Questions on: Snow on the Mountain

Ron Smith, Horticulturist, NDSU Extension Service

Q: I planted some snow-on-the-mountain as a border plant. Is it necessary or OK to lay down mulch around the plants or is it better to leave it as is? (e-mail reference)

A: You would not be wrong following either practice. Generally, mulching conserves moisture and helps the plants get through the first year of summer stresses.

Q: I need to eradicate some snow on the mountain. Digging it out is a real project because of its extensive root system. Is there something I can apply to the leaves that will kill the whole darn thing? I need to be careful what I use because the area also has rhubarb, coneflower and obedient plants. (Blaine, Minn.)

A: Good luck! The only stuff on the market is Roundup. Because of the other plants growing in the area, you will have to carefully paint the herbicide on the leaves and hope for sufficient translocation to kill the entire root system.

Q: Can you tell me where I can get seeds for snow on the mountain? I looked through a seed catalog, but what they are showing as snow on the mountain doesn't look the same as on your Web site. (e-mail reference)

A: I don't know, but perhaps some readers do, so keep your eye on the Web site.

Q: I have a variety of snow-on-the-mountain that is not variegated. It showed up in the middle of a variegated patch. Is this a common variation or do I have something wonderful? (e-mail reference)

A: Nothing wonderful, sorry! It is a simple reversion back to the original form. Cut it out unless you like that form better than the variegated. The green has more vigor and will eventually overcome the variegated plants.

Q: I have snow-on-the-mountain growing around my house and it is spreading more than I would like. What is the best way to get rid of it? I also have trumpet vine in the same area that I would also like to remove. Can you recommend a climbing vine that would go up a chimney, but not damage it? I read that trumpet vine and Virginia creeper can damage masonry. I have another bed that is constantly invaded by what I have been told is pin cherry (a shrub, with shiny leaves and dark berries). The pin cherry shrubs are in my neighbor's yard, so I can't remove them. I would like to plant something like periwinkle in that area. (Email reference)

A: Roundup or a dicamba containing (Trimec) herbicide will usually do the trick. All the vines I know of that are self-supporting have some kind of holdfast that gets into the brick and mortar. Unless the brick work is weak and old, the holdfasts from Boston ivy, Virginia creeper or any other vine should not be destructive, just unsightly after they have been removed. Concerning the pin cherry, birds consume them and then deposit the seeds. The seeds will germinate even after passing through a birdís digestive system. Vinca minor (periwinkle) should do well as long as there is some shade.

Q: I fertilized our snow on the mountain plants. They are now growing straight up, getting pods and seeding. Is this normal? (e-mail reference)

A: Going from a ground cover plant to an upright is hardly normal. You want to keep the seed pods from forming, so mow it down with the mower at its highest setting. It will recover, going back to the prostrate habit it had.

Q: I would like to know why my snow on the mountain gets brown leaves. (Oakes, N.D.)

A: This is just a reaction to the high pH and salts in the soil. Often mid summer mowing can prevent leaves from getting brown because it pushes out new growth.

Q: I have snow on the mountain under two trees. Both areas are browning and it looks like it's dying. Previously you said a leaf fungus causes the problem. What causes it and is there anything that I can do to avoid it in the future? We laid sod this year so we've been watering quite a bit. Could it be getting too much water? We started out the season with the fullest, nicest stand that we ever had so it's very discouraging. Will it come back again next year if we treat it with a fungicide? (E-mail reference)

A: The watering would do it. Mow it off for now and pick up all the clippings. Next spring, as the new growth is opening up, spray with a fungicide like Ortho's Multi Purpose Fungicide. Because this is a preventative application, you should get good control as long as you don't water like you did this year. Monitor the planting to be sure something doesn't get started again. If it does, reapply the fungicide.

Q: Can the seeds from snow-on-the-mountain be harvested and planted in the spring? How would I go about doing this? (E-mail reference)

A: You needn't worry about this plant producing viable seed for you. It will do it pretty much on its own, assuming we are both talking about the same plant, Euphorbia marginata. This plant is known for extensive self-seeding ability. If you want to control the seed, simply harvest the pods after the flowers fade, and scatter them where you want next spring.

Q: We have snow on the mountain on the north side of the house that is doing extremely well; however, the ones on the west side turned brown and are dying. Can you tell me why? (Thief River Falls, Minn.)

A: That is a leaf spot fungus that is causing the problem. I suggest mowing the planting back, collecting the mowed material, fertilizing with Miracle-Gro, and spraying with all-purpose fungicide such as Daconil 2787.

Q: I was wondering when I could plant snow on the mountain. I would also like some basic information about caring for this shrub. (Amidon, N.D., e-mail)

A: Snow on the mountain--Euphorbia marginata--is an annual that often self-seeds. It gets about 2 feet tall and likes well-drained soil and full sun. The
plant has a milky sap that is common to this genera, hence handling of the plant may cause a dermic reaction. Snow on the mountain does not transplant
well, so seed should be sown where the plant is intended to be.

The major value of the plant is the variegated leaves, which act as a foil or background for brighter-colored plants. It also is a good xeric plant, being
able to stand high temperatures and extended periods without water.

Q: What’s the difference between snow on the mountain and snow in summer? A lady gave me some seed and said it was snow in summer or snow on the mountain.
I don't have any more information from her than that. (Amidon, N.D., e-mail)

A: There’s a big difference between snow on the mountain (Euphorbia marginata) and snow in summer (Cerastium tomentosum). The former is an
annual that is a member of the Euphorbiaceae family; it is poisonous if consumed and gets 2 to 2.5 feet tall with white flowers. The latter is a perennial
that grows mat-like only to a height of 1 foot or less; it has nonpoisonous white flowers.

If you were given seed, I'm betting it was snow on the mountain, since snow in summer is usually sold as a transplant.

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