When you visit this year's Colorado Garden and Home Show, which opened February 15, be sure to visit the CSU Extension's Educational Garden on Aisle 1600. It was designed and built by Jefferson County's Colorado Master Gardeners.
Its theme is "Mulches for Every Garden." Six sections of the exhibit show how different kinds of mulching materials can be used effectively in the home landscape and garden. In one section, representing a home landscape with evergreen trees, flowering shrubs, and perennial flowers, both pine needles and recycled bark/wood chips are used to unify the planting and retain moisture moisture in the underlying soil. Informational signs note that a pine needle mulch doesn't blow away, that it protects soil in sloping areas from runoff, that it decomposes over time, and that it doesn't change soil acidity.
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Pine needle bark:
Spring-flowering shrubs blend with Ponderosa and Austrian pines in a landscape showing pine-needle mulch on the left and bark/wood chip mulch on the right. Columbines bloom along a flagstone path.
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Sunny Living Mulch:
Ground cover plants for sun function as a living mulch. Living plants are particularly useful in controlling runoff and soil erosion on sloping ground. Colorful foliage and flowers are a bonus.
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Bark and wood chip mulch, available in several colors, allows water penetration and air movement to the underlying soil and will last for several years without replacement. Neither pine needles or bark/wood chips should be used near buildings in wildfire-threatened areas.
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Rock Garden:
Pea gravel is the mulch of choice in this example of a rock garden filled with heat-loving and xeric plants. Cobbles form a dry creek bed cutting across the display.
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Pea gravel is the mulch in the exhibit section simulating a rock garden. It is a useful material when growing most rock-garden plants. It retains heat and allows moisture to drain away from plant leaves.
Two exhibit sections are dedicated to the vegetable garden. In one the mulch of choice is either straw or dried grass clippings over a couple layers of newspaper. Both reduce evaporation and soil temperature fluctuation. Straw often contains weed seed, which can be sprouted and killed by moistening the straw bale prior to scattering. Straw blows away easily, so is not good in windy spots.
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Straw grass clips:
Both straw and dried grass clippings serve as useful mulches in the vegetable garden. A couple sheets of newspaper under these materials helps to keep the soil moist and discourage weed growth.
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Grass clippings need to be completely dried out before they are spread as mulch. The clippings must not come from lawns where weed killers or "weed and feed" fertilizers have been used. Drip irrigation lines need to be installed before laying down the newspaper layers beneath both grass and straw mulch. Both materials decompose over time and when turned into the soil add nutrients and tilth.
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Plastic film:
Black, red, and silver plastic film is shown in a planting of warm-season vegetables, including tomatoes, peppers, melons, and squash. These mulches warm the soil for earlier planting, among other attributes.
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A second vegetable section demonstrates the use of plastic film over the soil where warm-season vegetables, such as tomatoes, peppers, melons and squash are to be grown. In the exhibit three colors of plastic -- black, red, and silver -- are shown. All three colors suppress weeds and reduce evaporation. Black is used to warm the soil, allowing plants to be set in the soil earlier in the spring. USDA and Clemson University researchers found that tomatoes grown in red mulch yielded 20 per cent more fruit. Reflective silver mulch is useful as a deterrent to aphids (and the viral diseases they carry) and whiteflies. Drip irrigation is installed before the plastic is laid over the soil. Planting holes are cut in the plastic after it has been spread and anchored down using ground staples.
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Shady Living Mulch:
Ground covers that thrive in shady and semi-shady locations illustrate how living plants can function as a mulch. Colorful foliage can brighten a dark spot in the yard.
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Finally, two sections of the exhibit illustrate the use of ground cover plants, both sun-loving and shade-loving, as a living mulch. Living plants generally are more attractive than the usual mulches made of dried materials. Careful selection of the ground cover plants may reduce the need for irrigation once they are established and growing well. Then they also will crowd out most weeds. Living mulches require continuing care and maintenance, however.
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Plant Talk:
Spring-flowering bulbs and perennials color this section of the CSU Educational Garden introducing the horticultural information offered by Planttalk Colorado™.
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Two additional sections of the CSU Educational Garden introduce Planttalk Colorado™ which provides reliable, timely information on more than 500 horticultural topics, and new introductions of plants especially suited to our area, under the Plant Select® program.
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Plant Select:
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New introductions for 2014 make an appearance alongside earlier selections of trees, shrubs, perennials, and trough plants of the Plant Select program.
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More information about various kinds of garden mulches is contained in "Mulches for Home Grounds," Fact Sheet No. 7.214, available at www.ext.colostate.edu/pubs/garden/07214.html .
Planttalk Colorado™ is at www. planttalkcolorado.org . Plant Select® is at www.plantselect.org .