- Mikl Brawner
STRETCHING OUR WATER
By Mikl Brawner:
Colorado’s climate is classified as semi-arid high desert. We know that water has always been our Achilles heel, our vulnerable spot; more and more people means less and less water to go around. Now Climate Change and drought are threatening.
Former Secretary of State, Bruce Babbitt, wrote in the Salt Lake Tribune “…a megadrought not seen in 500 years has descended on the seven Colorado River Basin states: Wyoming, Colorado, Utah, New Mexico, Arizona and California.” There has been great snowpack this year and progress in water conservation, but it falls far short of the need. So the U.S. Bureau of Reclamation will be finalizing a Five Point Plan that includes reducing water allotments to Arizona, Nevada and New Mexico. Babbitt pointed out that “…3 million acres of irrigated agriculture, mostly alfalfa and forage crops… consume more than 80% of total water use in the Basin.” His suggestion is to retire less than 10% of this irrigated acreage, which would make up for our current overuse of the Colorado River, and to financially compensate farmers who retire their land.
All seven states are asked to conserve water and the government may have to impose mandatory water conservation measures. This is a serious situation and the lesson is that we need to act now to conserve water in order to, hopefully, avoid dire water restrictions in the future.
About half of our household water is used for landscapes, including lawns. During the drought of 2002, water managers in local cities pounced on cutting outdoor water use as the quickest way to make sure we had enough water for drinking, and flushing toilets. The result wasn’t pretty. The outdoor watering restrictions were not only severe, they demanded watering be done at certain times, which meant some people weren’t able to water. Trees died and gardens declined. We don’t want to be surprised like this again. The City of Boulder responded by starting a water budgeting system that sets a budget for each property, allowing choice and flexibility in how and when water can be used during a drought.
Here are my recommendations for conserving water and making our gardens more resilient and drought tolerant. We can stretch our water right now, not just when restrictions are imposed.
Lawns are nice places for kids to play and to have a picnic, but as landscape architect Jim Knopf says, “Bluegrass has a drinking problem.”
Reduce the lawn to what’s needed for these activities
A NASA study found that 50-75% of a home’s total water usage is for lawn irrigation. Irrigation systems and irregular bed designs waste a lot of water. If residents watered only when lawns need it they would save 750-1500 gallons of water per month.
Lawns under trees need less water and are nicer places to play and picnic in the summer, but too much shade weakens grass and makes the lawn thin.
Aerate the lawn once a year followed by an organic fertilizer and a fine compost topdressing to strengthen the grass and make the lawn more drought resistant.
Reduce lawn watering in July when it needs twice as much water. Only water a quarter inch once a week. The grass will go dormant and turn brown. Resume watering in early August to bring Bluegrass out of dormancy; the brown grass won’t turn green, but new leaves will come from the roots. (This may not work for tall fescue lawns.)
Buy and install an evapotranspiration-based water controller that runs by water needs, instead of a fixed schedule.
If the only time you walk on your lawn is when you mow it, remove it and replace it with a native meadow or xeriscape garden. Native grass areas often take 3-4 years to fill in and will have some weeds until then. You can do this bit by bit.
You may have other reasons to remove your lawn: to save water, for a more Western look, to grow vegetables, fruits or pollinator plants. Aurora has a Grass Replacement Incentive Program. Your city may too.
For landscapes and gardens – trees, shrubs, perennials, vege-tables – the main water-stretching strategies are: soil culture, mulching, plant choice, and conservation.
2) SOIL CULTURE: Plants and Soil Life aren’t separate. More intimate than the most passionate lovers, they care for each other’s prosperity. How can gardeners support this partnership? By giving them our composted organic wastes. Compost both absorbs and holds water, and feeds the microorganisms that perform multiple functions for water stretching.
Mycorrhizae fungi collect water and bring it to plant roots in exchange for nutrients. Other soil organisms eat and digest organic matter and secrete substances, like glomalin, that hold carbon that holds water. Glomalin is sticky and binds tiny particles together to make aggregates with larger pore spaces. These larger particles improve infiltration of water and provide air, which multiplies the microorganisms. The living and dead bodies of these organisms build more organic matter that holds more water.
Gardeners can help further by providing rock minerals, manures, and organic fertilizers in small quantities. Incorporating coarse materials in dense clay soils, especially expanded shale which is porous and holds water, creates more air spaces. Gardeners can also provide some water, but not too much. A saturated soil has no oxygen; without it a plant can’t take up water.
To incorporate organic matter into the soil we have to dig and digging disturbs fungal networks and microbial communities. My suggestion is disturb at first to provide soil support, then continue to provide organic matter and nutrients from the surface without digging/disturbing.
One of the most important practices to prevent water loss is to keep the soil covered. Groundcover plants and gravel mulch, (which many dryland plants prefer), reduce water loss. A mulch of organic matter like wood chips both reduces water loss and provides nutrition for soil life and plants as it breaks down.
Mulch also insulates, which protects plant roots and soil life from overheating and drying out in the summer. This helps plants to keep metabolizing during the heat of the day, which means they continue to grow, make flowers and fruit. This cooling with moisture keeps soil life from going dormant. Applying mulch over weed barrier doesn’t feed the soil and will slide off any slope.
To get the most out of your mulch, here are some things you should know. Cedar and Redwood hold in moisture, but they repel microorganisms so it takes a very long time before they add any nutrition. Sawdust is too fine for a mulch, and very coarse wood chips take a long time to break down for nutrition. Since wood chips are mostly carbon and microorganisms need nitrogen to break down carbon, sprinkle organic fertilizer over your mulch for quicker nutrition.
4) PLANT CHOICE
It’s obvious that Bluegrass uses more water than sage or sedums. Most Western natives need less water. But how do you know which plants are truly water-wise? Books and the internet will give you some guidance if you search Western sources. Demonstration gardens are good guides if you know how much water they are using. Denver Botanic Gardens has both moderate water and very low water gardens. Some landscapers and nurseries can be reliable sources of information on the water needs of plants.
The most important principle is to group plants by their water needs. If you grow foxgloves, hostas, and willows that need moderate water, don’t mix them in the same garden with native Fernbush, sedums, and May Night Salvia, for example. You will be watering all of them to keep the thirsty ones alive which will drown the water-wise plants.
Gardens with automatic irrigation systems usually use a lot more water than those watered manually. This is due to frequent leaking, broken heads, and watering when plants don’t need it. Even if you have an automatic irrigation system, you should know how to turn it off if it’s raining, and you should be able to adjust it to less often in cooler, moister months.
If you have done good soil prep and covered the soil with mulch, you should be able to water your main garden only once a week (twice a week in July). Move any plant that can’t handle that schedule to your moderate water garden. Water deeply under the mulch. Dig into the soil after watering to make sure the water is going down 4"-8".
We want to be kind to our plants so we often water too much. Landscapers know that more plants are killed by overwatering than underwatering. We don’t have water to waste. I’ve managed a xeriscape garden for 35 years watering about once a month, twice a month in July. A “no water” garden is also possible, but will have a lot fewer plant choices. Once-a-week watering is plenty for a successful water-wise landscape. My garden taught me that a lot of plants grow well with little water and some care. Nature shows us this.
Mikl Brawner and his wife Eve own Harlequin's Gardens in Boulder, specializing in organic veggie starts and herbs, natives, sustainable roses, xeriscape, unusual perennials, and products to build healthy soils.