Welcome, again, for part two of our look at cool season grasses. If you have not read part one, please take a moment and start there.
Here, at Creative Concepts Landscape, we often hear new clients say that they let their lawn go to dirt and weed. This makes sense. Turf grass lawns are not adapted to our ecology, as discussed in part one. They need continual maintenance and supplemental water to stay healthy.
If you have decided that a living turf lawn is important to you, then there are certain practices to keep it as healthy and efficient as possible. We are focusing on cool season grasses in this blog, which are some of the most popular grass types in California, especially fescue. Some of the below information can be applied to warm season grasses as well (St. Augustine and Bermuda, which are also common in Southern California), however we will be taking a more in depth look at those grass types when the weather warms up in spring.
Without further delay, cool season grass maintenance information for your approval!
Evaluating an Existing Lawn
Do you want to revive an unhealthy lawn? Evaluating and renovating an existing lawn is often less laborious, and less expensive than installing a new sod lawn, however it presents its own challenges.
We will be happy to help you determine the best course of action. When evaluating an existing lawn, here are common issues to be diagnosed:
- An ineffective irrigation system
- Poorly managed irrigation or fertilization practices
- Inadequate drainage
- Excessive foot traffic (or vehicle traffic…)
- Improper selection of grass species
- Weed invasion (which is usually a secondary management issue- something else is allowing the weeds to take advantage of the lawn’s poor health)
- Excessive shade
- Insect or disease damage (which also tends to be a secondary issue)
An initial consultation, and often, a follow up irrigation system diagnosis can determine what course of action might be taken to help revive your lawn. With that said, sometimes it is best to completely remove the remnants of an unhealthy lawn, correct the deep systematic issues, and install new sod. Each landscape must be evaluated for its own specific needs.
Southern California has many microclimates and soil types. This can make broad maintenance recommendations difficult when trying to formulate a general program for the health of your lawn. All maintenance programs need to be customized depending on the specific site needs, and continual modification throughout the year with the change of seasons. Below are basic recommendations for cool season grasses.
The lawn at the Griffith Observatory in Los Angeles
Mowing is an important maintenance practice for an attractive turfgrass lawn (long bladed ornamental grasses, which we are not discussing here, should not be mowed). Mowing at a height and frequency that complements the growth habit of cool season grasses helps to create a dense, uniform turf that discourages weed growth.
Cool Season Grass Mowing Height Recommendations:
- Kentucky bluegrass: 1.5 to 2 inches
- Ryegrass: 1.5 to 2 inches
- Tall fescue: 1.5 to 3 inches
Mowing too low weakens grass, causing it to thin out, which encourages weeds to grow in the bare soil. One must remember that weeds are simply plants that we don’t want in our yard due to either their invasive quality or unwanted aesthetic. ‘Weed’ is a cultural term, not any specific plant. Weed seed surrounds us at all times, much like bacteria and viruses. They will take advantage of openings in the ecology of a region or a yard. A dense, healthy lawn is the best defense against unwanted weed seed germination and growth, and proper mowing height is one of the more simple and effective ways to help a lawn stay healthy.
Excessive weed growth in a turfgrass lawn
Conversely, mowing too high can produce an unkempt, unattractive lawn appearance (you’ll be ‘that house’ on the block, much to the dismay of your neighbors, the Joneses). Mowing too high can also encourage the buildup of thatch, which is a layer of plant debris and soil. Thatch naturally happens within all grass types, although some, such as the warm season St. Augustine, are more susceptible to excessive thatch. A moderate amount of thatch is healthy; the organic material comprised within it provides fertilizer for the soil. Too much thatch can harbor disease and pests.
Cool season grasses have a higher growth rate during the cool seasons of the year, and so they will need to be mowed with more frequency during that time. During the summer, these grasses should be mowed less frequently, and at the higher end of the mowing height spectrum, when there is more heat stress on the plant.
It’s important to remember that when there is more water and fertilizer for the lawn, the grass will grow faster, needing more frequent mowing.
Effect of Mowing
Mowing removes a portion of the grass blade, decreasing the leaf’s surface area, which decreases the plant’s ability to photosynthesize. Photosynthesis is the process by which plants convert light into carbohydrates, which are used for the growth of all parts of its structure. You could become a billionaire by inventing a cost effective way to allow humans to directly convert light into carbohydrates. In the meantime, we will have to continue to eat the middle man, plants.
A very basic photosynthesis diagram
Higher mowing increases photosynthesis, reduces stress on the grass, and increases low water condition survival rates by promoting deep root development (which is directly encouraged by maximum photosynthesis).
Grass should be mowed often enough that no more than one-third of the existing green foliage (the grass’ height) is not removed at any one time. Mowing more than this will detrimentally effect root growth, because the plant is not making the necessary amount of carbohydrates. Repeated excessively low mowing will cause the grass to use stored carbohydrate reserves, and eventually will starve the grass of food.
Mowing wounds grass blades (although grass is well adapted to recuperate from this wounding, hence why we are able to mow it at all). Mowing with a dull mower inflicts more severe wounds than sharp mower blades do. Dull blades do not cut as cleanly, tearing the blades and creating larger wounds. Using improperly sharpened mowers will progressively weaken your lawn.
The blades of a mower should always be kept sharp.
Grass clippings make up a large proportion of solid green waste in California. With few exceptions, it is best to leave grass clippings on the lawn after mowing. This is called grasscycling. It is effective at reducing the amount of waste going to landfills, and grass clippings decompose quickly, releasing valuable nutrients back into the soil. Grasscycling is most effective when done in concert with proper mowing techniques, and should be avoided when the grass is wet because too much layered moisture without air flow can encourage pests. Grasscycling should also be avoided when the grass is being cut down more than 1/3 of its total height, which is never recommended. In this case the grasscycling can then create too thick of a layer that will not decompose quickly on top of the lawn, again, inviting disease and pests.
If you have excessive grass clippings or wet grass clippings, do not throw them away! They can still be used for compost. However, do not put grass clippings in compost if the grass has recently been applied with herbicide, or if the grass is an invasive type, such as Bermuda grass (a warm season grass). If you do this, you might soon find Bermuda grass growing wherever you applied the compost.
Mowing Height Basics to Remember:
- Within its optimal mowing height range, each grass type will be healthier and have a deeper root system the higher it is mowed
- A grass that is mowed higher (within its optimal height range) is more tolerant of drought, heat, foot traffic, shade, disease and pests.
- In spring and autumn, cool season grasses require more frequent mowing (because they are growing at a faster rate).
- If you like the look of very long grass, it does not need to be mowed, however, culturally, this can look very unkempt. Remember, it is unhealthy to remove more than 1/3 of the length of the grass blades at any one time. Long grass that is going to be trimmed down severely should be done so over a period of time. This is difficult to do. Most mowers are not made to do this, and string trimming down long grass sectionally is imprecise and will cause excessive damage to the grass blades.
Turfgrass grows best when it has an adequate amount of nutrients. Most soils naturally have enough nutrients to support turfgrass growth (however some do not). With that said, a greener, denser lawn can be obtained with the proper application of fertilizer. The main three nutrients that grass needs are nitrogen, phosphorus, and potassium. These are the big three, which can be found in most all commercial fertilizers, especially those labeled ‘balanced’ or ‘complete’ fertilizer.
Lawn fertilizer granules
Turfgrass should only be fertilized during its growing season, thus cool season grass, generally, should be fertilized during the early fall and spring.
Generally, for established lawns, nitrogen is the only supplemental nutrient that should be supplied on a regular basis, however, generally additional phosphorus and potassium will not be detrimental. Phosphorus is vital in root development, potassium helps in better water and nutrient uptake, and nitrogen promotes healthy photosynthesis (making the grass greener).
Excessive nitrogen can promote excessive growth, which can be detrimental to the plant structure. Always read fertilizer labels completely before applying them.
Fertilizer comes in two basic types (there are others but we will keep it simple here). Quick release and slow release. Quick release fertilizer is water soluble and is immediately useable by the plant. Slow release makes the nitrogen and other nutrients available to the plant over time, and therefore can be applied at higher rates than quick release.
Fertilizers should be applied evenly over the lawn and applied when grass is dry, to avoid leaf burn. Then the fertilizer should be watered into the soil. If any fertilizer gets onto your driveway, sidewalk, or other hardscape, immediately sweep it up and put it on the lawn. Fertilizer should never be washed into a storm drain. Also, do not apply fertilizer within a day or two before considerable rains. The rain will wash the fertilizer into the storm drain system or out into other planters.
The irrigation management of lawns is vital to reduce water waste and maintain healthy grass. Although, ecologically speaking, we have concerns about water use for commercial and residential lawns (which we discussed in part one), a well designed, well maintained, and well managed irrigation system is absolutely necessary for your turfgrass lawn.
A well designed and maintained sprinkler irrigation system provides even water coverage over your lawn.
Lawns can use 1.5 inches or more of water per week during the hot season. Rainfall is scarce in Southern California and summer irrigation is absolutely needed to keep your lawn alive, especially with cool season grasses.
A lawn should be watered when the soil begins to dry out, but before the grass actually wilts. There is no one formula for this. A watering schedule will need to be continually changed throughout the year to accommodate the best watering practices. At the wilting stage, areas of the lawn will begin to change color, displaying a blue-green or smoky tinge. Loss of grass resilience can be seen when the grass retains footprints rather than springing back up while walking on it. Too much water is equally as common. Spongy lawns are getting far too much water.
Dead blades of grass can be a sign of too little, or too much water.
Cool season grasses often become semi-dormant in the hottest part of the summer, and then return to full vigor once cool weather returns. Regular, deep watering is necessary to keep the lawn green throughout summer. Light sprinkling of the grass surface is harmful because it encourages root development near the surface instead of deep root growth. Deep root growth allows the grass to collect more nutrients and water, and is encouraged by infrequent, heavier watering.
Deep grass roots (not just for political activism)
A poorly designed, maintained, or operated irrigation system can create excessive water runoff. Early morning is the best time of day for lawn irrigation (2 am to 8 am), because evaporation is at a minimum. Night time watering can cause issues if the temperate becomes very cool. Blades of grass that stay wet for extended periods of time can harbor diseases and pests.
During the cool, rainy season, often December through May/April, lawn irrigation can be turned off completely.
The design and installation of a proper sprinkler irrigation system is fundamental to lawn health. Contact us to set up a consultation, and proposal, to install a water efficient and effective irrigation system for your new lawn, or an irrigation system check for an existing lawn. We find that most irrigation systems are in need of help.
A welcoming stream of green lets the eye flow across the landscape.
Lawns can be great places to play with your children, set up an outdoor summer movie night, or just lay down and watch the clouds go by. Although they are not truly ecologically appropriate for Southern California, they are still a major part of our culture, and smaller accent lawns can provide beautiful aesthetics for the eye to sweep over, unifying a landscape. If we must have lawns, then we must be responsible about them. That means proper design, installation, and management of their complex components.
Creative Concepts Landscape is here to help. This blog topic has covered a brief overview of cool season (and general) lawn information. We will go into further depth of specific lawn information in the future, so check back in with us each Wednesday.
If you are interested in a new lawn, rehabilitation of an existing lawn, repairing or updating an irrigation system, or any other landscape need, contact us today to find out how we may be of service for you.
By Daniel Williams
Client Liaison for Creative Concepts Landscape Management