Ever walk through a grove of pine trees? Inside, sounds are muffled, wind is tempered, and the smell of tree sap can take your breath away. The ground is springy and soft from years of needles piling up and slowly decaying. Wind whistles through needles in the treetops.
Tree trunks stand straight, dark, tall, and at times massive — like at the Pioneer Forest original, uncut grove owned by the L-A-D Foundation along Highway 19 south of Round Spring, Mo. These towering shortleaf pine trees started growing in 1791, according to dendrochronologist Richard Guyette. At times, however, old shortleaf pine are demure, like the old-growth grove at Dan Drees and Susan Farrington’s property near Eminence, Mo. These 200- to 300-year-old dwarfs are growing on bedrock with a dash of topsoil. As with many living things, size relates to available nutrients. The more nutrients, the bigger the grass, the bird or pine tree.
At Shaw Nature Reserve in Gray Summit, Mo., there are many planted pine groves. One, in the Whitmire Wildflower Garden, is perhaps 80 years old. Years of pine needle decay has changed the soil pH beneath these stately white pines from 6.4 to 5.8, which is acidic. This is the only place in the garden where we can grow mountain azalea, which requires acidic soil.
After nearly 20 years of weeding, watering and pine-needle mulching, five of the dozen plants growing here are mature enough to bloom. Flowers appear in the first two weeks of May and are light pink, tube-shaped and very sweetly scented.
Other native acid-loving shrubs that tolerate partial shade include Virginia sweetspire, deerberry and leadplant.
How to plant pine
Occasionally there are shortleaf pine planted in groves around old houses. They have a dramatic evergreen canopy and multiple tall dark trunks, and are reminders of Ozark wilderness. Because they are narrow, single specimens can be planted in small urban spaces, but not under power lines. They grow tall and lose all their lower branches in a short period of time, so they make poor screens. They work well in groves — five to 50 planted close together — because that’s how they often grow in nature, and because the multiple dark vertical trunks make a bold statement.
To create a natural-looking grove, plant seedlings 15 to 20 feet apart in a random pattern, with wide and narrow gaps. In deep, well-drained soil, they grow fast. One planted by my office door is 7 years old and 20 feet tall, with a 6-inch trunk diameter. The soil doesn’t have to be acidic for them to grow well. They grow in soil with a pH of 5 to 7. They also tolerate growing in poor soils, as long as they are well-drained and gently sloping.
Beautiful companion plants for shortleaf pine that prefer dry acidic soils and half shade-half sun include cream wild indigo, shooting star, smooth blue aster, goat’s rue and zig-zag goldenrod. Other stunning acid-loving perennials include slender bush clover, violet bush clover and bush clover.
Where to find seedlings
The Missouri Department of Conservation sells bundles of 1-year-old shortleaf pine seedlings online. Forest ReLeaf, a non-profit organization in St. Louis, offers them in containers, as does Forrest Keeling Nursery and Missouri Wildflowers Nursery.
Larger field-grown shortleaf pine is difficult to find and should only be transplanted balled and burlapped.
Horticulturist Woodbury is curator of the Whitmire Wildflower Garden at Shaw Nature Reserve in Gray Summit, Mo., where he has worked with native plant propagation, design and education for 27 years. He also is an adviser to the Missouri Prairie Foundation’s Grow Native! program. Find suppliers of native plants for woodlands and more at grownative.org; click on the “Resource Guide” button.