Tree and Shrub Care Checklist
Ash Tree Alternatives
Looking for a replacement for an ailing ash tree? Dr. Andrew C. Bell, curator of woody plants, offers these suggestions. The first three selections are Chicagoland Grows® introductions. Use the new GardenGuide app (available at chicagobotanic.org/app) to locate these trees within the Garden and to learn more about them.
Named by the Society of Municipal Arborists as the 2012 Urban Tree of the Year, Accolade™ elm is one of the top-performing trees for urban and residential planting in the Chicago region. This hybrid elm provides the iconic vase-shape American elm habit but is resistant to Dutch elm disease and elm leaf beetle.
State Street™ miyabe maple
This maple is very hardy and free of pest and disease issues. The golden-yellow fall color, uniform habit, and tolerance to urban pollution make it an excellent candidate as a street tree. Unlike the widely planted Norway maple, miyabe maple is not invasive in our region and should be planted as a replacement for ash or Norway maple.
Exclamation!™ London planetree
Selected for its uniform, upright pyramidal habit and resistance to frost cracking and anthracnose, this planetree has excellent tolerance to urban landscape settings. The exfoliating bark that has made planetree a popular ornamental is very prominent with this selection, providing year-round interest especially in the winter months.
Autumn Gold ginkgo
One of the finer selections of ginkgo, 'Autumn Gold' has a more upright habit that is maintained with maturity. This male selection does not produce messy, foul-smelling fruit, and its bright golden-yellow fall color has made the ginkgo one of the most beloved shade trees each autumn.
Fall Fiesta™ sugar maple
Another wonderful shade tree for fall color, Fall Fiesta™ is a beautiful selection of our native sugar maple. Although sugar maples lack tolerance to the heat of crowded urban areas, they perform very well in parks and parkways. Fall Fiesta™ displays brilliant autumn shades of orange and red.
Shawnee Brave™ bald cypress
The bald cypress is one of our most beautiful, versatile, and adaptable native trees. It's extremely drought tolerant once established, with finely textured, feathery foliage that turns a rusty orange-brown in the fall. Shawnee Brave™ is an upright narrow selection for those landscapes with limited space.
Trees and shrubs, including balled and burlapped evergreens, can still be planted this month. Plant on a cloudy day, early in the morning, to prevent heat and transplant shock. Water thoroughly and gently at planting time and continue for the first year with 1 inch of water a week, spread throughout the root zone. Mulch root zones to conserve moisture.
Prune spring-flowering shrubs and ornamental trees immediately after they bloom. These include forsythia, viburnum, lilac, small magnolias, rhododendrons, and azaleas. Prune to the ground old canes of forsythia and lilac. Alternative time to do renovation pruning is in late winter when plants are dormant. Deadhead (or lightly prune) spent lilac blossoms to increase flower production. Avoid fertilizer with excessive nitrogen; it can encourage foliage at the expense of flower production.
Lilac blossoms will last longer indoors if they are cut in the morning on a long woody stem when the flower is only half open. Cut a second time indoors before putting in a vase and make a vertical slit up the woody tissue.
Gently pull off dried flowers of azaleas and rhododendrons. New sticky shoots are located at the base of these flower trusses. Take care not to break these shoots when removing flowers. To increase flower production for the following year, pinch off one-half of this new green growth when it is at least one inch in length.
Pinch off terminal growth buds on rhododendrons to increase next year's buds.
Prune all spring-flowering shrubs, if necessary, immediately after they flower.
Evergreens, such as boxwood or yew, can be lightly pruned after the new growth fills in to maintain a formal shape.
If not done yet, renovate overgrown shrubs including redtwig dogwood, lilac, and forsythia by removing one-third of the oldest canes.
Prune out all ground-level sucker growth from crabapple, apple, plum, peach or apricot trees by cutting out growth below soil level.
Prune out weak, green but very fast-growing water sprouts that grow vertically from branches of fruit trees, redbuds, or other ornamental flowering trees.
If necessary, boxwood and yews can be lightly pruned to maintain geometric form. Avoid overpruning, especially in very sunny, hot weather.
Monitor newly planted trees and shrubs for insects or disease. Succulent new growth is often the first area to be attacked by insects. Aphids can be hosed off foliage. Many sucking, piercing, and chewing insects will finish feeding this month, leaving cosmetic damage but nothing serious enough to warrant chemical control.
All gardeners should familiarize themselves with the Asian longhorned beetle — what it looks like, how it damages trees, and how to tell if your tree harbors these fatal pests. Monitor for Japanese beetle damage. These iridescent insects skeletonize foliage but will finish feeding by the second week in August. Favorite host plants include roses and grapevines, and linden, maple, elm, birch, and crabapple trees. They are often found feeding on the tops of plants. If possible, hand-remove them by knocking them into a large jar of soapy water. Hold the jar directly below the feeding beetles. When disturbed, they usually drop straight downward — right into the jar.
Continue to water newly planted trees and shrubs each week if rainfall is insufficient. Watch closely for signs of scorch on tender new foliage — the margins of leaves turn brown and crispy — indicating lack of water and/or exposure to hot drying winds.
Pruning is generally not advised this month, with the exception of shrubs that have just flowered. They are pruned immediately following their flowering.
Wait until trees and shrubs drop their leaves or undergo color change before planting them or digging and moving them to new sites. At that time they are entering dormancy and will not suffer as much transplant shock when moved.
Broadleaved and needled evergreens, both dwarf and standard, are best planted or moved by October 1. Water deeply and thoroughly at planting time and each week up until the ground freezes.
Continue to water large trees and shrubs, especially evergreens, until the ground freezes hard. Evergreens continue to lose moisture through their needles throughout winter and must have adequate water in their root zones to avoid winter burn or dessicated needles.
Wait until next month to fertilize any tree or shrub that looks like it might benefit from extra nutrition — for example, has stunted growth, has failed to fully flower or leaf out, or has undersized fruit or off-color foliage.
Consider applying fertilizer this month to trees or shrubs that have not received any fertilizer this year and/or have demonstrated need — for example, stunted growth, failure to fully flower or leaf out, undersized fruit, off-color foliage, recovery from disease, or insect attack.
Continue to water newly planted trees and shrubs, especially evergreens, up until ground freezes. Milder temperatures can fool gardeners into thinking woody plants don’t require as much moisture in fall as they do in summer.
Many deciduous trees and shrubs can be planted when they demonstrate fall color or drop their leaves. This indicates they are initiating dormancy. Water well and mulch with 2 to 4 inches of shredded bark. Do not fertilize at this time. Wait one year before applying a balanced, slow-release granular 10-10-10 fertilizer. Certain trees are better planted in spring, among them magnolia, redbud, Japanese maple, dogwood, doublefile viburnum, rhododendron, and any other woody plant considered marginally hardy in zone 5.
If rabbits, rodents, or deer have been a problem in past winters, take precautions with valuable woody plants now. To keep deer from rubbing antlers on tree trunks, spread garden netting or snow fencing around abused trees. Creation of physical barriers is more effective than sprays. Deter rabbits and rodents from overwintering in gardens by cutting down their winter habitats, such as ornamental grass clumps or perennials left standing for winter interest. Protect tree trunks from gnawing rabbits by setting up 12 to 16 inches of hardware cloth tacked into the soil three inches away from the trunk.
Continue to plant deciduous trees and shrubs as weather permits. The alternate time for planting is next March, before plants leaf out. Apply 2 to 4 inches of wood chips, shredded bark, leaves, or compost to root zones of newly planted trees and shrubs. Be sure to pull mulch 4 inches away from tree trunks.
Continue to water trees and shrubs, especially evergreens, until the ground has frozen completely.
If rabbits, rodents, or deer have been a problem in past winters, take precautions with valuable woody plants now. To keep deer from rubbing antlers on tree trunks, spread garden netting or snow fencing around abused trees. Creation of physical barriers is more effective than sprays. Deter rabbits and rodents from overwintering in gardens by cutting down their winter habitats, such as ornamental grass clumps or perennials left standing for winter interest. Protect tree trunks from gnawing rabbits by setting up 12 to 16 inches of hardware cloth tacked into the soil 3 inches away from the trunk.
If necessary, construct burlap windbreaks 12 inches away from any newly planted, sensitive shrubs. The screens will buffer damaging effects of bitter, northwest winter winds.
Antidessicant sprays are not recommended for routine use on broadleafed evergreens. Some gardeners have used these products on rhododendron, azalea, boxwood, or holly to protect foliage from the drying effects of wind. Research indicates, however, that the waxy coating these products create can interfere with normal transpiration in the plants' foliage.
Light pruning of deciduous trees and shrubs can be done this month. Heavy pruning is best done in late winter or very early spring before buds break. Immediately prune back any branches damaged by snow and ice.
During periods of thaw, continue to water trees and shrubs, especially newly planted trees and all evergreens. Take advantage of thaw to water plants or garden areas that receive salt spray. The water will dilute the salt concentration absorbed by plant roots.
Continue to monitor for rodent or animal damage if this has been a problem in the past. Problems to look for include rubbings on tree trunks from young deer bucks and gnawed or stripped bark from lower trunk areas due to rabbits, mice, and voles. Creation of physical barriers such as deer netting, deer fencing, or hardware cloth tacked around tree trunks works more effectively than repellents.
In the event of heavy snows, remove snow loads from evergreen branches by gently sweeping snow off with a broom. Branches that have been anchored to the ground may be lifted gently from underneath with a broom. Avoid banging tree branches with any heavy tools.
Ice accumulation on tree branches should be allowed to melt. Avoid cracking ice with heavy objects.
Later this month, selectively prune branches from flowering trees and shrubs and bring them indoors for forced blooming. Most flowering plants can be successfully forced if they have had at least a six-week cold period. Even branches with only foliage can make interesting arrangements. For flowering plants, choose branches with plenty of fat flower buds. Prune carefully, using proper pruning techniques, taking care not to interfere with the natural shape of the tree or shrub. Branches should be at least 1 foot long, cut when the temperature is above freezing. Lay branches overnight in a bathtub filled with room-temperature water. Make cross cuts in stem ends or smash the ends of very large branches so they can quickly take up water. Arrange them in a bucket or vase and keep them in a 60-degree room out of direct sunlight. Change the water every other day. As buds begin to swell or color up, make final arrangements and bring into a cool room, out of direct sun. Good choices for forcing in January and February include serviceberry (Amelanchier), magnolia (Magnolia), flowering quince (Chaenomeles), forsythia (Forsythia), crabapple or apple (Malus), flowering pear (Pyrus), flowering cherry (Prunus), honeysuckle (Lonicera), spring-flowering witch hazel (Hamamelis vernalis) and redbud (Cercis).
Light pruning of deciduous trees and shrubs can be done this month, weather permitting. Heavy pruning is best done in late winter or early spring immediately before bud break. Another time to prune ornamental flowering trees is immediately after they flower. (This avoids sacrificing their spring flower display.) Fruit trees are best pruned in late February or early March. Oak trees must be pruned in dormant months to minimize risk of oak wilt disease. Immediately prune back any branches damaged by snow and ice.
If tree branches become covered with ice, let the ice melt naturally rather than cracking it with a heavy object. If large evergreen branches are anchored to the ground with snow, gently sweep off snow with a soft broom and then elevate the tree branch from underneath. Using heavy objects like shovels risks cutting the tree bark — a possible point of entry for infection and insect attack.
Continue to monitor for animal damage if this has been a problem in the past. Rabbits will gnaw or strip off lower bark from trees. They can stand on top of snow piles to reach higher up on trees. Young bucks will rub their antlers on tree trunks as they try to remove the velvet. Create physical barriers such as deer netting, snow fencing, or hardware cloth tacked around tree trunks.
Check newly planted softwood trees for frost cracks or sun scald injury that might occur when winter temperatures fluctuate dramatically from a sunny warm day to a subzero night. Consider wrapping vulnerable tree trunks with protective wrap in fall and remove wrap in spring.
If necessary, construct burlap screening supported by wooden stakes to protect evergreens in path of salt spray.
This is the month to check host plants for overwintering Eastern tent caterpillar egg cases. Check crabapple, apple, hawthorn, mountain ash, flowering cherry, and other members of the rose family for signs of dark, iridescent egg cases encircling small twigs, giving a pencil-like shape to the twig.
Unusually mild weather might cause some buds on flowering shrubs to bloom prematurely. These flower buds will not rebloom in spring, but there will be enough of the unopened buds to flower at their appropriate time. Forsythia, viburnum, flowering quince, weigela, and magnolia will often bloom sporadically during warm periods in late fall or early winter.
Continue to cut branches for forcing indoors. Branches with interesting foliage as well as flowering branches can be forced. Prune carefully, using proper pruning techniques and cutting off only those branches that are not essential to the plant’s basic shape. Branches should be at least 1 foot long, full of fat flower buds, and cut on a day above freezing. Lay the branches in a bathtub filled with room-temperature water. Make crosscuts in stem ends or smash woody ends with a hammer to allow quick uptake of water. Keep branches in a cool room out of direct sunlight and change the water every other day. When the buds color up or the foliage begins to unfurl, arrange the branches in a vase and display them in a cool room out of direct sunlight.
Good choices for forcing this month include serviceberry (Amelanchier), magnolia (Magnolia), flowering quince (Chaenomeles), forsythia (Forsythia), crabapple or apple (Malus), flowering pear (Pyrus), flowering cherry (Prunus), honeysuckle (Lonicera), spring-flowering witch hazel (Hamamelis vernalis), and redbud (Cercis).
Heavy pruning of large woody plants can be done this month, weather permitting. To avoid sacrificing spring flower display, prune large flowering trees and shrubs after they bloom in spring. Fruit trees are best pruned in late February or early March.
If tree branches become covered with ice, let the ice melt gradually rather than cracking the ice with a heavy object. If large evergreen branches become anchored to the snow, gently sweep snow with a soft broom and then elevate the branch from underneath. Using heavy or sharp objects like shovels to remove snow on trees risks cutting the tree bark and creating a point of entry for disease or insects.
Check newly planted softwood trees for frost cracks or sunscald injury that might occur when winter temperatures fluctuate dramatically from a sunny warm day to a subzero night. Consider wrapping vulnerable tree trunks with protective wrap in fall and removing it in early spring.
If weather is unusually warm, avoid pruning trees that will "bleed," or discharge large amounts of water, such as elms, maples and birches. Prune these trees only when weather is quite cold or in summer.
Immediately prune out broken or damaged branches.
Watch weather conditions for an appropriate window of time to spray fruit trees or large deciduous trees with dormant oil. Spray if aphids, scale, or mites were a problem in the past. Temperatures must be at least 40 degrees Fahrenheit with no chance of freezing or rain within the following 24 hours. Avoid spraying on a windy day. Certain trees have a phototoxicity to dormant oil and should not be sprayed. A few common ones are arborvitae, beech, red maple, Japanese maple, sugar maple smokebush, blue spruce, blue cultivars of juniper, and yew. Call Plant Information if in doubt.
To reduce the spread of oak wilt, all oak pruning should be completed in March, or before the oaks begin active growth. Pruning should not resume until after the first frost, or around November 1.
Prune fruit trees in early March on a dry day before buds swell. As with all pruning chores, sterilize pruning tools with a 10 percent solution of bleach before each cut. Prune out sucker growth, water sprouts, and any diseased or dead branches. Remove crossing branches, rubbing branches, or those that grow toward the center or the plant rather than outward, away from the interior. Fruit trees benefit from having their canopies opened up to permit more sunlight and air into their centers.
Prune spring-flowering trees and shrubs immediately after they flower to preserve this season’s flower display.
Prune roses when the forsythia begins to bloom. When pruning roses, make a 45-degree cut above a healthy bud, angled away from the center of the plant. If not done last fall, prune hybrid tea roses and grandiflora roses back to 12 inches to reinvigorate growth. Prune out dried, darkened, and broken canes and any dead tips. Prune shrub roses to remove dead wood and very lightly to shape to size.
Fertilize woody plants four to six weeks before they begin new growth only if they have shown signs that they could use it. These would include poor leaf color, failure to completely fruit or flower, or stunted growth. Use a slow-release granular fertilizer or an organic product and water in well. Do not fertilize newly planted trees or shrubs. Wait one year before making this application.
Plant trees and shrubs before they break bud and when soil conditions permit. If spring weather is unusually wet, consider planting in the fall when the plants begin their dormancy. With all woody plants, avoid planting too deep. Research indicates that more trees suffer from being planted too deep in the hole than any other problem. Plant with one-third of the root ball above ground. Taper soil away from the trunk back to ground level. Mulch the entire root zone with several inches of shredded or chipped bark.