Thinking of swapping out your front lawn for a new xeriscape? Don’t forget to think of the trees. If a tree has been growing in your lawn for decades, you can be sure that it’s gotten used to the extra water.
Contrary to common belief, the majority of tree roots are near the soil surface and widely spread. While it’s impossible to know exactly where the roots of a tree are without digging them all up, a good rule of thumb is to assume that the vast majority of roots are in the top 2 feet of soil and spread out as wide as the tree is tall.
It’s important to consider your tree’s roots before, during and after your project. In compact or clay soils, 90 to 95 percent of roots are in the top foot of soil, with 50 percent of roots in the top 4 to 6 inches, and spread up to five times the width of the tree’s canopy.
What to do before
removing your lawn
Plan ahead. It’s all about planning. If you have mature trees, minimize reshaping the landscape as much as possible. This means that berm you were dreaming of may need to be smaller. If you do want to add topography, stay as far from the tree(s) as possible.
After you convert your lawn to a xeriscape, you won’t need to replace all the water your sprinkler had been putting down around your tree because your lawn was also using water.
However, it’s a good idea to know a number in order to provide a starting point for your estimates.
• Do the math: If you have sprinklers and already know your flow rate, it’s a straight-forward arithmetic problem to compute how many inches of irrigation water you’re applying.
• Set out catch cans: If you aren’t sure how much water you’re using, you can find out by running the irrigation system with several “catch cans” (any set of uniform containers will do).
First, run the sprinklers long enough to get a measurable amount of water in each cup, usually 10 to 15 minutes.
Second, divide the average volume in each container by the number of minutes, then multiply by 60 and you will have the precipitation rate of your system in inches per hour.
Considerations when removing your lawn
During your project, your focus should be on avoiding damaging your trees’ roots. Remember, roots can be shallower than you think.
• Minimize digging and keep it as far from the tree as possible.
• Always choose the lightest option for any equipment you use — like sod cutters, tillers, etc. — to prevent soil compaction. This will also make it easier for you to operate the equipment, especially if you haven’t done it before. Even better, if something can be done by hand, do it by hand.
• Don’t stockpile materials beneath your tree. It’s a good idea to establish a “tree protection zone” that is at least as wide as the dripline of the canopy and to keep all construction activity and materials out of the area for the entire duration of the project. Trees operate on a slower time scale than we do; it may take years for damage done during construction to cause visible symptoms.
• Use mulch. Incorporating mulch into your xeriscape plan is a great idea for your tree. Mulch will not only keep weeds down but help to keep water in the soil. Use a 4-inch layer of wood chips or gravel uniformly spread over bare soil.
• Don’t use weed barrier. Black plastic (polyethylene) and woven plastic weed barrier fabrics (polypropylene) are not recommended.
What to do after
converting to xeriscaping
Compare your new watering plan with the old. Presumably, you’re applying less water to the landscape, but this is not always the case. Verify that your xeriscape conversion is actually saving water and make adjustments as needed.
Water the tree’s entire root zone. Remember the roots are spread widely, and that roots grow wherever they can find water and oxygen. The broader a tree’s roots are, the more resilient the tree will be to stress.
By watering the tree over a wide area, extending well past the dripline in most cases, you are ensuring that your tree keeps its wide root system.
How to water a tree
without an irrigation system
Watering with a hose
1. Deep soaking: Place your hose at the base of the tree and let it run on a slow trickle for 20 to 30 minutes, moving it around the root zone every 5 to 10 minutes to ensure even coverage.
2. Soaker hose: If available, lay a soaker hose in a circular pattern around the drip line of the tree (the area directly under the outermost branches) and let it run for an hour or more, depending on soil absorption.
3. Best timing: Water in the early morning or late evening to reduce evaporation.
Bucket drip irrigation
1. Take a 5-gallon bucket and drill several small holes (about one-eighth of an inch) in the bottom.
2. Fill the bucket with water and place it near the tree’s root zone, allowing water to slowly seep into the soil.
3. Use multiple buckets spaced around the tree for even coverage.
4. Refill as needed to provide deep watering.
5. The benefit of this method is you’ll know exactly how many gallons of water you’re giving your tree.
Watering can
1. Clear your schedule for the afternoon, pick up your most ergonomic watering can, do some shoulder stretches and get to work.
2. But, seriously, this is a tree we’re talking about. You’re going to want to use a hose.
Figure out how much water you need. This is where things get tricky. Some trees will use just about all the water you give them, even if they don’t need it. Others truly need lots of water and could require as much water as you were applying to your lawn beforehand.
Some trees can be gradually weaned to reduced irrigation. Other trees will need ample water throughout their lives, regardless of what’s happened to the lawn. These include most oaks and maples, ash, blue spruce, aspen and Ohio buckeye.
Monitor for signs of stress. The only way to know for sure that your tree is getting what it needs is to keep careful track of its condition over the several years following your project.
Poke around in the soil in the tree’s rooting area and ask yourself, “Is the soil damp or dry, and how far down?”
If the tree’s canopy is thinning or its growth is slowing over years, water more as soon as possible. Because trees lead slow lives, even a gradually developing growth problem could be the sign of a tree-mergency.
Other signs that your tree is under water stress include brown leaf edges, early fall color and leaf drop, and twig dieback.
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CPR and first aid classes
CPR and first aid certification classes are offered every other month at the CSU Extension office, generally on the third Monday and Wednesday from 6 to 10 p.m. The cost for the classes is $80 for combined CPR/first aid and $55 for CPR, first aid or recertification. Call the Extension office at (970) 264-5931 to register.
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Field to Freezer Course
Colorado Parks and Wildlife will be holding a Field to Freezer Course on May 16 and 17 at the CSU Extension building located at 344 U.S. 84.
Trained professionals will teach you how to responsibly care for and process the meat from any big game ungulate in Colorado. Participants must be at least 16 years old. Visit https://forms.gle/owfhB5R8PTpYYHGGA to register.
There are limited spots available. Applications are due by May 9.
