Tag Archives: 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

Lavelle

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

“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

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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.

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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.

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Baptisia ‘Dutch Chocolate’, photo courtesy of Proven Winners