Everyone can save water outdoors! Start watering wisely today with the Weekly Watering Number.
Here in the greater Portland metro area, we like to joke that summer officially begins July 5th. While summer weather may finally start then, we often start watering our yards much earlier. And, we keep on watering them until the fall rains begin.
That’s where the Weekly Watering Number (WWN) comes in. Sign up for the WWN and we'll tell you when to start watering and how much to water each week through mid-October. We will also send you a seasonal smart watering tip to help you use water efficiently outdoors.
How to get started with the Weekly Watering Number
Before you can start using the WWN, you will need to take 15 minutes to figure out how long it takes you to water one inch. Don’t worry, this is a one-time thing! Once you have this information, you can use it adjust the amount of water you give your landscape or garden throughout the irrigation season.
What many people don’t know is that established plants (those that have been in the ground a year or two) usually don’t need to be watered that early! It’s best to hold off until warmer temperatures are more regular. So, don’t be fooled by those first warm and dry spring days. Wait until the heat sets in and dries out our region’s clay soil. In fact, spring can be a great time to conserve water!
How to use the Weekly Watering Number
The WWN is the amount of water in inches that your lawn will need each week (Thursday - Wednesday). See below for more information on how you can use the WWN for other types of plants.
The other key to watering efficiently is to adjust the amount you water as the weather changes. For example, we’ll let you know if a rainstorm or heat wave means you should change how much you water. We also include weekly watering guidelines to help you understand the changes!
Can I use the Weekly Watering Number for other types of plants?
Yes. While the WWN is designed to be used for lawns, it can also be used for other types of plants with these general guidelines:
- Lawns: 100% of WWN
- Shrubs and Perennials: 50% of the WWN for established plants. Follow the watering instructions on plant tag or from your local garden center for new plants.
- Vegetables: 75% of the WWN (new starts may need more water)
- Trees: The WWN is not recommended for trees, but that doesn’t mean that your trees don’t need water during the summer! Newly planted trees need regular watering for up to the first couple of years. Established trees may need a deep soak or two in summer. Consult with staff at local nurseries or arborists for your tree’s specific water needs.
Why does the Weekly Watering Number change each week?
The WWN changes with local weather conditions. So, in the cooler, wetter spring it tends to be lower. And, in the hotter, drier summer it tends to be higher.
What does my zip code have to do with this?
Sometimes weather is warmer, cooler, wetter or dryer where you live than it is across town. We customize your WWN based on your specific zip code so that it is more accurate.
Where does the data for the Weekly Watering Number come from?
The Consortium contracts with a weather forecasting service to provide the data. This includes rainfall, evapotranspiration, and solar radiation, all needed to generate the WWN.
Why do you use historical data to create the Weekly Water Number?
We base the WWN on the previous week's weather (heat, rainfall, wind, etc.). It is meant to replace any moisture that your plant's soil lost the previous week.