Real Solutions: Spring Cleaning
New England’s winters seem to last a long time and certainly make us yearn for spring’s reawakening. Adding trees and shrubs with winter appeal — particularly those featuring spectacular dormant-season foliage or early blooms — can help.
Many conifers — including juniper, cypress, and spruce — bear colorful foliage all year long. The stems and branches of some deciduous trees — including paperbark and three-flower maple (Acer griseum and triflorum) and Japanese pseudocamellia (Stewartia) — are strikingly attractive.
Shrubs and small trees such as seven-son flower (Heptacodium) and several of the dogwoods (Cornus), including cornelian cherry (Cornus mas), are also great choices. Other plants with early flowers are andromeda (Pieris) and certain magnolias, including ‘Leonard Messel’ and ‘Centennial’.
Many of these season-expanding plants are recipients of the prestigious Cary Award. This is a plant recognition program established in the 1990s by the Worcester County (Massachusetts) Horticultural Society at Tower Hill Botanic Garden. The Cary Award has recognized more than 30 hardy woody plants that are attractive in several seasons, easy to use, and readily available at garden centers, but underused in New England gardens. For more information, ask at your local garden center, or visit: caryaward.org
We’re trying to use organic gardening around our yard, and for the past few years I’ve been adding lots of compost to the soil. My rhododendrons, azaleas, and blueberries are looking weak and have yellowish leaves. I’m wondering whether I’m doing something wrong. Can you advise us? — S.P., Salem, NH
Many plants such as those you describe need acidic (low pH) conditions to grow their best. Most composts, despite the addition of organic content, tend to have a higher pH than ideal for acid-loving plants. Testing your soil is easy to do at home; most garden centers sell kits for simple acidity testing.
When you plant acid-loving species, it’s always a good idea to add peat moss to the soil before you backfill around the roots, and then to mulch with pine needles or composted oak leaves, all of which are acidic. If your soil pH tests above 6.0, you can also increase its acidity (reduce the pH) by about a half-point by mixing in about a pound of ground sulfur (flowers of sulfur) and a half-pound of ferrous sulfate per 100 square feet.
Note that sandy soils require less sulfur, and heavy clay soils more. Depending on conditions, soil pH may take months to adjust, so be patient, measure again before reapplying, and don’t overdo it!
— R. Wayne Mezitt, Chairman, Weston Nurseries, Hopkinton, MA