Backyard Gardener: Sedum a tough plant

Hello Mid-Ohio Valley farmers and gardeners! It is so funny how time slips away (thank you Willie Nelson). As we say goodbye to August and summer we look forward to all the rewards of the fall harvest. However, looking at the forecasted high temperatures for next week summer is still hanging on. Canning, freezing and other preserving of vegetables and fruit is going on all over the valley. Homemade tomato juice and frozen sweet corn are still some of my favorites to enjoy this winter.

As fall approaches, gardeners need to be thinking about dividing spring and summer blooming perennials. As many of our herbaceous perennials grow, their roots spread out into large clumps. After a few years the centers may die out and plant health and blooming may decline. The plant needs to be divided to keep them vigorous and as an added bonus you have plants to share with friends and neighbors.

Fall division should take place from early September to mid-October. Allow at least four weeks before the ground freezes for plants to become established. Divide perennials when they are dormant. When the plant is not flowering, all the energy it produces is going to the roots and leaves. As summer moves to fall we typically experience cooler temperatures and more precipitation to encourage good root system development before next season.

Divide plants by pulling them apart at obvious separation points. Select vigorous shoots with both root and crown sections. Discard woody centers and cut off unhealthy roots. Healthy roots are white in the center. Make large divisions as smaller pieces will be slow to reestablish and plant the new divisions at the same depth as older plants. Now is the time to amend the soil if needed with aged manure of compost. Dig holes that are large enough for the division roots to fit without being crowded.

It is recommended to mulch fall divided perennials with straw or other appropriate material the first winter to prevent heaving (alternating freezing and thawing of the soil). Mulch should be applied early to mid-November when temperatures are dipping to 20° Fahrenheit.

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This week I want to discuss a hardy and low maintenance perennial, sedum. They offer amazing diversity and durability in the landscape. Sedum’s alternate name of “stonecrop” is indicative of their toughness as they shine during hot, dry weather. Furthermore, they are not only drought proof but deer resistant as well. Their thick, sturdy, wilt-proof leaves give way to massive heads of clustered mauve-red flowers in late summer that serve as a magnet to butterflies.

What really makes sedum unusual is how well is thrives under neglect. It will grow well in hot, dry locations with full sun, where other perennials would wither and die. As a succulent plant, sedum tolerates drought well and must have well drained soil. In fact, if the soil remains too wet the plants are prone to rotting. If the stems are falling over, then the plants have received too much water, too much fertilizer or are growing in too much shade.

Sedums are succulents and very drought tolerant. Keep newly planted sedums well-watered the first year. Once established, they should grow fine without any additional watering. In fact, too much water can cause sedum stems and roots to rot and die. That’s why well-drained soil is imperative to keeping sedums healthy. Sedums tolerate low-fertility soils. A soil too rich in nitrogen can cause clumping plants to flop and flower later. Adding a one inch thick layer of compost when planting and annually in spring should be enough to keep your sedums growing and flowering strong.

Worldwide there are over 500 species of sedums but only a few varieties are usually available in garden centers. ‘Autumn Joy’ and ‘Dragon’s Blood’ have dominated the market in the past but there are many more varieties available now. At least eight species, originally from Japan, China, Korea and the Caucasus Mountains, are available in local nurseries with over 50 more species and numerous varieties available from mail order nurseries.

Sedums are a diverse group when it comes to leaf sizes and colors. Leaf colors vary from light green, blue-green, grey-green, variegated green and white, and dark maroon. Flower colors may be white, shades of pink or yellow. If diversity and durability were not enough then maybe you will be swayed by their flower’s entrancing attraction for hungry butterflies. From lime-green leaves to five-inch long blue-green leaves, they all offer durability in dry sunny areas. A good clue to their survivability is in their thick succulent leaves.

Sedums are customarily divided into low-growing and upright species. Low-growing species such as ‘Goldmoss’ are traditionally used as groundcovers and in rock gardens. It is a good choice for green roof gardens, a popular trend on flat-roof surfaces to improve surface water runoff while cooling the building. Foliage can be the main reason for planting low-growing sedums but their flowers can be equally rewarding when selected carefully. Colors vary from burgundy bronze on some species to pinks, whites, grays or greens on others. Flowers commonly are yellow or gold but some may be pink and ‘Dragons Blood’ is red.

Upright species include spectabile and telephium, also know as “live forever” or “orpine.” These are used as specimens or in a mixed perennial border. Flowers on the upright sedums are red, pink or white. These flowers will attract butterflies. The dried seed stalks are persistent and decorative through the winter. The most common and my mother’s favorite is ‘Autumn Joy’, an upright variety with pink flowers that seem to be a favorite for bees. All sedums can be grown and thrive in containers.

Varieties also recommended include ‘Angelina’, which is larger than ‘Goldmoss’ at three to six inches tall and is a great filler plant. During cold weather the chartreuse leaves tinged with purple are striking when little else is notable.

Purple Sedum is probably one of the best for dark burgundy leaves and rose red flowers. ‘Vera Jameson’ is another excellent selection for dark leaves and pink flowers. ‘Matrona’ is from Germany and its name means “lady of well-rounded form”. It is about two feet tall with blue-grey leaves on deep maroon stems. When in bloom, hungry butterflies form clouds over her fetching flowers. Most sedums grow best in full sun but will do fine in some shade including a native sedum, Whorled Stonecrop.

Clumping sedums can grow large and form a dead area in the center of the plant. This usually means it needs dividing. Sedums typically need divided every three to five years. In spring, dig up the whole plant. With a sharp spade or garden knife, cut the plant into one foot diameter sections and replant into an area with similar growing conditions or share with family and friends to plant in their yard. Contact me at the Wood County WVU Extension Office at 304-424-1960 with questions. Good Luck and Happy Gardening!

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