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If the plants in your landscape and garden aren’t growing or producing quite the way you had hoped this season, blame it on the heat and lack of rain.

In extreme heat, plants often hunker down to protect themselves. Their stoma – the microscopic holes on the bottom of the leaves where they give off moisture and oxygen and take in carbon dioxide, close to conserve water. Leaves may curl to conserve moisture and reduce the exposure to sun and heat. If the heat wave is extended, plants will go dormant to conserve energy.

Chemicals, fertilizers and pesticides applied at the wrong time and/or in the wrong dosage may damage and kill plants, but during a heat wave they are even more lethal. Chemical fertilizers tend to be high in salts that can be caustic and plants are more vulnerable when suffering heat stress. So even a weak salt solution applied during a heat wave can burn plants. Chemical damage may appear as red, yellow or brown spots on foliage or leaf tips turn brown, stunted or misshapen. Spray drift or the careless use of herbicides often damages non-targeted plants, but during a heat wave they to can be deadly.

Water is the life’s blood of any plant. Too keep a plant healthy, most need to grow in moist soil. But for many, too much water is as bad as too little.

Self-watering containers should not be watered at the soil surface unless the reservoir is empty and the soil has dried down. In this case water from the top to rehydrate the potting soil. Depending in the size of the pot, the reservoir may fill up quickly, however, with larger pots it can take several minutes for the reservoir to fill. So as not to over wet the soil, after making sure the potting soil is thoroughly moistened, I top off the reservoir from the overflow hole at the side of the pot where water is regularly added. To keep the plants in this type of container healthy, the reservoir should be kept full so dry downs don’t happen.

When containers become waterlogged, oxygen is forced out of the soil and plants that have not adapted to wet soils drown. Leaves of over-watered plants turn yellow and may wilt – growth becomes stunted and eventually the roots rot and the plants die.

Watering is a skill, and one of the best tools to use in a heat wave is your finger to test the moisture level of the soil.

Nancy Szerlag is a master gardener and Metro Detroit freelance writer. Her column appears Fridays in Homestyle. To ask her a question go to Yardener.com and click on Ask Nancy. You can also read her previous columns at detroitnews.com/homestyle.

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