Smart watering: how much, when and how long to water–In Harmony Sustainable Landscapes

smart watering: how much, when and how long to water--in harmony sustainable landscapes

smart watering practices will help you make the most effective use of water. your plants’ health will be affected by how much, when and how long you water. thomas bresson photo.

You're reading: Smart watering: how much, when and how long to water–In Harmony Sustainable Landscapes

our current warm, sunny weather is the beginning of the dry season. your plants will need water throughout the summer. here are some tips on smart ways to water.

water slowly and deeply for healthy plants. 

the best practice is to water deeply and less often. shallow, frequent watering creates plants with shallow roots. deeper watering creates plants with deeper roots. they will be healthier and will tolerate hot, dry conditions better.

you need to water your plants in such as way as to maximize the water penetration in the soil and minimize the amount of evaporation. if water cannot get into the soil, it is essentially wasted. if your soil is already dry, it may take a few waterings to “soften” up the top of the soil layer so water can penetrate.

soil is like a sponge. if it is allowed to dry out completely, you cannot just pour water quickly onto the top of the sponge. it will run off and not penetrate the top at all. but if you slowly pour water on the sponge and allow it to soften up the surface, then it will begin to percolate through the rest of the sponge.

check your soil. if it is dry, you will need to water slowly to get the top to soften. we highly recommend oscillating sprinklers as they allow the water to infiltrate slowly. the water will penetrate more deeply into the soil.

watch our video: watering 101: create strong and healthy plants.

water the entire root zone area, and then let it partially dry out.

smart watering: how much, when and how long to water--in harmony sustainable landscapes

oregon state university extension service.

where is the root zone? for most trees and other plants, the active root zone is at the outer tips of the leaves or even further out. the area under the outer edge of a tree is also known as the drip line. for many trees this can be a large area.

Read more: Your Guide to Growing the Vegetable Garden of Your Dreams

most water is absorbed at the drip line and beyond. this is where tiny terminal rootlets take up water and nutrients from the soil for the tree. trees should be watered here.

it will not do any good to water nearer the trunk of the tree. no root tips are there bringing in moisture for the plant. if a tree is watered by the base of the trunk, it may develop root rot.

make sure you are watering the entire root zone area of the plant. then wait until the upper few inches of soil are dry before watering again. this encourages deeper roots.

know your plants and trees. some have shallow roots near the surface. others have deeper roots. they will need more water to soak down to their feeder roots.

no roots want to be waterlogged all the time, except for rice. unless you are trying to grow rice, the roots need oxygen. roots get air when the soil is allowed to dry out some between waterings.

how much, when and how long should i water?

we are asked this question a lot. and most people are looking for an easy answer. the answer is not always easy.

how much should i water?

the safe number is to apply one inch (1”) of water every week during the dry season. in order to know if you are watering one inch, you need to measure the sprinkler’s output.

measuring sprinkler output

  • put out several same-sized containers into the area to be watered. for example, use tuna cans, cat food cans, cereal bowls or whatever is available and about the same size.
  • turn the water on for a specific amount of time, such as one-half hour.
  • measure the water in each container with a ruler. write down each container’s amount.
  • add up all the amounts and then divide by the number of containers to arrive at the median amount.

this will give you a few pieces of information.

  • now you have a base number to figure out your one-inch output. if in one-half hour your average measurement is 1/4-inch, then you know you have to water four times that time amount to receive one inch of water.
  • you can tell if some of the containers have a lot less or a lot more than the median number. because all sprinklers have inefficiencies, you can see if the sprinkler has a good throw with the water.
  • if some of the containers have one inch and some have one-eighth inch, your sprinkler has some irregularities. you may need to move the sprinkler during watering so it reaches all
    zones evenly.

here is a short video on how to measure one inch of water.

when should i water? 

there are a few general rules.

water when it is cool. this makes perfect sense. if you try to water in the heat of the day, most of the water will evaporate into the air before it has a chance to get to the soil.

mornings are the best time to water. the day is cool, the wind is usually not blowing and water has a chance to percolate into the soil profile before it warms up.

the next best time is early evening after the day begins to cool. be aware that watering in the evening can promote some diseases. if you water in the evening, start in a shady area for less evaporation from the sun.

if the day is cloudy, any time during the day will be ok. the key is to get as much water into the soil profile as possible for plants to use with minimum waste from evaporation.

if your plants are showing water stress, water them immediately. do not wait for the perfect time. if the plant is struggling, this moment is the perfect time.

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how long should i water?

there are many factors that go into watering correctly, and every landscape situation is unique and different. how long to water depends on:

  • types of plants. for example, lawns will need more water than drought-tolerant ground covers.
  • maturity of plants. anything that has been newly planted, including trees, shrubs, lawns, perennials, grasses, vines, etc., needs to be watered regularly for the first two or three growing seasons so it can establish a strong root systems. mature plants will need less water.
  • plant canopies. plants under trees or shrubs that offer shade will need less water.
  • property microclimates. perhaps you have an area that is more exposed to the wind. that will dry out plants sooner.
  • types and depth of soil. sandy soils won’t hold water as long as clay soils.
  • organic mulch layers. mulch insulates the soil, so plants need less frequent water.
  • sun orientation and exposure. plants in the sun will need more water than those in the shade, and those with afternoon sun exposure will need more than those with morning sun exposure.
irrigation efficiency

the efficiency of your watering system also affects how long you need to water. every type of sprinkler or sprinkler system has certain advantages and disadvantages when it comes to efficiency. our video on watering systems shows some options for wands, hoses and sprinklers.

other factors contributing to water efficiency include weather temperatures, wind and soil readiness (i.e., does the soil already have some moisture in it or is it completely bone-dry).

watering can be a time to relax and restore.

for most people the hardest part of watering is the time commitment. a lot of people say they do not have the time to water. if you would like healthy plants, you really need to find the time to water.

watering can be a time to relax and enjoy your landscape. “i love to water,” said ladd smith, in harmony co-owner. “the sound of the water running, the look of the soil and plants after watering and the cool feel when i am around water make it enjoyable. plus the results are amazing because a little bit of water makes a huge difference in how plants respond.”

ladd especially loves watering his berries: blueberries, raspberries, strawberries and thornless blackberries. he washes off the berries while he is watering and eats them right off the vine.

“nothing is more satisfying and delicious,” ladd said. it only takes 15-20 minutes to give them a good watering, and the entire time he is eating and enjoying the experience. “that small amount of time just being a part of the garden can change one’s entire mood and outlook on the day.”

ladd says he is an old-fashioned guy when it comes to watering. his favorite sprinklers are the oscillating types of sprinklers and a hose-end fixture with several different settings. he uses the oscillating sprinkler for large
zones and areas that can just run the sprinkler for a few hours. he uses the hose end fixture for smaller beds, containers and vegetable beds.


our youtube playlist on watering your lawn and garden has several videos on the basics of watering, watering systems, watering new plants and trees, and more.

the saving water partnership has information on watering systems and other watering tips.

swanson’s nursery has a great article on best watering practices.

we have written several blog posts about watering this year, all based on thoughts and ideas developed by ladd smith. here are the ones we have published so far. more to come.

  • plants need water to survive and thrive.
  • invest in watering for landscape dividends. 
  • choose drought-tolerant plants and reduce time you spend watering.

Category: Garden