Gardening: Deep watering can help plants through the heat

The heat is hanging on a little longer than usual this summer and that has added stress to our garden plants.

Because of the cool wet spring, most plants put on 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 are showing signs of water stress. Leaves are drooping and curling, and some plants droop excessively during the heat of the day. All this means that water is not getting deep enough to supply the roots with what they need.

An easy test to do to confirm this is to dig a 6-inch deep hole in the plant’s root zone. If the soil at the bottom of the hole is dry, then you need to up your watering schedule and then do some selective deep soaking.

This time of year, both our conventional and drought-tolerant gardens need about 1½ inches of water a week. This is best applied as two to three longer cycles a week rather than as daily waterings. Adding more water at one time allows the water to soak deeper into the soil where the roots can use it. To measure your output, set out flat containers like tuna or pet food cans around the yard, run your system for 15 minutes and then measure the depth of the water in the cans. Do the math and determine how long it takes to get the required amount of water on the area.

As for shrubs and plants that seem to be struggling, a long, overnight soak will get water deep into the soil. Stage a spot sprinkler or soaker hose around the root area and let it run all night. This is particularly important for shrubs that are in lawn areas as their roots are much deeper that the sod 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 a soaking rain, neither of which is on the short-term weather outlook.

Hold off doing any fertilization until it cools off in September. Most plants, but especially lawns, are dormant now and not growing, so they can’t use the fertilizer. Cut your lawn long to let the longer grass blades shade the soil and reduce water loss.

With the apparent rise in the frequency of heat waves, we are going to have to think about gardening in different ways. As a result, this may be a good time to re-evaluate your sprinkler system and upgrade it with some of the easy to install new technologies that have come on the market. Timer boxes now have many more programing options that can help tailor your settings. Some of them can be operated with cellphone apps. Older sprinkler heads can be replaced with more efficient technologies. Many of these changes can be done as DIY projects if you are the least bit handy.