Mt. Cuba Center Puts Nativars to the Test

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By this point, most gardeners will have undoubtedly heard about the importance of using native plants in our landscapes. Though the idea is not new, Doug Tallamy’s landmark publication “Bringing Nature Home” put native plants on the radar for more gardeners than ever. There is no debate that utilizing native plants in our landscapes offers us a chance to bring back some of the biodiversity that was lost when our homes and work places were built. And, at the end of the day, who doesn’t love the sight of a swallowtail butterfly flitting from flower to flower or a pair of warblers nesting in their Viburnum? The rise of native plants in horticulture and landscaping is truly something worth celebrating.

At the same time, however, capitalism is capitalism, and many nurseries are starting to jump on the bandwagon in alarming ways. The rise of native cultivars or “nativars” is troubling to many. Nativars are unique forms, colors, and shapes of our beloved native plants which have been selected and propagated by nurseries and plant breeders. This has led many to denounce the practice of planting nativars as a slap in the face to the concept of native gardening.

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Nativars are frequently seen as unnatural mutant versions of their wild counterparts whose use overlooks the whole point of natives in the first place. Take, for instance, the popularity of double flowered nativars. These plants have been selected for an over-production of sepals and petals that can be so dense that they preclude visitation by pollinators. Another example that will be familiar to most are the bright blue hydrangeas that have become to popular. These shrubs have been selected for producing bright, showy flowers that, depending on your soil chemistry, exhibit a stunning blue coloration. The downside here is that all of those flowers are sterile and produce no nectar or pollen for visiting insects.

It would seem that nativars are a slippery slope to yet another sterile landscape incapable of supporting biodiversity. However, anecdotes don’t equal data and that is where places like Mt. Cuba Center come in. Located in northern Delaware, Mt. Cuba is doing something quite amazing for the sake of environmentally friendly landscaping – they are putting plants to the test.

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Mt. Cuba has been running trial garden research and experiments on native plants and their nativars for over a decade. The goal of this research is to generate and analyze data in order to help the public make better, more sustainable choices for their yards. Mt. Cuba aims to better understand and quantify the horticultural and ecological value of native plants and related nativars in order to better understand the various ecosystem services these plants provide. In collaboration with academic institutions in the region, popular nativars are established and grown under similar conditions to those experienced in the yards of your average gardener. They are monitored for years to assess their overall health, performance, and ability to support wildlife. Thanks to the help of countless volunteers, these trial gardens paint a holistic picture of each plant and related nativars that is sorely lacking from the gardening lexicon.

This is very exciting research to say the least. The data coming out of the Mt. Cuba trial gardens may both surprise and excite gardeners throughout the mid-Atlantic region of North America. For instance, their latest report looked at some of the most common Phlox varieties on the market. At the top of this list is Garden Phlox (Phlox paniculata). This lovely species is native throughout much of the eastern United States and has become quite a rockstar in the nursery trade. Over 580 cultivars and hybrids have been named to date and no doubt many more will be introduced in the future. Amazingly, many of these Phlox nativars are being developed in the Netherlands. As such, Phlox arriving in regions of the US with vastly different climates often fall victim to novel diseases they never encountered in Europe. What’s more, people often plant these nativars in hopes of attracting butterflies to their garden. Despite their popularity for attracting various lepidopterans, no one has ever tested whether or not the nativars perform as well as their native progenitor.

Phlox paniculata  'Delta Snow'

Phlox paniculata 'Delta Snow'

Starting in 2015, Mt. Cuba began trials on 66 selections and hybrids of Garden Phlox along with 28 other sun-loving types of Phlox. The plants were observed on a regular basis to see which of the nativars experienced the least amount of disease and attracted the most insects. The clear winner of these trails is a nativar known as Phlox paniculata ‘Jeana’. This particular selection was discovered growing along the Harpeth River in Tennessee and is known for having the smallest flowers of any of the Garden Phlox varieties. It also has the reputation for being rather resistant to powdery mildew. Alongside other selections such as Delta Sno’ and David, Jeana really held up to this reputation.

As far as butterflies are concerned, Jeana blew its competition out of the water. Throughout the observation period, Jeana plants received over 530 visits from butterflies whereas the second place selection, Lavelle, received 117. A graduate student at the University of Delaware is studying why exactly the various nativars of Phlox paniculata differ so much in insect visitation. Though they haven’t zeroed in on a single cause at this point, they suggest that the popularity of Jeana might actually have something to do with its small flower size. Perhaps the density of smaller flowers allows butterflies to access more nectar for less effort.

Phlox paniculata  ‘Jeana’

Phlox paniculata ‘Jeana’

Monarda is another genus of North American native plants that has seen an explosion in nativars and hybrids over the last few decades. The popularity of these mints is no surprise to anyone who has spent time around them. Their inflorescence seems to be doing their best impression of a fireworks display, an attribute that isn’t lost on pollinators. These plants are popular with a wide variety of wildlife from solitary bees to voracious hummingbirds. Even after flowering, their seeds provide food for seed-eating birds and many other animals.

As with Garden Phlox, a majority of the commercial selection and hybridization of Monarda occurs in Europe. As a result, resistance to North American plant diseases is not top priority. Many of us have experienced this first hand as our beloved bee balm patch succumbs to aggressive strains of powdery mildew. Though there are many species of Monarda native to North America, most of the plants we encounter are nativars and hybrids of two species – Monarda didyma and Monarda fistulosa.

Monarda fistulosa  'Claire Grace'

Monarda fistulosa 'Claire Grace'

Again, Mt. Cuba’s trial gardens put these plants to the test. A total of 40 different Monarda selections were grown, observed, and ranked based on their overall growth and vigor, pollinator attractiveness, and disease resistance. The clear winner of these trials was a naturally-occurring form of M. fistulosa affectionately named ‘Claire Grace.’ Its floral display lasts a total of 3 weeks without waning and managed to attract over 130 visits by butterflies and moths. Though plenty of other insects such as short-tongued bees visited the flowers during the trial period, they are too small to properly access the nectar inside the flower tubes and are therefore not considered effective pollinators.

Another clear winner in terms of pollinators was possibly one of the most stunning Monarda selections in existence – Monarda didyma ‘Jacob Cline’. This tall, red-flowering nativar was a major hit with hummingbirds. During the observation period, Jacob Cline received over 270 visits from these brightly colored birds. Researchers are still trying to figure out why exactly this particular selection was such a hit but they speculate that the large flower size presents ample feeding opportunities for tenacious hummingbirds.

Monarda didyma  'Jacob Cline'

Monarda didyma 'Jacob Cline'

Claire Grace and Jacob Cline also outperformed most of the other selections in terms of disease resistance. Even in the crowded conditions experienced by plants in the trail garden, both selections faired quite well against the dreaded powdery mildew. Though they aren’t completely resistant to it, these and others did not succumb like some selections tend to do. Interestingly enough, most of the other pure species tested in the trial faired quite well against powdery mildew as well. It would appear that Mother Nature better equips these plants than European breeders.

These reports are but two of the many trials that Mt. Cuba has undertaken and there are many, many more on the way. Thanks to the hard work of staff and volunteers, Mt. Cuba is finally putting numbers behind some of our most commonly held assumptions about gardening with native plants and their cultivars. It is impressive to see a place so dedicated to making our landscapes more sustainable and environmentally friendly.

If you would like to find out more about Mt. Cuba’s trial garden as well as download your own copies of the trial garden reports, please make sure to check out

Of Acorns and Squirrels

I find it fun to watch squirrels frantically scurrying about during the fall. Their usually playful demeanor seems to have been replaced with more serious and directed undertones. If you watch squirrels close enough you may quickly realize that, when it comes to oaks, squirrels seem to have a knack for taxonomy. They quickly bury red oak acorns while immediately set to work on eating white oak acorns. Why is this?

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Artist: Botanist
Track: Stargazer



Whether you like wasabi or hate it, there is a very high probability that you have never actually tasted it. It is estimated that only about 5% of Japanese restaurants around the world actually offer the real stuff. Instead, the wasabi we most often indulge in is a mix of mustard, European horseradish (Armoracia rusticana), and green food coloring. This begs the question, why is real wasabi so hard to come by?

The answer to this lies in the plant. Real wasabi comes from a species of mustard native to the mountains of Japan. Flowering for this group consists of an inflorescence packed with small, white, 4-petaled flowers shoots up above the leaves. There exists two species within the genus - the uncultivated Wasabia tenuis and the cultivated Wasabia japonica. It has been suggested that these plants be moved out of the genus Wasabia and into the genus Eutrema. Regardless of their taxonomic affiliation, these are beautiful and interesting plants. 

Whereas W. tenuis tends to grow on mesic mountainsides, W. japonica prefers to grow in and around streams. In fact, it can often be found growing right out of the gravelly stream bed. Its strict riparian habit has made it hard for this plant to catch on commercially. Although it doesn't grow submerged like an aquatic plant, it nonetheless needs running water. Without it, the plant will languish and die. Although methods of soil growing W. japonica are sometimes used, these are very labor intensive and require a lot of inputs in order for the plants to thrive. The plant also seems to be highly susceptible to disease if planted in high densities. Overall this has made finding real wasabi a difficult, and not to mention expensive, venture. 

Photo Credit: Qwert1234 (Wikimedia Commons)

Further Reading: [1]

The Benefits of Houseplants

I don't know about you, but I find indoor gardening to be just as satisfying and intellectually stimulating as any amount of outdoor gardening. Coming from a temperate climate, I don't think I would be able to survive the long winters if it were not for my houseplants. The benefits to keeping plants in the home as well as the office are numerous and range the spectrum from improving air quality to diminishing stress and aiding in healing.

Few would probably argue that a room with plants in it feels far more lived in and hospitable than an empty, sterile room. It makes sense. We evolved, like everything else on this planet, in a natural setting filled with seemingly endless varieties of different plant species. It should be no surprise that our minds would be more at ease the more natural any environment seems. Studies have shown that in an indoor work environment, offices that contained plants had statistically significant reductions in employee discomfort, stress, and an increase in their overall well being. It doesn't end at work either. Hospitals and other medical facilities also showed that overall well being improved both physically and mentally with their residents. In patients suffering from dementia, indoor plants are said to "stimulate residents’ senses, created positive emotions, and offered opportunity for rewarding activity."

Plants do so much more than just improve our moods and reduce stress, they also clean the air we breath. Many every-day household items off-gas some pretty nasty chemicals. Insulation, particle board, PVC and vinyl, carpets, flooring, even our own clothing, all of these things come with their own gaseous and particulate chemical cocktails. It has been shown time and time again that many species of commonly kept house plants help to remove these molecules from the home environment. Some species are better than others. For instance, spider plants (genus Chlorophytum), are exceptionally good at removing formaldehyde compounds in the air. A room full of plants also exhibits statistically significant reductions in particulate matter as well as a measurable increase in humidity levels.

Whether they make you feel at ease or because they clean the air you breath, having house plants is a good thing. There are many species that are available both in nurseries as well as online. Some of the best plants for the home are also the most sensibly priced. Get online and do some research. There are a lot of easy plants to care for out there if you don't necessarily have a green thumb.

Further Reading: [1] [2] [3] [4] [5] [6] [7]

Rattlesnake Master


I first heard of rattlesnake master (Eryngium yuccifolium) in William K. Stevens' book “Miracle Under the Oaks: The Revival of Nature in America.” Ever since then I have been enamored by this species. Who could blame me? Such a common name deserves a deeper inquiry. It would take a few years before I would be able to see an actual tall grass prairie and lay eyes on this wonderful, albeit strange member of the carrot family. 

Rattlesnake master gets its common name from the erroneous belief that the roots of this plant could be used to cure rattlesnake bites. I don't know about you but I certainly will not be chancing it. Its specific epithet "yuccifolium" comes from the resemblance its leaves have to that of Yucca. Unlike most carrots, which have dissected, lacy foliage, the leaves of rattlesnake master are strap-like and pointed with teeth running up the margins.

Eryngium root borer moth ( Papaipema eryngii )

Eryngium root borer moth (Papaipema eryngii)

The clustered flowers exhibit protandry meaning the anthers mature and senesce before the pistils become receptive. This reduces the chances of self-fertilization, which increases the amount of genetic variation in a population. Being a member of the carrot family, rattlesnake master develops a very deep taproot making it a difficult species to transplant. Despite this fact, it grows readily from seed making it an excellent addition to a native prairie planting. What's more, the caterpillars of the Eryngium root borer moth (Papaipema eryngii) live solely off the roots of rattlesnake master. Without this plant, the moths could not survive. 

Photo Credit: [1]

Further Reading: [1] [2] [3] [4] [5]

The Truth About Peat


Peat moss is not a sustainable option for gardening on any level.

No matter how good of a product it may be for anyone, the mining of peat moss is an incredibly destructive industry that is harming not only sensitive habitat but some of our largest carbon stores on the planet. Now, before you think I'm all up on my high horse about this subject, please note that I still use it in some of my gardening projects. It is hard not to. I am writing this post as a cry for help in order to get a conversation going about some sustainable and effective alternatives to this "blood soil."

Peat is the product of the natural processes that bogs go through. Sphagnum moss, the main species of a bog ecosystem, and other plant materials don't decompose in bogs. Instead they build up and compact to form what we know as peat moss. For centuries, this has been harvested and dried as a source of heat and energy for native peoples. Today, because of its moisture holding abilities and rather sterile, acidic nature, it is heavily mined for the horticultural trade. Most of the peat sold comes from Canada. Canadian companies mine their bog habitats for this product. The Canadian peat companies will tell you that it is a renewable resource and that mitigation offsets any damage being done. This is a bold faced lie. Bogs are incredibly sensitive habitats. They are the product of thousands of years of very particular natural processes. They hardly regenerate themselves if at all. Mitigation efforts are also pointless. Bogs that have been "mitigated" do not return to their fully functioning state ecologically.

To make matters worse, the industry loves to claim that there are no alternatives to peat moss out there. This is simply not true. I have researched some interesting sustainable alternatives to peat moss. One product is coconut coir "dust." This product comes from ground up coconut husks. From what I have read, it is also a much more sustainable option. Now, a few things must be said about the efficacy of this material. First off it is naturally high in salt. Most brands must be thoroughly washed before using. I have gotten around this issue by purchasing coconut coir used for amphibian and reptile bedding. It comes in compact bricks and it has the lowest salt levels on the market. Also, it is really low in nutrient value. I do some water gardening so I have a very mature fish tank running and using aquarium water seems to solve this issue for me. Adding coffee grounds can mitigate this as well. I have heard mixed reviews about coir and it is not necessarily the best choice for all types of seeds but it works quite well for me and in the last 4 growing seasons I have finally switched to using coir for germination.

By far my favorite media to use is good compost. Having ready access to a big pile goes a long way. Because compost can be very rich and heavy, I like to mix in wood chips and gravel. This not only weighs my pots down and keeps them from falling over, it increases the amount of roots my plants produce considerably. Every time a root comes into contact with a piece of gravel or wood chip, it branches off hundreds of tiny root hairs, thus increasing the surface area available for water and nutrient absorption. Since I switched over to mixing my own soil using compost, I have noticed my plants are more vigorous and are flowering more often. 

Another option I have come across is pine bark. I have not used this but some research papers rank it as good as peat moss in seed germination trials. Has anyone here tried this? If anyone has an opinion on this subject or better yet, first hand experience, PLEASE chime in. If we can't make growing plants a sustainable process then what good are we as a species? Finally, does it make sense to destroy one habitat to foster a handful of species in your back yard?

Further Reading:

Growing Ferns

I am finally having some success intentionally growing ferns from spores. I collected and sowed spores from some interrupted ferns (Osmunda claytoniana) over the summer. They have been hanging out as gametophytes for months now and some are finally starting to grow sporophytes. Here is how it worked for me:

I kept my eye on a batch of adult plants this summer. Once their fertile fronds developed I would flick them every now and then to see if they were releasing spores. Once I saw that they were I shook the fronds over some paper to collect the spores. I then took some old potting soil and sterilized it with boiling distilled water. I use old takeout containers because they are small and have clear lids that form a seal which keeps the humidity high.

Once the soil was cool I sprinkled the spores over it and then placed it on a shelf where it gets a small amount of ambient light every day. The rest they did themselves. You just have to remember to check on them and keep the humidity quite high because they can dry out really fast. They seemed stuck as gametophytes for months. I just noticed the start of these sporophytes the other day.