Weekly Watering Number

Weekly
Watering
Number
www.regionalh2o.org
0.5 inches
May 16–22, 2019more info

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Up to half of the water used to water our gardens is wasted because of over-watering, so sign up and start watering smart with the Weekly Watering Number today!

Watering guidelines:

Cooler temperatures and scattered showers are expected in the next week, so you may not need to water established plantings. Newer plantings and those under covered areas may need water to make up for last week's dry weather. More rain is predicted later in May, so if you use an automatic sprinkler to water we recommend keeping it on manual this week and not setting it to automatic yet. 

Weekly Waterwise Tip:

Hopefully you’ve had the opportunity to make sure your watering system is in tip top shape for its summer workout. This week, we recommend creating a watering schedule if you don’t already have one. If you water by hand, this can be as easy as picking the days that you plan to water (e.g. Wednesday evening and Sunday morning). If you have an automatic sprinkler, you will have to program this in - but keep your system on manual for now until we know you’ll need to water weekly.

Everyone can have a blue thumb – start watering smart today with the Weekly Watering Number! 

Here in the Portland metro area, we like to joke that summer officially starts July 5th. But, while summer weather may finally kick in then, we often start watering our lawns and gardens the first or second warm-ish spring day. And, we keep on watering them until the fall rains begin.

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 until the warmer temperatures set in and dry out our clay soil. In fact, spring can be a great time to conserve water!

That’s where the Weekly Watering Number (WWN) comes in! We will tell you when to start watering, and how much to water each week through mid-October. We will also send you a Weekly Tip, along with your WWN, throughout the watering season to help you use water efficiently outdoors.

How to get started

Before you can start using the WWN, you will need to take 15 minutes to figure out how long it takes your watering system 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.

How to use the Weekly Watering Number

Different plants have different water needs and you can use the WWN to tailor the amount of water you give to different plant types (e.g. lawns, perennials, vegetable, trees). See below for more information on how the WWN can be used for lawns and other types of plants.

The other key to watering efficiently is to adjust the amount you water as the weather changes throughout the irrigation season. For example, we’ll let you know if a rain storm or heat wave means you should change how much you water – and we will tell you how much of a change is needed.

Can I use the Weekly Watering Number for different types of plants?

Yes. Different types of plants have different water needs. The WWN is the amount of water in inches that your lawn will need each week. Here is how to adjust the WWN so that it can be used for other plant types:

  • Shrubs and Perennials: 50% of the WWN 
  • Vegetables: 75% of the WWN (new starts may require more water)
  • Trees: Newly planted trees need regular watering for up to the first couple of years, while established trees may need a deep soak or two in summer.

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 (e.g. rain fall, evapotranspiration, solar radiation) needed to generate the WWN.

Why do you use historical data to create the Weekly Water Number?

The WWN is based 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.