Archives For Horticulture & Display Gardens

Learn more about the plants and gardens at the Chicago Botanic Garden.

A Year in Bulbs

Tom Weaver —  April 10, 2014 — Leave a comment

Bulbs are often thought of as a single season “wow,” beautiful in spring and gone by summer. This couldn’t be farther from the truth!

With a little planning, you can have beautiful displays of bulbs throughout the season. You can blend colors seamlessly for a year-long display, or you can mix things up seasonally to give yourself three or four new displays, one for each season! The ephemeral nature of most bulbs allows you to keep things fresh without constantly replanting.

This summer, we’ll be following the Graham Bulb Garden throughout the year to show how a palate of background perennial plants can be transformed into a stunning display of different colors and textures throughout the season.

PHOTO: View of the Bulb Garden.

Iris reticulata ‘J.S. Dijt’ provides some of the earliest color in the Bulb Garden.

 

PHOTO: View of the Bulb Garden.

A bed of Scilla rosenii, Ornithogalum umbellatum, and Chionodoxa luciliae ‘Alba’ getting ready to burst forth with color.

 

PHOTO: View of the Bulb Garden.

It may not look like much now, but soon this hillside will be a sea of Narcissus, Muscari, Lilium, Allium, and dozens of other bulbs blooming continuously for the entire season.

So what’s blooming now in the Bulb Garden? 

Winter aconite (Eranthis hyemalis) provides an important source of nectar and pollen for early pollinators. On any warm day, you can see hundreds of honeybees scurrying among the flowers.

Giant snowdrop (Galanthus elwesii) is often one of the first things we see blooming in the Bulb Garden. This year, the first flowers were seen on March 20, well-timed for the start of spring! Snowdrops are best planted near doors or paths where you can appreciate their delicate nature.

Dwarf reticulated irises (Iris reticulata) come in a wide variety of colors, but the one thing they all have in common is their rich color and striking presence in the garden.

Early scilla, or white squill (Scilla mischtschenkoana ‘Tubergeniana’), might not be the most readily available bulb, but its icy blue color and ease of growth make it a great choice for early spring color.

PHOTO: Giant snowdrops in bloom.

Giant snowdrop (Galanthus elwesii)

PHOTO: Winter aconite in bloom.

New-blooming winter aconite (Eranthis hyemalis) is already being pollinated by honeybees.

PHOTO: Scilla mischtschenkoana 'Tubergeniana' in bloom.

Delicate Scilla mischtschenkoana ‘Tubergeniana’ in bloom.

PHOTO: Iris reticulata 'J.S. Dijt' in bloom.

Miniature Iris reticulata ‘J.S. Dijt’ is an early spring bloomer.

©2014 Chicago Botanic Garden and my.chicagobotanic.org

Trialed and True

Plant Evaluation Program Helps Gardeners Choose the Best Plants for the Area

Renee T. —  April 9, 2014 — Leave a comment

When the glossy gardening catalogs come in the mail, or when you stop by to see what’s new at your local nursery, it’s tempting to dream—wouldn’t those pink-hued purple coneflowers be lovely in the front yard? Or what about that new, show-stopping snowflame hibiscus?

But before you grab your credit card, consider the pertinent question: which plant would work best in your garden? That’s where the Chicago Botanic Garden’s Plant Evaluation Program comes in. For more than three decades, the program has conducted scientific studies to determine which plants offer superior performance in the Upper Midwest and in areas with similar climate and soil conditions.

PHOTO: Overhead view of the bridge and gardens in mid-spring.

A view of the Serpentine Bridge and Plant Evaluation Gardens

 “So many plants have a premium price, and if they don’t perform as expected, people get disenchanted,” said Richard Hawke, plant evaluation manager. “You’ll find what’s hot and new in catalogs and magazines, but I’m all about the tried-and-true. We’re here to tell the average gardener and the green industry how plants performed in our evaluations.”

Few plant evaluation programs are as large or as diverse as this one. There are currently 30 groups of plants growing in the Bernice E. Lavin Plant Evaluation Garden, a 2.5-acre site in full sun, and in the William Pullman Plant Evaluation Garden, which has perennials, vines, shrubs, and small trees growing in partial shade.

Plants are rated based on their ornamental characteristics, how well they adapt to the site, whether they are winter hardy, and how well they resist diseases and pests. “When we look at winter hardiness, it’s not just for cold temperatures but for wet soil, which can be very detrimental,” Hawke said. None of the plants is treated for diseases or insects.

The length of the evaluation varies from four to ten years based on the type of plant. Perennials are studied for four years, while shrubs and vines are a six-year study, and trees may take seven to ten years. “We observe and review them over a long period so we can say with fair certainty how the plant performs for us,” Hawke said.

The results are published in the Garden’s Plant Evaluation Notes, a series of reports made available to home gardeners and the green industry and available on the Garden’s website at www.chicagobotanic.org/plantevaluation.

The latest issue of Plant Evaluation Notes reports on Joe-Pye Weed. Click here to view the full list of plant evaluations.

PHOTO: Closeup of a Joe-Pye weed in bloom.

A Joe-Pye weed cultivar, Eutrochium maculatum ‘Glutball’ in bloom

Hawke is also involved in evaluating the potential for some popular ornamental plants, such as maiden grass (Miscanthus) and smartweed (Persicaria/Polygonum), to be invasive. This is a concern not only for home gardeners, but also for forest preserves and other open spaces where invasive plants compete with native plants.

It’s easy for visitors to check out the plant trials underway—the Trellis Bridge connects Evening Island to the Lavin Evaluation Garden across from the Daniel F. and Ada L. Rice Plant Conservation Science Center, and there’s a new path within the evaluation site. “What’s great about the evaluation gardens is they are densely planted with things that you won’t necessarily see anywhere else in the Garden,” Hawke said. “You can see a group of different filipendulas or lavender growing side-by-side.”


The Plant Evaluation Notes are made possible in part by the Woman’s Board Endowment for Plant Evaluation Research and Publication. This post was adapted from an article by Nina Koziol that appeared in the winter 2013 edition of Keep Growing, the member magazine of the Chicago Botanic Garden.

©2014 Chicago Botanic Garden and my.chicagobotanic.org

Spring isn’t progressing very quickly outside, so we stopped by the production greenhouses to find out how spring is growing behind the scenes. Tim Pollak, outdoor floriculturist, was excited to show us what it takes to grow thousands of the spring annuals and vegetables that will soon be planted outdoors.

Tim told us we are growing 73,000 spring annuals and vegetables this year to be planted outside in the gardens in April. If you like pansies and violas, you are in for a treat, as we’ve planted almost 30,000 of them! A lot of planning goes into scheduling when to start seeds, thin them, transplant them, and harden them off to be ready when each horticulturist needs them. The production team of more than 50 staff members and volunteers makes it all look easy, but I’m guessing with this harsh winter, it hasn’t been easy.

Just one of the wows visitors will see this spring are the hayracks that hang over the bridge from the Visitor Center to the main island. Staff members and volunteers just recently spent 12 hours planting them with 1,200 plants. They will grow safely in the greenhouses until the weather gets warm enough to bring them outside. Can’t wait!

Click on the video link above or watch on YouTube to learn all about getting ready for spring!

©2014 Chicago Botanic Garden and my.chicagobotanic.org

Historically, fruit trees, shrubs, and berries were grown at home out of necessity. Colonialists were entirely dependent on what they could produce themselves, and in time, a fruitful garden became a common symbol of independence from foreign imports—highlighting a new American pride in agriculture.

The farm-to-table movement of today epitomizes the fruit-growing traditions of the past by “growing as close to the plate as possible.” Sweet, juicy fruit can be easily grown in gardens of all sizes: on small urban lots, in containers on terraces, or in large suburban gardens. Harvesting homegrown fruit continues to be a gardener’s most satisfying pleasure, and with a bit of advance planning, choosing suitable varieties to plant this spring is possible. Here are a few ideas to get you started creating, and/or caring for, your edible landscape.

PHOTO: A hanging basket growing a mix of strawberry cultivars and lettuces.

Day neutral strawberries are grown in our vertical wall and hanging baskets in the Regenstein Fruit &  Vegetable Garden.

Plan to plant strawberries

No grocery store strawberry ever tastes as good as one grown in your own yard. An easy starter crop, strawberries are self-fertile, so you can start small if you like—plant just one variety or only one plant—and still reap a reward. Choose strawberry varieties carefully, however—they vary greatly in flavor, disease-resistance, tolerance of different climates, and harvest time.

Good choices for Illinois gardens are larger June-bearing strawberries such as ‘Earliglow’ and ‘Allstar’. Day-neutral or everbearing strawberries were developed to produce flowers and fruit continuously throughout summer and fall, ignoring the seasonal effects of day length on fruit production. Of the many day-neutral and everbearing varieties to choose from, ‘Tristar’ is a reliable berry for our zone. At the Garden, we grow everbearing strawberries ‘Mara de Bois’ and ‘Seascape’ in hanging baskets and vertical plantings, because they are among the first to fruit in the spring, but also produce a June crop followed by a final fall crop.

Planting several varieties together in your garden extends your harvest time, ensuring there are plenty of strawberries for eating out of hand and enough fresh berries left over to make strawberry jam.  

Choose healthy plants for a healthy harvest

Start with quality, virus-free, and disease-resistant plants. Mail order nurseries and garden centers have bundles of bare-root plants available. Lesser quality plants are prone to fruit rot, mold, and fungal diseases like Verticillium wilt.

PHOTO: Glass cloche cover strawberry plants in a garden plot in early spring.

Strawberry flowers are susceptible to frost. Here, a transparent plant cover called a cloche (from the French word for bell) is used to protect plants if frost is expected.

Select a planting location in full sun; avoid low-lying spots or crop beds that have grown tomatoes, potatoes, or cane fruit in prior years. These crops can harbor soil pathogens like Verticillium and Phytophthora which can affect new plantings. While strawberries prefer to grow in soil with a bit of acidity, a pH of 6.2 is ideal; the varieties mentioned above perform well in Chicago.

Aim for early spring planting, as soon as the soil can be worked, and its temperature is above 40 degrees Fahrenheit. Mid-April to mid-May is ideal. Space plants 12 inches apart, leaving 3 feet between rows. Fifty plants produce enough fresh home-grown fruit for four people all summer long.

Plant with midpoint of crown at soil level. Roots should be planted straight down. Strawberries are shallow-rooted, and mother plants spread by runners—which can be removed if desired, to develop stronger plants and to promote bigger fruit.

Water your plants well, particularly when they are fruiting. Mulching with straw helps keep fruit clean and dry, and up off the soil.

Spring tasks: Prune Raspberries

Red, yellow, black, or purple raspberries are easy to grow in hedgerows as natural barriers along lot lines or on post-and-wire trellises. Cane fruit is best managed with proper spring pruning, which prevents a tangled mess and makes your late-summer harvest far easier. Regular pruning keeps brambles in line while allowing air flow through the plant—lessening the risk of fungal diseases like Botrytis and rust, and increasing both yield and berry quality. Both types of raspberries—summer-bearing and everbearing (or fall raspberry)—benefit from a good March pruning.

PHOTO: Different kinds of berries in baskets, lined up in a grid.

A bountiful berry harvest on its way to our Farmers’ Market? A bountiful home harvest is also possible with vigilant pruning.

Summer-bearing raspberries produce a single crop in the summer on canes which have overwintered. It is important to confine them to a 1- to 2-foot-wide hedgerow to encourage air flow and sunlight. Begin your pruning by removing dead, diseased, or damaged canes first. Then, head back (prune) the spindly top 6 inches of cane tips. Removing the thinnest wood which produces the smallest berries forces the growth into the more vigorous lower part of the plant.  Finally, remove less vigorous canes—in an established plant, those canes with less than a pencil’s diameter thickness—leaving 6 inches between canes (enough room to easily pass your hand between canes).

Fall-bearing red and yellow raspberries can produce fruit on both the current season canes (called primocanes) and second-season growth (floricanes). Thus, they can be pruned to bear one or two crops with a method called, “double cropping.” (We demonstrated both methods last year on our brambles in the Regenstein Fruit &  Vegetable Garden.)

  1. To produce one heavy fall crop, cut all autumn raspberry canes back to ground level in the spring. Canes should be cut as close to the ground as possible to encourage new buds to break just below the surface. All new canes will grow from this radical pruning and produce a single crop of berries.
  2. A second method of pruning produces a small crop on the previous year’s growth and later, a second crop on the current season’s canes. When a double crop is desired, remove dead, diseased, or damaged canes in March, leaving the vigorous canes to fruit. Tip-prune those back by one-third of the total length of the cane, or to trellis height. The new shoots or primacies will produce the second larger crop. After the second fruiting, the canes will die and should be removed.

Pruning for blackberries is similar to raspberries. They are also pruned in March by heading back the “leaders”—the main canes—by one-third (or about 36 inches). This tip-pruning helps to stimulate the growth of lateral branches, which is where blackberry sets fruit. The lateral branches should be pruned back to 12 inches, or where the branches’ thickness is about the diameter of a pencil. 

Want to learn more about cultivating berries? Join us for Growing Fruit Trees and Berries, May 29 to July 10, or check out other fruit cultivation classes at the Garden this spring.

©2014 Chicago Botanic Garden and my.chicagobotanic.org

We learned about some of the more unusual orchids featured in the Orchid Show (purchase tickets here) when we toured with Boyce Tankersley, director of living plant documentation.

PHOTO: Dendrobium Comet King 'Akatsuki' orchid.

Dendrobium Comet King ‘Akatsuki’

Boyce told us we have 183 taxa of orchids in our plant collections and 53 of those are straight species found in the wild. Of course, none of our orchids are wild-collected because that does damage to the species, so the orchids we acquire are propagated through tissue culture. We display the orchids that do best in our greenhouse growing conditions, and most of those do best in the Tropical Greenhouse.

Some of the orchids Boyce shows us in the video below are Vandas, which are native to the Philippines and other islands in Southeast Asia.

Boyce shared his love of Dendrobiums and revealed a goal to visit an area of the Himalaya Mountains where they cover the oak trees. But watch out: Boyce warns us of leeches in the area! (Don’t worry, we don’t have those in our greenhouses!)

Finally, we examined an interesting ground orchid, Phaius tankervilliae ‘Rabin’s Raven’, which is growing very well in our greenhouse conditions.

Vanda Orchid

Vanda manuvadee

Nun orchid

Phaius tankervilliae ‘Rabin’s Raven’

Click on the video link above or watch on YouTube to get the full tour! The Orchid Show closes March 16, 2014.


©2014 Chicago Botanic Garden and my.chicagobotanic.org