Summer heat without water equals supplemental watering

From: Laura Kieser, Dan Martens and Nathan Winter, University of Minnesota Extension

According to the Minnesota Agricultural Statistics Service, much of the area has an adequate amount of topsoil moisture, but we should expect to start having some moisture issues if the temperatures stay high without rain. If we do not see rain in the region in the next few days or weeks, supplemental watering is going to be essential for plants. Plants will be put under high amounts of stress, wilting, or could possibly die without an adequate amount of water.

First of all, most of you have already been watering plant containers fairly regular. They are going to continually need water anywhere from every day to a week between watering. Check moisture by touching the soil to see how much water is available. Often it is recommended to water with a liquid fertilizer at half the recommended rate every time you water.

Flower and vegetable gardens will also need supplemental water. Water these once to twice weekly depending on how dry they get. Any areas in full sun may need additional watering. Water heavily each time the flowers and vegetables need watering and then do not water again until the soil appears dry. A little bit of water stress on the plants will push the root systems down deeper into the soil.

Lawns will also need watering if hot dry weather persists. The University of Minnesota Extension recommends 1 to 1 1/2 inches every 7 to 10 days. Raise mower height to 2 1/2 to 3 inches to help increase the size of the root system. Watering early on in the growing season will make the lawn more dependent on future watering during dry weather. Many people acclimate their lawns to the dryer conditions by not watering, thereby making the lawn more tolerant to drought later.

Trees also need water even though their root systems are deeper. Trees also need about 1 inch of rain per week to maintain their vegetative needs. Typically, the best way to water trees is to slowly run the hose under the drip line of the tree. Slowly saturate the soil and then do not water for 7 to 10 days. Slowly run the hose for 2 to 6 hours depending on the size of the tree and move the hose around some as well. If you receive an inch of rain during that time, don’t worry about watering.

Be most concerned with trees that look stressed. Sometimes the stress is not water-related, but the tree does not need to have disease problems and a lack of water as well. Making sure those trees have water will help strengthen them against other environmental stresses. A good rule of thumb with lawns and trees is to water them heavily and infrequently rather than lightly watering frequently.

Stay cool and let’s hope for some rain in the near future!

(Laura Kieser is an Extension educator for Scott and Carver counties, Dan Martens is an Extension educator for Stearns, Benton and Morrison counties and Nathan Winter is an Extension educator for McLeod and Meeker counties with the University of Minnesota Extension.)