Q.snow-in-summer (cerastium tomentosum)
Our snow-in-summer has brown, bald spots. We have a beautiful carpet of snow-in-summer in the front lawn area. It gets full sun in Southern California (we have a bit of ocean breeze), but there are more and more bald, brown, dead spots. Our neighbor has the same plant but no bald spots. What might it be? Thank you.

Certified GKH Gardening Expert
First, check whether your garden provides the best conditions for this plant. Snow-in-summer does best in gardening zones 3-7, while most of Southern California is in zones 8-10, so the weather is probably a bit hot for them (although the ocean breeze probably helps). Make sure your soil is well-drained and doesn't have patches that stay wet for too long. They also prefer poor soil with not very much organic matter, and with a pH between 6 and 7.8.
To fill in the gaps, you could pull out the dead areas and reseed or divide some of your existing plants.