How to keep your plants colorful in the heat | The Compleat Home Gardener
Also some tips on ajuga and ribbon grass.
On Sunday, July 28th at 11 a.m., Marianne Binetti will be at Highline Botanical Gardens' Ice Cream Social (free and with ice cream!) to speak about “Plants the Lazy Gardener Should Avoid and Plants to Grow. ” For more information, visit www.highlinegarden.org.
Towards the end of July, gardens can start to look a little shabby. To bring back freshness, pluck out dead perennial flowers or remove all dead blooms, and give long-stemmed annuals like petunias a quick pruning to revive them. Remove dead stems from delphiniums, cut back oriental poppies, and prune dead flowers from lady's mantles. Give your roses some attention this week, cutting back any long branches that have already flowered, and when you bring hybrid tea roses indoors, follow the stem to the point where a five-leaflet bud emerges from the branch. This midsummer pruning will encourage fresh new growth and even a second bloom.
Q. Help! A few years ago I planted some green and white “ribbon grass” in my flower bed. At first it was very pretty among the white astilbes and other shade plants in the flower bed. But now it seems to be taking over the flower bed. I've tried pruning it back, but it just keeps growing in more places. Can you tell me how to take care of this ornamental grass? TR, Sumner
A. First the bad news. Ribbon grass spreads from underground rhizomes, so pruning it will not stop it from spreading as you have discovered. The good news is, we all need to exercise more, so grab a shovel and dig it up. Removing all of the tuberous roots is the only way to get rid of this rather invasive ornamental grass, also known as variegated ribbon grass. If you want to enjoy the soft texture and variegated stripes in your flowers, you can grow it in a container buried in the ground. You can also plant variegated ribbon grass in a pot on your patio and enjoy it as a container plant for years to come. This grass prefers shade and moist soil, but will also adapt to sun and drier soil. The less water it takes, the more likely it will stay docile and stay in your own flower bed. In woodland gardens with dry soils, variegated ribbon grass spreads docilely and adds beautiful texture and color to shady areas. Don't let this moisture-loving grass escape onto the side of a stream or creek; it can become a noxious weed and crowd out native plants needed for wildlife. Tip: I grow my variegated river grass in metal pots so it doesn't spread and shows off its color upright without the need for repotting and deadheading every summer. When growing ambitious plants, “in the right place” is a good rule.
Q. What about growing ajuga as a shady ground cover? Will it become invasive and take over my lawn or flower beds? I've noticed that there are many different species of ajuga. I'd like to try planting the dark-leaved “Metallica crispa” under my rhododendrons. The leaves are crinkly and shiny. W., Email
A. I agree with using slow-growing, showy-leaved ajugas in shade. The crinkly “Metallica crispa” is known as a very slow-growing plant with deep blue spring flowers. Two other ajuga varieties, “Silver Beauty” and “Variegata,” have mostly white or silvery foliage, and neither will take up space. Variegated plants naturally spread more slowly because the white in the leaves limits the amount of chlorophyll, slowing growth. Rhododendrons and azaleas have shallow roots, so overrunning them with a thick ground cover that competes for water can be a nuisance to the shrub. Keep the ground cover 12 to 24 inches away from the rhododendron trunk.
Q. Can you tell my neighbor not to plant bamboo? I used to live next door to a plant fanatic whose bamboo invaded my yard. Now he's older and lives in a different house. The new homeowner wants a Japanese style yard and insists on planting bamboo. My anger has stopped him for now, but I'm worried he'll be tricked by the nursery and secretly plant bamboo. I told him it would just ruin the neighborhood. CL, Sumner
A. Don't plant spreading bamboo. (I told you so) In our warm climate, bamboo has escaped yards, sparking lawsuits and destroying native habitats. But there are some compromises. Some bamboos grow clumpy or don't spread as fast. Some gardeners cover their bamboo with concrete, and there are stories that the bamboo eventually breaks through, but it takes time. The safest way to enjoy the look of bamboo without the headaches is to plant Nandina domestica or “heavenly bamboo.” This is a neat, well-behaved shrub that looks like bamboo but never spreads. Visit your local nursery and you'll find dwarf forms of Nandina. Some have red leaves, and many varieties of Nandina with copper and gold leaves. Gift your neighbors a Nandina plant. They'll love it so much they'll never think twice about dangerous real bamboo. Now they've been fooled.
Marianne Binetti has a degree in horticulture from Washington State University and is the author of “Easy Answers for Great Gardens” and several other books. For answers to your gardening questions, visit plantersplace.com and click “As The Expert.” This column is copyrighted by Marianne Binetti. For more gardening information, visit her website at www.binettigarden.com.
