Garden Calendar | The Morton Arboretum

Check young trees and shrubs for deer, rabbit, and rodent damage.
Use fencing or protective collars to prevent injury.
On warm days, check perennials for heaving.
Abrupt temperature changes can cause shallow-rooted plants to push out of the ground, exposing roots. Cover plants with a three- to four-inch layer of mulch, such as woodchips, straw, or evergreen branches.
Keep road and sidewalk salt away from plants.
Shovel snow away from plants.
Uncover plants weighted down with heavy snow.
Gently brush off branches to prevent breakage. If frozen, let snow melt naturally.
Prune dead, diseased, crossing or rubbing branches anytime.
Remove water sprouts and suckers now, too.
Prepare for spring planting.
Evaluate last year’s garden and decide what changes need to be made.
Draw garden plans on paper, including a wish list of plants you would like to add.
Continue to feed birds.
Many plants offer winter berries, seeds, and pods for birds and other wildlife. Consider adding four-season plants to your landscape.
Clean and sharpen garden tools.
Get ready for the upcoming growing season.

Don’t be fooled by warm, sunny days.
It is still too early to remove mulches, screening, and other winter plant protections. Make sure they are still in place.
Monitor tree health.
It is easier to notice dead branches, hollows, and cankers on trees. Cankers are signs that the tree has a disease.
Prune trees and shrubs.
The ideal time to prune is in the dormant season, just prior to new growth.
Wait to prune spring-flowering plants to avoid removing this year’s flower buds.
Wait to prune birch, elm, maple, and walnut trees until late fall.
Although harmless, these trees “bleed” sap on sunny days when pruned during the winter.
Re-apply anti-desiccants to evergreens.
If the temperature is above freezing, a second application can be made.
Clean and sharpen garden tools.
Get ready for the upcoming growing season.
Check the summer bulbs that are stored in a cool, dry place.
Make sure they have not sprouted or dried out.
Order seeds and garden plants.
Add new plants to your landscape.
Remember to feed the birds.
Create a sense of spring.
Force branches of early spring flowering plants, such as forsythia, crabapple, and lilac. Place in a container of water in a cool place, away from direct sunlight. (Cuttings can take from two to three weeks to force.)

Wait until new growth is established before removing winter protection.
Mulch protects plants from late spring freezes.
Begin general clean up.
Rake the lawn to remove leaves, twigs, and debris.
Check for winter snow and salt damage.
Prune dead tips and broken branches.
Cut ornamental grasses back to a few inches before new growth begins.
Prevent soil compaction.
Avoid walking across saturated lawns and garden beds.
Remove tree wraps applied last fall.
Before buds break, but when temperatures remain above 40°F, spray trees with dormant oil for overwintering insects and scale.
Read label directions.
Prepare new planting beds if the soil is dry.
Work organic matter and compost into the soil before planting.
Fertilize trees and shrubs before new growth appears.
A soil test will indicate a nutrient deficiency. Follow recommendations for fertilizer and pH adjustments.
Prune summer-flowering shrubs before new growth begins in spring.
Abelia, butterfly bush, panicle hydrangea, beautyberry, and snowberry.

As the temperature warms, remove winter protective covering from plants.
Replenish mulch around existing plants to a depth of 3 to 4 inches.
Keep mulch away from trunks.
Fertilize trees and shrubs before new growth appears.
A soil test will indicate a nutrient deficiency. Follow recommendations for fertilizer and pH adjustments.
Weather permitting, dig and move trees and shrubs prior to bud break.
Watch for insects and diseases that gave you problems last year.
The sooner you detect damage, the easier it is to control.
Control apple scab on crabapple with a fungicide just as leaf buds begin to open.
Spray should be repeated every 10 to 14 days until dry weather begins.
Avoid pruning oaks and elms between mid-April and October.
Oak wilt and Dutch elm disease are spread by sap-feeding insects carrying the disease from tree to tree.
Divide and move perennials every three years to prevent them from overcrowding.
Deadhead spring bulbs when they are finished flowering to direct energy back into bulbs.
Discard tulips that only produced large leaves and no flowers.
Plant a tree in celebration of Arbor Day!

Begin planting trees, shrubs, and perennials now.
Divide and transplant perennials after they flower.
Plant annuals after all danger of frost has passed.
The average date is May 15.
Deadhead spring bulbs when they are done flowering to direct energy back into bulbs.
Do not remove foliage, let it die back naturally.
Prune spring-flowering trees and shrubs immediately after blooming.
Crabapple, forsythia, lilac, viburnum.
Avoid pruning oaks and elms between mid-April and October.
Apply 3 to 4 inches of mulch around plants.
This reduces weeds, conserves moisture, and controls temperature fluctuations in soil.
Stake tall and floppy perennials (peonies, delphiniums) as they grow.
Monitor all plants regularly for insect and disease problems.
Check evergreens, especially spruces, for spider mites; treat as new growth begins.
Place a white sheet of paper under branch and tap lightly, looking for moving pin-head size spots.
Apply fungicide sprays to roses to control diseases, such as black spot.

Water trees and shrubs deeply if natural rainfall is less than one inch per week.
Water the soil and not the foliage to reduce leaf spot diseases.
Replenish mulch under trees and shrubs to conserve moisture, reduce weeds, and control temperature fluctuations in soil.
Prune late spring flowering shrubs and hedges now.
Avoid pruning oaks and elms between mid-April and October.
Oak wilt and Dutch elm disease are spread by sap-feeding insects carrying the disease from tree to tree.
Monitor all plants regularly for insect and disease problems.
Early detection can make a difference!
Pull weeds before they go to seed.
Plant summer flowering bulbs and annuals.
Avoid deep cultivation around shallow-rooted plants by hand pulling weeds when they are small.
Monitor container plants daily, especially those in clay pots, for watering needs.
Pinch garden mums and asters once a month for bushier growth.
Stop pinching after July 15 so plants can set flower buds.
Remove faded blossoms from flowering annuals, perennials, and roses to encourage more blooms.

Plants should receive 1 to 2 inches of water every 7 to 10 days. Supplement water if we have not had a natural rainfall.
Pay particular attention to drought-sensitive plants such as maples, birch, hydrangea, and katsuratree.
Remove water sprouts and suckers from ornamental fruit trees.
Monitor all plants regularly for insect and disease problems.
Improper use of pesticides can be harmful to plants.
Contact the Arboretum’s Plant Clinic, 630-719-2424, for proper identification, diagnosis, and control of plant problems.
Cool weather and excess moisture allow many fungal diseases to thrive.
To prevent re-infection, remove infected leaves that have fallen to the ground.
Cut rose blooms back to the first set of five leaves after blooming to encourage stronger canes and more flowers.
Divide and replant iris. Discard any plants showing signs of insects or disease.
Iris should be divided every 3 to 5 years.
Remove spent flowers and pinch back leggy foliage from annuals and perennials to promote bushier growth and more flowers.
Check container plants frequently for watering needs.

Monitor rainfall and keep plants well-watered during times of heat or drought, especially newly-planted trees and shrubs.
Continue to remove faded flowers on roses, annuals, and perennials.
Pinch back leggy growth.
Don’t fertilize trees and shrubs now.
New growth will not have time to harden off before winter.
Mid-August through mid-September is an ideal time to establish a new lawn or to seed in bare spots.
For advice on establishing lawns, contact your county cooperative extension service. In DuPage County, the number is 630-955-1123.
Late summer or early autumn is the best time to divide perennials that bloom in the spring and summer.
Plant peonies from the end of the month through October.
Continue regular weeding and monitoring for insect and disease problems.
Start cuttings of herbs to grow on a sunny window sill during the winter.
Order spring-flowering bulbs to plant this fall.
Treat lawn for grubs and Japanese beetle larvae in mid-August through September.

Plant new trees and shrubs early in the month so they have time to develop a good root system.
Divide perennials that bloom in the spring and summer.
Now is a good time to divide peonies, phlox, daylilies, and iris.
Apply broadleaf weed killers to lawns.
Follow label directions.
Cut flowers, such as strawflower, statice, and celosia, for drying.
Hang upside down in a dry, well-ventilated area out of direct sunlight.
Bring houseplants indoors before night temperatures drop below 55°F.
Check for insects.
If the weather is dry, water plants deeply.
Evergreens will especially need moisture in the soil for the winter months ahead.
Deadhead perennials.
Remove and discard dead and diseased foliage to reduce infection next year.
Spring flowering bulbs can be planted from September until mid-November.
Leave the last rose blossoms of summer on plants to encourage dormancy.
Birds are beginning to migrate south.
Restock bird feeders and put out fresh water to help them on their long journey.

Protect tender plants and annuals from light frosts by covering them with sheets, plastic, or newspaper on nights when frost is predicted.
If soil tests indicate nutrient deficiency, fertilize trees and shrubs once leaf growth has stopped.
Plants will store fertilizer in roots until needed next spring. Wait until spring to fertilize evergreens.
If weather is dry, water plants deeply, especially evergreens, before the ground freezes.
Continue to mow lawn as needed.
After first frost, lift dahlias, gladiolus, cannas, and begonias as their foliage starts to yellow.
Discard tops and store bulbs, corms, and rhizomes in dry peat moss or vermiculite.
Begin to tidy up flowerbeds by removing faded flower heads and cutting back dead stems from perennials.
Remove annuals that have finished flowering.
Start a compost pile. Add plant debris, such as leaves, lawn clippings, and garden plants.
Discard heavily diseased and infested foliage.
Empty large flower pot containers of plants and soil.
Bring containers indoors to prevent breakage from alternating freeze and thaw cycles.

Fall is a great time to prepare for a new flower bed.
Turn soil and amend if necessary. Freezing and thawing over winter makes soil more friable.
Rake fallen leaves and compost or shred with lawnmower and place around landscape plants.
Discard diseased leaves, twigs, and fruits.
Plant hardy, spring-flowering bulbs outside until the ground freezes.
Start spring bulbs in containers inside forcing you to enjoy a little bit of spring in February.
Water landscape plants deeply, especially evergreens, before the ground freezes.
Cut back foliage of perennials to the ground after a few hard freezes.
Leave unusual seed heads and ornamental grasses for winter interest.
Apply winter mulch to perennials and roses after a hard frost and as ground begins to freeze.
Drain and store garden hoses.
Store garden chemicals in an area above 40°F.
Keep out of reach of children and animals.
Construct a cylinder of hardware cloth, chicken wire, or fencing around plants to protect against rabbit, mice, and deer that damage the bark and twigs of plants.

Begin light pruning on trees and shrubs by removing water sprouts and dead or crossing branches.
Pruning trees and shrubs can be done more easily in winter without leaves on branches, but avoid pruning spring-flowering plants at this time.
Protect shallow-rooted perennials, such as mums, coral bells, shasta daisy, and crocus, from the freeze-thaw cycles of winter by covering plants with evergreen boughs from leftover holiday greens.
Apply winter mulch to base of roses once the ground begins to freeze.
Applying too early can prevent the ground from freezing naturally.
Clean, sharpen, and repair all garden tools before storing.
Protect multi-stemmed evergreens, such as upright arborvitae, junipers, and yews, from heavy snow or ice damage during a winter storm by tying trunks together with old nylons or cotton twine.
Be sure to remove in the spring!
Avoid using heavy quantities of deicing material along sidewalks and parking areas near landscape plants.
Gently shake or brush off heavy snow that accumulates on shrubs and small trees before it freezes.
Do not attempt to remove ice.
Begin monitoring for animal damage when food sources become scarce, but don’t forget to feed the birds.

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