Watering guidelines for lawn, vegetable garden, and perennials

Asked June 26, 2019, 5:14 PM EDT

We recently put in an irrigation system in our front and backyard and were trying to establish an acceptable amount of water for different areas. I was wondering if you might be able to provide us with some guidance on how much water and length of time each area would need. Our yard, both front and back for the most part, is full sunshine most of the day. Our new irrigation system is very efficient in terms of how much water it produces since it’s directly hooked up to the water main. Here are my questions: 1 – We put in new sod in the backyard and I would like to know how often it should be watered and for how long. 2 – Length of time and how often our existing lawn in the front yard should be watered. 3 – Length of time and how often our raised beds (18 inches off the ground) vegetable garden should be watered. 4 – Length of time and how often are perennials such as rhododendrons, junipers, roses, lilacs, etc. should be watered. Thank you, Tim Shearer timwshearer@comcast.net

Lane County Oregon

1 Response

Hi, Tim,
It's good that you are investigating how much water your different types of landscaping will require - as you are obviously aware, the needs of a shallow-rooted lawn are quite different from the needs of deep-rooted shrubs or trees. Unfortunately there is no one-size-fits-all answer, because the amount of water needed also varies by soil type, weather conditions, and how established the plants are. As for application time, that depends on how much water is being applied - the issue of concern is the amount of water that will stay and soak in, rather than running off.
What it comes down to is, you need to observe and keep records in your own yard to determine how much is enough, and it will vary over time. There's no such thing as a successful "set-it-and-forget-it" irrigation system.
A place to start could be to apply 1" per week as the weather gets hotter and the soil dries out. Your new lawn will need more frequent, briefer waterings to stay green through summer - maybe 3x per week. Check and see if the water has soaked in to a depth appropriate for the plants you are watering. If not, water more. If your soil is heavy and holds moisture well, you may be able to water less.
Here are a couple of Extension publications https://catalog.extension.oregonstate.edu/ec1521, https://catalog.extension.oregonstate.edu/search/content/watering?page=10 that might help, but I would also suggest you talk to your irrigation specialist, or get a good book on the subject.