Plants, Stone, California Landscapes


Lawn Conversion with a Cover Crop Phase

This is a lawn conversion we did a couple of years ago. Usually we convert lawns by leaving the lawn in place and covering it with sheet mulch. I’ve posted about the process in the past. This one was a little different. When I first got involved, most of the lawn had already been removed by hand. The client had also decided to do a cover crop for a season to regenerate the soil. Generally, I think that by sheet mulching, the decomposing lawn will accomplish pretty much the same thing as a cover crop. But a cover crop is certainly another effective way to do it. This lawn had tired, depleted soil, and several Mulberry trees had roots everywhere that would compete with the new plants, so I’m sure the cover crop was beneficial.

We used vetch as the cover crop. We seeded it just after Thanksgiving, gave it about five months to grow, and then removed it at the end of April. There are a few ways of dealing with the vetch. Most of the research and info about it is geared towards agriculture, and my experience with it was for lawn and veggie garden projects rather than ornamental plantings. For the lawns and veggie gardens, I had tilled it directly into the soil. For this garden, to avoid disturbing the roots of the mulberry trees, we left the roots of the vetch in place and tore off the tops of the plant, chopped those tops a bit, and spread them on the surface to rot beneath the fir bark mulch. Supposedly that gives less nitrogen gain, but the layer of vetch helps retain moisture in the soil. I don’t really know, there are too many variables to conclude anything other than that the planting did well enough with this method. I’m still partial to sheet mulch and generally still recommend that method, but I’d be happy enough to do it again this way. Seeing the vetch grow throughout the winter was fun, and rolling it away in the spring went quickly and was actually kind of fun too. I was worried the vetch might reseed itself and make a mess in the new planting, but as far as I know it hasn’t been a problem. The photo below was when we were half way through removing the vetch.

Above shows the new planting with the dried out vetch hidden beneath the fir bark mulch. Below is what it looks like now after two years of growth. This, with the Bearded Iris in bloom, is the showiest the planting gets. They’re pretty much the biggest flower I know that won’t get eaten by deer. Next month there’s a fair bit of Teucrium, Linaria, and Verbena to bloom, but those make a lot of little flowers. For this garden, I like seeing the fist-sized purple flowers.

Below is the view of the garden from the other direction, starting with google earth’s view of the lawn, then the space after the lawn was dug out, with the vetch growing, and how it looks this spring.

As I said, I was worried that the vetch would reseed and make a mess the next year, so we removed the vetch bfeore it could set seed, and we also spread corn gluten seed inhibitor throughout the planting as well. I don’t know if the corn gluten made an impact or not. I use it sometimes but have never had a control group to compare and decide if it is actually effective.

As part of the new planting, we made a path and a seating area, the client had some chairs that we put around a boulder with a sawed off top. The photo above is the view from one of those chairs. So much nicer than a tired old lawn.

Tags: , ,

2 Responses to “Lawn Conversion with a Cover Crop Phase”

  1. February 6th, 2018 at 2:47 pm

    Laura says:

    What level of sunlight is this site? I love the bearded iris and have heard they need full sun. I’m in San Diego and my front lawn is northern exposure, so in winter it has been quite shady even at high noon. I think during summer it gets more direct sun.

  2. February 18th, 2018 at 11:22 pm

    ryan says:

    It gets a full day of sun at some times of the year and gets quite a bit of shade from the fruitless mulberry trees at other times of the year, depending on angle of the sun and whether or not the trees are in leaf. Competition from the roots of the mulberries is as big of an issue as sunlight.
    In my experience Bearded Iris are pretty forgiving, doing fine with a half day of sun during their growing season. Also if you find they aren’t getting enough sun you can move them to a sunnier location and they will recover. They’re usually worth a try.

Leave a Reply