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LAWN HEIGHT, SLUGS, SHADE, DAYLILIES & APHIDS
Q: My neighbor said I shouldn't cut grass as short in summer. Is this good advice?
According to Deb Brown, University of Minnesota extension horticulturist, it's a good idea to raise the lawnmower blade in summer somewhere between 2-1/2 and 3-1/2 inches. This accomplishes three things. First, taller grass blades help shade the crowns and roots, protecting them from the sun's heat. That means they won't dry or wilt as rapidly.
Second, research has shown grass that's maintained at a taller height actually grows deeper roots than grass that's mowed short. If moisture is scarce, the deeper roots will do a better job than shallow ones. And finally, when you mow too low, you see more narrow stems. It can take days before the grass looks good again. Lawns definitely appear greener and fuller when you allow more leaf blade surface to remain after mowing.
Q: I've noticed holes in my hosta leaves. What's the cause?
The holes in my hosta leaves were caused by hail several weeks ago.
Another common cause of holes in hosta leaves, as well as other plants, is slugs. They're particularly damaging in moist, shady gardens.
Slugs are best described as snails without shells. They have soft bodies and are generally brown or gray, with eye stalks. They vary in size from 1/4 inch to 2 inches or longer. Slugs use file-like mouthparts to rasp and chew plant tissue, leaving irregularly shaped holes. Several garden flowers that are seldom affected by slugs include astilbe, dicentra, lobelia, ranunculus, vinca, viola, phlox, campanula, hemerocallis and mentha.
Q: My daylilies were beautiful this year and I'd like to plant more. Can daylilies be divided?
It's a good idea to remove seed capsules that form after blooming to enhance future blooming. The best time to transplant or divide plants is early spring or immediately after flowering. Be sure you complete the task at least six weeks before the first fall frost to allow the plants to become reestablished. Divisions should include at least three fans (clusters of leaves) with roots attached.
Till the soil deeply before planting. Work in well-rotted manure or compost to increase organic matter. Apply fertilizer based on a soil test. Dig a hole large enough for the roots without bending or crowding them. Make divisions by digging the entire plant and gently pulling the fans apart. Cut the foliage back, leaving only five or six inches. Place the plant in the soil so the crown (the portion where the stem and root meets) is one inch below the ground line. Water thoroughly after planting. A winter mulch of straw or shredded leaves helps ensure against winter injury for newly established plants. Daylilies are vigorous growers and can be divided every three to four years.
Q: I have a garden area that is constantly wet. Are there flowers that will perform in wet soil?
Flowers that perform well in sites that are wet in the spring and become dry during the summer months include Japanese iris (Iris ensata) and butterfly iris (Iris spuria). Other flowers that will tolerate periodic wet sites include forget-me-nots, astilbe, pansy, Missouri primrose, Virginia bluebells, daylilies, spearmint, peppermint, and cardinal flower.
If you site is constantly wet, you might want to consider creating a small pond garden and growing aquatic plants such as water lilies, water buttercup and water aloe. Other plants that can tolerate standing water include yellow flag iris (Iris pseudacorus) and blue flag iris (Iris virginica). Siberian iris (Iris siberica) can be planted just above the water's edge.
Q: The branch tips on my highbush cranberry bush are covered with tiny insects, and the leaves are curling. What's my problem?
I've received many calls this summer about this condition. The culprit most likely is aphids. Aphids are small, pear-shaped, soft-bodied insects that feed on plant sap. They are often found in large numbers clustered on the underside of leaves or on developing stems.
Aphids can cause leaves to yellow or wilt, and it is common to notice a shiny, sticky material known as honeydew on the tops of leaves, branches, and other objects underneath the aphids.
In most cases, aphids have little impact on healthy, well-established trees. Even when large numbers are present, you can ignore aphids without worrying about plant health. As aphid numbers increase, they attract natural enemies, such as ladybugs, which help control aphids.
Aphids can injure young or unhealthy trees or shrubs. To control aphids, try knocking them off with a hard stream of water. A heavy rainstorm gives the same results. If you want to use an insecticide without harming natural enemies, try insecticidal soap, which is very effective against aphids and has little impact on beneficial insects. However, it only affects the aphids it directly contacts so repeat treatment may be necessary. Also, do not spray insecticidal soap on tender, young leaves as it can damage the new leaves!
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PUTTING DOWN ROOTS:
A Delightful Blend of
Gardening Wisdom, Wit
and Whimsy
$10 + $2 for shipping
by Cliff Johnson |
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