At 11 a.m. on Sunday, July 28, Marianne Binetti will be at the Highline Botanical Garden Ice Cream Social event (free, and with ice cream!) speaking about “Best Plants to Avoid and those to Grow if you are a Lazy Gardener”. For more information, go to www.highlinegarden.org.
Near the end of July the landscape tends to become a bit seedy looking. A good way to freshen things up is to deadhead or remove all the faded flowers from spent perennials and to give leggy annuals such as petunias a quick haircut to revitalize them. Remove the spent stalk of delphiniums, cut back the Oriental poppies and shear off the faded blooms of Lady’s Mantle. Give your roses some attention this week by cutting back long branches that have already bloomed and when harvesting hybrid tea roses to bring indoors make sure you follow the stem down to a point where there is a five-leaflet sprout emerging from the branch. This mid-summer pruning will encourage fresh new growth and even a second wave of blooms.
Q. Help! I planted a green and white “ribbon grass” in my flower bed area a few years ago. At first it was lovely among the white astilbe and other shade plants in the bed. Now, however it seems to be taking over the bed. I tried cutting it back and it only popped up in more places. Please tell me how to control this ornamental grass. T.R., Sumner
A. First the bad news. Ribbon grass spreads from underground rhizomes so cutting it back will not stop it from spreading as you have found out. The good news is we all need more exercise so grab a shovel and dig in. Removing all the tuberous roots is the only way to get rid of this rather invasive ornamental grass which is also called Variegated Ribbon Grass. It can be grown in a container sunk into the ground if you want to enjoy the soft texture and variegated stripes amidst your flowers. You can also plant variegated ribbon grass in patio pots and enjoy it year after year as a container plant. This grass loves shade and moist soil, but it will adapt to sun and dry soil. The less it has to drink the more likely it will behave itself and stay in its own bed. In a woodland garden with dry soil variegated ribbon grass will spread politely adding a lovely texture and color in the shade. Do not let this moisture-loving grass escape to a stream or creek side. It can become a noxious weed crowding out native plants needed by wildlife. Tip: I grow variegated river grass in metal urns so it can’t spread but makes an upright show of color every summer without the need for replanting or deadheading. Right plant right place is a good rule when growing overly ambitious plants.
Q. What about growing ajuga as a groundcover in the shade? Will it become invasive and take over my lawn and beds? I have noticed lots of different varieties of ajuga and would like to try the dark leaved ‘Metallica Crispa’ under my rhododendrons. The foliage is rather crinkled and shiny. W., Email
A. I vote yes for using the slow growing fancy leaved ajuga in the shade. The crinkly ‘Metallica Crispa’ is known as a very slow grower with deep blue, spring flowers. Two other ajuga varieties that will not steal real estate are ‘Silver Beauty’ and ‘Variegata’ both with a lot of white or silver in the foliage. Plants with variegation are naturally slower to spread as the white in the foliage limits the amount of chlorophyll and slows down growth. Rhododendrons and azaleas do have shallow roots so smothering them with a thick groundcover that will compete for water might bother your shrubs. Just keep your groundcover 12 to 24 inches from the trunk of your rhododendrons.
Q. Can you please tell my neighbor not to plant bamboo? I once lived next to a plant geek and his bamboo invaded my garden. Now I am much older and have a different home. The new homeowners want a Japanese style garden and insist on adding bamboo. My outburst has stopped them so far, but I fear they may become “bamboozled” at a nursery and sneak in some bamboo. I told them any bamboo would just ruin the neighborhood. C.L., Sumner
A. Do not plant spreading bamboo. (There, I said it.) In our mild climate bamboo has escaped from gardens and caused lawsuits and ruined native habitats. There is however, some compromises. Some bamboos are clumping or not as fast to spread. Some gardeners have encased bamboo in concrete – with stories of the bamboo eventually breaking through but it takes a while. The safest way to enjoy the look of bamboo without the headache is to plant Nandina domestica or ‘Heavenly Bamboo.” This is a tidy and well-behaved shrub that looks like bamboo but never spreads. Visit a local nursery and you will find Nandina in dwarf forms, some with red leaves and many Nandina varieties with copper or golden foliage. Buy your neighbors a Nandina plant as a gift. They will love it so much they will never again consider the dangerous real bamboo. There, you have them bamboozled.
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 gardening questions, visit plantersplace.com and click “As The Expert”. Copyright for this column owned by Marianne Binetti. For more gardening information, she can be reached at her website, www.binettigarden.com.
