Trees are especially important in arid, urban environments like Albuquerque and Bernalillo County. They provide shade, mitigate urban heat, reduce greenhouse gasses and air pollution, and create wildlife habitat, among many other benefits. All trees, even climate-resilient and drought tolerant species, need to be watered adequately.
It’s worth the investment to keep our mature trees healthy. The mature trees on your property are worth much more than the cost of your treasured appliances and, yes, even more than your roof. Keeping our trees healthy and happy over their lifetime is a minimal investment and a valuable contribution to our community urban forest.
In Albuquerque, we tend to overwater our lawns and underwater our trees. It’s important to understand the basics of how best to water trees. For instance, a tree has two different main types of roots. The feeder roots lie within the first 6-24”of the ground, and the stabilizer roots can be at least 3’ deep You may think your trees’ roots can reach the water table, but you should think again — most of Albuquerque has a water table between 20 and 150 feet’ deep. Your roots are never getting that deep.
Due to the importance of our urban forest and how many people are seeking guidance on how to water their trees, the Bernalillo County Water Conservation Program, and Let’s Plant Albuquerque, partners collaborated to create this How to Build an Efficient Tree Watering System guide and the associated workshops.
The tree irrigation system is inexpensive, flexible, easy to install and long-lasting. It uses drip irrigation attached to your hose bib and can be easily expanded as your tree matures.
When assembling your system there are a few key parts to consider:
- Teflon tape is needed to seal the threads at every connection to prevent water coming through.
- Take note of the two different types of threads: hose threads and pipe threads. Hose threads are straight and require a washer to seal. Pipe and coupling threads are tapered for water use and will seal with just the application of Teflon thread seal tape.
- Timers should be uninstalled and stored with the batteries removed over the winter. Some people like to install fresh batteries every spring to ensure there is no interruption during the growing season.
- A pressure regulator is important for all drip systems due to the high pressure in our Albuquerque water lines. The regulator reduces the water pressure coming in from the main water supply. Then, it creates a constant low water pressure through the system, allowing the drip tubing to put out the correct volume of water per minute.
- Distribution (lateral line) drip tubing comes in two general sizes, and each has advantages and limitations:
- 1/2” tubing is more common, and parts are available at big box stores. The run of distribution tubing must be less than 200 feet.
- ¾” tubing is available from irrigation supply stores. It holds pressure better, and tubing runs can be up to 600 feet.
- Inline drip line (emitter line) drip tubing comes in two sizes and includes drip emitters pre-installed in the line every 6”, 12” or 18”.
- ½” Netafim inline dripline tubing for use around medium and large trees. Use 12” emitter spacing.
- ¼” Netafim inline dripline tubing for use around small trees. Use 6” emitter spacing.
- A flush type of end cap is handy for flushing out the system at season start-up or if a break occurs. It is recommended to remove and store flush caps over the winter.
The watering guidance for the system was developed to not under or over water most trees in Albuquerque. However, irrigation is highly dependent on site conditions such as soil type and microclimate as well as the species of tree. This guidance is meant to be a rule of thumb or starting point, and adjustments should be made based on the local conditions and tree species.
Below are some of the factors that should be considered in generating a watering schedule for your yard:
- Soils affect how often and how long you need to water — see the Water Authority’s Irrigation Guide for more details. In general, sandy soils require shorter but more frequent run times while clay soils need longer but less frequent run times.
- Always check your plants to evaluate irrigation scheduling. Most plants will look a little bedraggled at 3 p.m. during the summer so check in the morning. Do they seem wilted or pale or have cupped leaves? These can be signs your tree needs more water.
- Be aware that symptoms of overwatering and underwatering may look similar.
- Occasionally, feel the soil the day after irrigating or use a soil probe such as a screwdriver or coat hanger to evaluate the level of moisture in the soil. If the probe is easy to push in and there is a swampy smell, the soil has too much water. If you can’t get the soil probe more than 4” into the soil, it’s too dry. Ideally, the soil probe can be pushed 12”-18” into the soil 24-48 hours after irrigating.
- Consider what size tree you are trying to water. Check out the diagrams above and below to determine how much tube length you will need to meet the required water needs of your tree.
The next How to Build an Efficient Tree Watering System workshop will be held from 10:30 a.m. to noon Saturday, Sept. 28, at the International District Library at 7601 Central Ave NE. The first 20 registrants will receive a free tree irrigation kit that includes a hose-bib timer, backflow preventer, pressure regulator, filter and drip tubing. Register at bernco.gov/openspacesignup.
Other articles that might be of interest:
The Balancing Act of Watering Trees in the Fall and Winter
How to make a Tree Watering System for your established and mature trees
Tips to Keep Mature Trees Healthy
