When in doubt, prune dying roses so plant looks good
Deadhead hybrid roses as soon as the flowers fade. Many shrub roses are self-cleaning and don't require deadheading.
When in doubt, lightly prune old blossoms to keep plant looking attractive. Do not deadhead any roses that are being grown for their hip production.
• Mowing is one way to control weeds in a large, natural prairie area that is being established in your garden. Native plants typically develop their roots, not their foliage or flowers, in their early years of getting established, which gives weeds the opportunity to gain a foothold.
Mow weedy areas now at a high height to cut back the weeds and keep them from choking out the native plants. In small areas, weed by hand. You can also carefully spot-treat weeds with an herbicide.
• Prune out water sprouts (vigorous shoots on the inside of the tree and on the trunk) and suckers (vigorous shoots growing from the base of the plant).
Crabapples and hawthorns tend to send out lots of water sprouts and can benefit from this type of pruning, especially the spring after they have been heavily pruned in the winter.
• Anthracnose, which refers to a group of fungal diseases, is more prevalent this year due to the cool, wet spring weather the region has had. It causes discolored spots on leaves and occasionally cankers on twigs and branches.
These spots usually are tan, purplish, dark brown or black and merge into dead areas that sometimes follow the leaf veins. The infected areas will often expand out toward the leaf margin and causes the irregular brown patches and distorted leaves.
Some leaves may drop prematurely to the ground. It rarely kills a tree or seriously affects its health, though in more severe cases a tree may defoliate.
The best thing to do is to clean up and dispose of any fallen diseased leaves and provide supplemental water for any severely affected trees during any extended hot and dry periods later this year.
• Tim Johnson is director of horticulture at Chicago Botanic Garden, chicagobotanic.org.