1. Some of the annuals you’ve planted in the ground or containers this spring or summer have reached the end of their season.
They may be overgrown and leggy or done blooming for the season. Remove the old plants and fill in bare spots with vibrant colored, cold-tolerant annuals such as Mums, Calibrachoa, Pansies, Celosia, Ornamental Kale, Cabbage, Peppers, and Grasses. Most will last up until the first frost and give you a couple more months of colorful decor.
2. Yes you can plant in fall!
The majority of trees and shrubs can be planted up until the ground is frozen. See our planting instructions. The cooler air temperatures combined with the warm soil temperatures help plants set down roots this fall for a head start next sprint. Perennials make new roots quickly when soil is warm and not compacted but be sure to get your grasses in before the end of the month for best results. You can also divide spring blooming perennials in fall. Lift and split large perennial clumps, or ones that have thinned in the center, or plant a few new perennials before the soil is too cold and wet.
3. Always check the soil to determine when to water all plants.
Water deep and slowly in the morning at the root base, not on leaves, to prevent disease. Plants still require water when the temps cool, some may not need as much. Keep our watering instructions at your fingertips.
4. Clear beds of weeds and search for areas to plant bulbs late fall for spring flowers.
A general rule of thumb is to plant bulbs at a depth of three times their height and two to three bulb-widths apart. For example, dig down 6″ to plant a 2″ high bulb, point side up, flat side down.
5. Cut back plants prone to powdery mildew.
Some susceptible plants include herbaceous Peonies (do not cut down Tree Peonies), Phlox, Menarda, Hosta, Lilac, and Ninebark. Throw away debris and sanitize the tools. Read more about powdery mildews from the Morton Arboretum.
6. Leave perennials and hydrangeas intact over the winter
The different shapes and sizes of flower heads and grasses add beauty to your winter garden and provide shelter for beneficial insects as well as seeds for overwintering birds. If you must cut down some perennials, leave ~6” of old stem to protect the plant crown by catching snow and blown leaves for added insulation.
7. Mulch provides a layer of protection against winter winds and temps.
Add 1”-2” layer of pine fines or leaf mulch to perennials and 2”-3” layer of hardwood mulch to trees and shrubs. Do not let the mulch touch the crowns and stems of plants to prevent insect damage and disease. Remember — no volcano mulch!
8. Leaves on trees and shrubs may change early due to the environmental stress of our hot and dry August.
Leaf scorch turns leaf edges brown and crispy when the plant has not had enough water or the roots are not yet sufficient enough to support the leaves on the tree. Some trees, like the River Birch, shed their leaves to conserve energy, much like a dog does with too much hair.
9. Some trees and shrubs are prone to fungus, such as apple scab or cedar apple rust.
They require cleaning up, throwing away the debris, and sanitizing the tools used. Do not fertilize but continue to water these plants. The Morton Arboretum Plant Clinic helps identify plant diseases.
10. Evergreens go through a seasonal needle drop.
The interior needles turn brown and fall off. This is a normal process and different than browning on one side or at the top.