Too much rain is as stressful for garden plants as is drought or extreme heat and cold. Central Indiana has been undergoing an extended rainy period. © Jo Ellen Meyers Sharp
I don’t know about your garden, but part of mine is thriving and another part is suffering.
All this rain has pushed lush growth on hosta, hydrangea, coneflower and a lot of other plants, including weeds. Other plants are suffering with too much water, such as the dogwoods, even though they generally tend to prefer it more wet than dry.
The National Weather Services says June 2015 was the 7th rainiest on record in Central Indiana, with Indianapolis receiving 8.36 inches, 4.11 inches more than normal. Bloomington received 10.57 inches in June, more than twice its normal amount. July hasn’t been any drier. Before mid July, Indianapolis received 4.43 inches, which is very close to the 4.55 inches we normally receive for the full month.
Plants, including trees, shrubs, perennials and annuals, can be as stressed by too much rain as they can by drought. Stressed plants are more susceptible to insects and diseases.
One of the telltale trouble signs of too much water is reddish-streaks on the leaves of trees and shrubs. My native flowering dogwood (Cornus florida) shows the early signs of mildew, a leaf fungus. This has never happened before on these trees. Other symptoms include bleached, yellow or discolored leaves and wilting.
Too much rain can cause red streaks in plants, including dogwoods, such as ‘Cayenne’ (Cornus amomum) and other shrubs and trees. © Jo Ellen Meyers Sharp
It may be difficult to image, but plants suffocate as heavy rains force oxygen out of the soil. The rain also flushes nitrogen and other elements quickly from the soil. Don’t do any supplemental watering, including the lawn when we’re in rainy periods.
Replenish lost nutrients with fertilizers, especially for vegetable plants. Read and follow label directions. And, as we discussed a few weeks ago amid the June deluge, keep an eye open for fungus disease. Pick off any yellow or splotchy leaves from tomato plants, peppers, herbs and other edibles as soon as you see them. Dispose of the diseased leaves in the trash, not in the compost pile. If watering becomes necessary, avoid overhead sprinklers.
Avoid walking on wet soil. Doing so, compacts the soil, which makes it harder for roots to grow and develop. It undoes all the hard work of working adding organic matter to improve the soil quality.