Divide and replant bearded irises after they have finished blooming. Discard any shriveled or diseased parts. Courtesy of Chicago Botanic Garden
It's time to start summer pruning the garden, and pruning is one of my favorite gardening tasks.
I've seen a lot of shrubs growing vigorously this year and it's important to prune them to keep them at a reasonable size for the garden. New growth often stops by early July so now is a good time to prune.
To create a more natural look by making individual cuts at different heights throughout the shrub, we recommend using manual pruners rather than electric hedge clippers.
For a more formal look, make cuttings at the same height. Prune just above the leaves to hide the cuttings.
Careful pruning keeps the plant smaller but doesn't look “cropped.” Remove dead wood as needed.
No need for a cicada net
Remove any netting that has been put up around trees to protect them from cicadas. If you notice any broken branch tips falling to the ground, they may have been damaged by cicada eggs.
Although the visible damage to trees continues to increase, most of the damage I see is not cause for concern.
Hybrid roses and black spot disease
If your hybrid rose's lower leaves are falling off and the remaining leaves are yellowish with black spots, you may have black spot disease, a common fungal disease.
Immediately begin a spray program with an approved fungicide. Fungicides are effective at preventing disease, but will not cure existing infection, and should be applied every 7 to 10 days.
Be sure to remove any fallen leaves from the plant. Many garden shrub roses are resistant to black spot and do not need to be sprayed.
Fungicides used to control black spot should not be sprayed on Rosa rugosa as they can burn the leaves.
Care of the garden
Bearded irises can be divided and replanted after flowering has finished. Discard any shriveled or diseased parts. Be careful not to plant the new plants too deeply.
Prune hedges when new growth begins to keep them looking neat. To keep hedges looking their best, you'll need to prune them a few times throughout the summer.
Weeds that grow in the cracks of bricks or sidewalks are unsightly, but they are easy to remove. Treat the weeds when they are small with a non-selective herbicide so you don't have to pull them out by hand. Avoid spraying on windy days to avoid damaging nearby plants. You can also use a weed whip to remove these weeds.
• Tim Johnson is horticulture director at the Chicago Botanic Garden (chicagobotanic.org).
