Water by the Seasons
Summer Irrigation for Tree Health
Folks, it’s a hot, dry summer here in central New Mexico. No surprise, you say — we live in a desert. Even for our location, though, it’s hot and dry. This creates a little conundrum for us: keeping our landscape plants growing while using water efficiently.
This applies especially to trees because as large plants with lots of leaves, they need regular adequate water for their size and species to remain happy and continue creating positive benefits for your yard and the city as a whole. Call that a biological law and reality. As temperatures go up, trees’ water demand goes up. That is a good starting point to keep in mind — in times of drought, you should water your trees a little more frequently than you would in a year with abundant rainfall.
It turns out that over 90% of the water that comes into a tree simply escapes through the leaves as water vapor; the tree keeps very little water inside to grow. This loss of water vapor provides the “suction” that causes more water to enter the root system. It also cools the leaves and keeps them within comfortable working temperatures. Someone once said trees (and plants generally) have figured out a way to guide the natural movement of water from soil to atmosphere, channeling it through their bodies and using it to grow and function, which is one part of the water cycle. Having trees increases moisture in the air, allowing your swamp cooler to perform better.
Trees “drink” very differently than you and I. We have one fairly large mouth into which all the water goes. However much we need, we have one target to hit in order to drink that water. Trees, on the other hand, take water in through their tiny, young roots out in the soil. Water has to get to a lot of soil in order to hit enough of those “mouths” to matter. A lot of tree irrigation eventually fails because there are only a few emitters (and those are often too close to the trunk). Those few emitters cannot put out enough water to satisfy the tree’s demand, nor do they wet enough surface area. (See examples in the photos below.)
What matters to a tree is the volume of water it has to work with. That volume is entirely dictated by the volume of soil that is holding water. And THAT volume is dictated by the surface area that received and absorbed water. The key is to disperse the water throughout the main root zone and do it in a way that allows the water to soak in where applied and not flow to low spots on the ground (which often are gutters. Science has found that most tree roots are located within the top three feet of the soil surface and quite likely even more shallow in landscapes that have not been deeply irrigated for the life of the tree, which is a common condition in Albuquerque.
To properly water your trees, you will need some sort of irrigation system. It could be a bucket you fill from the sink or a state-of-the-art sensor-controlled automated drip system. But somehow you need to put water on the soil surface in a slow, controlled manner so that it can soak into the soil where it is applied. While buckets and hoses work, their simplicity makes them very labor intensive. In-line emitter drip tubing, laid out in a spiral or concentric circles, does a much better job. Once in place, these drip systems can be set to run for two to four hours at a time, about once a week during the hottest part of the year and less often during other seasons. Irrigation improvements qualify for the Water Authority Treebate. See our rebates here.
The ideal target area to irrigate is both theoretical and grounded to the reality of the site. Imagine a donut shaped area centered around the tree trunk. The trunk sits in the center of the donut hole. The body of the donut begins halfway between the trunk and the edge of the branch canopy and extends some distance beyond the edge of the canopy. This theoretical donut represents the ideal critical irrigation zone.
Now enters site reality — maybe there is a house or driveway or sidewalk covering part of the donut (or all three, with the tree located in a tiny unpaved space). We don’t want to encourage root growth at the house foundation, so don’t water within a couple of feet of it. Similarly, where concrete or asphalt covers the soil, root growth is moisture-limited and concentrated immediately under the impervious cover and under any planned or accidental cracks that allow rainwater to slip through. Ideally, we don’t want to water next to the pavement. The more of the donut that is unavailable for watering, the more often you may need to water the limited areas of open soil. Even so, it may simply not be enough soil volume to support the tree, which will then decline. In that case, replace it with a nice xeric shrub!
Learn more here:
How to Make a Tree Watering System.
Best Practices for Watering with a Drip Irrigation System
The “Wow Factor” – Summer Containers Simplified
One of our favorite things to do at Bennu Organics is design container gardens. We like to talk about the “wow factor,” and containers are a fantastic way to add stunning, season-long color to our landscapes without digging a single hole in our hard, unforgiving soil.
Here are six helpful hints for creating your own successful container designs:
1) Location: Will the containers be in full sun, partial sun or full shade? In most cases, full sun containers in New Mexico require daily watering. If you don’t want to water every day, consider selecting plants that require less water, like succulents, cacti or perennials. Placing containers in partial shade will also save water. It’s important to know the amount of sunlight you will have available for each container prior to purchasing plants.
2) Size: What size are the containers, or what size do you want them to be if you’re purchasing them? You’ll need plenty of soil to fill or refresh the containers, and you want to make sure you have enough plant material to give your containers a nice, full look.
3) Design: Well-designed containers require three types of plants: thrillers, fillers and spillers. The thriller is something tall and showy, while fillers are shorter plants that fill in the spaces. Spillers are those low vining-type plants that spill gracefully over the sides of the container.
4) Color theme: I like picking a color palette and then selecting different plants within that palette. I don’t want my containers to be identical, but I do want them to complement each other. Also, depending on the locations of the containers, I will often do a “mirror image” design if the containers are on either side of an entry way, for example.
5) Lighting and water: Select plants that have similar lighting and water requirements. You don’t want to put a cactus as a thriller and wave petunias as your filler. One or both will suffer from too much or a lack of water.
6) Maintenance: Besides watering consistently, you will want to trim and deadhead your designs frequently. Petunias and calibrachoa (classified both as fillers and spillers) need regular deadheading to keep the blooms going strong. Trim them heavily when they get “leggy.” They respond well to a really good haircut. If you are consistent with your maintenance and watering, the containers should keep their “wow factor” all season long. Also, regular fertilizing is crucial to maintaining season-long blooms. In the active growing season, we fertilize our containers every two weeks.
While the following list of possible plants you can use in containers is hardly comprehensive, it should help get your creative juices flowing:
Shade/Part Shade
Thrillers: caladium, alocasia, sansevieria/dracaena, colocasia, cordyline, etc.
Fillers: bacopa, begonias, Boston fern, caladium, coleus, begonias, dusty miller, impatiens, etc.
Spillers: asparagus fern, tradescantia, creeping wire vine, dichondra ‘Silver Falls’, helichrysu, ‘Licorice Vine’, ivy geranium, variegated lamium, lobelia, Tahitian bridal veil, vinca major/minor, (vine), etc.
Full Sun/Partial Sun
Thrillers: lantana, papyrus, pentas, purple fountain grass, dracaena spikes, small topiaries and trees, etc.
Fillers: nemesia, nierembergia, osteospermum, pentas, petunia, calibrachoa, salvia, etc.
Spillers: plectranthus, portulaca, trailing petunia, vinca (vine), verbena, and sweet potato vine (Ipomoea batatas), etc
Finally, your container designs should bring you joy, so get creative! What do you love? What are your goals? Do you want to attract hummingbirds and butterflies? Do you want fragrance? Do you want a color explosion, or are you looking for something more subdued? Your containers should reflect their designer, so pick things that you really enjoy — not just the plants you see on Pinterest or in magazines, although if you love the ones you see in those places, imitation is the sincerest form of flattery! Some people like to use all annuals, some like a combination of annuals and perennials and some even add edible plants into their designs. The sky is the limit!
As with all things related to plants, design and gardening, remember that everything we do is a grand experiment. Don’t feel guilty if you mistakenly combine a low-water plant and a high-water plant in the same container and one of them dies. Learn from your experience and simply replace the dead plant with something more suitable.
Learn more about gardening here:
Easy Edible Plants for First Time Growers
Water Harvesting for Residential Landscapes
5 Steps to Stunning Fall Container Gardens
Irrigation Service Tip and Watering Recommendations for the Summer Season:
Service: Direction is Everything!
- Your irrigation system is only as good as its aim. Adjust sprinklers and emitters to make sure they are delivering water to the landscape and not onto rocks, bare earth or pavement.
- June is a great time to check and replace any clogged spray nozzles or drip emitters. Remember, each spray head also has its own filter insert that needs checked as well.
Watering Recommendations: Summer is here and so are hotter temperatures! Follow the Water by the Seasons Summer watering recommendations to keep your yard looking healthy. For turf, water 2-3 times per week. Start watering your trees and shrubs 1 time per week to keep them looking good.
Remember, if it rains more than a half inch you can skip your next scheduled watering as there is no need for supplemental irrigation.
Got questions? Contact us at AskAnExpert@abcwua.org
Avoid water waste! Follow Time-of-Day Watering Restrictions from April 1 to Oct 31
A lot of things have changed since last spring, but at least one thing is the same: April 1 is still the date on which time-of-day watering rules go into effect for Water Authority customers in Albuquerque and Bernalillo County. That means sprinkler and spray irrigation is not allowed between 11 a.m. and 7 p.m. from now until Oct. 31 in order to minimize losses to wind and evaporation.
Using spray irrigation during the hottest, windiest part of the day is not efficient. Instead, water in the early morning or in the evening when it’s cooler. Another good way to avoid water waste is by troubleshooting your irrigation system on a regular basis to identify leaks and make sure water is directed properly to the plants. Follow these tips for a desert friendly yard:
- For turf, follow the Water by the Numbers program and adjust your watering schedule as the season changes: Two days per week in April and May, three days per week in the summer, and ramp down again in the fall.
- Irrigate only when your plants need it, and water them deeply rather than too frequently. Use a long screwdriver or soil probe to check soil moisture.
- Add compost to your soil to increase moisture retention and boost soil fertility.
- Mulch around plants to help retain moisture and reduce weeds.
Grow strong and healthy trees by watering infrequently, to a depth of at least 24,” in a wide area around the tree’s canopy. Many of our trees only need deep watering 1 -2 times per month (depending on the species and conditions).
Summer Blooming Lavender
The genus Lavandula is a favorite group of ornamental herbs native to southern Europe and the Mediterranean. These are sun-loving plants that thrive in hot weather and grow well in the West in a wide range of soils, even compost-enriched garden loams, as long as they are well drained. Heavy, poorly drained clay soils can be fatal to lavenders.
In spring, before the plants begin to show signs of new growth, cut back the old stems by one-third to
re-invigorate the plant and encourage a good show of summer flowers. Lavender plants require two to three growing seasons to reach mature size.
The two major groups of Lavenders include the English Lavenders (L. angustifolia varieties) and the Lavandins (L. x intermedia varieties), which are hybrids between English lavender and another species, Lavandula latifolia. Generally speaking, the English lavenders have the deepest flower color, while the Lavandins are taller plants with larger flowers and longer flower stems.
The English lavenders are often preferred as a source of dried flowers while the Lavandins are typically used for oil production, potpourris and lavender wands.