Archives For Horticulture & Display Gardens

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

It’s officially summer in Chicago, and you’ll start to notice a plethora of begonias, impatiens, marigolds, cannas, dahlias, and elephant ears, all planted for a temporary taste of the tropics.

If you’ve dreamed about creating an exotic vacation look at home, but wanted to reduce your yearly investment in annuals, consider pairing them with tropical-looking hardy perennials that come back yearly. The following additions will help give your garden that south Florida feel.

PHOTO: Hibiscus 'Midnight Marvel'

Hibiscus ‘Midnight Marvel’

Midnight Marvel hibiscus

You don’t have to live in Hawaii to grow hibiscus. There are actually two species native to Illinois. Several others occur in the southeastern states. These hardy plants emerge late in the spring, get quite large and shrubby, bloom their hearts out in late summer, and then retreat underground when winters comes along.

Midnight Marvel is a spectacular hybrid with very deep wine-colored foliage and dinner-plate-sized crimson flowers. Each flower lasts just a day a two, but are so plentiful that the show lasts for weeks, and hummingbirds love it. After each flower passes, the light green calyx tubes look pretty set against the dark leaves. Midnight Marvel reaches 4 to 5 feet tall, so is best placed at the back of the bed in a site with full sun.

PHOTO: Belamcanda chinensis 'Freckle Face'

Belamcanda chinensis ‘Freckle Face’

Freckle Face blackberry lily

Orange is a hot color, perfect for a tropical garden. The flowers of Freckle Face blackberry lily (Iris domestica ‘Freckle Face’) are a gorgeous carroty shade with many vivid red spots covering each petal. The blackberry portion of the name refers to shiny black seed clusters that pop out of the split open pods. Sprays of flowers bloom for several weeks in late summer on these 2-foot-tall plants.

Despite its name, this plant isn’t actually a lily at all, but resides in the iris family. The blue-green spiky leaves even resemble bearded iris foliage. Taxonomists very recently changed the name, so when searching online, you will most likely find it under Belamcanda chinensis ‘Freckle Face’.

PHOTO: Aralia cordata 'Sun King'

Aralia cordata ‘Sun King’

Sun King udo

Here’s a statuesque perennial for the part-sun area of your tropical garden. An enormous specimen, reaching 6 feet tall and 3 feet wide, Sun King udo is mistaken for a shrub, but is completely herbaceous. This is definitely a shade plant, but providing it with just a few hours of sun will really enhance the gold color of its foliage.

In summer, Sun King udo’s many umbels of greenish-white flowers are total bee magnets. By autumn, the spent flowers have changed into densely fruited clusters of wine red berries. The fruits are attractive, but best left for the birds, since they are not remotely tasty.

Shieldleaf rodgersflower

If you’ve got shade, consider mixing bold and tropical-looking foliage for a jungle effect. The perfect non-invasive perennial for this is shieldleaf rodgersflower. Formerly in the genus Rodgersia, Astilboides tabularis produces gigantic 2 to 3-foot-wide parasol-like leaves.

PHOTO: Astilboides tabularis

Astilboides tabularis

While the leaves are the most striking part, creamy-white astilbe-like flowers do sprout up through the dome of foliage in late June. With enough moisture, the foliage remains light green and attractive until autumn. This is not a plant for dry shade or windy spots, but perfect for moist, rich soil. For additional large leaves in the shade, try Ligularia dentata ‘Othello’, Hosta ‘Sum and Substance’, and Rodgersia.

PHOTO: Dryopteris goldiana

Dryopteris goldiana

Goldie’s fern

Tropical gardens are meant to invoke a relaxing vacation, and what is more cool and calm than ferns? Many gardeners grow ostrich fern, which is one of the largest and most tropical-looking spore producers in the Northern Hemisphere. However, ostrich fern can be a bit of a thug if space does not permit. Instead, try growing Goldie’s fern, which is a slow spreader and the largest species of Dryopteris in the United States. Under the best conditions, it will reach 4 feet tall and 3 feet wide. The fronds are a soothing shade of dark green and not golden as the name implies. (It is actually named after Scottish botanist John Goldie.)

The trick to getting the tropical look to work in your garden is to create a framework of dramatic, large-leaved perennials, and lacy, soothing ferns, then surround those with some hot red, orange, and yellow annuals. Top it off with some tiki torches, bamboo fencing, and a few lawn flamingos and you’ll have the perfect paradise for a hammock and mai tais!


©2016 Chicago Botanic Garden and my.chicagobotanic.org

We’ve officially reached planting season, and it is now safe to put in warm-season flowering annuals, vines, herbs, and vegetables. Horticulturists at the Chicago Botanic Garden do recommend waiting until Memorial Day for cold-sensitive plants such as tomatoes, peppers, eggplants, and squash. Happy planting!

Summer plantings await in the Production Greenhouses.

Summer plantings await in the production greenhouses.


Looking for a challenge? Try these techniques from our blog and the Smart Gardener:

Diascia Barberae 'Flirtation Pink'.

Diascia barberae ‘Flirtation Pink’

Get the best performance from your plants with these tips from the Garden’s Plant Information Service:

  • Pinch back one-third of new growth to encourage stocky habit (except vines).
  • Be sure newly purchased annuals have been hardened off properly before planting them outside. That means moving plants outdoors for a portion of the day to gradually introduce them to the direct sunlight, dry air, and cold nights.
  • Avoid fertilizing newly planted annuals for two weeks.
  • Continue to plant new perennials, ornamental grasses, and roses in containers. If plant roots are root-bound (encircling the pot), make four cuts into the bottom of the root ball with a sharp tool, and flare the sections outward when planting.
  • Stake tall perennials before they reach 6 inches. Begin to regularly pinch back fall-blooming perennials such as chrysanthemums, asters, and tall sedums. Pinch once a week until the middle of July. This promotes stocky growth.
  • Continue to direct the growth of perennial vines on their supports. Climbing roses should be encouraged to develop lateral, flower-bearing canes.
  • Let spring bulb foliage yellow and wither before removing it. The leaves manufacture food that is stored in the bulb for next year’s growth. Even braiding the foliage of daffodils can reduce the food production of the leaves.

Our monthly checklists and Plant Information Service have a host of other gardening tips—including care for lawns, shrubs, and roses.


Photos by Bill Bishoff
©2016 Chicago Botanic Garden and my.chicagobotanic.org

Attention orchid fans: our vanilla orchid is blooming in the Tropical Greenhouse at the Chicago Botanic Garden. It’s a rare occurrence in the wild—and in a greenhouse. Wade Wheatley, assistant horticulturist, seized the moment to hand-pollinate the flower. 

Vanilla planifolia before pollination

Vanilla planifolia before pollination

Why hand pollinate? In hopes of producing a vanilla bean. Yes, the fruit of a vanilla orchid is used to make pure vanilla extract, which flavors many foods we enjoy.

Vanilla vines typically begin to flower at five years or older. Flowers are produced in clusters, with one flower opening each day in the morning. Stop by the Tropical Greenhouse soon to see what’s in bloom. 


©2016 Chicago Botanic Garden and my.chicagobotanic.org

It is our responsibility as citizens, but especially as practitioners in the fields of horticulture and botanical sciences, to be good stewards of the land and ensure that what we are growing in our backyards and at the Chicago Botanic Garden will not contribute to problems in the future. That is why the Garden recently replaced the callery pears at the entrance to the Visitor Center.

In addition to the callery pear, the Garden also removed winged euonymus (Euonymus alatus) and tamarisk (Tamarix spp.).

Callery pear and euonymous plantings at the Visitor Center entrance in autumn of 2010.

Callery pear and euonymus plantings at the Visitor Center entrance in autumn of 2010.

One threat to our natural world is invasive plants. While many of these plants may on the surface appear to be attractive additions to the landscape, they can force out native species. Short of complete destruction of a natural area, I cannot think of anything more unsightly than a natural area that has been completely consumed by an invasive species to the point that it is no longer recognizable and holds very little biodiversity.

The list of invasive plants and potentially invasive plants is not set in stone; it is an evolving list and one that will continue to change as our climate changes. The callery pear (Pyrus calleryana) was not on the invasive species lists for our region a decade ago, but today it is in Illinois, along with Alabama, Georgia, South Carolina, and Tennessee. Most are familiar with the cultivar ‘Bradford’, but there are several others, including ‘Aristocrat’, ‘Autumn Blaze’, and ‘Cleveland Select’.

Garden staff plant non-invasive American yellowwood (Cladrastis kentukea) at the entrance to the Visitor Center.

Garden staff plant non-invasive American yellowwood (Cladrastis kentukea) at the entrance to the Visitor Center.

This spring we replaced all of the Pyrus calleryana ‘Autumn Blaze’ at the front entrance of the Visitor Center with the non-invasive American yellowwood (Cladrastis kentukea). As a result, the front entrance is noticeably more open in appearance, and the low canopy and refreshing shade that existed in years past is now gone; it will return as the plantings grow.

Although both of these species are medium-sized deciduous trees with white flowers, the yellowwood has different ornamental characteristics. The callery pear flowers in the early spring, while the yellowwood flowers in late spring to early summer. The callery pear has unrivaled fall color in shades of red, orange, and yellow, while the yellowwood is one of the best for yellow fall color. 

Why is the callery pear called an invasive?

This pear has abundant seeds that can be carried by birds to natural areas. Plants can then become established, thus displacing native species. As land stewards, the Garden is very mindful of prohibiting and eliminating any plants known to be invasive in our region.

The new plantings at the Visitor Center entrance.

The new plantings at the Visitor Center entrance will take time to grow, but will someday provide the shade and fall color of their predecessors.

I have no doubt that some of these recently removed invasive plants were favorites among Garden visitors, our staff included. But sometimes what we like isn’t always good for us, or good for the environment.

New seasonal plantings replace the previous shrubs in the entry beds.

New seasonal plantings replace the previous shrubs in the entry beds.

I encourage you to review and continue to consult invasive species lists, including on the invasive.org website, and do your part by removing invasive species from your garden and resist purchasing and adding more. There are so many benign, beautiful options available to gardeners, and the Garden, along with numerous other organizations, has done the work for you by listing alternatives for the invasive plants that we feel we cannot live without. View a list of our recommended alternatives to invasive plant species here

Each of us can play an important role in preserving the natural landscapes for future generations.


©2016 Chicago Botanic Garden and my.chicagobotanic.org

With the Kentucky Derby—and mint julep season—approaching, it’s time to consider mint, a fast-growing, almost wonderfully invasive plant.

PHOTO: Spearmint in bloom.

A refreshing digestive, mint can be harvested more than once in a season; use it fresh in your mojito, or dried as tea.

Mint survives Chicago winters and comes back hardier than ever. Cuttings easily take root and begin propagating anywhere they touch soil. For these reasons, grow mint in a plastic pot, so it doesn’t take over your yard. (The roots are so strong they can crack clay pots.) Mint needs at least four hours of sunlight per day, so pick a sunny spot. It is tolerant of most soils and weather conditions—just be sure it gets some water every week to keep it from becoming bitter.

Maintaining flavor

Mints spread in two ways: by runners and by seed. However, many plants are hybrids, which means the sprouts that shoot up from the broadcast seed will probably not be the same as the plant you bought. To keep that lovely flavor you brought home, trim the plants down when they have flowered, but before they drop seed. This causes the plant to bush out and spread from the roots only.

Choosing your flavor

PHOTO: Mint julep by Bill Bishoff.

Mmm-Mmm mint julep—a Kentucy Derby favorite! Photo by Bill Bishoff

There are more than 600 types of mint on the market. Here are a few that work best in the kitchen:

Kentucky Colonel spearmint (Mentha spicata ‘Kentucky Colonel’) got its fame from being the leaf of the classic mint julep, but it’s also perfect for any mint sauce or jelly.

Banana mint (Mentha arvensis) is part of the spearmint family, but grown mostly for its incredible smell. It still maintains a good flavor in cooking, though.

Peppermint (Mentha piperita) is most often used for its peppermint oil. Peppermint family plants are strong flavored and best used dried or in small quantities because they contain menthol (think Vicks). They soothe stomachs, but are difficult to cook with fresh.

Variegated pineapple mint is a lovely, sweet-scented peppermint hybrid that makes a great tea. To keep it variegated, you need to cut off any green stems.

Orange mint is the most invasive of all mints, so plant accordingly. It smells sharply of orange peel and can turn a nice burgundy color during winter It also works beautifully in baking recipes.

Easy Mint Simple Syrup

PHOTO: Mint simple syrup.Making simple syrup is a great way to put your mint to good use.

What you need:
½ cup mint of your choice (washed leaves; lightly chopped pieces packed down)
1 cup water
1 cup sugar

Directions:
Rinse and drain mint leaves. Bring water to boil in a small pot on the stove. Add mint leaves and sugar. Stir until sugar dissolves, and then turn off heat. Let mixture cool (approximately 30 minutes). Strain off leaves.

Store the syrup in the refrigerator for use within two weeks, or freeze for later use.

To use:
Add this simple syrup in place of sugar in your favorite ice cream, sorbet, lemonade, soda, or cocktail to add balanced mint flavor to any recipe. Even better, add to a dry wine or prosecco for an easy happy hour treat.

Want to take it higher? Freeze the syrups in ice cube trays with a few small leaves and use as a sweetener for tea or cocktails. A glass of bourbon becomes a Mint Julep when you add Mint Syrup ice cubes.

Peppermint Extract

PHOTO: Peppermint extract.Peppermint oil is often used for cleaning, pest control or aromatherapy. What you produce is not the professional essential oil (that takes more time and effort than most of us can muster), it will do the jobs needed.

What you need:
A sealable/airtight jar or glass container
Enough chopped peppermint or peppermint family leaves to fill the jar
Vegetable oil, olive oil or nut oil 

Directions:
Place washed chopped mint leaves in the container (no need to pack; they need to breathe a bit). Heat the oil of your choice (use enough to fill the jar) on the stove in a small pan until it is too hot to touch. Pour the oil over the leaves and seal the container. Let the mixture sit on the counter until it has cooled, then move it to a dark place or cupboard for a week and a half to two weeks. Once it has set, strain out the liquid into a spray bottle.

Uses:
Peppermint oil sprays are said to prevent mold and can be mixed with vinegar to create a simple disinfectant cleaner. They also create a great air freshener, massage oil, or natural control against ants, mosquitos and even rodents.

PHOTO: Tarragon simple syrup and fresh peaches enliven a sparkling wine cocktail.

Add simple syrup to Prosecco and peaches: lovely.

Want to save more of the amazing herbal flavors in your yard this year? Check out our post on Herbal Mixology for ideas.


©2016 Chicago Botanic Garden and my.chicagobotanic.org