 4.4 sun rating
  • C. cherokeensis (Cherokee sedge): 4.7 shade rating, 4.3 sun rating
  • C. bromoides (common brome sedge): 4.6 shade rating, 4.3 sun rating
  • C. haydenii (Hayden’s sedge) 4.5 shade rating, 4.5 sun rating
  • C. stricta (upright sedge) 4.2 shade rating, 4.5 sun rating
  • C. emoryi (Emory’s sedge) 4.1 shade rating, 4.4 sun rating
  • C. sprengelii (long-beaked sedge) 4.4 shade rating, 4.0 sun rating
  • C. pensylvanica (Pennsylvania sedge) 4.3 shade rating, and 4.2 sun rating
  • C. pensylvanica ‘Straw Hat’ (Straw Hat Pennsylvania sedge) 4.4 shade rating, 4.1 sun rating
  • C. muskingumensis ‘Little Midge’ (Little Midge Muskingum sedge) 4.3 shade rating, 5.2 sun rating
  • C. albicans (white-tinge sedge) 4.3 shade rating, 4.1 sun rating
  • C. jamesii (James’s sedge) 4.3 shade rating, 3.9 sun rating
  • C. muskingumensis ‘Oehme’ (Oehme Muskingum sedge) 4.1 shade rating, 4.4 sun rating
  • C. crinita (fringed sedge) 4.0 shade rating, 4.2 sun rating
  • C. leavenworthii (Leavenworth’s sedge) 4.2 shade rating, 3.7 sun rating
  • C. plantaginea (plantain-leaf edge) 4.2 shade rating and failed to thrive in full sun and did not complete trial for sun rating

Because Carex plants are wind pollinated, there is no benefit to pollinators, but the plants are important as host plants and for habitat. Small mammals and birds eat the seeds and caterpillars of butterflies and moths consume the leaves. Toads, frogs, and turtles like to take up residence in the plants.

Looking down on Carex muskingumensis ‘Little Midge’ which has unusual foliage

The report also assessed Carex as a lawn alternative. In 2022, they did a year long mowing trial to identify which ones would be tolerant of regular mowing, grown both in sun and shade. Most were tolerant but those with medium to coarse textured foliage were not as aesthetically pleasing as mowed turf grass. Fine textured foliage looked better after mowing. The trial did not assess foot traffic which would occur in a home landscape. The top five top performers for this trial are:

  • C. woodii (Wood’s Sedge): 4.9 shade, and 4.9 sun
  • C. eburnea (bristle-leaf sedge) 4.6 shade, and 3.6 sun
  • C. socialis (low woodland sedge) 2.4 shade, and 4.6 sun
  • C. pensylvanica (Pennsylvania sedge) 4.3 shade, and 4.4 sun
  • C. jamesii (James’s sedge) 4.0 shade, and 4.4 sun

Carex crinita has pretty flowers

As I mentioned before, my ‘Evergold’ is a brightly colored cultivar that I found in a local garden center. None of these native species mentioned in the report were at the center, nor have I seen them at any other local garden center. In fact, there are many native species but you may not find them at your nursery. So if this report has you salivating for these plants, you may want to try these nurseries below. Full disclosure: these were not listed in the report and do not imply endorsement by Mt. Cuba Center.

Prairie Moon Nursery
Digging Dog Nursery
Izel Native Plants
Plant Delights Nursery

Also, if you are intrigued and want to learn more about carex plants, Sam Hoadley, who manages the Mt. Cuba Center’s Trial Garden and was responsible for this trial, will present Carex for Every Garden on February 1, 6 to 7:30 pm, virtually for a nominal fee. Register here.

Mt. Cuba Center is a destination garden, a public garden in Delaware that highlights the beauty and value of native plants to inspire conservation. I highly recommend visiting them and checking out their website for educational events and past reports on other plants.

All photos are courtesy of Mt. Cuba Center.

Best Helenium Plants for the Mid-Atlantic Area

Kanaria, top rated, with good powdery mildew resistance and a pollinator favorite

The Mt. Cuba Center has just published Helenium for the Mid-Atlantic Region, a 16-page report detailing the results of a 3-year trial of 44 taxa of Helenium plants. A member of the Aster family, the genus Helenium has summer to fall-blooming perennials with daisy-like flowers about 2 inches across. The flowers are in various colors of yellow, orange, and red, with raised yellow to brown centers, making them look like buttons.

The flowers are beautiful, but the plants are not commonly found in American gardens. Part of this may be because its common name “sneezeweed” leads people to erroneously assume the flowers cause allergies. In fact, the flowers are pollinated by insects, not wind. Sneezeweed is finely ground plant parts that are inhaled, like tobacco snuff. Part of the unpopularity may also be the plant’s tendency to flop over, exhibit powdery mildew, and/or contract a disease called aster yellows. Although they require full to partial sun, they are not drought tolerant and native plants are found growing in wet areas.

When asked why this genus was chosen for the trial garden, Sam Hoadley, Mt. Cuba Center’s Horticultural Research Manager, answered: “Helenium really is a genus that is native to the Americas, and there are several species native to the eastern United States. They are really not well represented in American horticulture. I think, outside of the native plant communities that will work with Helenium autumnale and Helenium flexuosum, we felt that this [trial] represents a fairly diverse group of plants and deserves a second look in American horticulture after it’s been so popular in Europe to see how these plants perform there. We also knew that they have significant benefits for bees and wasps, anecdotally. We really wanted to see how these plants would perform and what benefits or attraction they would have for these pollinators when brought back to the United States.”

Zimbelstern, second top rated, pollinator favorite, excellent powdery mildew resistance

Heleniums are popular in European gardens where extensive breeding has been done in Germany and the Netherlands. German breeders Karl Foerster, Gustav Deutschmann, Peter zur Linden and Dutch breeders Inez Arnold and Bonne Ruys have cultivated many Heleniums for exquisite flower colors, shorter forms, and increased resistance to drought. Karl Foerster in particular created more than 70 cultivars drawing on two native American species: H. bigelovii, which is found in Southern Oregon, California, and Arizona; and H. autumnale, which is found across the country. These plus a third species that is found in the eastern United States, H. flexuosum, were included in the trial.

“They really contribute some great late-season interest,” said Sam. “They are in bloom when gardens are in a lull, right at the end of summer and the beginning of fall, bridging a gap in the garden. There’s been a lot of Helenium breeding so that size, stature, and habit of the plant are becoming more and more diverse. For that reason, you are able to incorporate it into more garden designs.”

H. autumnale, a native species that is most visited by bees and wasps

In the trial at the Mt. Cuba Center in Delaware, forty-four taxa including three species were grown in full sun on clay-loam soil. By the beginning of the third or final year, only one-third of the original 220 plants remained. Plants were given minimal care although staff did try to prevent the flop with the Chelsea Chop and several staking methods on some plants to see which would work. Plants were watered during the first year for establishment and during any extremely dry periods. They were not sprayed with fungicides. Many plants succumbed to dry soil, powdery mildew, aster yellows, and possibly poor winter hardiness.

The downloadable report has three tables:  performance summary ratings and plants characteristics, plants that did not complete the trial, and best Heleniums for bees and wasps. Plants are rated on a scale of five (excellent) to 1 (very poor) and include a variety of criteria. None received a five but the top rated, Kanaria, is 4.3, followed by Flammenspiel and Zimbelstern at 4.2, Can Can at 4.1, H. flexuosum at 4.0, and H. autumnale at 3.9. The Mt. Cuba Center’s Pollinator Watch Team observed the plants and found that bees and wasps preferred H. autumnale followed by Zimbelstern, Kanaria, Can Can, and Tijuana Brass.

Can Can, one of top 4 rated, excellent powdery mildew resistance, and a pollinator favorite

Since 2002, the Mt. Cuba Center trial garden has been evaluating native plants and their related cultivars for their horticultural and ecological value. See their website for past reports on phlox, monarda, baptisia, coreopsis, heuchera, echinacea, and asters.

All photos courtesy of Mt. Cuba Center.

Best Phlox Plants for Mid-Atlantic Gardens

Lavelle phlox


Despite its tendency to get powdery mildew, phlox is a very common perennial in the mid-Atlantic area. Many gardeners –as well as butterflies– love the old-fashioned, native plant for its tall stems of summer-blooming pink, purple, or white flowers.  Phlox is actually a large genus comprising more than 60 species native to North America. There is wide variation — some plants are tall, low growing, or groundcovers, while some prefer full sun and others thrive in shady, woodland areas.

This year, before you purchase phlox for your garden, read about the recommended varieties in Mt. Cuba Center’s report. The horticulturists at the Trial Garden, Mt. Cuba Center, Delaware, completed a three-year study. They tested 94 selections of eight sun-loving species and 43 selections of two shade-loving species.  For the sun lovers, they deliberately tested for resistance to powdery mildew, a fungal infestation of the foliage that creates an unsightly white powder. (This usually does not kill the plant but detracts from its beauty).

Of the sun-loving plants, within the species Phlox paniculata, top performers are ‘Jeana’, ‘Glamour Girl’, ‘Delta Snow’, ‘Lavelle’, ‘Robert Poore’, ‘Dick Weaver’, ‘David’, ‘Ditomdre’ (Coral Cream Drop), ‘Shortwood’, and the hybrid P. x arendsii ‘Babyface’.


“Jeana,” according to the report, “is, without a doubt, the best performing phlox from the trial. This cultivar was discovered growing along the Harpeth River near Nashville, Tennessee and named after its discover Jeana Prewitt.”

Interestingly, volunteers who monitored pollinator visitations in the trial garden, noticed that ‘Jeana’s’ pink flowers received 539 visits from butterflies over 2 years. Others phlox flowers received at best 117 and lower.  ‘Lavelle’, second in place, received 117 visits indicating a marked preference for ‘Jeana’.


Blue Moon phlox

Blue Moon

Horticulturists also trialed shade-loving woodland phlox (Phlox divaricata) and creeping phlox (Phlox stolonifera). Their report stated that the creeping phlox was easy to grow while the woodland was more difficult. However, they conceded that their initial plants of the woodland may not have been the healthiest. The best performers of woodland phlox are Phlox divaricata and P. divaricata ‘Blue Moon.’ With creeping phlox, best performers are Phlox stolonifera ‘Fran’s Purple’, ‘Home Fires’, ‘Pink Ridge’, and ‘Sherwood Purple’.

Fran's purple phlox

Fran’s Purple

All photos courtesy of Mt. Cuba Center

Best Baptisia Plants for the Mid-Atlantic Gardens


Baptisia ‘Lemon Meringue’ photo courtesy of Proven Winners

Baptisia, also called false indigo, is an herbaceous perennial shrub that performs well in our hot and humid summers. Recent breeding efforts have expanded the range of flower colors requiring a new look into an old favorite. I myself have falling in love with two top performers according to Mt. Cuba Center’s 15-page report, Baptisia for the Mid-Atlantic Region. The Mt. Cuba Center’s Trial Garden, managed by George Coombs, research horticulturist, evaluates native plants and their related cultivars. From 2012 to 2015, staff evaluated 46 selections of Baptisia including representatives from 11 species to determine which performs best in the mid-Atlantic region. Over 60 percent of the plants tested receive 4 or 5 stars. Among those, 10 superior cultivars outperformed the rest. Fortunately for me my two recent Baptisia additions to my garden are included in the ten.


Pea-like flowers, photo courtesy of Proven Winners

This year I acquired two Lemon Meringue and two Dutch Chocolate plants. They are small now so a photo won’t give you the full flavor of their beautiful flowers but I was able to borrow Proven Winners‘ photos of what my plants should look like when they grow up. Baptisia plants die back every fall and comes back in the spring. By summer, the plants will have grown to their mature height of about 3 x 3 feet each year. However, they do not like to be moved so give them plenty of space when you do plant them. Chances are the nursery plants will be young thus small but they will grow into full bushes once established in the garden. In May, pea-like flowers bloom on tall spikes, similar to lupines. In the fall, pods appear, which can be used for dried flower arrangements. Baptisia plants are deer resistant, heat and humidity tolerant, and drought tolerant once established. These natives make great additions to the garden and the new cultivars increases the color selection.


Baptisia ‘Dutch Chocolate’, photo courtesy of Proven Winners