Gardening: Deep watering can help plants weather the heat

The heat is lasting a little longer than usual this summer and it has added stress to our garden plants.

Due to the cool, wet spring, most plants have extra growth and now they are struggling more than normal to maintain that growth. What can you do to help them?

First, even drought-tolerant shrubs and plants show signs of water stress. Leaves drop and curl, and some plants drop excessively during the heat of the day. All of this means that the water does not get deep enough to supply the roots with what they need.

An easy test to do to confirm this is to dig a hole 6 inches deep in the root zone of the plant. If the soil at the bottom of the hole is dry, you should increase your watering schedule and then perform a selective deep soak.

At this time of year, our conventional, drought-tolerant gardens need about 1½ inches of water per week. It is better to apply two to three longer cycles per week rather than daily waterings. Adding more water at the same time allows the water to seep deeper into the soil where the roots can use it. To measure your performance, place flat containers like tuna or cans of pet food in the yard, run your system for 15 minutes, then measure the water depth in the cans. Do the math and figure out how long it takes to get the required amount of water to the area.

For shrubs and plants that seem to be struggling, a long soak overnight will get the water deep into the soil. Place a spot sprinkler or soaker hose around the root zone and let it run overnight. This is especially important for shrubs that are found in lawns, as their roots are much deeper than grass roots. This needs to be done every two to three weeks or until our temperatures drop back into the 70s and 80s or we get pouring rain, which the short term weather forecast does not.

Withhold any fertilizing until it cools down in September. Most plants, but especially lawns, are dormant and not growing, so they can’t use the fertilizer. Cut your lawn long to let the longer blades of grass shade the ground and reduce water loss.

With the apparent increase in the frequency of heat waves, we are going to have to think about gardening in different ways. Therefore, now may be the time to re-evaluate your sprinkler system and upgrade it with some of the new, easy-to-install technologies that have come onto the market. Timer boxes now have many more programming options that can help you customize your settings. Some of them can be used with mobile phone applications. Older sprinkler heads can be replaced with more efficient technologies. Many of these modifications can be done as DIY projects if you’re the least bit comfortable.

Terri S. Tomasini