How, How Often, and How Much to Water

The Daily Ardmoreite
Pat Neasbitt
Master Gardener

One of my last articles was on how to deal with too much water in the landscape, and now our poor plants are not getting enough rain. This week we were supposed to get almost 1 inch of rain, and I was so excited because rain is much better than treated water any time; however, my rain gauge barely had enough to cover the bottom. If you get .25/1/4” of rain, that’s better than nothing, but it will just get the mulch damp. Plants are suffering even more right now than usual because of several events Mother Nature threw at us that were out of our control. First, there was the extreme low temperatures this past winter that killed many plants and severely damaged many more. Then, we had weeks of rain and even more weeks without sunshine at a time when plants needed it most to put on new growth this spring. As if that wasn’t enough, then we went straight to summer with lots and lots of hot sun and hot temperatures without giving already stressed plants time to adjust. I hope the following tips will help you help your plants survive.

· Container plantings need to be watered every day at least unless it rains and the weather cools off. While it was almost 100 degrees last week, and the sun was relentless, I needed to water twice a day to keep container plantings happy. Even plants that usually can take full sun can use some relief when it is extremely hot, and houseplants summering outdoors definitely need some shade. It helps to group containers together so that they get only morning sun, part shade from trees, or even from an umbrella or shade cloth. Annual plantings use extreme amounts of energy to flower for you all summer, and they need help in the way of fertilizer as well as water. Although daily watering of container plantings helps plants survive, it also continuously washes out nutrients the plants require. For containers, I like to use a time-released fertilizer such as Osmocote that lasts for several months in containers mixed with the soil at planting time and reapplied toward the end of July. It also helps to use a water-soluble fertilizer when you water every week to every two weeks if you want container plantings to keep looking their best all summer. Make sure there is a good layer of mulch in containers, and deadhead religiously if you want them to keep blooming.

· If you, like most of us in Oklahoma, had to replace quite a few plants that were lost to the severe freeze this winter, then they need more water than established plantings. They should be treated almost like container plantings the first season because the root systems have not developed enough to provide moisture and nutrients, and they are dependent on their gardener since Mother Nature is not cooperating right now. That means, if it hasn’t rained adequately and the temperatures are in the 90’s with hot sun and drying winds as usual, they need to be watered well about every 2 days until they are established. At that time, you can cut down on watering to probably twice a week. I say probably because there are so many factors involved such as soil type and amount of sun. The best thing for any gardener to be is observant. You will know when the roots are becoming established when you see the plant putting out new leaves.

· Many plantings this year were so severely damaged by the winter freeze that they had to have more than the recommended 1/3 removed because there was so much dead wood. I think it is best to treat severely freeze-damaged landscape plants like new plantings this season. They are so stressed from trying to survive the damage, put out new growth, and adjust to the hot temperatures and lack of rain, that they will need all the help they can get. On all my shrubs I cut out all the dead wood, pruned lightly to shape and encourage new growth, and fertilized with an organic fertilizer. I am also treating them like new plantings instead of established plantings and watering more frequently this season.

· As a general rule, landscape plants need 1 to 1½ inches of water weekly. Since Mother Nature is anything but consistent, it is up to us to supply water for our plants. We water in order to get moisture to the roots of the plants which for most shrubs and perennials is about 12” to 18” deep. That means it takes a lot more water than we realize to provide critical amounts of moisture so roots can support the plant, grow, and thrive. That also means it takes a lot longer to get enough water to the roots than most of us realize. I know it isn’t fun to stand and water each shrub for at least 5 minutes at a time when it is almost 100 degrees out; however, that’s about how long it takes. It doesn’t work to depend on a sprinkler, and it actually is important to water by hand if you want to do it right. Hose wand attachments work well because they put down a lot of water quickly without washing away the mulch and exposing soil and some come with longer handles so you can stand instead of bending to water each shrub. If you planted a 5-gallon shrub, it needs 5 gallons of water, and it takes about 5 minutes to provide that amount of water. You can, and I have done this often when it is super-hot and I am super busy, turn on the water so that it is barely dripping from the hose or watering attachment and lay it under the shrub for about 30 minutes before moving it to the next shrub. This can be a problem if you have many plants, if the soil is sloped so water runs downhill instead of soaking in, or if you don’t have good rich soil with a thick layer of mulch.

· Water early, and water at soil level. Do not get the foliage wet if possible. It is cooler for us and the plants early in the morning, and the water evaporates less. Watering late on a hot evening, especially if the leaves get wet, is a sure-fire recipe for numerous plant diseases.

· As always, get rid of weeds. They steal moisture and nourishment from your plants.

· MULCH, MULCH, MULCH!!! Mulch applied 3 or 4 inches deep around everything you can will save moisture, cut down on weeds, cool the soil, and save you as much as 80% of garden work this summer. Whatever you do, NEVER, EVER use fake dyed black mulch. It gets hot enough without putting something black around our plants that will absorb even more heat this summer. Happy Summer Watering!