A few weeks ago, we wrote about the large quantity of rain we were receiving and its effect on our plants and gardens. Now that monsoon season appears to be over, we have a different task: making sure our plants get the amount of water they need.

Water is absorbed into the plants through their roots. The plants lose water through their leaves by a process called transpiration. When the plants have the proper amount of water available, the leaves look like they should. They are standing up or branching out because the water adds mass to these plant parts making them more turgid (able to hold the plant and leaves up).

Plants with larger leaves such as hydrangeas are notorious for not being able to draw up water as fast as they are losing it through those large leaves. As they lose water, they lose turgidity, causing them to droop. Do they need more water? Yes, but you may not have to add water for them to be able to replenish their water and improve the turgidity of their leaves.

If your hydrangeas (or other plants) look droopy in the afternoon, but then perk back up by morning, they may not need more water. If they don’t perk back up by morning, they definitely need some water.

One of the problems with knowing how much to water is that under and overwatered plants can exhibit the same symptoms…droopy leaves. So, if you are pretty sure your plants are not drying out, check to see if they are waterlogged. Plants in containers are notorious for suffering from overwatering since the drain holes in the bottom of the plants can get plugged up. If you suspect that your plants in containers might be over-watered, just pick them up. Overwatered container plants feel much heavier than they should. If this is the case, try to drain the container and let your plant dry out for a few days. You may even need to remove the plant so it can dry.

As far as our yards go, this is a little more problematic. For the most part, people guess at how long they should let their sprinklers run. In most cases, we are probably overwatering our yards. To know how much you need to water your yard, you’ll need to perform an irrigation audit.

To do this, start with a single zone of your sprinkler. You’ll need half a dozen containers, something like a yogurt container or tuna fish can. They make special devices for this, but any container will work, just be sure they are all the same.

Scatter these containers out in the yard around the zone you are measuring. Let your sprinkler run for say 10 minutes, then visit each of your containers to see how much water each one collected. Let’s say you had 1/4 of an inch in them on average. So if you wanted to put down 1” of water on your lawn, you would know that you need to let the sprinkler run about 40 minutes on that zone. Then repeat this process on each zone. Now you know how long each section needs to run without needing to guess.

This time of year Bermuda grass needs about an inch of water per week and fescue needs about 2 inches per week. This can be broken up into a couple of different watering sessions but remember, it’s better to water less often and more deeply that to water more often but less shallow. Good luck and try to stay hydrated.

You can get answers to all your gardening questions by calling the Tulsa Master Gardeners Help Line at 918-746-3701, dropping by our Diagnostic Center at 4116 E. 15th Street, or by emailing us at mg@tulsamastergardeners.org. Photo: Tom Ingram