Smother it

Download PDF

It is already March and if you have not planted your native plant garden you might want to consider putting it off until next year. Once again this rain year is turning out to be rather disappointing, and it does not look like we will be seeing noticeable amounts this spring. Although the numbers are better further north, according to The California Weather Blog, most of the rain fell in two major rainfall events. Not only has it been dry, but it has also been warm. These conditions do not bode well for late planting.Nevertheless, it is not a bad time to attack your lawn. If you are sure that you will be putting in a low water-use garden next year, you can start ridding yourself of the lawn and planning the new garden now. And fortunately, Emily Green’s timely KCET series, After the Lawn, provides important information on how to do this safely and effectively.

In the coming weeks and months KCET will explore how safe lawn conversion can be done around existing trees. The online written series “After the lawn” will address landscape challenges from curb to back fence. If you want to keep lawn, it will tell you how to do it and save water. If you want to go native, we’ll be on it. The theme: How to look at your lot and improve its function and beauty while increasing its water efficiency. Stay tuned. Ah, in the meantime, remember your trees. Here’s a good brochure on tree irrigation from the Inland Urban Forest Council.

I have already discussed one method of lawn reduction, neglect, offering suggestions and discussing its pros and cons. Other Lawn Removal Methods can bring more rapid change; however, whatever method you use, follow Green’s suggestion in After the lawn: Part 1, “Cut your sprinklers by all means but run new irrigation to trees. Keep them healthy.”

Of all of the ways one can lose the lawn, I think smothering is my favorite. Yes, it sounds gruesome but it is really quite gentle. Basically, you cover the lawn with a layer of stuff, usually organic mulch. The mulch blocks the sunlight, reduces air exchange (though coarse mulch should be used to minimize this), and starts to decompose, warming the soil below. Most turf grass withers and dies beneath, though Bermuda grass will be a tough adversary with this and most other methods.

The lasagne method – in which cardboard or newspaper is laid beneath mulch – is a variation of smothering. Some descriptions of this method include mowing the lawn low, then digging it out or rototilling it. The surface is then watered well and covered with cardboard or newspaper, making sure to overlap the pieces for complete coverage. Brown and green organic material are layered on top of the cardboard. Each layer is amply watered to facilitate rapid decomposition. The gardener, then, just waits for nature to take its course.

This method is not without controversy (gardening is part art, part science and a whole lot of argument). If the area is on a slope, the mulch placed on top of the cardboard is likely to slide down, and in windy areas, it may be more likely to blow around. And of course, it is an extra step. If you don’t overlap the cardboard well, grass and weeds will grow between the pieces. This happened to me because I am not a neat and careful person, I’m kind of a mess. The Garden Professors point out that digging or rototilling damages soil structure. Furthermore, the cardboard or newspaper, in addition to being slippery, reduces air exchange at the surface of the soil which can lead to anaerobic processes and the proliferation of disease-causing microorganisms.

I, too, am not a big proponent of this method. For one thing, it is too much trouble, and I am averse to buying anything, except plants. Furthermore, although it may work well for vegetable gardens, the resulting soil is very high in organics, a condition not beneficial to many California native plants. A serious windstorm provided me with first-hand evidence that simply applying a six inch layer of mulch in the form of coarse wood chips is all that is required. This does increase the organic composition of the soil but leaves and wood chips are not nearly as rich in nitrogen as the soft greens of kitchen waste. Furthermore, the coarseness of the material killed the grass while allowing air and water to freely penetrate the soil. And of course, the process more closely mimics what happens in nature when trees succumb.

On November 30, 2011 a major windstorm hit our area. There was severe tree damage throughout the region. Two mature trees in our front yard, an avocado and a deodar, lost a lot of limbs. We called an arborist who removed broken limbs and chipped the smaller branches. All of the debris was kept on site. The following pictures show how easily and thoroughly simple mulching can get rid of lawn.

Front yard with lawn
St. Augustine lawn, old avocado on west (left) and deodar on east side (right). (Oct. 19, 2011)
Tree damage from windstorm
Windstorm does serious damage to area trees. (Nov 30/Dec 1, 2011)
Wood chips from tree work
Arborists cut up downed wood and remove damaged limbs from trees. All debris was left on property.
The pile of debris left at the base of the tree had to be – and was – removed immediately. A pile of mulch
left under a tree cuts off all air exchange to the roots and gets dangerously hot. Never leave a pile of mulch
beneath a tree! (Dec 22, 2011)
Wood chips moved off tree and spread
Debris is moved off base of trees. Some is spread on lawn, rest is piled on cement walk in front of porch. (Dec 25, 2011)
Temporary path created with tree debris. (Feb 16, 2012)
Temporary path created with tree debris. (Feb 16, 2012)
Festuca rubra 'Patrick's Point'
Fescue cultivars planted. Notice that grass is still alive beneath the mulch. (Mar 2, 2012)
All lawn is gone and decomposed with almost no weeds or grass emerging. (Aug 22, 2013)
All lawn is gone and decomposed with almost no weeds or grass emerging. (Aug 22, 2013)
Penstemon heterophylla 'Margarita BOP'
Planting Margarita BOP penstemons and deergrass in front yard. (Feb 6, 2014)
Bees living in a hive that had been in a large cavity of this tree suddenly  disappear. Within days ants are all over the trunk dropping wood from cavities. An arborist was consulted and he declared the tree unsafe with poor anchoring roots. During removal he noted that the tree swayed with the least pressure. (Oct 1, 2014)
Bees living in a hive that had been in a large cavity of this tree suddenly disappear. Within days ants are all over the trunk dropping wood from cavities. An arborist was consulted and he declared the tree unsafe with poor anchoring roots. During removal he noted that the tree swayed with the least pressure. (Oct 1, 2014)
Front yard without avocado
Front yard sans avocado tree. Although the tree was quite sparse near its demise, it provided more shade to the south-facing upstairs bedroom windows than we expected. The change was dramatic and
we are considering awnings to moderate the heat. (Oct 23, 2014)
Veg garden in sunny front yard.
This is the first time I have had a sunny space to garden in. The ground is covered with mulch and needs to rest before any serious landscaping can be considered so I moved large containers filled with herbs and lettuce to the front. (Oct 25, 2014)
Front yard
The house looks different! Sure could use a large tree on the west side. (Nov 12, 2014)
Front yard
Planting some perennials, moving deergrass from other parts of the yard, and putting in a few native shrubs like manzanitas and ceanothus. More permanent landscaping will have to wait another year. (Feb 9, 2015)
Front yard
Although non-native and weedy, the nasturtium that seeds itself all over the yard is a welcome sight in the front. Wildflowers, wiregrass, deergrass and herbs fill the space and help the soil settle down. (Mar 5, 2015)

3 thoughts on “Smother it

  1. Mike Letteriello

    Always helpful stuff. Smothering it is great. I dug it all out, painstakingly, over time. Then got some fill dirt to add berms, etc.

  2. Connie McGehee

    several of the photos aren’t coming up. but great article!

    • weedingwildsuburbia

      Thanks, Connie. Sorry about the photos. I corrected it – hopefully! There have been some issues with images when I changed my website/blog. I have been working on correcting these problems as I come across them.

Comments are closed.