Euphorbia marginata (Snow on the Mountain)
Euphorbia marginata (Snow on the Mountain) is a warm-weather, annual, single-stemmed plant that typically grows up to 3 feet (90 cm) tall…
Bishop’s Weed Plant – Keeping Snow On The Mountain Ground Cover Under Control
If you’re looking for a ground cover that thrives in deep shade where grass and other plants refuse to grow, look no further than snow on the mountain plant (Ageopodium podograria). Also called bishop’s weed or goutweed, the shallow roots of this quick-growing, deciduous ground cover sit above those of most companion plants so that they don’t interfere with their growth. Solid green varieties provide a lush, uniform appearance, and variegated forms have white highlights that glisten in deep shade.
Know Your Natives: Snow on the Mountain
If you’ve spotted a roadside field cloaked in what appears to be freshly fallen snow, it’s not a (complete) mirage. It’s actually a hardy summer annual wildflower that begins bursting into bloom around mid-July.
In late June and early July, an intriguing plant begins to make its presence known. Solitary stems with thick green leaves begin poking up past the shaggy grasses covering vacant lots.
For many, the first inclination is to call it a milkweed, and further inspection would reveal a sticky white sap. But all is not what it seems. It’s actually the sprouts of a hardy summer annual wildflower known as snow on the mountain.
While it does not serve as a host plant for monarch caterpillars, snow on the mountain is an attractive wildlife plant that occurs naturally along many roads and in city parks.
Although it produces a similar sap to milkweed, there are a few ways to differentiate it from milkweed. The leaves of snow on the mountain have a covering of hair on the underside and pointed tips, both features that are absent on all the common milkweed species of Bexar County. The growth habit of snow on the mountain is also conspicuously different. It rises as a single stem to about two feet and then begins to branch like a fractal into successively smaller stems until each branch ends with clusters of tiny white flowers.
The leaves rather than the flowers are the showiest part of snow on the mountain. The last few sets of leaves before the blooms have bold white margins and begin appearing around mid-July and last through October. En masse they blanket fields with a white cloak, similar to fresh snow. The plant itself is toxic and deer resistant, but the seeds are eaten by game and song birds.
Snow on the mountain is easy to grow from seed. Just check the ground beneath the plants for round, black seeds about 1/8 inch in diameter. Sow them in a wildflower meadow in either spring or fall. As spring wildflowers begin to die off, snow on the mountain will be just getting started. If you can get a little colony established you’ll be rewarded with unique and consistent blooms throughout the summer, providing color and food for wildlife during the otherwise lean summer months.
Snow on the Mountain - garden
Aegopodium podograria #1 by J.G. in S.F.
TheGardenLady received this question from Janet.
I was given some hostas and there were some pieces of Snow on the Mountain mingled with them, which is taking over everything. How can I kill the snow without killing the rest of my plants? I have dug until I’m blue in the face.
There are quite a number of plants that were brought to this country because they looked pretty and horticulturists or gardeners wanted to plant them in their gardens in America or wherever they moved then these plants became invasive. Unfortunately Snow on the Mountain, ‘Aegopodium podagraria Variegatum’, also known as Bishop Weed or Goutweed is one of them.
One nursery touts it as the number one seller for a ground cover. So it is still being sold. It is advertised to use for difficult sites. Many people say they love the plant and it isn’t invasive for them. However, some people rue the day that this plant entered their yard. One lady said when she sold her house she didn’t tell the new owners all they were getting. The government lists this plant as an AGGRESSIVE invasive (see here).
People who buy plants should check the invasive plant list before buying plants or buyer beware. Even nurseries don’t seem to keep on top of the invasive plant list, so they might not be aware of the problem. Always check pots when buying plants to be sure that you are not getting an unwanted guest, whether weed, disease or pest. But you seemed to have the misfortune of inheriting it when you got your hosta plants from a friend.
TheGardenLady thinks that you are doing the right thing by digging up the Snow in the Mountain. It is an uphill battle but gardening is not easy. And I think of the work as being cheaper than joining a gym.
It is best to try to get the plant out in early spring when it is just coming out. If you miss all the plants and the plant flowers, to prevent more plants by its self seeding you should remove the white flower heads before they set seed.
A friend with one of the lovliest and weed-free gardens swears by a tool called a Swoe that is a British garden tool invention. Her sister said that it is tricky to use but my friend disagreed saying that it is the easiest tool she ever found that is effective and easy for getting rid of weeds. It seems to just cut the weeds off at the ground level, but doing this enough times will prevent the weed from growing. The tool is not cheap- and the USA Amazon.com, the cheapest place I can find it, says it is sold out but Amazon UK talks about it (see here).
Another thing you can do is, after pulling or cutting down the Snow on the Mountain plant, try covering the area around the hostas with mulch or black plastic to try to kill the unwanted plants.
As a last resort, without using chemicals (see here), you could re-dig all the hostas with the accompanying Snow on the Mountain plants. Clean off all the soil around the hostas. Remove all the soil with any Snow on the Mountain plants or their roots. Hostas are a really resilient plant and this won’t hurt them. Bag everything you don’t want in black trash bags, including the soil. Then let the closed bags sit in the sun for a week or so to allow everything to bake in the bags. Do not compost this. Refill the area where you dug the plants with new topsoil- I would buy bags of it because you know there are no weeds or pests in the store-bought bags of soil. Replant the hostas. Watch the area carefully in case any seeds of the Snow on the Mountain plants took root or some of the root remained. Yank out the unwanted plants early so they can not spread.
I would not plant anything besides the hostas in the area until I was sure that I had removed all the Snow on the Mountain. The hostas should grow back beautifully- and if you bought some of the new soil with slow release fertilizer, I feel certain that your hostas will be the sensation on your block.
If you want to use a chemical, there is only one that seems to work (though some people say that it is not effective in eradicating Snow on the Mountain.) But this chemical can kill other plants like your hostas. So this product has to be used judiciously. The chemical is glyphosate and the brand names are Round-up, Rodeo or Pondmaster.
It is advised by the North Dakota extension office that you brush or paint the product on the leaves and hope that it will kill the roots. Whenever you use a chemical, READ the LABEL carefully and follow the directions. To me it seems like it would be easier to dig up the hostas and replant them. Also, I dislike using chemicals in the garden and glyphosate is being banned in Europe.
These methods can be used on other invasive plants. Please read the link to the USDA information on eradicating Snow on the Mountain or before buying any plant to check to see if the plant you want is now on the invasive plant list.
Snow-on-the-Mountain 'Variegatum' (Aegopodium podagraria)
One of the fastest growing groundcovers available! Valued for its handsome green and white foliage. White flower clusters in early summer may be removed if desired.
Excellent for use in difficult spots where nothing else can survive. A reliable groundcover for any location. Great for erosion control on steep banks and rough slopes.
Allow soil to dry between thorough waterings.
Adapts to most soil types.
Basic Care Summary
Adapts to most soil types. Allow soil to dry between thorough waterings. Performs best if given ample space to spread. Deadhead to prevent self-seeding.
Perennials can be planted anytime from spring through fall.
Prepare the garden by breaking up the existing soil (use a hoe, spade, or power tiller) to a depth of 12-16” (30-40cm). Add organic matter such as manure, peat moss or garden compost until the soil is loose and easy to work. Organic ingredients improve drainage, add nutrients, and encourage earthworms and other organisms that help keep soil healthy. Give plants an extra boost by adding a granulated starter fertilizer or all-purpose feed that encourages blooming (for example fertilizers labeled 5-10-5).
Check the plant label for suggested spacing and the mature height of the plant. Position plants so that taller plants are in the center or background of the landscape design and shorter plants in the foreground. To remove the plant from the container, gently brace the base of the plant, tip it sideways and tap the outside of the pot to loosen. Rotate the container and continue to tap, loosening the soil until the plant pulls smoothly from the pot.
Dig the hole up to two times larger than the root ball and deep enough that the plant will be at the same level in the ground as the soil level in the container. Grasping the plant at the top of the root ball, use your finger to lightly rake the roots apart. This is especially important if the roots are dense and have filled up the container. Set the plant in the hole.
Push the soil gently around the roots filling in empty space around the root ball. Firm the soil down around the plant by hand, tamping with the flat side of a small trowel, or even by pressing down on the soil by foot. The soil covering the planting hole should be even with the surrounding soil, or up to one inch higher than the top of the root ball. New plantings should be watered daily for a couple of weeks to get them well established.
Plan ahead, for plants that get tall and require staking or support cages. It’s best to install cages early in the spring, or at planting time, before the foliage gets bushy. Vining plants require vertical space to grow, so provide a trellis, fence, wall or other structure that allows the plant to grow freely and spread.
Finish up with a 2” (5cm) layer of mulch such as shredded bark or compost to make the garden look tidy, reduce weeds, and retain soil moisture.
New plantings should be watered daily for a couple of weeks. After that, depending on the weather and soil type, watering may be adjusted to every two or three days. Clay soils hold moisture longer than sandy soils, so expect to water more frequently in sandy settings.
Different plants have different water needs. Some plants prefer staying on the dry side, others, like to be consistently moist. Refer to the plant label to check a plant’s specific requirements.
Ideally water should only be applied to the root zone - an area roughly 6-12” (15-30cm) from the base of the plant, not the entire plant. A soaker hose is a great investment for keeping plants healthy and reducing water lost through evaporation. Hand watering using a watering wand with a sprinkler head attached is also a good way to control watering. If the garden area is large, and a sprinkler is necessary, try to water in the morning so that plant foliage has time to dry through the day. Moist foliage encourages disease and mold that can weaken or damage plants.
Thoroughly soaking the ground up to 8” (20 cm) every few days is better than watering a little bit daily. Deep watering encourages roots to grow further into the ground resulting in a sturdier plant with more drought tolerance.
To check for soil moisture, use your finger or a small trowel to dig in and examine the soil. If the first 2-4” (5-10cm) of soil is dry, it is time to water.
Incorporate fertilizer into the soil when preparing beds for new plants. Established plants should be fed in early spring, then again halfway through the growing season. Avoid applying fertilizer late in the growing season. This stimulates new growth that can be easily damaged by early frosts.
Fertilizers are available in many forms: granulated, slow-release, liquid feeds, organic or synthetic. Determine which application method is best for the situation and select a product with a nutritional balance designed to encourage blooming (such as 5-10-5).
Reduce the need to fertilize in general by applying a 1-2” (3-5cm) layer of mulch or compost annually. As mulch breaks down it supplies nutrients to the plants and improves the overall soil condition at the same time.
Depending on the flowering habit, snip off faded blooms individually, or wait until the blooming period is over and remove entire flower stalk down to the base of the plant. Removing old flower stems keeps the plant’s energy focused on vigorous growth instead of seed production. Foliage can be pruned freely through the season to remove damaged or discolored leaves, or to maintain plant size.
Do not prune plants after September 1st. Pruning stimulates tender new growth that will damage easily when the first frosts arrive. Perennial plants need time to prepare for winter, or “harden off”. Once plants have died to the ground they are easy to clean up by simply cutting back to about 4” (10cm) above the ground.
The flowering plumes and foliage of ornamental grasses create a beautiful feature in the winter landscape. Leave the entire plant for the winter and cut it back to the ground in early spring, just before new growth starts.
Perennials should be dug up and divided every 3-4 years. This stimulates healthy new growth, encourages future blooming, and provides new plants to expand the garden or share with gardening friends.