I looked back through all my posts for the one on Dymondia margaretae, and like Captain Renault in "Casablanca" I was shocked, shocked: I couldn't find one! I can't believe I have not sung the virtues of this wonderful little ground cover plant.
Dainty, wonderful Dymondia margaretae, which never gets too tall, which gets as thick and dense as a pricey plush rug, which can be walked on (within reason), which spreads fast enough, but doesn't become invasive. I have nothing bad to say about Dymondia, though it does need summer water here in Sunset zone 23--not a lot, but one irrigation a week makes it beautiful, once a month and it hangs on, no water at all and it's dead. Too much water and it's dead, too. It has a helpful habit of rolling the edges of its leaves inward when it gets thirsty, so if you see it looking very white (the undersides of the foliage is white) then you know it's in serious need of water. I've never given mine any fertilizer. It doesn't seem to need it.
Dymondia margaretae, superior as a low cover to the thymes, unless you want that wonderful thyme scent. Its' origin is South Africa, and it prefers milder coastal conditions, so keep that in mind--in Sunset 24 it may need even less water than here, but Barstow may be too hot for it, and is hardy only to about 25-30 F. It tolerates some shade, but too much shade makes it grow sparse, and sparse means weeds.
It does need careful weeding at first, but when it really thickens up, there won't be any more weeds, or very few, and the weeds stand up over the flat flat Dymondia, making them very easy to spot. Grow it in smaller areas and around stepping stones. A lawn--well, you'll have to be careful of weeds and too much traffic.
Dymondia underplanting a Coleonema:
One drawback of Dymondia is price--it is expensive when you buy it in flats--those big square 18"x18" (45 cm) plastic trays that are just a couple of inches (5 cm) thick. I've started flats of Dymondia myself, and have discovered that this plant and its depth-loving, fat root system hates being in a flat. In a flat it looks awful, and sulks, and because it looks awful, people see it and decide they don't want it. But in the ground it's a beauty.
I often recommend this plant. People see it in my garden and want this plant for their own garden. I help people remember the name by saying "Dymondia--like diamonds." Apt, because the plant is a jewel.