In the city of Sacramento, as in many other locales, watering a lawn every day is no longer an option. Ordinances throughout California mandate a maximum of three days a week for landscape irrigation.
And the response by some homeowners? "If I don't water my lawn every day, it turns brown!" I hear this far too often from listeners on my garden radio shows.
There are a lot of possible culprits for this scenario: compacted or poor soil, slow drainage, the wrong turf type for the area, sloping lawns, uneven coverage by sprinklers and more.
The biggest culprit in lawn problems? Watering a lawn every day. Daily, light irrigations causes lawn roots to remain near the surface, where they are more susceptible to damage from heat, cold, animals, disease, etc.
And those lawn roots may not be getting much water, because of thatch buildup.
According to the UC Guide to Healthy Lawns, thatch is the layer of living and dead stems, roots, stolons, and rhizomes between the green blades of grass and the soil surface. A thin layer of thatch (less than 1/2 inch thick) can be beneficial to the lawn because it helps to limit weed germination, reduce water evaporation, and protect from frost damage. However, thick thatch layers can prevent water, air, and nutrients from penetrating the soil, causing reduced root growth and increased potential for drought stress. Thatch also favors fungal growth and can harbor insect pests. Some turfgrass species, such as bermudagrass, bentgrass, and Kentucky bluegrass, have creeping growth habits and rapidly build thick thatch layers. But even the popular fescue varieties of lawn can build up a thick layer of thatch, even though the grass is green on the surface.
If you haven't dethatched your lawn in three years or more, September through mid-October is the time to not only dethatch, but to also aerate, fertilize and overseed your lawn.
If more than 40% of your lawn is in really bad shape, then consider a complete lawn renovation in September or early October here in the mild winter areas of California. In other parts of the country, spring is the best time for this makeover. A complete lawn renovation involves removing all the existing turf, improving the soil and reconfiguring the sprinkler system to better cover the entire area, as well as choosing the right turf type for your area. Directions for a complete renovation can be found here.
A partial lawn renovation involves uprooting thatch, aerating the soil, overseeding the lawn area and applying a thin layer mulch to maintain a healthy lawn throughout the coming year.
The first step is to cut your lawn as short as possible. Then, water your lawn thoroughly to soften the soil. Wait a day or two. Then bring on the necessary components: a dethatcher, aerator, starter fertilizer, compost for mulch, lawn seed, drinks and snacks. After all, if you've worked in the yard all day, who'll have the energy to run to the store for refreshments?
The dethatcher can be as simple as an iron rake or as complex as a power dethatcher or vertical mower, available at rental yards. Thatch - layers of dead grass - impede the movement of water and fertilizers to the root zone of a lawn and should be removed every two or three years.
During the dethatching process, you may be in for a rude awakening. See that pile of thatch? It's about two cubic yards. That's what we removed from about 4000 square feet of what looked to be an otherwise healthy lawn. You can't see thatch when it's just below the lawn's surface!
After dethatching, remove the dead grass and then aerate the lawn area. An aerator, a device with sharp, hollow tubes, removes soil cores that are three to four inches deep. Aeration relieves soil compaction, allowing air, water and fertilizer to pass more freely through the soil, stimulating root growth. Hand aerators are available, but rented roller or power-driven aerifiers do the job more quickly and effectively, albeit more expensively.
Then, spread starter fertilizer and a lawn seed that closely matches your existing grass over the area. However, for Bermudagrass lawns, overseed with an annual or perennial ryegrass; this will keep your lawn green during the winter and spring while the Bermuda grass is brown and dormant.
After overseeding, press the seed into the ground with a water-filled roller, or rake the seed lightly to make sure it is in contact with the soil. Finish up by spreading a thin layer of compost over the entire area.
Keep the reseeded lawn area moist; the new seeds will sprout in seven to ten days. This is the ONLY time you need to water a lawn every day, keeping the seedbed evenly moist until the grass is up and growing. Then, set your sprinklers to come on for a period of time that's appropriate for the weather: two or three times a week during the hottest months; once a week during the cooler months when it doesn't rain. And turn off the system entirely during the rainy season.
After dethatching, aerating and overseeding, your lawn will look absolutely terrible. Do not fear.
By Thanksgiving, you will have the greenest lawn on the block!