Sunday, May 29, 2011

Silver carpet (Dymondia margaretae)

I don’t remember when and where I first read about the groundcover known as silver carpet (Dymondia margaretae). Native to the coastal plains of South Africa, this diminutive plant (only 1-2 inches tall) forms dense mats over time and chokes out virtually all weeds. In fact, this mat supposedly withstands foot traffic and, according to succulent guru Debra Lee Baldwin, is tough enough to park cars on.

Since dymondia has a fleshy taproot that goes straight down, it is drought-tolerant and can cope with temperatures above 100°F. It is relatively slow-growing but regular irrigation, at least in the first year, will speed up its growth. Gardeners who have experience with silver carpet say that it’s worth the wait.

If all these wonderful attributes are true (and I have no reason to doubt they are), dymondia would make a perfect ground cover for much of California where conserving water is always a top priority. That’s why I’m baffled that it’s so difficult to find this plant in nurseries. Is it that nurseries don’t carry it because there’s no demand? But how can gardeners buy it when it’s not for sale?

In light of that, I was extremely happy to finally find Dymondia margaretae locally. Kudos to Green Acres, one of my favorite nurseries in Sacramento County. They had both 6-packs and full flats. I grabbed two 6-packs for a project that needs immediate attention, and I think it’s the perfect plant for that.

Between the flagstone walkway leading up to our front door and the adjacent lawn there is a narrow planting strip that provides a visual transition from softscape to hardscape. Originally I had planted blue star creeper (Isotoma fluviatalis). It filled in nicely, especially where it received overspray from the lawn sprinklers, but it never formed a mat thick enough to keep out weeds. As I mentioned before, we have a real problem with oxalis, or wood sorrel (Oxalis stricta). Eventually there was so much oxalis growing between the blue star creeper that I simply couldn’t take it anymore. I applied Round-Up to the entire planting strip and then removed the dead matter to create a blank slate. As you can see in the photo below, all kinds of weeds are already making a comeback, including oxalis. High time to take action!

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Weedy planting strip

Removing the 2-inch plugs of dymondia from the 6-pack, I was impressed by the fleshy roots on these small plants. It’s easy to see how they will form a sturdy root system capable of sustaining the plant in times of drought.

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Dymondia margaretae plug from 6-pack

The soil in this planting strip was remarkably friable. I must have amended it when I planted the blue star creeper three years ago. Dymondia prefers lean and friable loam but can handle a variety of soils as long as they are well drained. Unamended, our native clay soil would be a challenge so if you are afflicted with a similar soil, I suggest adding things like pumice or decomposed granite to improve drainage. Dymondia doesn’t need a particularly rich soil, and fertilization shouldn’t be necessary.

Here is the final product. 12 plants planted approximately 11 inches apart (the entire planting strip is 13 ft. long and 11 in. wide). In hindsight, I should have gotten one more 6-pack but such is life.

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After weeding and planting

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Small Dymondia margaretae starts

In the summer, dymondia produces bright yellow flowers that resemble daisies—not surprising since dymondia is in the daisy family (Asteraceae).

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Close-up of daisy-like flower

I’m very glad I finally found a source of this wonderful groundcover, and I hope that it will live up to my expectations. It would be wonderful if I didn’t have to worry anymore about keeping this planting strip weed free.

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Leaves with typical curling that exposes part of the underside, giving the plant a variegated look

For more information on this very promising groundcover, check out these articles:

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2 comments:

  1. Seems you're still plagued by Oxalis. Hopefully the new groundcover would work. It's a lovely looking plant and would look great in a swathe :)

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  2. We'll never be able to get rid of the oxalis. It comes up everywhere. Round-Up (glyphosate) works great, but it kills everything else as well. Plus, I try to use as few chemicals as I can.

    I think the dymondia will do the trick. Now to be patient...

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