Summer can cause problems for plants. From humidity to bugs, from inconsistent temperatures to rain, gardens are often at the mercy of Mother Nature.
Bugs, in particular Japanese beetles, can be problematic for plants. This year, said Kat McGraw, day manager at Ooltewah Nursery, the beetles seem to be short-lived, lasting only two or three weeks. In that short time, however, insects can do damage, eating rosebuds or tender leaves on trees and shrubs such as hydrangeas. Insecticides are available. However, she said she doesn't prefer them as they can cause harm to beneficial bugs such as bees and ladybugs.
Heat and humidity can cause issues as well.
"This year we've seen a lot of fungus, especially powdery mildew, and it's because we've had a variation in temperature," said McGraw.
Even the hardy Knockout roses, which are meant to be hardy, have had problems, she said.
Fungicides can be applied in the soil, to the roots or externally with a hose or sprayer, depending on the type.
When it comes to water, plants are a little like Goldilocks. They have too much or too little; they need to have just the right amount.
During dry times, be sure to water regularly. The recent rains have been good for the gardens, McGraw said.
"Right now, I think they're all loving it. They've had 100 to 105 degrees for almost a month, which is just not kind to them."
Too much rain, however, can cause problems if the plants are just sitting in still water with no drainage.
Keep gravel underneath small trees, shrubs and bushes to carry the water off. Otherwise, root rot can set in.
"Root rot will kill the plants. It will basically mold in the ground," McGraw said.
A few plants, she said, such as weeping willows, like a lot of water, but most need to be well-drained.
The humidity also can cause the same sort of fungal problems.
"This year has been very erratic," McGraw said. "It's been like a roller-coaster."
Humidity, she said, can be especially tough on older varieties of roses.
"They're prone to black spot, and that just breeds and goes rampant in very humid conditions."
To deal with this, be diligent about spraying the plants, she said.
1. To deal with too little rain: Water frequently. Make sure the soil is moist.
2. To deal with too much rain: Be sure the plants have good drainage. Gravel underneath trees and shrubs can help with water runoffs.
3. To deal with bugs: Insecticides are available that can be applied, but they also kill beneficial insects, so hold off if you can.
4. To deal with heat: Inconsistent temperatures can cause fungus, especially white, powdery mildew. Use an antifungal, either in the soil or directly on the plant. Be sure to water sufficiently.
5. To deal with humidity: Humidity can cause black spot, particularly on delicate rosebushes. These can be treated with diligent use of a sprayed antifungal.