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Friday - August 01, 2008

From: Denver, CO
Region: Rocky Mountain
Topic: Non-Natives
Title: Failure to thrive of non-native Lamium maculatum
Answered by: Barbara Medford

QUESTION:

Hello: Approximately 3 to 4 years ago I planted approximately 20 Lamium Beacon Silver plants in a shaded area of my yard, with limited sun. The first year they seemed very hearty and expanded. I certainly thought they would take over the entire area as I wanted them to do. Each year they keep dying out, so that now very little is left of them. What can I do to revive them? They are on a spray system for water (well) and are in the shade of a tree. Is there a way to treat the soil or fertilize the plants so they will grow, or should I replace with something else? Thanks for your help.

ANSWER:

Lamium maculatum is a non-native spreading groundcover, having originated in Europe and Asia. "Beacon Silver" is a named variety of the plant, with color variagation. At the Lady Bird Johnson Wildflower Center we encourage the use of plants native to the area in which they are being grown, because those plants will already be acclimated to the soil, ordinary rainfall and fertilizer needs of the area. Since it is not native, we have no information on the plant in our Native Plant Database, but will try to find some answers to your question.

From this Ohio State University Education site Lamium maculatum we found this list of what Lamium maculatum expects in order to thrive:

  • partial shade to full shade
  • needs an evenly moist, well-drained, moderately rich soil in partial shade for optimum performance; not at all urban tolerant, including a disdain for poor soils, poorly drained soils, compacted soils, heat, prolonged drought, or sunny spots
  • propagated by crown division, lifting of rooted stem segments, or rooted stem cuttings
  • Mint Family, with no disease problems, but slug and snail pest problems may cosmetically affect the foliage on occasion, and exposure to excessive sun and drought will scorch the foliage and lead to dieback
  • often melts out in the heat of Summer (that is, the Spring foliage and stems die back to the original crown or new peripherally-rooted crowns), but may rejuvenate in the coolness of Autumn

We wouldn't think that in Denver high Summer heat would cause dieback, but if the stand has only the shade of a tree, perhaps it does not extend far enough to satisfy the conditions the plant needs. Also, if you did not begin with a rich soil, well-drained, it would be difficult to go back and fix that now. On the same site, under Liabilities, Lamium maculatum was characterized as being subject to crown or stem rot in moisture retentive situations (frequent irrigation, poorly drained location or heavy rain periods) and mass groundcover plantings often develop "holes" as individual plants die.

This USDA Plant Profile for Lamium maculatum does not show the plant growing at all in Colorado, or the other western states. That would indicate a possible problem with the natural soils in the area. Whether it would be worth it to completely redo the area, making amendments to increase the drainage and even perhaps alter the soil composition, would be a decision only you could make.

If you decide to abandon the Lamium, you might go to our Native Plant Suppliers area. Type in your city and state in the Enter Search Location box, and you will get a list of native plant nurseries, seed companies and landscape professionals in your general area. They can probably make a much more educated suggestion on alternative groundcovers than we could.

 

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