I would like to clear some existing beds of snow on the mountain. I have tried pulling (two years now) them, covering with cardboard and mulch, and a commercial weed spray. Any suggestions?
Try placing black plastic over the area which will draw heat and kill the roots while smothering them as well.
My snow on the mountain has turned my backyard into a battle zone and snow on the mountain is winning. I talked to a wonderful local nursery about non-toxic ways to eradicate it. Your website says herbicides may be the only solution, but I refuse to use herbicides and will use what they say is very effective, horticultural vinegar. I'll let you know how it goes. If it works, I hope you will suggest that rather than herbicides, which can be so harmful.
Where can I buy snow on the mountain plants?
Many reputable nurseries and garden centers sell these plants. You can also search online for snow on the mountain/bishops weed retailers. In my experience, eBay is actually a great place to find many types of plants. Just check the feedback on the seller before you buy, but there are many excellent sellers of plants on eBay.
Everything I read about Snow on the Mountain (Euphorbia marginata) tells me that it is not Bishops Weed or Gout Weed (Ageopodium podograria). Why do you think these two are often confused as being the same plant?
The Euphorbia Snow on the mountain is a different plant from Bishops weed/Goateed. However, this plant - Bishops weed - also goes by the same common name of Snow on the mountain. There are a number of plants that share common names, even though they may be distinctly different plants. This is the reason for scientific names, which are unique to each individual plant. This article explains more: https://www.gardeningknowhow.com/garden-how-to/info/latin-plant-names.htm
I planted Snow on the Mountain several years ago in a shady spot and it did well for years. Around August it would start to get brown so we would cut it and it would come back looking nice. A couple years ago, other weeds started growing in what was a solid patch of Snow on the Mountain. Now it is competing with other plants. Do I need to do something with the pH of the soil or is there another solution? Thank you
Generally Snow On The Mountain needs little care. It can become invasive, I have not had an issue with that myself.
You could use an all purpose fertilizer to give the plants a little boost. If the soil needs some amending, you could top dress the soil with some compost.
For the past 2 summers the above plant has suffered considerable brown dieback in August. It's planted on the west side of the house under a maple and is in shade all day except for the very southern edge, which doesn't get brown and die. The plant recovers and regenerates before winter comes. What does it need to stop the dieback and browning? Thank you
Since the browning happens in August, it is possible that the plant needs more water to get through the hot part of the year. Another possibility is that the browning portion is old foliage that is less hardy. Mowing the plant one or several times during the growing season (before August) will encourage new, healthier growth and may prevent the plant from turning brown.
I would like to remove this plant from a garden bed, salvaging the good plants (Hosta, Day Lily, etc). If I remove everything and place new soil in the bed, will this eliminate the groundcover and, if so, how far will I have to dig down?
Bishop's Weed or Snow On The Mountain can become invasive and is difficult to remove. Even the tiniest of root or rhizome left behind can recolonize the plants.
Digging down 2 1/2 feet and carefully removing all the plants and their roots is the best approach.
It can also be recommended to solarize the bed after the removal to help kill any remaining plant material.
These links have more information.
https://www.gardeningknowhow.com/ornamental/groundcover/snow-on-the-mountain/snow-on-the-mountain-plant.htm
https://www.gardeningknowhow.com/garden-how-to/projects/how-to-solarize-garden-beds-to-eliminate-garden-pests-in-the-soil.htm