Watering Trees & Shrubs | How-to Tips

Welcome to Part 2 of my 5-part series on efficient watering in your garden and landscape. Last week, I covered some of the fundamentals – how to get the right plant in the right place. Doing that right will save you money and time in the long run. This week, let’s explore how to get those right plants off on the right foot – and, then, how to determine watering frequency, timing and more. Watering trees and other plantings properly will make all the difference.

Let’s get started!

Watering trees properly as they establish can make all the difference in their survival and strength.

Regardless of the species, all trees and shrubs will be stronger and more drought tolerant long term when you take the time to water them properly during their first year and continue providing extra attention during their second and third seasons.

Watering New Shrubs and Trees

A well-planted tree or shrub will be healthier, more resilient and better-equipped to thrive with less water down the road.

Also, timing really is everything here. Plant your trees and shrubs in fall or spring – avoid planting during the heat of summer. You will save a lot of water, time and heartbreak simply by planting during the cooler seasons of the year. Fall, in particular, is the ideal time. The soil is still warm – ideal for root development, yet the air is cooling down. So, there’s a lot less stress and demand on the above-ground growth of that new plant.

I demonstrate the seven steps for properly planting a tree in my how-to video from an earlier post. These steps are easy to do and will get your plant off to the right start every time.

Once planted, how you water while that new tree or shrub becomes established will make a big difference in the long-term health of your green investment.

The moment immediately after you get that plant in the ground is pivotal. Provide a good soak using the low and slow approach. Heavy, stiff streams of water will quickly erode the soil you just placed around the roots.

Too much water too fast can’t be taken up by the roots, so most of it washes away – taking valuable topsoil, compost and/or mulch with it. I like to use a bubbler attachment (more on this invaluable little device in Part 3 of this series) to provide a gentle, steady flow that is easily controllable and taken up by the roots.

Initially, I water newly-planted trees and shrubs every day for about the first week. For the next two weeks, I ease off to about every other day. Then, I gradually ease back from there.

Newly-planted trees benefit from several inches of water per week throughout the first season, but be careful not to overwater during this period. It’s a delicate balance, so observe how the tree is responding. While it’s common for trees to lose up to half their leaves to transplant stress, more loss can indicate a potential problem. If you sense the plant is responding poorly, and you are watering consistently; you’re likely overwatering. The soil within the drip line (the area of ground within the spread of branches) should be moist but not soggy.

Your trees and shrubs need more time than you might expect to fully establish. I have made the mistake of discontinuing supplemental watering too soon and have paid the price in loss of trees. Ouch. Establishing roots need continued supplemental watering in order to expand outward and sustain top growth until they become self-sufficient. Surprisingly, this can take two years or more, depending on environmental conditions above and below ground.

Fall is a great time to plant new trees and shrubs. Once in the ground, they will require several inches of water per week throughout the first year to get them off to the strongest start.

Watering Established Plants

Once your plants are in place and have established, ongoing maintenance begins. Efficient watering comes down to:

Method
Frequency
Timing

Whichever water delivery method you choose (my recommendations to come in Part 3 of this series), you want that method to provide water in a manner that is low to the ground and at a slow, absorbable pace. Watering low and slow directs water to the roots, where the plant needs it most and when they can take it up easily.

Watering your landscape from above – as with a sprinkler – directs water over the foliage. This typically provides uneven water distribution to plants. More importantly, transporting that water through the air increases its evaporation rate – decreasing the amount that is actually able to be taken in by the plants. Remember too that, when plant foliage is wet, it is much more susceptible to disease.

Soil can only take up so much water at a time, depending on its structure. Too much water too quickly erodes the soil, can expose the plant roots (never a good thing), and can leach important nutrients. By providing water to your plant at a slow rate, you increase the amount of water the ground is able to absorb and make available to the roots.

How often should you water? For established trees, shrubs and lawn, it’s a good rule of thumb is to water once or twice per week to provide a total of one inch per week (in the absence of rain). While you can water more frequently for shorter periods of time, this short watering period means the water doesn’t absorb as deeply into the ground.

Roots are opportunistic – they go where the water is. Water always near to the surface encourages the roots to remain near to the surface too. With this system, your plants may look robust for awhile, but shallow watering doesn’t set them up well for times of drought.

Watering for a longer period once or twice per week, means the water will be absorbed more deeply into the soil. This encourages the roots to grow more deeply to follow the water. There, the soil remains cooler, and the roots are at less risk of drying out. Watering less often also “trains” the plant to better sustain during periods of drought which naturally translates to less frequent watering. Also good news: less frequent watering means less work for you.

How to know when your method of choice has provided an inch of water? Behold, the humble tuna can. Simply place an empty tuna can where the irrigation lands. For example: Set tuna cans in a few areas of your yard. Once the can is holding an inch of water, you know you have watered enough.

You can test the amount of water you are providing plants by placing a tuna can in the line of the water. Once the can has collected an inch of water, your plants will have received the same.

Watering Annual Beds and Containers

Your vegetable garden and containers will require more frequent watering, particularly during the hottest times of summer. Rapid root growth of annual plants, like vegetables, and the smaller spaces of containers mean there is less soil to hold water. Consequently, more frequent supplemental watering is best here.

Your best guide for annual beds and containers is observation. Spend just a little time in your garden each day to note how plants are responding.

If plants show signs of drooping, stick your finger in the soil. If your finger comes up dry, increase watering frequency. If soil is soggy, back off on watering. More plants die from overwatering than underwatering, and plant droop can also be a sign of too much water.

The small spaces of your containers will require more frequent watering, particularly during the hottest times of summer. Plan for providing water at least once daily.

Watering New or Established Lawn

Most lawns are comprised of Bermuda, Zoysia, Centipede, St. Augustine (all known as warm season grasses), or Fescue grasses. These are traditional turf grasses that require one inch of water over the course of a week, irrigating once or twice during the week.

First, though, consider low or no-maintenance options, like Mondo Grass. Mondo Grass is being used more often than ever in the urban landscape. Installation can be laborious, but Mondo Grass remains a deep green all throughout the year, only needs mowing once per year, never needs fertilizer or supplemental water, is disease and pest free, and looks just as good in sun or shade.

Sadly, Mondo Grass is not hardy in areas colder than zone 6, but some varieties are known to be hardy to zone 5. It is said to retain its deep green appearance down to a temperature of 0 F. However for the rest of the country, Mondo Grass grows well, albeit slowly.

Although it is slow to establish, mondo grass is as low maintenance as it gets for a home lawn.

There are a few other low maintenance lawn options, such as a prairie lawn. Prairie lawns don’t have the manicured look that we envision when we think “lawn space,” but it is an extremely low maintenance and waterwise option. Although wildlife and beneficial insects will love you for installing a prairie lawn, some Homeowner Associations won’t (and your covenants may restrict against it). Do a little research to decide if any of the non-traditional lawn materials might be a good option for your home landscape.

For those of us who do have those traditional grass lawns, efficient watering practices will have a significant impact on the strain on water resources – plus, they will save you time and money.

Since watering your lawn means overhead water delivery with some sort of sprinkler system, the absolute best time to do so is early in the morning. Heat and wind both take a toll on water moving through the air, increasing evaporation. That means less water hits your turf and is able to be taken in by the roots. Your lawn is also more susceptible to disease when it’s wet.

So, choose your timing wisely. Water during nature’s dew cycle, generally between 4:00 and 7:00 am. With less heat and wind in these early morning hours, you will decrease the amount of evaporation and increase the time the water has to absorb into the ground. Plus, grass blades will dry off quickly in the morning sun.

When watering with a sprinkler, do so only during the dew cycle of early morning hours. This reduces evaporation, and allows plenty of time for foliage to dry off in morning sun.

Throughout the growing season, it’s a good idea to periodically check your sprinkler heads and the area they are covering and redo the tuna can test.

If you are planting new lawn (whether an entire area or re-seeding a damaged spot), treat that young grass as you would treat a new plant or tree. Remember that the sod roots (just like the root ball of a sapling tree) need to establish into their new environment. As those new roots take hold, they require more moisture for healthy development.

Grass seed requires moisture for germination. Seedlings are very delicate and susceptible to drying out, so water often to keep the grass seedlings moist.

If you can install sod or seed during a rainy period, that’s the best case scenario, and planting during the cooler seasons of spring and fall is another good option. Depending on weather, it may be necessary to water briefly more than once per day. Bear in mind that you should still keep overall water delivery to one inch during the course of the week.

Next week’s Part 3 of this Efficient Watering series will cover water delivery methods. How you provide water to the plants in your landscape does make a significant difference. I’ll explain options and what I prefer in my landscape.

Coming up in the final two parts of this series is tips for drought resiliency in your landscape as well as water harvesting and more on how to avoid overwatering.