The two most important things to know about killing your lawn are these:
- You must be certain the lawn is completely dead (and we mean really, really dead) before planting your new landscape, or your new landscape will be ruined; and
- Even after you plant your new landscape, new weeds will continue to establish themselves; you must remove these weeds as they emerge. If you are diligent and you keep the non-plant areas covered with mulch, then over time very few weeds will get established in your new landscape, making the weeding easy and keeping your landscape looking wonderful.
In addition to the following tips on how to kill your lawn, be sure to see our “Money Saving” tips on digging up and on disposing the old lawn.
Tips for killing and getting rid of the old lawn, from people with successful L2G projects
- Give yourself plenty of time to kill the grass, at least 3 to 6 weeks, making sure it’s dead, dead, dead.
- During the rainy season it will be harder to kill the grass (especially grass that is dormant) and to haul it away (the soil will be heavier as it fills with rain water).
- Some folks found it easier to remove all the grass first, than kill new shoots as they emerge from the soil.
- Hands down the best tip for people comfortable with using tools: if you plan on cutting the grass out yourself, rent a sod cutter from a big box store – using a shovel or pick is truly back-breaking.
Links to other sites
- LA Times wonderfully summarize many issues related to killing your lawn.
- UC Davis on using chemicals to kill the lawn.
Rancho Santa Ana Botanical Garden on using Solarization to kill your lawn.
(Potential problems with solarization: may kill beneficial organisms living in the soil, may not kill roots that are deep in the soil, may damage a tree’s roots if done under the tree’s drip line and may require an awful lot of non-biodegradable plastic)
- Tree of Life Nursery provides an easy to read guide on how to kill your lawn.
Solarization – a non-chemical way to kill your lawn
“Solarization” is a process of killing the lawn by using the sun’s heat to roast the grass.
- Cover your entire lawn with black plastic sheets and weigh down with bricks or rocks.
- The lawn must stay covered for at least 6 weeks to ensure that it has been properly killed.
- Water and fertilize the (hopefully) dead lawn for a couple of weeks after removing the plastic to make sure all the grass is dead. Dig up or use chemicals to kill shoots that emerge.
- Mow the dead grass to a very short length and remove with a sod cutter or shovel.
Sheet Mulch – another non-chemical way to kill your lawn
Some people prefer not to use chemicals to kill their lawn. One of the more popular non-chemical methods is to put down layers of paper and mulch on the living grass, then waiting 2 or 3 months for the grass to die. This method is sometimes call “sheet mulch”.
- Cut the grass as low as possible, then cover it with old newspapers or with “painter’s paper” (purchased at big box stores; a material expected to decompose in about one year); the advantage of using painter’s paper is you don’t have to deal with the disadvantage of newspapers: you may need to collect a lot of old newspapers in order to cover your whole lawn 8-sheets deep.
Cover the paper with a thick layer of mulch, say 4 to 6 inches.
- Alternatively: if you removed a few inches of soil, you can put the new soil on the paper. This would make it possible to install plants with root systems that a fairly shallow, such as many varieties of groundcover.
- Normally you would want to leave this alone for two or three months; if you are in a hurry, you can move to step #4, but deal with grass that might come up through the holes you cut for the plants.
- Plant shrubs and trees by cutting through the sheet mulch and into the soil.
Here are the main advantages and disadvantages of “sheet mulch”.
Pros: this process kills the grass without chemicals, eliminates the need to dig up and remove the lawn, and the dead grass will eventually provide nutrients to the soil as it decomposes.
- Con: it may take longer (8 to 12 weeks) to kill the grass than with chemicals (4 to 6 weeks); it will be impossible for certain plants, like groundcover and many succulents, that spread across the soil to do so if they cannot reach the soil; the height of the landscape will increase by the thickness of the mulch, and grass may emerge where opening for the plants were made in the layers. (You might fix the problem with groundcovers and succulents by substituting new weed-free soil for mulch.)
For these reasons, layering may work very well in some parts of your new landscape but not in others.
Herbicides – using chemicals to kill your lawn
According to the UC Guide to Healthy Lawns, the most effective way to kill your grass lawn is through the application of a nonselective herbicide, like glyphosate. Glyophosate is the main ingredient in “Roundup”, which is readily available at most garden supply stores. While herbicides are undeniably effective, they also pose threats to the environment if used improperly. It is up to the consumer to determine the costs and benefits of herbicide use. Here are some key points to consider if you plan on using this technique:
- Water, grow, spray, kill; repeat; repeat; repeat. Apply herbicide while your turf is actively growing (non-winter months) to ensure proper absorption. Don’t apply if it is expected to rain within 24 hours; don’t water for 24 hours.
- Do not disturb the sprayed area for at least 7 days, as it may take up to 7 days for the plant to fully absorb the herbicide.
- Once the grass has died, mow the lawn at a very low setting—as close to the bare soil as possible—and collect the resulting material.
- Water and fertilize the (hopefully) dead lawn for a couple more of weeks; spraying any live shoots that appear. Remove remaining material with a sod cutter or shovel.
Cautionary notes on the use of chemicals
In order to reduce pollution and the destruction of non-targeted plants, do NOT apply herbicide in windy conditions or 24 hours before it rains. Visit Cornell University’s Pesticide Management Education Program for more information on the use of chemicals to kill lawns. Before applying any herbicide, be sure to read and understand the label. When it comes to herbicide, the label is the law.
Free Disposal of the Dead Grass
People had different strategies for disposing of the dead grass. The easiest thing to do is just pay someone to haul it away; this might cost $150 to $300, depending. But if you are a thrifty gardener, here are a few alternative strategies:
Shake the dirt off the dead grass then throw the dead grass in the trash can. The trash can might not be large enough to take all the grass in one week; so you might have to add a little grass to the can each week for several weeks.
Free City pickup
After shaking off the dirt, put the grass in bags and call the City for your annual FREE bulk-trash curbside pickup (call 562.570.2876; only limited quantities will be picked up and the trash must be bagged according to the City rules, so call the City before bagging up tons of grass).