Passive rainwater harvesting allows you to collect rainwater runoff from roofs, patios and driveways as well as the overflow from rain barrels and cisterns (active rainwater harvesting sources) and direct it into the landscape. The water then gets stored in the soil where plants can take advantage of the moisture.
Several rainwater harvesting techniques can turn potential problems (i.e. erosion, flooding or excess moisture near foundations) into water for your plants. Rainwater contains extra nutrients not always found in potable water, so the plants receive additional benefits. Passive rainwater harvesting also helps filter out pollutants, increase infiltration to the aquifer and provide healthier ecosystem habitat.
Start by calculating the amount of water that flows from your potential runoff sources. For every 1,000 square feet of hard surface, 1 inch of rain will generate approximately 600 gallons of water. It’s easy to see why rain barrels or cisterns can quickly fill during medium to larger rain events, so a passive collection system for overflow is always a good idea. You want to make sure whatever system you create will be able to handle a
good-sized rain event (refer to the link above). It’s very important to create a directed overflow so that when there is a large rainstorm, the excess water will flow into a basin or other feature onsite or into the street (if your capacity is limited) without creating erosion.
There are many different techniques, and some can be used together to enhance the benefits. These techniques include rain gardens, swales, basins, soil sponges, curb cuts, French drains and pumice wicks, check dams and gabions. Study your site and these techniques to determine the best option for your garden. Watch your site during a rain to see where the runoff comes from and where it goes. You may want to take advantage of existing patterns.
Rain gardens are depressions to catch surface runoff from slopes and are best planted with native plants that can take occasional flooding.
Swales are sloped depressions that convey water into basins or rain gardens from canales, downspouts or other drains. Make sure the slopes consistently move the water downhill and are large enough to not get overwhelmed. Swales are usually lined with large gravel or cobble to prevent erosion. If you have extra material onsite, this is a great recycling solution. Make sure that swales are designed to catch the slow drip of a light rain as well as the powerful flow of a heavy downpour.
Basins are catchment ponds designed to handle large rain events and provide a great place to plant trees and larger shrubs or heavy water use plants that can benefit from the extra water. Calculating the size to match your runoff is vital here. The area where the runoff from your swale(s) enters the basin will need gravel to dissipate the erosive forces. Shredded wood mulch works best in the bottom of the basin. The capacity of the basin and the health of the plants can be further enhanced by installing soil sponges (see below) in the low points. In larger yards, you may want to create a series of basins to increase capacity and opportunities for plantings.
Soil sponges are post holes dug and filled with a soil mix containing compost to increase infiltration and introduce organic matter and beneficial microbes to the soil sponge and surrounding soil. These also provide an avenue for plant roots to quickly grow deeper, improving health and drought tolerance.
Curb cuts are made with a concrete saw to channel runoff into a basin. This can be done on your own property, but permission is needed to cut into a public curb to direct excess water into the street.
French drains and pumice wicks are progressively deeper trenches lined with geotextile fabric (to prevent silting up) and filled with gravel or pumice. These are best used when you have existing trees or large shrubs and the base of those plants is on the same level or higher than where your runoff originates. Aim them directly at the tree or shrub to minimize root damage while still providing additional water to the plants’ root zone. The open space in pumice provides additional water capacity.
Check dams and gabions are small dams used in areas where existing runoff has started to erode and cut deeply into the soil. These small dams slow down the water so it infiltrates and lessens erosion. Gabions are a type of check dam constructed of riprap (oversize gravel/cobble) held together with a wire basket. Generally, both have an area of cobble below to prevent erosion.
Passive rainwater harvesting is a great way to lessen your use of potable water, reduce erosion and provide a supplemental water source for your garden. Remember, you still will need to water your plants (through irrigation or hand watering) to establish them and, in most cases, to maintain their health.
This airy plant bursts with delicate white and pink flowers whirling off of a central stem. In fact, one of its cultivars is called “whirling butterflies” due to the nature of the plant. The graceful stems are tall, narrow and fan out in a whirl that blows in the breeze. This airy plant flowers from June through September and brings a unique spray of flowers to the garden.
The jujube is just one of those trees that is extra! Extra fruitful, extra nutritious, extra hardy, extra beautiful. This medium sized tree comes in 400 varieties, many of which are being cultivated and taking root in Albuquerque.
The jujube tree, often called Chinese date, has been cultivated for thousands of years around the world, in Albuquerque for nearly 60 years and in the panhandle of Texas since 1875. Its small abundant fruits are high in fiber, vitamin C, potassium, antioxidants and phenolic compounds and have been used to support nervous system, cardiac and digestive health. Medicinally, it is used as a tonic sweetener in many supportive Chinese herbal remedies.
The fruit can be eaten raw, dried or cooked. Fresh from the tree, when they’re mature and a luscious mahogany brown, they have a crunchy refreshing taste, like a cross between an apple and a date. As they dry, they become sweeter and chewy. Dried, they are delicious in oatmeal, cookies, trail mix or anywhere you would use dried fruit. They make an excellent chai — just boil dried pieces with other ingredients, letting the earthy sweet flavor complement ginger, cinnamon, cardamom, pepper and other traditional chai ingredients. You also can find recipes from Korea, China, Vietnam, India, Italy and many Persian cultures that incorporate the jujube for both sweet and savory dishes.
The fruit is very easy to dry and, in fact, many that you miss harvesting will dry right on the tree. However, we do recommend bringing them inside to dry and cutting the pits out before drying so they are easier to eat and enjoy down the road. If you have a dehydrator, that will speed the process, but they will also dry if you place them on cookie sheets in a spare room, on top of a shed in the sun or even in a car and let our New Mexico dry air work its magic. Jujubes don’t bruise and spoil quickly like other stone fruits, so windfalls and bird-pecked fruits don’t make a mess and are still usable.
We love edible landscapes, so we’re naturally drawn to these fabulous trees. But even if you aren’t looking for food, the jujube is a wonderfully hardy tree for Albuquerque. This tough specimen hails from the buckthorn family, Rhamnaceae, and will grow in USDA hardiness zones 6-11, which is an extraordinary range for any tree! At the moment, Albuquerque is generally zone 7, but as we face climate disruption, landscapers and planners are encouraging planting with an eye to zone 8 or 9 so our shade and habitat trees can withstand increasing heat. Jujubes are deeply rooted and can tolerate drought and saline and alkaline soils. Once established they can survive with small amounts of water, though a strategic watering schedule will increase your yield. Because they’re so drought tolerant, we don’t recommend planting a veggie garden under them or they’ll drink up all the water intended for your zucchini. They do well in full sun or light shade. They can handle sustained days and weeks of 100 degree plus heat, 23 below zero in winter and anything in between. They must have a frost to produce fruit, which isn’t a problem here. Jujubes do sucker quite a bit from their roots, and this rootstock, if allowed to sprout, produces very small, almost inedible fruits that are mostly pit. So, we do suggest being vigilant in cutting down the root sprouts as they appear.
Jujubes make a beautiful addition to any landscape. They have an elegant zig zag branch growth pattern and bright green, shiny oval leaves that can even withstand severe hail. They can be trained to a traditional tree structure or allowed to be a little wild and shrubby. They provide cool shade and habitat for birds, pollinators and other wildlife. Speaking of wildlife, one of us has a friend whose small dog Kipper grabs himself a couple from the ground during ripening season, carrying them happily to his bed to snack on … he’s not wildlife, but that little dog seems to love a jujube even above his biscuit treats. These trees benefit from cross pollination so plant yourself two of these beauties!
Planting trees not only gives you the riches of your tree, but it is also a love letter to the future. As gardeners who are tending land and each other in the midst of climate chaos, we have the opportunity to cultivate healing, repair and hope. With every tree we plant, we can try to leave our small patch of earth a little better than how we found it — cooled with shade, brightened with birdsong and providing nutritious food via a resilient, prized and giving tree. The next time you’re sitting in your garden, allow yourself to dream of a future where someone is harvesting jujubes and appreciating the ancestors who cultivated and left these sweet trees for them.
Learn more about specific types of gardening here:
Author: Corva Rose is an arborist and founder of Tree School, and can be reached through treeschoolNM.com, Jennifer Gardner has been gardening in Albuquerque for 30 years, with an emphasis on residential scale food planting. Have a question about the article? [email protected]
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.
Author: Megan Marsee is the Water Conservation Program Lead for Bernalillo County and can be reached at [email protected] Have a question about the article? [email protected]
Just as its name declares, this perennial brings a little bit of white brilliance to the summer garden. It thrives well in shade and in part sun, thereby spreading and filling in a lot of space. The name doesn’t tell the entire story because this plant is also admired for its delicate silvery leaves. It makes an excellent ground cover for dry areas. The leaves spread a mat of foliage from which the flower stems rise. It also will cascade over rocks and walls.
