Ask Mr. Smarty Plants

We always try to check first to see if the plant in question is native to the area in which it is being grown. This USDA Plant Profile Map indicates that Dichondra argentea (Silver ponyfoot) grows naturally nowhere near Brazos County. We grow it at the Wildflower Center and offer it at the Plant Sales, where it is always very popular because it is native to a dry, hot area in Texas. As our climate changes, with more heat and less rain, plants that can suck it up and survive in those conditions are invaluable. We believe you may be providing your plants a much too lush place to live. You no doubt are watering your flower beds well, and the other plants are providing some shade. Most dichondras prefer some shade and certainly are not adverse to slurping up extra water. From our webpage, here are its growing conditions:

"Growing Conditions

Water Use: Medium
Light Requirement: Sun , Part Shade
Soil Moisture: Dry
Heat Tolerant: yes
Soil Description: well draining soil.
Conditions Comments: A perennial groundcover useful for covering large areas in open, sunny sites in well-drained soil. The silver gray foliage has a metallic appearance in the sun."

We also prefer not to have herbicides used in the garden, but whatever you do, don't spray anything. Droplets of the spray could easily land on some treasured plant and kill it.

You might want to read this Dave's Garden forum on Silver Ponyfoot. The comments are all favorable and some of these especially are praising the fact that it can drape over a wall or cover and protect roots in a flower bed. However, it is pretty generally agreed that while this plant does not need excess moisture, it sure loves it.

Since you obviously don't want to create a dry flower bed just in order to control your dichondra argentea, we have a couple of off-the-wall ideas for keeping it where you want it. Using a sharp shovel, draw a line in the sand, as it were. Go around the part of the plant that is where you want it and dig the shovel down deeply into the soil all around. Anything beyond that, pull it out, hoe it out or try covering with mulch. Buy a small  bottle of a liquid herbicide meant to kill plants that are dicots and some small sponge-tip disposable brushes. Anything that sticks its head out beyond the perimeters that you have set either gets yanked out or painted with the herbicide. Because it does indeed spread with underground runners you will have to persevere, because it isn't easy to get the poison down to the roots. It will recur, so you will have to keep at it or learn to love it.