2. The Native Meadow Experiment
I’ve decided to do a little experimenting in my own back yard with the idea of converting a small lawn (190 square feet) into a native grass and wildflower meadow. I’ve read a lot about it and seen some large scale efforts that had varied success, and I think that there is still a lot to know about the specifics of getting it done on a residential scale.
Step 1: Lawn Eradication –
Getting rid of the lawn and the weeds is the key step in providing a good environment for native grasses and wildflowers to thrive. Most of them can’t out-compete the weeds on their own. This is the unfortunate fact of our urbanized landscape: human exploration and settlement introduced non-native species and the ones that could out-compete the natives have often taken over. I've read in several places that weed control is the biggest obstacle to establishing the native meadow, so how do we tackle it?
From what I've read, these are generally the possible weed eradication techniques:
Rototill soil and apply herbicides several times to kill off weeds.
Scrape off the surface lawn, sheet mulch and install plants within the mulch.
Sheet Mulch for a while and then remove it and spread seed or install plugs.
I definitely want to avoid the use of chemicals, and so I’ve decided to go with something along the lines of #3. However, I’m going to let the sheet mulch sit for a longer time than most sources say. My reasoning is that the area should be covered up before the beginning of the rainy season so that the weeds don’t have a chance to grow, and continue to be covered until the ideal time for planting in late fall.
Implementation of Step 1 – December 30, 2011 thru January 6, 2012
The end of 2011 was quite dry so I was able to wait until the winter holidays to take action. I started by digging trenches around the edges to allow a place to weigh down the cardboard and create a sort of weed-free “moat”. Then I mowed the area as low as possible and left the clippings in place. This was my last chance to look at that weedy water consuming lawn and say “goodbye.”
After a trip to the Berkeley recycling center where I took a pile of cardboard out of the recycle bins, I laid the cardboard down, overlapping the edges, and weighted it with spare rocks. You want to use unbleached (brown) cardboard and get as much of the stickers, tape and staples off of it – obviously that part isn't going to biodegrade. I decided that one layer of cardboard would be enough since that amount pretty much filled up my car. The following day I went and filled up bags with Albany’s free arbor mulch (chippings of the City’s tree trimming work). After wetting the cardboard thoroughly, I laid down the mulch over the area; it ended up being about a 1 ½” thick layer, which is thinner than is recommended.
Early Spring Update – March 17, 2012
As the rains have continued, I have definitely started to see some weeds poking up through my cardboard and mulch layers. They are pretty easy to pull, but it is now obvious to me that I should have made the extra effort to follow what I read exactly: use 2 or 3 layers of cardboard, and 3” to 4” of mulch. My weedy lawn isn't getting completely smothered like it should. I have been diligently removing weeds and added another inch or so of purchased fir bark mulch.
Late Spring Update – May 27, 2012
Now that the rain has tapered off there are much fewer weeds are and I feel like most of the lawn has been eradicated. Now starting to think forward to the next steps this fall – soil preparation and planting – very exciting!
References:
Sheet Mulching - on the Alameda County Stop Waste web site: http://www.stopwaste.org/at-home/home-gardening/go-from-lawn-to-garden
Handouts and Notes from my attendance at the California Native Grass Association’s workshop: Using California Native Grasses in the Water-Conserving Landscape www.cnga.org
Creating a California Native Meadow by David Amme, as published in Grasslands, A publication of the California Native Grass Association.
Earthcare Landscapes – Natural Front Yards program - www.naturalfrontyards.com