Odd as it might seem, the third installment of "After the Lawn" is about turf care. The thinking: While Southern California is paying residents to peel away millions of square feet of grass to alleviate pressure on reservoirs, lawn is still this highly tarmacked region's single most ubiquitous mitigator of urban heat. Most of the Southland's trees grow in lawn. Going forward, turf will not be the all-purpose groundcover that it once was, but it will still have an important place in the landscape. The ability to manage it judiciously will be vital during transition to drier planting schemes and well into the future.
The tips below start conventionally enough. Nuggets such as urging residents to know their soil type could be mowed into the grounds of the Lawn Institute. However, the recommendation that Southland residents flout the irrigation schedule stipulated in the lawn-watering ordinance of the City of Los Angeles is my own. If you follow the steps outlined under tip number 8, know that you will be breaking the letter, if not the spirit, of the law. You will be using less water on turf than allowed under the ordinance. The water captured from this method can either be saved for the public supply or, if you have valuable trees and shrubs, diverted to them.
And so, about watering all that grass:
1. Know your soil type. If you follow the methods in this Colorado State University tip sheet, testing a sample of your soil will be more fun than building an exploding volcano with a third grader. If the soil is clay, then you will need to irrigate more slowly, even dividing irrigation sessions into several separate intervals to allow time for water to sink in the ground. The optimal depth of penetration for lawn is six inches.
2. Skip planting "cool season" grasses. The winter ritual of over-seeding semi-dormant Bermuda or St Augustine lawns with perennial rye, then covering the seeds with manure-based "toppers," makes for more headaches than the short burst of electric green grass is worth. Winter rains carry the topper's nitrogen and urea into storm drains where they become watershed pollutants. Think of the egrets. Think of the surfers. Moreover, the rye seeds will blow around and you'll be weeding rye seedlings from cracks in paths for years to come. Think of your knees.
3. Consider switching to weather-based irrigation controllers. Unlike older sprinkler timers, these modern successors check the weather so that sprinklers won't go off in the rain or when it's foggy and cool.
4. Or become a weather controller yourself. Turn off sprinklers after the first meaningful downpour of the November-to-March rainy season. Turn them back on in persistently dry weather and/or when you feel hardening of the ground underfoot or the turf doesn't bounce back from footprints.
5. Replace old misting sprinkler heads with new rotary nozzles. Rebates are available for these though, with the more expensive ones running roughly $7 each, the cost is swiftly offset by water savings. Rotary nozzles fit on existing sprinkler heads and have easily adjustable spray patterns, which help to prevent pavement wetting. Rotary nozzles also spin out less water per minute in heavier droplets than conventional sprinklers, so less irrigation is lost to wind and evaporation. Angle the nozzles for low trajectory dispersal to further reduce evaporation. Rotary nozzles are especially good for slopes where fast-falling water tends to run-off the surface instead of soak into the ground.
6. Water before 9 a.m. or after 4 p.m. in winter and 6 p.m. in spring, summer, and autumn. Evaporative loss can reach as high as 50% if you water mid-day in the summer. The best time to irrigate is late at night or early in the morning when the air and ground are coolest.
7. Check your city's lawn-watering ordinance. Chances are good that it will be similar to that of Los Angeles. This entails short frequent applications of eight minutes per station three times a week (or 96 minutes per month). Rotary sprinkler heads, which emit water more slowly, may run for two 15-minute cycles per watering day. Some cities, such as Pasadena, reduce lawn watering to one day a week in winter.
8. Observe the spirit, not the letter, of the City of LA's lawn watering ordinance. The ordinance was written in 2010 under pressure from a city council determined to keep lawns green during the housing crisis. The problem is that ultimately the frequent, shallow watering is destructive for the turf. UC Davis's "Lawn Watering Guide for California" is typical of turf care guides recommending deeper, less frequent irrigations because "they promote deep root growth."
This is orthodoxy because shallowly watered lawns with weak roots become chewed up by mower blades. The lawn soon turns into a rutted, compacted mess. By contrast, a lawn with strong roots can withstand mowing, trampling, heat, and sun. When under stress from heat or dryness, the foliage becomes tawny as nitrogen and moisture is drawn down and stored in the roots. If you've irrigated properly, the water is where you need it -- in the roots and the soil -- where it will push up lush new foliage as soon as the worst of summer passes.
To maximize root health and soil buoyancy, don't panic at some seasonal change in the foliage. A light green or tawny lawn is perfectly normal when it's hot and dry. Even at the height of summer heat -- especially then -- instead of pursuing phony-looking spring green turf by watering the legal three times a week for eight minutes each cycle, water only one day a week. Or, if this water season is as disappointing as it looks like it might be for California reservoirs, water only every two weeks, or even once a month. Brown lawns aren't dead. They're dormant. This dormancy isn't a scourge, but a terrific tool for hunkering through drought.
If you have the newer rotary sprinklers, again only water one day a week (or less). Run the two legal 15-minute cycles with a time break for infiltration. If needed, run a third. Break again. You might not need a fourth. Test between cycles by plunging a screwdriver into the ground. If it penetrates easily to six inches, the water is where you need it. Watering this way, or variations of this way depending on your climate zone and soil type, will ensure a lawn can bounce back green and lush when days shorten and cool, which is happily exactly the time of year when you'll want to be outside lolling around on it.
Watering your lawn this way will save a third or more of your irrigation budget. If you have trees, they will need the savings. Whereas lawn needs water to travel at least six inches below the soil line, trees need percolation of three to six feet. Mature trees should be watered once a month, not once a week. So a trickling hose, soakers, or drip system should be used to irrigate trees separately from sprinklers. More on how to do this will be touched on in subsequent installments; however for instant advice, refer to this flyer from the Inland Urban Forest Council.
9. Mow less. Cut your grass no more than twice a month, preferably only once if it is dormant. Do mow when it starts to go to seed. Runaway turf seeds can invade garden beds of neighbors and wild spaces. Set the mower height at 1 ½ or even 2 inches. Allow the grass to grow to two, even three inches. Cut no more than one third of the total height of the turf in any one pass. The longer the grass, the less evaporative losses the lawn will have in heat.
10. Grass-cycle. This means forget bagging the grass and throwing it in the green bin. Leave it where it falls. As it decomposes it will add nitrogen and organic matter to the soil. This should reduce or even eliminate any need to fertilize a well-managed lawn.
11. Meet with your gardeners. If you have gardeners who come once a week, ask them to do other tasks during the no-mow weeks such as pruning and hand weeding. Prohibit the use of leaf blowers outside of exceptional circumstances, such as dangerous work clearing leaves from pitched roofs. The reasons not to use blowers are numerous. Suffice it here to say that turning what are in essence huge blow dryers on your garden is incompatible with water conservation. Cutting the mowing sessions and grasscycling should compensate for any additional work created by raking rather than blowing.
12. Avoid pesticides. Common lawn weeds such a dandelions are harmless, even edible and certainly pretty. Once mowed, these mixes still add up to a lawn. Pull only noxious weeds such as burclover and foxtails that can injure pets.
Happy gardening. Please return for the next installment on how to remove established lawn -- including from tricky spots around established trees.