Archives For Horticulture & Display Gardens

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

Overwintering Your Bonsai

Chris Baker —  November 18, 2015 — 1 Comment

Like so many things in tending bonsai, how you overwinter your trees is specific to the tree species and the region in which you live.

PHOTO: Bonsai in fall color.

Bonsai in fall color, before being prepped for storage.

PHOTO: Bonsai tree prepped for winter storage.

The same bonsai prepped for winter storage; tags indicate tasks to do in spring on this tree.

Here in the Chicago area, we need to take special care to protect our trees from cold temperatures and windy conditions. Prior to bringing in your tropical trees and tucking your cold hardy trees away for the winter, there is some work to be done. In this post, we will discuss fall and early winter care that lead into winter storage of tropical, deciduous, and evergreen bonsai.

PHOTO: A plant grow light gives tropical bonsai more daylight in winter.

This far north of the equator, tropical bonsai will need supplemental lighting for the winter months.

To maximize growth and tree health, your tropical bonsai should be outside during the summer months, getting the most of the warm temperatures and full sun. But before the temperatures drop—most tropical bonsai will not tolerate temperatures below 40 to 45 degrees Fahrenheit for any length of time without some damage—it is a good idea to slowly move your trees into lower light conditions. This will prepare your trees for the conditions in your house, and result in less leaf drop when they are moved inside. During this time you should also decrease the feeding of your tropical trees, slowing down the growth.

There are four things to consider when picking a spot in your house for your tropical bonsai.

  1. Lighting: Even if you have a south-facing window, most trees are going to require supplemental lighting for the winter months.
  2. Heat: Trees should be in a warm spot in your house, but should never be subject to hot, dry forced air or radiant heating.
  3. Humidity: Due to the dry nature of our heating, supplemental humidity should be provided. Humidity trays, spraying your trees daily with a spray bottle, and humidifiers are all good ways of increasing the humidity around your trees.
  4. Watering needs: Tropical trees tend to use less water in the winter. Over watering can cause root rot and a decline in tree health.

The preparation for hardy trees (both deciduous and evergreen) starts long before they are put away for the winter.

In late summer to early fall, you should stop feeding your trees with nitrogen. Nitrogen—the “N” in N.P.K.-based fertilizers— stimulates foliage growth. As fall approaches, we want to start sending energy to the roots, so using a “bloom” fertilizer with higher phosphorous and potassium values (P and K) is important. This will feed the roots and strengthen the tree for winter. It will also provide the tree with the energy for the spring flush. In bonsai, it is important to be proactive rather than reactive. The things we do in the fall determine how trees respond in the spring.

Snow on quonset.

A dusting of snow coats the ground and the outside of the quonset.

PHOTO: Quonset full of bonsai.

Inside, the cold-hardy specimens of the Garden’s Bonsai Collection enjoy being out of the wind and cold temperatures.

The pre-storage work done on your trees is important.
Our winter cleanup on all deciduous trees entails the following:

  1. Removing all the old foliage from the deciduous trees. This is most often done with tweezers to prevent any damage to the branches and next year’s buds. This step helps to prevent fungal disease forming on those leaves.
  2. Cleaning the bases of the trunks, and removing moss and weeds from the soil surface. This prevents constant moisture from touching the trunks and allows better air circulation to the roots.
  3. Performing minor pruning work. The larger cuts will wait until spring when it is safer. All cuts are covered with “cut paste” to seal the wound and prevent disease and damage to the branch.
  4. Tagging. Finally, each tree receives colored tags that indicate whether it needs repotting in the spring, has wire, needs wire, etc. These indicators are very important when managing about 250 trees!
PHOTO: Bonsai foliage is removed with tweezers before storing the tree for the winter.

Foliage is carefully removed by hand before storage.

PHOTO: Cutting away moss from the trunk of a bonsai.

Moss which has grown over the summer is removed.

PHOTO: Moss has been removed from the trunk of this bonsai pre-storage.

Moss has been removed from the trunk pre-storage.

PHOTO: Cut paste covers the fresh pruning cut.

Cover fresh pruning cuts with cut paste.

Evergreen trees and pines get their own pre-storage cleanup.

  1. Instead of removing leaves, we remove old needles on the pines. This is also done with tweezers, and needles are pulled in the direction in which they grow to prevent damaging the branch.
  2. Some light pruning is done as well as cleaning the surface of the soil.
  3. Winter is a great time to do major work on pines like wiring, making big bends, and carving dead wood.
PHOTO: Pre-wintered bonsai pine.

A bonsai pine awaits overwintering preparations.

PHOTO: The same bonsai pine after overwintering prep.

The same tree after overwintering preparations. It’s ready to be placed with others in the quonset.

We overwinter our cold hardy trees in a climate-controlled quonset. Through a process of heating and venting (if needed), the temperature is maintained at about 34 degrees Fahrenheit, which allows the trees to experience a dormancy period without getting a hard freeze on the roots. This allows us to keep very hardy trees along with those that might like things a little warmer. In the future, we will be adding an additional quonset that maintains temperatures in the mid-40s to accommodate more tree species properly.

PHOTO: Bonsai being trained with big bends.

Winter is the time for major work on pines like making big bends.

There are many variations of this type of storage that you can implement at home. Creating a space in a garage where you can protect the roots by packing mulch around the tree pots is important. Protecting the trees from wind is also important. High winds will dry out your evergreen foliage and deciduous tree buds, causing damage. Once deciduous trees have dropped their leaves and evergreen trees have experienced a frost, they will have minimal need for light, especially as the temperatures continue to drop. Using snow to cover pots and roots is a good idea. Snow is an excellent insulator, and if temperatures rise enough for it to melt, it will water your trees. (Note: You should never water a tree with a frozen root system—this will damage the roots!)

Proper winter storage will ensure that your trees wake healthy and ready to bud out in spring.

©2015 Chicago Botanic Garden and

While El Niño might be giving us a warmer winter, it’s never a bad idea to prepare against winter burn, or scorch. Three simple steps will make a big difference in preventing winter burn.

PHOTO: a burlap fence protects the Esplanade hedge from wind and deicing grit.

A burlap screen on the Esplanade path protects young boxwoods in this highly-trafficked area.

PHOTO: Viburnum winter damage.

Fencing may keep nibbling down in winter. This viburnum will need pruning.

Prepare properly

The right plant for your design goals should help reduce maintenance.

  • Choose the right plant for your garden’s growing conditions and design goals. A plant that is well-adapted to your site will perform better and have fewer problems. Proper siting makes a big difference for some plants. Plant salt tolerant plants along busy roads; broad-leaved evergreens perform best when sited so that they are protected from the winter sun and wind. The later in the season an evergreen is planted, the more at risk it is for winter burn.
  • Tree wrap may help prevent frost cracking in young, smooth-barked trees in some situations. Garden staff use tree wrap on a limited basis to protect certain plants from animal damage. Cut back herbaceous plants that are growing up around the base of trees and shrubs if you have had problems with vole damage in the past. The herbaceous plants provide cover for them in the winter while they are eating your plants. Fencing is more effective in keeping deer and rabbits away from plants.
  • Using burlap screens in winter can also help shade plants that need extra protection from the effects of wind, sun, and salt spray.

Plant well

  • Amend your soil with compost when possible, and install your new plants properly to get them off to a good start. Many trees and shrubs are planted too deep.
  • Be sure to break up the circling roots of plants that have been grown in containers before planting. The alternate freezing and thawing temperatures in spring can push out newly installed plants that are smaller in size or were grown in containers if not mulched well. Install one to two inches of mulch around the new plantings, taking care not to bury the crowns of perennials, or mounding the soil around the base of trees and shrubs. This will help prevent frost heaving in spring, and helps mitigate big temperature swings in the soil.

Provide good follow-up care

PHOTO: Andorra juniper with winter damage.

The brown-gray tips of Andorra juniper show where evaporation has damaged the foliage.

Commonsense care will go a long way to keeping plants healthy.

  • Provide supplemental water to newly installed evergreens in late fall when conditions are warm and dry so they do not go into winter under stress from being dry. Pay extra attention to plantings under 3 years of age.
  • Do not pile snow that has salt in it on plants. If you are using a combination of shoveling and ice melt on your driveway when snow is fast and heavy, make sure to shovel away from plants. Products that are safer to use are those containing calcium chloride, or calcium magnesium acetate. (Different products work differently at different temperatures.) Make sure to use the right amount as specified on the packaging! Mix ice melt with sand to reduce amount used, or use just sand near sensitive plantings.

©2015 Chicago Botanic Garden and

Fall is family photo time, as the holidays near and thoughts turn to cards, gifts, and updates. The Chicago Botanic Garden makes a beautiful background! 

 PHOTO: Crescent Garden.

No. 1: Crescent Garden
Works great for: groups large and small. Chrysanthemums and Japanese maples in shades of burgundy and wine.

PHOTO: English Oak Meadow.

No. 2: English Oak Meadow
Works great for: families. As our silhouette “family” shows, position the group on the path, then stand on the grassy area to take the shot. It’s a good vertical backdrop for larger groups.

PHOTO: Home Landscape Garden.

No. 3: Farwell Landscape Garden
Works great for: couples, kids. The “arm” of a copper beech creates a creative arch for framing. 

PHOTO: English Walled Garden.

No. 4: English Walled Garden
Works great for: tight-knit clusters. The perfect blue, the perfect bench, always a perfect picture.

PHOTO: Puryear Point.

No. 5: Puryear Point
Works great for: close-ups. Want the grand vista in the background? Head up to the hill between the Elizabeth Hubert Malott Japanese Garden and the Arch Bridge, where two Martin Puryear sculptures offer not only a nice place to relax, but also a grand vista of the Japanese islands.

PHOTO: Arch Bridge.

No. 6: Arch Bridge
Works great for: group selfies. Try this at sunset, as golden light illuminates the bridge.

PHOTO: Lakeside Terrace.

No. 7: Lakeside Terrace
Works great for: formal photos. Beautifully designed water-level terrace has seating, water, and a view of Evening Island.

PHOTO: Circle Garden.

No. 8: Circle Garden
Works great for: short-distance walkers. Just a few steps outside the Regenstein Center, the Circle Garden’s beautifully designed beds and “secret garden” benches are ideal for grandparents and little ones.

PHOTO: Outer Road.

No. 9: Outer Road
Works great for: getting away from the crowd. On the outer road, between the Bernice E. Lavin Plant Evaluation Garden and Dixon Prairie, rows of trees make a nice background with a view to the grasses beyond.

PHOTO: Evening Island.

No. 10: Evening Island
Works great for: everyone. Evening Island has broad paths, drifting grasses, big sky, a grand lawn, and a handy wall for perching at the Nautilus.

Note: With the turn of the season, backgrounds are changing every day! Use these as guidelines for your photos, and let us know your favorite backgrounds! 

©2015 Chicago Botanic Garden and

Conifornia Dreaming

Tom Weaver —  November 3, 2015 — 1 Comment

In early September, I had the privilege of attending the annual meeting of the American Conifer Society in Sonoma County, California. My first (and wildly inaccurate) thought was, “What could we possibly see aside from redwoods? There aren’t any conifers that thrive in that area.” Well I couldn’t have been more wrong, as the next two days showed me.

PHOTO: Tour at the Golden Gate Bridge.

In the early days of colonial settlement, the hills surrounding the Golden Gate Bridge were covered with forests of lush coastal redwood (Sequoia sempervirens).

Our first day included stops at one private garden, Hog Hill; a trip to an old growth redwood forest; and a very informative demonstration by the Aesthetic Pruning Association. Hog Hill is notable for having a dawn redwood (Metasequoia glyptostroboides) that is likely one of the very first grown from seed after being rediscovered in China in 1941. The rest of the garden featured a wide array of South African and Mediterranean plants that were well suited to the semiarid climate.


Redwoods in Armstrong Woods

The part of the trip I was looking forward to most was next. After waiting my entire life to see them, I was finally getting to see coast redwoods in their home. While I’ll never be able to grow them here in the Chicago area, it was still inspiring to see such majestic trees in person. Armstrong Woods State Natural Reserve was owned by a lumberman in the 1880s who recognized the area’s beauty and set aside this tract of land as a public park. While it doesn’t contain the largest trees in California, it still is home to an outstanding number of trees. Nothing reminds you of how big the world is like standing next to a plant more than 300 feet tall! We also had a chance to take a guided walk with docents from the park, where we learned that the vast majority of wildlife resides way up in the canopy, which explains why the forest floor was so eerily silent. 

After touring the redwoods, we traveled to Circle Oak Ranch, an equine center that also features an amazing collection of dwarf conifers. Unfortunately, my camera’s battery was dead by this point, so I don’t have any photos to share. We were treated to a tour of the gardens followed by an outstanding pruning demonstration by the Aesthetic Pruning Association. Several volunteers were stationed throughout the gardens giving demonstrations on how to properly prune various growth forms of dwarf conifers. This garden was also a highlight, because it was located in an area that experiences colder temperatures and heavy clay soil, and therefore featured numerous plants that would also thrive in our midwestern climate.  

Quarryhill Botanical Garden

Quarryhill Botanical Garden

The following day was a trip to Quarryhill Botanical Garden. Quarryhill features a vast collection of temperate climate Asian plants. More than 90 percent of the plants were grown from wild collected seed in places ranging from Japan to India. The gardens date from the late 1980s, when the property owner at the time decided to convert the abandoned rock quarries on her property into a lush garden. Quarryhill included many unusual conifers in their collection, which made it a great opportunity to see plants I will likely never see again such as Pinus roxburghii and Cupressus chengiana.

However, I will admit that my favorite plant from the garden ended up being—of all things—a rose. Rosa roxburghii features very large (nearly golf-ball-sized) hips of vibrant yellow with small, reddish spines covering their surface. Sure, it might not be conifer-relevant but it never hurts to learn a new plant, right?

PHOTO: Rosa roxburghiii at Quarryhill Botanical Garden.

Rosa roxburghiii at Quarryhill Botanical Garden

PHOTO: Pinus roxburghii.

Pinus roxburghii

PHOTO: Wollemia nobilis.

Wollemia nobilis

Our final stop on the trip was the San Francisco Botanical Garden (formerly Strybing Arboretum). Their 55 acres packed an incredible number of plants into one place. The conifer highlight of the garden was a very rare albino redwood. Unable to survive on their own, albino redwoods are mutations that lack chlorophyll, typically found growing at the base of an otherwise normal redwood tree. Other highlights included some magnificent specimens of conifers from the Southern Hemisphere including Araucaria and Wollemia nobilis, a tree that was only known from the fossil record until 1994, when a small grove was discovered near Sydney, Australia. We are fortunate to have a specimen of Wollemia on display in our Heritage Garden as well, but it was exciting to see a larger specimen such as this.

PHOTO: Albino redwood at San Francisco Botanical Garden.

Albino redwood at San Francisco Botanical Garden

In addition to seeing such an amazing array of plants in two days, this trip also gave me the opportunity to meet dozens of other professionals and hobbyists who share my love of conifers. The amazing thing about trips like this is seeing just how much there is in our world and how important it is to share ideas and see new things. If I had never taken this trip I would probably go on thinking that everything in northern California east of the coastal hills was a barren grassland, not an area teeming with native plants, and I never would have had a chance to meet so many interesting people, each with their own unique take on the world of conifers.

©2015 Chicago Botanic Garden and

On September 19 and 20, the Regenstein Fruit & Vegetable Garden hosted a fantastic Harvest Weekend for a crowd of enthusiastic visitors eager to learn more about extending their harvest and preserving the fruits of their labor. 

As an interpretive programs intern, I was lucky enough to run a honey-tasting demonstration that introduced many guests to the breadth of flavor, color, and aroma of a favorite sweetener. By extension, I was able to add yet another check mark to the long list of reasons we should actively participate in the protection and conservation of honeybees. 

Getting the goods with a hand-cranked honey extractor

PHOTO: View inside a honey extractor.

Tasting  A view inside the top of a honey extractor. Centrifugal force is used to “spin” the honey from the frames into an attached receptacle. Photo by Audriusa (Own work) [CC BY-SA 3.0 or GFDL], via Wikimedia Commons

Harvest Weekend was favored with two beautiful fall days—breezy and clear, with plenty of sun—and I was stationed next to our wonderful beekeepers, who oversee the popular display and free-standing hives.

They brought along authentic beekeeping gear for curious individuals to try on and a hand-cranked honey extractor (generously loaned by Windy City Harvest), positioned near the tent. On Sunday, we featured a live honey extraction demonstration, much to the delight of the onlookers.

Once the visitors had chatted with our beekeepers, they could then engage their palates and senses by tasting three very distinct types of honey: basswood, wildflower, and buckwheat.

The Color of Honey

PHOTO: Basswood (Linden flower) honey.

Basswood (linden flower) honey

Basswood is made from the blossoms of the basswood, or linden tree (Tilia americana). It is especially light in color and very sweet, with a delicate floral aftertaste. Overall, it was the most popular flavor of the weekend.

PHOTO: Wildflower honey.

Wildflower honey

Wildflower honey refers to any honey derived from a mix of flower blossoms, that is—distinct from a monofloral crop such as clover or orange-blossom honey. As such, the flavor is more complex and the color is darker than basswood honey, though not as dark as buckwheat.

PHOTO: Buckwheat honey.

Buckwheat honey

Interestingly, the majority of our Sunday visitors found this flavor to be their favorite. Derived from the nectar of buckwheat (Fagopyrum esculentum) blossoms, buckwheat honey is one of the darkest available, and perhaps the most polarizing—people either really liked it or they really didn’t. Our visitors described it as “molasses-y,” “malty,” “smoky,” “yeasty,” and according to one visitor, “like an animal”—gamey.

Want to make your own very local honey?

PHOTO: Bee life-stages models.

Learn more about bees and beekeeping: take our upcoming Beginning Beekeeping workshop!

While lining up for samples, recipes were exchanged: honey mixed with sesame seeds for energy and promoting childrens’ growth, several tonics of honey and cinnamon to soothe sore throats and coughs, and a tangential recipe for cooking buckwheat grains with salt or mushrooms as a side dish. Visitors had questions too, like how to ensure a pure single-blossom crop (hive location and timing), or what makes honey “raw” (the minimal steps used during processing). I heard loads of stories illustrating how visitors have interacted with bees, from the fellow who grew up on a farm with hives to the guests who were just expanding their understanding of bees as hardworking, fastidious insects.

Discover liquid gold.

PHOTO: Tasting honey takes all this small boy's concentration!

Honey tasting requires focus and concentration! Find out more about honey varietals from the National Honey Board.

The Garden visitors also proved to be very adventurous tasters, with most of them sampling each variety of honey. Unsurprisingly, basswood and wildflower were the predominantly favored flavors, although buckwheat tended to be preferred by adults with a penchant for molasses and, surprisingly, by several children with impressively sophisticated palates. Happily, guests were also adventurous about the bees themselves—even the occasional wandering honeybee, drawn by the hopes of a quick meal, was greeted more with humor than apprehension and provided yet another learning experience in what has been a season full of education and outreach!

Things have quieted down for the bees over here at the Fruit & Vegetable Garden as the cooler weather sets in, but I hope that visitors to the Garden will have as much fun as I did, and will take the time to learn from our hardworking and tireless volunteers, and admire the occasional honeybee going about her day.

©2015 Chicago Botanic Garden and