The recent record high temperatures have been tough on us and on our plants. Then the storms came and brought a little rain, and then it dried off again. This makes it tough on grass, shrubs and trees, but there are ways that plants can be helped to survive the drought and hot weather. It all starts at planting.
The best way to make a plant drought-tolerant is to plant it properly. It doesn’t matter whether shrubs, trees or grass are being planted; how the soil is prepared will determine how well the plant does.
Before the first shovel full of soil is moved, a soil sample will help determine what nutrients need to be added. It is easier to change the chemical makeup of the soil before the plants go in the ground than after they are planted. The soil sample will tell if lime needs to be added and how much fertilizer will need be used around the plants.
The next step is to till the soil. A strong root system will make plants more drought-tolerant. The best way to have a strong root system is to have the best rooting zone possible. This is accomplished by tilling the bed area or turf area. The general guideline is 3 inches minimum, but the deeper the better. By tilling the whole bed, the soil is softened so roots fill the bed area. The more roots the better the plant handles drought. To prepare the soil like this takes more time, but the end result is healthier plants. This guideline applies to turf as well.
To better help rooting, the soil needs to be amended. It doesn’t matter the type of soil, clay or sand, the plants will benefit from amending the soil. Some of the amendments that can be used are compost, peat moss, topsoil or very fine ground pine bark. These products will help keep the soil from compacting, improve rooting, hold nutrients and water, and provide microorganisms to help the plant.
What about adding sand to clay soils? This is not a recommended practice. Sand doesn’t hold nutrients or moisture. Also, when sand is added to a clay soil and the soil dries out, the soil can become harder.
Soil amendments need to be spread 2 to 3 inches deep across the area to be planted. Then, incorporate the amendment by tilling it into the soil.
Mulch will help plants conserve moisture when the temperature gets hot. The mulch slows the evaporation of water from the soil. A 3- to 4-inch layer of mulch around the shrubs, flowers and trees is needed. The mulch needs to extend to the end of the limbs on trees. In the flower beds and shrub beds that were tilled, the mulch will help keep soil loose and pliable.
After the soil is prepared and the plant is planted, it needs to be watered properly. This is the area where I see the most mistakes. The major problem is that there is not enough water being applied to greatly benefit the plant. Research has shown that most plants do best when they receive an inch of water a week. This water needs to be applied at one time unless it is in very sandy soils. Then, the water needs to be split into two applications.
Research has shown that there is a correlation between the frequency of watering and the amount of root mass on turfgrass. The grass that received water every day or every other day had a smaller root system than grass that received water every five days. In fact, the longer the grass went between irrigations, the root systems got larger. The roots had to look for water, so they produced a larger root system.
When I talk about watering deep, I mean applying an inch of water. When an inch of water is applied, the grass should need to be watered every five to seven days.
Also, don’t water unless the grass shows signs of drought stress. When the grass turns a blue-gray color, this is the sign that it needs water.
The last practice that can help plants endure a drought is to fertilize them properly. Nitrogen fertilizer increases the amount of water that a plant needs. However, the plant needs plenty of potassium. This is the last number on a fertilizer bag. Potassium helps with drought resistance, disease resistance and winter hardiness.