By Sharon Cohoon, Sunset senior garden writer

 Though it has been over a year since our blog post on Dymondia margaretae, the carpet-flat South African ground cover shown below, we are still getting comments and questions about it because more and more people are taking out all or part of their lawns and looking for substitutes.  

Phil's recent question seemed like one a lot of readers might have.  I quote him below:

"We have a space of about 200 - 300 sqf.  We purchased flats of Dymondia for it. What size clumps should be planted and what should be the correct spacing? The area had a lawn before which we sprayed a few times and lightly tilled. We are in Southern Cal. about 15 minutes inland. What would be the expected time frame for it to fill in and what's the best way to handle grass that keeps growing through? "

Though I have literally seen D. margaretea in hundreds of gardens--and liked it every time--I don't have it in my own garden and had no personal experience regarding growing it.  So I went to an expert, Randy Baldwin, general manager at San Marcos Growers, a wholesale nursery in Santa Barbara that propagates the plant.  Here's his answer.

"I tell people to plant this plant as close as they can afford.  But, if the area is irrigated and the soil decent, this plant can grow fairly fast, and a one-foot spacing would be adequate.  It would fill in within 6 months, assuming you planted in late winter through spring in an area with full sun and regular irrigation.  Buy flats if you can and cut them into squares.  As long as each piece has nice roots, they can be as small as one inch.  But test out a few to see if you need to make bigger squares to get clumps with roots before cutting up the whole flat.  If you can't find flats, break up one-gallon plants into multiples.

Regarding weeds, this plant can eventually do a good job smothering out new weed seed grasses, but when the Dymondia is young and there is space between plants, diligent hand-weeding is a must.  Site preparation ahead of time really is the key, though.  You need to get rid of the grasses that were there before you plant.  If you are dealing with Bermuda, it often takes repeated treatments of an herbicide used during the grass's growing season and while it is being irrigated so that the Bermuda thoroughly takes in the herbicide.  There are selective post-emergence herbicides that work on grasses that do not harm broadleaf plants, but my observation is they don't do a great job in controlling Bermuda.  Also I am not sure whether Dymondia is tolerant of these herbicides.  If a homeowner wantsto go this route, they should talk to a pest control advisor for specific recommendations.  And, even so, I would test a small area first before treating the entire planting."

Thanks, Randy, for such a thorough answer.  I'm sure a lot of our blog readers will find this immensely useful.