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Invigorate your summer garden | Column
The end of August means water, water, water if you want a big spring show from your rhodies, azaleas and camellias next spring.
This is the time of year when these spring flowering plants are setting buds, and if they suffer from dry soil, these flower buds turn into foliage.
Rhododendrons and their cousins have a dense and shallow root system. This means it is easy to saturate the root ball by letting a hose run slowly right on top of the roots. A mulch will help seal in the moisture, but if you pile bark or compost up next to the stem of a rhododendron or azalea, you’ll have the poor plant gasping for air. Feather the mulch so that it barely covers the soil under the drip line or overhang of the branches and keep mulch one inch away from the trunk.
This also is the time of year when drought-stressed lawns are at their worst. You can still renovate a sad lawn before winter. Choose a fertilizer with slow-release nitrogen or one that says it is “fall and winter lawn food.”
Q: I am a lazy gardener and love all your low-maintenance tips. Here is my problem. I use a lot of groundcovers like pachysandra and periwinkle in my beds to keep down the weeds. This works pretty well until the groundcovers start spreading underground into my lawn. I can use a string-trimmer to control the groundcovers that come from above, but what about those sneaky underground roots?
A: If you have submarine roots sneaking into your sea of lawn, there is an underground strategy that can cut them short. Dig a trench at least 8 inches deep but only a few inches wide all along the length of your bed.
Next insert tiles, roofing shingles or lengths of fiberglass into this trench and backfill with the soil. You can also purchase plastic curbing strips that extend beneath the soil to act as a barrier to groundcovers, but choose a curbing at least 8 inches deep. Some gardeners with mole problems even dig down a foot or more and install solid barriers to keep moles in the flowerbeds and out of the lawn. Most groundcovers including labium, vinca and pachysandra can handle mole invasions without looking unsightly.
Q: My question is about clematis. I would like to know how to make starts. I have two favorite varieties and this year the oldest one did poorly (it is 15 years old) and the newer one did great.
A: Get ready for some new arrivals because clematis are easy to reproduce this time of year.
In late summer or early fall, you can bend a clematis vine down to the ground, dig a shallow trench three inches deep and add compost to this ditch. Lay the middle of a clematis vine into this ditch, snip off any clematis leaves that will be inside the trench and cover this section of vine with soil. Do not cut this vine from the mother plant until next year. New roots will form from the leaf nodes that are now bare and underground.
You can also take stem cuttings from any clematis this time of year. Take the cuttings from the middle of a vine, not from the soft, new tip growth. Remove all but one leaf from a 3-inch cutting and poke it into a pot of damp potting soil, making sure the leaf node, where you removed the foliage, is under the soil.
Stem cuttings will root in just a few months but must be kept moist with frequent misting. Take at least 10 stem cuttings per pot as only one or two will survive.
Q: Can you recommend some shrubs or trees that would grow in a low, wet spot? We have drainage issues on our property.
A: If you’re looking for shrubs that are part duck and like wet feet, plant the members of the willow family (pussy willows and weeping willows) and Populus family (black and white poplar trees) the yellow twig and redtwig dogwoods (cornus stolonifera) and fill in with groundcovers that like damp soil like the Japanese rush (Acorus gramineus “Ogon”) and Siberian iris (Iris siberica). Remember that some of these water-loving plants have invasive, water-seeking root systems, so keep them far away from septic systems and drain lines.
Q: Every year my hollyhocks get brown spots on the lower leaves. What can I do?
A: Your hollyhocks — and everyone’s in our area — are suffering from rust disease. This fungus among us grows underneath hollyhock foliage and quickly spreads its rusty orange spores to other parts of the plant.
Pull off the lower leaves from all hollyhocks as soon as the rust appears. Clean up any hollyhock foliage in the fall so the rust spores cannot overwinter. Just like black spot on rose leaves, preventing the problem by removing the first infested leaves and keeping the foliage as dry as possible is the best way to control this fungus among us.
Send questions for Marianne Binetti to P.O. Box 872, Enumclaw, WA 98022. E-mail: email@example.com.