What to do this week: Finish buying annual and vegetable starts, sowing seeds, and planting woodies and perennials (until fall rains return). Move houseplants outdoors for a summer vacation. Start them off in a shady outdoor spot. Your highest priority should be to kill invasive plants before they go to seed. Bad actors include a purple-flowered creeping ground ivy called anthriscus sylvestris, which looks like Queen Anne’s Lace, and garlic mustard with its four-petaled white flowers. Roots pull out easier in deeply damp soil. Apply mulch after weeding. I use old Globes covered with cosmetic bark mulch. Let bulb foliage turn yellow before you remove it, but pull out any “blind’’ tulip leaves and bulbs that failed to bloom, otherwise they will sprout each spring, engendering false hopes. Think of tulips as expensive annuals. Lightly sprinkle bulb fertilizer around the yellowing foliage of other bulbs.
Q. Thank you so much for letting me tour your garden with the Garden Conservancy. It was a pleasure to meet you. Here is my question: We installed a Korean stewartia 10 years ago. It was about 4 feet tall at the time. It’s probably 5 feet tall now. It’s in full sun in the lawn, and there’s no grass for about a 4-inch diameter circle around the trunk. It has been lightly mulched. I wish it would grow more. Any advice would be greatly appreciated.
C.L., Newton
A. While some types of trees, like red oak, grow faster when they are young, a stewartia starts slow and then gradually picks up speed. Mine barely grew 2 feet the first decade. But it was healthy and pretty, so I just planted shrubs and wildflowers around it. Now, two decades later, those plants are in deep shade because the stewartia is getting bigger faster. It is 25 feet and headed for 40. I was surprised by how many on that garden tour complimented my stewartia, and it wasn’t even in bloom yet. While most trees flower in the spring, a stewartia blooms in July with camellia-like flowers, followed by spectacular orange fall foliage. But the feature garden tour people liked was the crazy peeling bark in shades of gray, brown, orange, and buff. How do you make it grow faster? Like I always say: Water, water, water. But most important: Check the pH. A stewartia needs acidic soil. It’s not a good lawn tree because it dislikes full sun, and liming the grass around it could kill it. Use Espoma Organic Soil Acidifier around the root area this fall. Stewartia likes the same conditions as our native dogwoods: part shade, moist acidic soil, mulching without root competition from grass, and good drainage like a hillside. A dogwood will try to meet you halfway, but a stewartia will just die if you don’t meet its needs.
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