Archives For recommended plants

Some of the star attractions of Wonderland Express at the Chicago Botanic Garden are the dozens of beautiful dwarf conifers used to create Chicago in miniature. What you might not know is that many of these conifers are great plants for the Chicago area and can easily be incorporated into your home landscape.

Dwarf conifers are a good way to add four-season interest and wildlife habitat to your yard, and with their unique colors and growth habits, they are practically living sculptures. I’ve selected four of my favorite interesting and unique conifers (found in Wonderland Express—go check them out) that are hardy in the Chicago region.

Picea englemanii 'Bush's Lace'

Picea englemannii ‘Bush’s Lace’ features elegantly draping stems.

Picea omorika 'de Rutyer'

Picea omorika ‘de Ruyter’ displays bright blue needles.

Engleman spruce (Picea engelmannii ‘Bush’s Lace’) is a tall, powder blue spruce that is grown for its upright habit and pendulous side branches. Unlike some evergreens, this spruce will keep the gorgeous blue color throughout the year. This tree thrives in the extremes of Chicago’s summers and frigid winters. It is a vigorous plant and will often put on two feet of growth in one season, so make sure to plant it somewhere where it has some room. Engleman spruce are happiest in full sun with well-drained soil. A mature specimen of this tree can be found in the Dwarf Conifer Garden.

De Ruyter Serbian spruce (Picea omorika ‘de Ruyter’) is another spruce that will thrive in the Chicago region. Serbian spruce typically feature dark green needles with silver undersides that shimmer in the breeze, but on this variety, the silver is on top, making for a pop of silvery blue on each branch. This is a slower-growing cultivar, often growing only six to eight inches a year in a loosely conical shape. Because it is a spruce, it requires full sun and well-drained soil to look its best. There is also a large specimen of De Ruyter in the Dwarf Conifer Garden.

Pinus mugo 'Tannenbaum'

Pinus mugo ‘Tannenbaum’ holds its beautiful green color all winter.

Tannenbaum mugo pine (Pinus mugo ‘Tannenbaum’) is a twist on a classic mugo pine. Most people are familiar with mugo pines as the little round pines that often resemble boulders in the landscape. Tannenbaum, as the name suggests, is an upright form that grows as a perfect green pyramid, with the classic Christmas tree shape. It is a relatively slow-growing plant—approximately six inches per year—and holds its dark green color all year. Mugo pines are amazingly hardy and should do well throughout the Chicago area, provided they receive full sun and have relatively well-drained soil.

Glauca Prostrata noble fir (Abies procera ‘Glauca Prostrata’) grows as a creeping mat of icy blue foliage. Weeping blue noble fir makes an unusual addition to the landscape due to its rounded needles, unlike the similar weeping Colorado blue spruce, which has incredibly sharp needles. This makes it a far better choice for placing near walkways. This slow-growing plant averages four to six  inches of growth a year, eventually forming a clump about two feet tall and about six feet wide. As with other conifers, this noble fir prefers full sun and well-drained soil.

Abies procera 'Glauca Prostrata'

Abies procera ‘Glauca Prostrata’ stands out among the surrounding greenery.

Top tips for keeping your conifers happy:

  1. Most conifers prefer full sun and have very little shade tolerance. All of the trees in this article prefer full sun.
  2. Conifers are generally adapted to areas with well-drained soil. Avoid places that stay wet to prolong the life of your plant.
  3. Avoid windy locations. Because conifers keep their needles all year, it is best to site them in less exposed places so they don’t dry out and lose their needles.
  4. Water thoroughly in the fall. You only have once chance to make sure the plant has enough water before the ground freezes and you can’t water it anymore. If we have a dry fall, it is helpful to water your newly planted trees until the ground freezes so they have enough water to last the winter.

©2016 Chicago Botanic Garden and my.chicagobotanic.org

Water Works

Undercover Science

Julianne Beck —  January 2, 2016 — Leave a comment

In a first-time summer internship research project, two college students set out to understand how plants were responding to the Garden’s shoreline restoration projects. They took a deep look into how variations in water levels may be affecting the health of the young plants. The results of their work will help others select the best plants for their own shorelines.

A silent troop of more than one-half million native plants stand watch alongside 4½ miles of restored Chicago Botanic Garden lakeshore. The tightly knit group of 242 taxa inhibit erosion along the shoreline, provide habitat for aquatic plants and animals, and create a tranquil aesthetic for 60 acres of lakes.

PHOTO: The North Lake shoreline.

The North Lake shoreline restoration was completed in 2012. Photo by Bob Kirschner

Now ranging from 2 to 15 years old, the plants grow up from tiered shelves on the sloping shores. Species lowest on the slope are always standing in water. At the top of the slope, the opposite is true, with only floods or intense downpours bringing the lake level up to their elevation.

Wading In

Jannice Newson and Ben Girgenti moved through clusters of tightly knit foliage along the Garden shoreline from June through August, taking turns as map reader or measurement taker. On a tranquil summer day, one would step gingerly into the water, settling on a planting shelf, before lowering a 2-foot ruler into the water to take a depth measurement. The other, feet on dry land, would hold fast to an architectural map of the shoreline while calling out directions or making notes.

Newson, a Research Experiences for Undergraduates (REU) intern and sophomore at the University of Missouri, and Girgenti, a Garden intern and senior at Brown University, worked under the guidance of Bob Kirschner, the Garden’s director of restoration ecology and Woman’s Board curator of aquatics.

PHOTO: Interns Ben Girgenti and Jannice Newson.

Interns Ben Girgenti and Jannice Newson gather plant data on the shoreline.

When the summer began, Girgenti and Newson had hoped to locate and measure every single plant. But after the immense scope of the project became clear in their first weeks, they decided to focus on species that are most commonly used in shoreline rehabilitation, as that information would be most useful for others.

View the Garden’s current list of recommended plants for shoreline restoration.

“We’re interested in which plants do really badly and which do really well when they are experiencing different levels of flooding, with the overall idea of informing people who are designing detention basins,” explained Girgenti, who went on to say that data analysis of the Garden’s sophisticated shoreline development would be especially useful for others.

“The final utility of this research will be to inform other natural resource managers,” confirmed Kirschner, who added that successful Garden shoreline plants must be able to withstand water levels that can rise and fall by as many as 5 feet several times in one year.

Steering the Ship

Along the shoreline, the interns followed vertical iron posts that were installed as field markers during construction, in order to find specific plants shown on the maps. “The posts are pretty key to being able to map out the beds,” said Girgenti.

PHOTO: The Malott Japanese Garden shoreline 3 years after the 2011-12 restoration project.

The Malott Japanese Garden shoreline two years after the 2006 restoration project.

Once they found a target plant, they then counted clumps of it, and put it into one of six categories based on the amount of current coverage, ranging from nonexistent to area coverage of more than 95 percent.

They also measured the average depth of water for beds with plants below the water line, noting their elevation. For plants above the water line, the elevation was derived from the architectural drawings.

Data about the elevation and coverage level of each measured plant, together with daily lake water level readings dating back to the late 1990s, was then entered into a spreadsheet and prepared for analysis to identify correlations between planting bed elevation and plant survival.

Beneath the Surface

For her REU research project, Newson was careful to collect data for one species in particular, blue flag iris. “As a preliminary test of the project hypothesis, data relating to 101 planting beds of Iris virginica var. shrevei were analyzed to see if there was a significant correlation between the assessed plant condition and each planting bed’s elevation relative to normal water,” she explained in her final REU poster presentation in late August.

PHOTO: Southern blue flag iris.

Southern blue flag iris (Iris virginica var. shrevei), photo by Jannice Newson

An environmental science major, she initially experienced science at the Garden as a participant in the Science First Program, and then as a Science First assistant, before becoming an REU intern.

Girgenti began his Garden work in the soil lab, where his mentor inspired him to focus on local, native flora. “I was kind of pushed up a little bit by the Garden,” he said. The following year he did more field work in the Aquatics department. “I wanted to come back because I really enjoyed being here the last two years,” he said. “Every year I’ve come back to the Garden, I’ve been very excited about what I’m going to do.”

Aside from the scientific discovery, the two also refined their professional interests. “I do enjoy being out in the field as opposed to maybe working in a lab; it’s a lot more interesting to me. And also just working in the water with native plants is very interesting,” said Newson.

“I was really interested in getting into more of the shoreline science and also learning which native species were planted there,” said Girgenti. “I really love working here. I’ve never really been involved this much in science, so this has been a really great experience—just all of the problem solving that we’ve had to do over the course of the summer.”

Newson also enjoyed the communication aspect of her work, as Garden visitors stopped to ask what work she and Girgenti were doing along the shoreline. She was especially excited to share with them and her fellow REU interns that “the purpose of why we are doing this is that it provides a beautiful site for visitors to see, it helps with erosion, and also improves aquatic habitat.”

PHOTO: View of the Kleinman Familly Cove.

A view of the Kleinman Family Cove highlights the small bay where our youngest science explorers can learn about the shoreline.

Although the interns have left the Garden for now, the data they collected will have a lasting impact here and potentially elsewhere. Kirschner is currently working with his colleagues on the data analysis to complete a comprehensive set of recommendations for future use.


©2016 Chicago Botanic Garden and my.chicagobotanic.org

Each fall, we sing the praises of fall allium and autumn crocus blooms. This year, however, a special mention must be made for the glorious gladiolus! Especially the delicate, 4-inch salmon pink flowers of the salmon gladiolus (Gladiolus oppositiflorus spp. salmoneus).

Hailing from the summer rainfall areas of the cold, higher elevations of the Drakensberg Mountains of South Africa, this beautiful wild species has proven amazingly hardy in the Chicago Botanic Garden’s Graham Bulb Garden over the last five years—including a couple of winters with record-setting cold temperatures!

PHOTO: Gladiolus oppositiflorus ssp. salmoneus.

Gladiolus oppositiflorus ssp. salmoneus produces elegant, upright flower stalks that do not require staking!

Two characteristics of its native habitat nominated the gladiolus for trial at the Garden: first, it is a winter-growing bulb in South Africa, which translates to summer growth in North America. Second, this plant thrives in moist soils in grassy areas—it was perfect for the site we chose in the Bulb Garden.

Based upon its initial success in our plant trial program, other gladiolus (also currently in full flower) were added to the trials. We’ve also discovered that these wild species thrive and multiply in well-drained soils (but do not tolerate flooded soils). The beautiful, red-flowered Gladiolus saundersii is also native to the Drakensbergs, but from a higher, colder, and snowier habitat. And a third selection is probably a close relative of Gladiolus dalenii var. primulinus. Discovered in an old, abandoned farmstead in North Carolina, and sold under the name ‘Carolina Primrose’, this gladiolus generally blooms in July and early August (although it is still blooming now). All have come through the record-breaking cold of the last couple of winters. 

Gladiolus is the largest genus in the Iridaceae (iris plant family) with 255 species worldwide; 166 of them in southern Africa. The genus was given its name by Pliny the Elder, in reference to the size and shape of the leaves, which are similar in shape and size to a short sword favored by Roman-era gladiators: the gladius.

It’s not easy to find commercial sources for these bulbs, but it’s well worth the effort to obtain an elegant, refined, fall-flowering, and hardy gladiolus.


©2015 Chicago Botanic Garden and my.chicagobotanic.org

We’ve selected the top 9 plants for green roof gardens from our 5-year study of 216 taxa. Download the results of plant evaluation manager Richard Hawke’s extensive study. 

INFOGRAPHIC: Top 10 plants for green roof gardens.

©2015 Chicago Botanic Garden and my.chicagobotanic.org

The Sky’s the Limit

Results (and Surprises) from the Green Roof

Richard Hawke —  July 20, 2015 — Leave a comment

When the Green Roof Garden was first planted in 2009, everything we knew about long-term rooftop gardening was theoretical. Which plants would live more than one year on the roof? No one knew for sure. Were native plants better to plant than non-natives? Unknown. What about soil depth, extreme weather, pests, diseases? The list of questions was long.

Download An Evaluation Study of Plants for Use on Green Roofs here.

PHOTO: The Roof Garden at the Chicago Botanic Garden Plant Conservation Science Center.

Download the results of this 5-year study. Click here.

Today, after five years of watching, waiting, documenting, and evaluating, we now have actual data to guide us—and others—on the ever-more-popular topic of green roofs! I’ve just published the Plant Evaluation Notes from our research—the first national plant evaluation study of its kind.

Among the data are a few surprises.

The biggest surprise may seem the most obvious—it’s that the green roof survived as well as it did!

I was blown away by the survival rates among plants, and by the fact that so many of them thrived and even excelled in such a challenging landscape. Of the more than 40,000 plants that we installed on both roofs, 30,568 of them were still alive in 2014. Just 14% of the 216 taxa died—that’s a pretty good success rate when you consider rooftop conditions. In fact, adaptability was one of the main criteria that we evaluated each plant on. Here’s the five-point list:

  • Adaptability (to hot/cold, dry, windy conditions, plus shallow soils)
  • Pests/diseases
  • Winter hardiness
  • Non-weediness
  • Ornamental beauty

Other surprises? Definitely the wild white indigo (Baptisia alba var. alba). Although I didn’t expect it to fail, I also didn’t expect it to be as large and vigorous as it has become. By year five, it was nearly three feet tall, with dramatic spires of white flowers. Meadow blazing star (Liatris ligulistylis) was in the same elegant category. But the absolute standout was prairie dropseed (Sporobolus heterolepis). It looked good all year, at all soil depths, and the fragrant flowers made the roof smell like popcorn in August and September.

PHOTO: Antennaria dioica.

Antennaria dioica

PHOTO: Baptisia alba var. alba.

Baptisia alba var. alba

PHOTO: Phlox subulata 'Emerald Blue'.

Phlox subulata ‘Emerald Blue’

PHOTO: View of the Green Roof Garden from above.

The Green Roof Garden today: a tapestry of plant life

It also surprised me that some of the drought-tolerant plants like sulfur flower (Eriogonum umbellatum), tufted fleabane (Erigeron caespitosa), and long-petaled lewisia (Lewisia longipetala ‘Little Plum’) didn’t do better on the green roof. Same goes for sundial lupine (Lupinus perennis). In a broader sense, I’m disappointed that we haven’t had greater success with plants in the shallowest, 4-inch soil depth. It’s the most challenging area on the green roof, so we’ll strive to add more types of plants to this trial area in the coming years.

PHOTO: Richard Hawke, Plant Evaluation Manager.

Monitoring plants in the field

Top 10 starstarstarstarstar Performers
on the Green Roof

  1. Pussytoes (Antennaria dioica)
  2. Dwarf calamint (Calamintha nepeta ssp. nepeta)
  3. Juniper ‘Viridis’ (Juniperus chinensis var. sargentii ‘Viridis’)
  4. Creeping phlox ‘Emerald Blue’ (Phlox subulata ‘Emerald Blue’)
  5. Creeping phlox ‘Apple Blossom’ (Phlox subulata ‘Apple Blossom’)
  6. Creeping phlox ‘Snowflake’ (Phlox subulata ‘Snowflake’)
  7. Aromatic sumac ‘Gro-Low’ (Rhus aromatica ‘Gro-Low’)
  8. Prairie dropseed (Sporobolus heterolepis)
  9. Prairie dropseed ‘Tara’ (Sporobolus heterolepis ‘Tara’)
  10. The 69 other plants that got four-star ratings (good)! 

 

What else is coming to the Green Roof Garden?

We’ll bring in a new set of plants (both native and non-native) to be evaluated and increase the replication of trials in 4-, 6- and 8-inch soil depths. Our goal is to compile a broad list of proven plants so that anyone—businesses, architects, governmental groups, and residential homeowners—has the information they need to grow a green roof. The sky’s the limit!

Visit the Green Roof Garden at the Daniel F. and Ada L. Rice Plant Conservation Center—open ‘til 9 p.m. all summer. The garden has two halves: the Ellis Goodman Family Foundation Green Roof Garden South and the Josephine P. & John J. Louis Foundation Green Roof Garden North.


©2015 Chicago Botanic Garden and my.chicagobotanic.org