Soil Demystified

By Lauren Sims
Photo by William Cullina.

Red clay soil, like sweet iced tea, is an ever-present and oft-romanticized symbol of Southern living. However, not everyone waxes poetic about it. For many Triangle gardeners, the clay can be more of a bother than a blessing.

William Cullina commiserates.

Going through a gardening magazine and selecting plants you like may be a challenge for clay soil – some plants just don’t like to grow in clay, says Cullina, former nursery manager for Chapel Hill’s Niche Gardens and now director of horticulture at the Coastal Maine Botanical Gardens.

But don’t give up on your garden just yet. That same troublesome soil also has some great advantages. Cullina likens it to a sponge, absorbing and retaining both water and vital nutrients.

“Clay soils can be very fertile soils and rich soils,” he says, “if they are managed the right way.”

Those management techniques will be the subject of Cullina’s Feb. 12 workshop at Duke Gardens, “Beyond the Surface: Soil Demystified.”

The growth and activity that is ongoing below the ground in a garden is really more important that what you see above the ground, says Cullina. “But it’s hard for us to get a handle on it, since we don’t live underground and we’re not microscopic.”

Cullina aims to make the science of soil intriguing and accessible to home gardeners, so that they can tie it in with their everyday horticultural practices. He has helped many a home gardener with his books on plants, including “Understanding Perennials: A New Look at an Old Favorite” and “Native Trees, Shrubs and Vines: A Guide to Using, Growing, and Propagating North American Woody Plants.”

Healthy soil contributes to healthier plants and greater ecological function, and Cullina encourages natural methods to maintain it. There are organic solutions to every situation that are more effective than synthetic solutions for a lot of different reasons, he explains. And the more living material those organic solutions involve, the better.

One common practice is to add compost, or organic soil amendments, to your garden. Effective organic amendments have two components: the living and the dead. If you purchase compost directly from the supplier who produces it, you’ll receive not only the dead material but also a wide array of living micro- and macro-organisms that can feed and enrich your home garden.

It is, at its core, a simple idea. “This is just nature,” he says. “This is the way that life on earth has functioned for millions of years.”

Cullina’s soil workshop will be from 9 a.m. to noon in the Doris Duke Center. He will also make a presentation titled “The Botany of Design” from 3 to 5 p.m. For information or to register for either event, please call 668-1707 or email our registrar. You may also read more about these events and others in our full program guide (PDF), or glance at a full list of Jan.-June 2011 classes.

Sarah P. Duke Gardens creates and nurtures an environment in the heart of Duke University for learning, inspiration and enjoyment through excellence in horticulture. The Gardens is at 420 Anderson St.

Lauren Sims is a graduate student at Duke Divinity School and a work-study assistant at Duke Gardens. This column first appeared in the Durham Herald-Sun on Jan. 29.

Annuals or Perennials?

The echinacea coneflower is among perennials
that live for a long time.

By Lauren Sims
Photo by Alice Le Duc

As we prepare to flip to the next page on the calendar, we are reminded that spring is inching ever closer. That means it’s time to start thinking about our spring gardens, and one of our initial planting questions may be, “Annuals or perennials?”

Bill Cullina, author of Understanding Perennials: A New Look at an Old Favorite and other plant books, and director of horticulture at the Coastal Maine Botanical Gardens, would have us ask an even more fundamental question first: "What does it mean for a plant to be perennial, anyway?"

Often, says Cullina, people operate under the assumption that “perennial” indicates a plant that continues to grow and bloom for many years. While some perennials do last for generations, many of them only live for a few years. Perennial plants must store away enough energy to survive months of dormancy every year and regenerate the following season. This is a costly process, and many of the plant’s resources are invested in preparing for and living through this dormant period.

Annuals, on the other hand, have no need to store energy or conserve resources. They give everything they have for a short period of time, burning brightly but extinguishing quickly. The biological strategy for annuals is to produce the most seed possible.

“So it’s hard to find perennials that bloom the way an annual plant does or a tropical plant does, that doesn’t have to worry about stocking things away for the dormant season,” says Cullina, whom local gardeners may recall from his days as nursery manager at Chapel Hill's Niche Gardens.

“The idea of the non-stop blooming perennial, while there are a few things that might fall under that category, is sort of a pipe dream because when it’s blooming it’s using up its resources.”

To learn more about perennial plants and the design opportunities they offer, join Bill Cullina on Feb. 12 from 3-5 p.m. for “The Botany of Design” presentation at Duke Gardens. Cullina will also do a 9 a.m.-noon workshop for a small group titled “Beyond the Surface: Soil Demystified.”

The fee for “The Botany of Design” is $35; $30 for Gardens members. The soils workshop is $70; $55 for members. For more information or to register, please call 668-1707 or e-mail registrar Sara Smith. Please also see our online education booklet (PDF) for other discovery programs for adults and children.

Sarah P. Duke Gardens creates and nurtures an environment in the heart of Duke University for learning, inspiration and enjoyment through excellence in horticulture. The Gardens is at 420 Anderson St.

Lauren Sims is a graduate student at Duke Divinity School and a work-study assistant at Duke Gardens.

Duke Gardens: Exploring Winter Botany

Article by Lauren Sims
Photos by Rick Fisher

For many, a walk through the woods to identify plants is an activity restricted to the spring and summer seasons. Plants, after all, are identified by their leaves—nature must be in bloom in order to learn about them. Right? Not so fast, says Ken Moore.

“Take a walk in the woods in the wintertime, and try and contrast it with a similar walk that you would make in the middle of the summer,” says Moore, the former assistant director of the N.C. Botanical Garden. “In the wintertime, you don’t have all those leaves on the trees. So you can really see the whole nature of the landscape. You can see the ups and downs, you see the beautiful architecture of the whole forest.”
A forest is lovely in the summer, Moore says. But despite the cool shade and the vibrant greens, “you can’t really see the forest because of the leaves. You’re so busy looking at the color of trees and flowers and the texture of ferns, you’re sort of unaware of the characteristics of individual plants.”

“With all the leaves gone, you’re forced to concentrate on other aspects of the plants,” he says. And, surprisingly, bare branches can actually be more clearly identifiable than foliage. According to Moore, leaves on the same plant may vary widely in their color, their size and even in their shape. In many cases, using them for identification purposes can be more confusing than helpful. More stable identifiers like bark and the configuration of buds at the ends of branches are often a surer bet, and they are showcased during the winter months.
Winter may appear to be a barren or uninteresting season for nature lovers, but do not be fooled. There is much to learn about your favorite plants this time of year. In fact, you may come to prize those winter nature walks even more than their summer counterparts.

“Most of us walk around in the winter saying, ‘I don’t know what any of these things are, I’ll have to wait until the leaves come out so I can tell you.’ My feeling is, ‘I can’t wait until the leaves all fall off, and then I can have the forest back!’ ”
To learn more about nature in winter, consider taking Moore’s “Winter Botany” 2-day class at Duke Gardens on Jan. 23 and 30 from 1 to 4 p.m. For information or to register, call 668-1707, e-mail the registrar or see page 12 of our full education brochure (PDF).
Sarah P. Duke Gardens creates and nurtures an environment in the heart of Duke University for learning, inspiration and enjoyment through excellence in horticulture. The Gardens is at 420 Anderson St.

Lauren Sims is a graduate student at Duke Divinity School and a work-study assistant at Duke Gardens. This article first appeared in The Herald-Sun on Jan. 15.