Rain Gardens: Harvesting the Heavens

For imaginative landscapers, rain gardens may represent the perfect marriage of heaven and earth. Specially-designed garden areas help to receive and store rainfall, using that moisture to nourish an oasis of interesting native plant communities reminiscent of lush stream banks and freshwater marshes.

The notion of developing rain gardens has received a lot of attention across the country. Jurisdictions from Seattle, Washington, to Prince Georges County in Maryland, have made considerable progress in developing “bioretention” structures to control the quantity and quality of stormwater runoff, seeing rain gardens as attractive, cost-effective options to curbside storm drains and large stormwater ponds.

In essence, rain gardens function like miniature wetlands. Rainwater from paved surfaces and downspouts is directed to a low-lying garden area which allows the water to be stored temporarily until it is absorbed by the plants and soil. Any pollutants, such as fertilizer, pesticide residue, or even oil, grease, and heavy metals from roadways, are effectively trapped by the rich organic soil and root systems in the garden, permitting clean water to slowly soak down through the soil and rocky subsoil until it “recharges” groundwater supplies.

Sophisticated rain gardens are designed to accommodate all of the rainwater from a surrounding area: rooftop, driveways, walkways, and so on. Moreover, a true rain garden is developed with consideration for existing soil types, and often includes underdrain systems, in addition to lasagna-like layers of gravel, landscape fabric, sand, and amended soil. However, while effective, the bonafide approach is complicated and relatively expensive. And most homeowners do not have the stomach for bringing earth moving equipment into their backyards and turning 60 percent of their landscape into a stormwater marsh.

Fortunately, many of the features and benefits of a carefully engineered rain garden can be employed by backyard gardeners willing to give up a bit of lawn in favor of a colorful, low maintenance backyard habitat.

A basic approach might be to identify at least one downspout which can be redirected toward an area which slopes gradually away from your home. Keep the rain garden at least 15 feet away from the building, and ensure that all water flows away from the house to prevent dampness or flooding in your basement.

Layout your garden on the gentle slope, preferably in an irregular shape, such as a kidney bean or round-cornered crescent. Use an old hose to help create an attractive outline and start removing the top layer of turf and soil. For your garden to effectively capture runoff, dig down on an angle to about one foot. Most of the material you remove can be used to build up or “berm” the sides of the garden.

The next step is the most crucial. Your goal is to create an area which will act like a sponge to soak up hundreds of gallons of rainwater. Local heavy clay soils will never function properly, and you will need to amend or replace the clay with compost – and lots of it. You can use the compost by itself, or mix it with topsoil and even some of the soil you have excavated. You might also want to add well- rotted leaves to the mix.

Flexible downspouts can deliver water to your garden, or you might bury corrugated drainage pipe in a trench and bring it to within one or two feet of the garden. It is important to allow rainwater to run over a grassy area or planted buffer before reaching the garden. You do not want a surge of rainwater to start eroding soils and washing away mulch.

Planting is, of course, the fun part of the process. But before planting, let your garden handle several rainstorms first, to ensure that your soil amendments have settled appropriately, and to guarantee that water will not pond in the garden more than three days. If done properly, excess rainfall will flow over the garden and continue across your lawn, and water “harvested” by the garden will be absorbed within 24 hours. If water ponds for three days or more, you will need to improve the soil with more organic amendments and possibly lower the downslope side of the garden to improve runoff.

The plants you select for your rain garden are often unlike those used in conventional settings. Native perennials that enjoy moist and even saturated soils will thrive in your garden, and will encourage visitation by butterflies, hummingbirds, and other nectar and berry feeders. Your pallette can include swamp milkweed, columbine and asters, ironweed, lobelia, blue flag, bluebells and bluestem grasses, bee balm, ferns, sedges and switchgrass, boneset, gentians, liatris, and much more.

Many of these natives are now sold by local nurseries, where experienced horticultural staff can help match suitable plants with your rain garden needs. You will need to consider sun or shade exposure, how moist your garden soil is and the duration of wetness, and also think about how well your plant selections can tolerate drought periods. And, after planting, be sure to mulch your garden to save every drop of precious rainwater.

For more information about rain gardens, be sure to check out my former website: RainScapes.org.

Copyright 2010, Joseph M. Keyser

A Clean Sweep for the Spring Garden

With warmer days at hand, many of us are heading outdoors to spruce up our yards. These spring chores offer an excellent opportunity to significantly improve the health of our lawns and gardens, which will later save time, energy, and resources.

To begin, start cleaning up fallen leaves, broken branches, twigs, and dead foliage lying under shrubs, trees, and in planting beds. Sanitation is important in maintaining a healthy garden for a number of reasons: fallen leaves can clump together, inhibiting the passage of air and water to the root systems of your plant. Don't use or plan to use whole leaves as a mulch. Also, there are a number of pests and disease organisms which can winter-over in garden debris. Removing these havens removes the pests.

But don't throw those leaves and other trimmings away! All of them can be easily composted, breaking down into a wonderful mulch or soil conditioner for use this coming fall. Branches and larger twigs can be placed on the ground or inside the bottom of a compost bin to facilitate drainage and aeration. Leaves and other materials -- including some of those weeds which are now popping up -- can then be added to the pile. Gradually moisten materials as you put them in. Avoid adding twigs larger than your thumb in diameter -- and no more than 6-10 inches long.

After your "clean sweep," it's time to consider mulching. There are numerous organic and inorganic mulches from which to choose. Most are helpful in suppressing or eliminating weeds (no weeding! no toxic chemicals!), conserving soil moisture and moderating soil temperatures -- which is critical during droughts and heat waves -- and most can improve the appearance of your yard. However, by using materials like shredded leaves, leaf mold, compost, or wood mulch, you are restoring vital nutrients and organic matter and improving soil health. Remember that healthy soil produces healthy plants.

Mulches can be purchased, made, or picked up free. Many municipalities have wisely elected to make chipped or ground-up leaves and woody debris available for free to residents -- either to be picked up from a central location, or even delivered for a nominal fee in some really progressive communities. Bear in mind that this shredded mulch -- like mulch from tree care companies -- is unaged and only suitable for application around established plantings, or used for pathways or play areas. Fresh-shredded wood mulch should be aged or composted for at least six months before using around tender plants like ground covers, flower beds, or vegetable gardens.

Many gardeners and professional horticulturists prefer using leaf mold or leaf mulch. This material breaks down more rapidly than wood mulch and is easily turned into the soil as an organic conditioner. Leaves which have been shredded by a lawn mower or chipper-shredder can be used immediately as a mulch -- or aged for several months to achieve a finer texture and darker color. Whole leaves which have been composting for six to twelve months can also be used, provided they have decomposed and fall apart while handling. And rich, crumbly black compost naturally makes an excellent mulch.

To ensure weed suppression, it often helps to first lay several sheets of newspaper (not this column) or cardboard on the ground around and under trees and shrubs -- or in garden beds. Dampen the newspaper with your hose to keep it in place, and then pile the mulch on. Never apply a layer of mulch over four inches deep, and never place it directly against the trunks of trees and shrubs.

And now you can enjoy the warmer weather -- and the rest of the year. By cleaning, composting, and mulching, you've established a yard which will stay healthy year-round. Back-breaking weeding can be avoided, many plant diseases have been physically eliminated, climate-related stresses have been headed-off, and your organically-enriched soil will grow healthy, beautiful plants naturally. The way Mother Nature intended.

Growing Fun With Your Compost Bin

You can start to enjoy your compost long before it's ready to use. Since many of us set up compost bins in our vegetable garden, it's time to use those bins to their best advantage. Here's how:

Compost cages can be made from sturdy 10 to 13 foot lengths of wire mesh. Make your cage, fill it with compost-ables (leaves and other trimmings), and plant four to six tomato plants (or veggie of your choice) around the base. As the vines grow, tie them to the cage and guide them up and over the top of the pile. Your compost bin now doubles as a tomato cage -- so you're not wasting space, the materials in the bin serve as a mulch to keep plant roots cool and moist during the hottest weather, and -- best of all -- as the materials decompose, nutrients and micro-nutrients are fed directly into the root systems. No fertilizing, no fuss -- just fruit!

In any sunny location, you can grow pounds and pounds of wonderful sweet potatoes in almost any sort of compost bin using leaves alone. Place moistened leaves in a bin, packing them down, and filling to the top. One full month after the last frost, plant six sweet potato slips (root sprouts -- available at many nurseries and garden centers) into the top of the leaf pile. YOU MUST KEEP THE PILE MOIST AT ALL TIMES. After several weeks the vines will take off, soon cascading over the sides and covering the entire bin. It's compost camouflage! After leaves begin to yellow in the fall, harvest your tubers, use the composted leaves in your garden, and add the vines themselves to next year's compost pile.

Copyright 2010, Joseph M. Keyser

Dwarf Citrus Trees: Big On Flavor & Fragrance

During the cold, gray days of winter, few things brighten and warm a room like the sweet, rich aroma of lemon blossoms or the glow of maturing oranges among glossy, green leaves. Thanks to the widespread cultivation of dwarf citrus trees, any gardener with a bright window can enjoy all the sensory pleasures of lemons, limes, oranges, and more, all year long.

Like most fruit tree cultivation, where a branch or scion of a desirable variety of tree is grafted onto a sturdy rootstock, dwarf citrus trees are grafts of a normal fruit-bearing branch onto dwarf rootstock, which keeps the plant at a manageable size for summer patios and year-round enjoyment in your solarium.

Because the fruiting branch is from a full-sized tree, the fruits which develop are also full-size, and full-flavored. However, that also means that like a dutiful orchard manager, you will have to prune your tree periodically to keep it within bounds. Normally, pinching off growing tips will help maintain an attractive shape, which is preferable to letting the plant send out tall shoots requiring severe pruning.

In addition, always remove shoots or “suckers” which tend to pop out from the dwarf rootstock. Look for a diagonal scar running the trunk’s circumference around about six inches above the soil surface. Snip off any shoots below the graft union as those pesky shoots will sap energy from the desired plant, and produce, if at all, inconsequential or tasteless fruits.

The majority of dwarf citrus used as container or houseplants tend to grow between four and six feet tall, and do best in pots ranging from 12 to 16 inches in diameter, although some popular cultivars can be grown in containers as small as eight inches.

In milder climates, dwarf trees can reach up to nine to 12 feet when grown in halved whiskey barrels or redwood tubs. Around here, though, citrus must be taken indoors before any danger of frost, and most of us would rather not lug a several hundred pound giant into a standard family room.

To keep your dwarf citrus in check, you will actually borrow some techniques from the world of bonsai. Root pruning is usually required every three years or so, which will control overall growth, while also allowing you to replenish soil and soil nutrients. Without root pruning, you will have to continually repot your specimen until it becomes a behemoth.

To begin, carefully remove the plant from its pot and use a sharp knife or pruning shears (or even a pruning saw) to trim off several inches of root from around the sides and bottom of the root ball. Use a standard container soil mix to replace and reposition the plant at its previous height in the pot.

Incidentally, root pruning is often traumatic for many novices, who are more comfortable with watering and feeding their plants. But fear not, eventually everyone gets used to it, and your tree will continue to thrive and flourish for many years, possibly even dozens or more.

Ongoing care for your dwarf citrus requires plenty of bright light and even exposure. Be sure to slowly rotate containers every week or so. After all, no one likes a lopsided lemon tree.

Dwarf citrus prefer evenly moist soil. Do not allow the soil to completely dry out, and do not waterlog the soil or allow the plant to sit in standing water. Many practitioners consider an inexpensive moisture meter indispensable and as important as a good pair of pruning shears. Plan to water a bit more frequently than you might with other houseplants, perhaps every three to four days, especially during warm, dry weather.

Note that citrus are heavy feeders, especially as frequent watering will leach out water-soluble nutrients like nitrogen. It is recommended to use a fertilizer with a ratios two to three times higher in nitrogen than potassium and phosphorous (an N-P-K of 3-1-1). Be sure to use a complete fertilizer periodically to replenish essential micronutrients.

Of course, the most important element in dwarf citrus cultivation is selecting a plant that will intoxicate you with its fragrance and tickle your taste buds.

The choices are delicious in their own right, ranging from typical naval oranges, tangerines, lemons, true limes and grapefruits, to a host of hybrids with special characteristics. For the most part, growers have selected varieties specifically for container and indoor use which will do well in relatively cool environments. You do not have to replicate Floridian heat to achieve sweet and luscious fruit.

Among oranges, some of the most readily available and favored are Trovita, with a thin skin, which is equally prized for juice or eating. Satsuma oranges, sometimes considered a mandarine, like Valencia, are smaller, with an easy-to-peel fruit and a truly intoxicating aroma from spring-borne blooms which last up to a full month.

And while oranges might be the first citrus variety you are considering, spare a thought for the lemon tree. While most citrus bloom in the spring and produce fruit the following winter (or later), lemons actually bloom throughout the year, providing four seasons of fragrance, and year-round fruit. The most popular varieties include Lisbon, Eureka and Meyer, the latter of which is thought to be a cross between a sour orange and a lemon, and is perhaps the most popular variety of all thanks to its somewhat sweeter, slightly tangerine flavor.

Limes aren’t only for margaritas and gin-and-tonics! In addition to favorites like Bearss Seedless, one of the most intriguing offerings is Kaffir (or Thai) lime. In addition to tangy juice and a zesty zest, the glossy, dark green leaves of this variety can be chopped or julienned and used much like lemon-grass in Thai and other related Indonesian cuisine.

And while grapefruit are available, why not explore the exciting world of hybrids. For example, consider the increasingly popular Minneola Tangelos, or Honeybell, a cross between tangerines and grapefruit. This juicy, bell-shaped find offers a bright, reddish-orange skin, easily peeled like its tangerine ancestor, and sharing both a tartness and intense tangerine flavor.

Clearly, while these varied citrus trees may be dwarf in size, the selection, flavors, fragrance, and rewards of raising them are truly enormous.

Copyright 2010, Joseph M. Keyser

GreenMan & the Home Energy Audit

Join the GreenMan as he learns they whys and wherefores of conducting a home energy audit.

The Legend & Lore of Holiday Plants

For many people, the upcoming holiday season is the most special time of year. It is a period somewhat set apart from daily living and reserved for families, friends and celebrations. Above all, it is a time rich with customs and rituals, where even our simplest holiday decorations, songs and stories are the product of complex legends and myths from numerous countries and religious traditions, curiously blended together, transformed and reinterpreted over thousands of years.

The decorative plants we associate with the holidays are an important part of this cultural evolution, with none more significant than the leaves and boughs of evergreens. Imagine a much earlier time, where as the winter solstice approached, a once bright and fertile world became cold and dark. Fields became barren and seemingly lifeless. As a means to offset this chilling mortal experience, many cultures used cut branches of evergreens to decorate their dwellings and serve as symbols of undying life and continuity. In fact, our popular evergreen wreaths are themselves important representations of this cyclical nature of time and the passage of seasons.

Today, we may “deck our halls with boughs of holly” because it is attractive or traditional, but it is among the most important evergreens used throughout history. For the ancient Romans, holly was sacred to the god Saturn, who is associated with time and agriculture. Romans celebrating their midwinter Saturnalia exuberantly employed garlands and wreaths of holly.

Druids appreciated the evergreen nature of holly in their midwinter observances, even to the point of recognizing a mythic Holly King, who served as lord of the waning year. In their culture, holly represented masculinity and steadfastness, and was paired with ivy, another evergreen, which was considered feminine — in part owing to misogynistic notions of it being clinging and requiring support, as the two plants were often found together in the wild. By combining the attributes of holly and ivy in their decorations, Druids believed they could ward off evil spirits.

Christian and pagan traditions combined in the legend of Gawain and the Green Knight, wherein the green knight arrives at King Arthur’s court at midwinter brandishing a holly branch. The green knight is beheaded, but survives as a dramatic symbol of resurrection. Moreover, the character is closely connected with ancient and medieval legends of the Green Man, yet another symbol of masculinity and vegetative regeneration, and also related to the Holly King.

Beyond its association with holly, ivy maintains its own significance thanks to the Greek myth of Cissos, a dancing girl whose tireless performance during a feast left her dead at the feet of Dionysus. Cissos was granted immortality by being transformed into the vining plant. Moreover, the Romans knew Dionysus as Bacchus, and ivy was popularly worn as a garland during their Bacchanals in the belief that it would stave off drunkenness.

There is no more complicated and widely used symbol than the Christmas tree. Some accounts attribute the first decorative tree to Nimrod, one of Noah’s wayward relations. Druids were known to decorate the Oak of Thor. And Romans probably included evergreen trees along with their other Saturnalia wreaths and garlands.

One of the earliest legends introducing an evergreen tree as a Christmas tree of sorts concerns St. Boniface in the eighth century who had an Oak of Thor cut down and replaced with an evergreen fir. During the Middle Ages, villagers performing mystery plays typically used fir trees decorated with apples to represent the tree in the Garden of Eden. Much later, Martin Luther is attributed with introducing the first lighted Christmas tree, allegedly inspired by seeing stars shining through the branches. The combination of lights and trees follows a convoluted path. Certainly, using lights during the holiday period owes much to the symbolism of a sun god, or the return of light and the rebirth of a dead world. Pagan traditions often involved bonfires and Yule logs, while Christians invoked the Star of Bethlehem. There are also associations connecting tree lighting with Hanukkah, the festival of lights.

The first written record of a Christmas tree places it in Germany in 1605. Later, Charlotte, George III's German wife, is credited with bringing the Christmas tree to England in the 1800s. Afterwards, Victoria and Albert's custom of erecting a Christmas tree in Windsor Castle, complete with cranberry garlands and gingerbread cookie ornaments, led to the widespread appeal of a lighted, decorated tree and traditions throughout Britain and America. The United States also owes much of its Christmas tree observances to the Northern European immigrants who brought their traditions to the New World.

Another popular evergreen with a dizzying pedigree is laurel. The laurel known and used in the classical Mediterranean world is Lauris nobilis, always associated with the golden-haired god Apollo. The connection with a sun god had strong appeal for Romans and Greeks busy with midwinter decorating. In northern Europe, branches of cherry laurel were used, also for its evergreen properties, although it is a different species. Adding to the horticultural confusion, Americans further use the term laurel to describe decorative evergreens of many other species, some of which are also called bay laurels or bayberry laurels — which itself is associated with the candleberries or waxberries (actually myrtles) used to scent candles. Once again, one tradition leads to another, from sun gods reflected in evergreens to popular holiday candles, fragrant symbols of light and nature.

Mistletoe enjoys a long and varied history. The “golden bough” of Aeneas was thought to be mistletoe plucked from an oak by the hero entering the underworld in yet another rebirth myth. The plant, sacred to the Druids, was used to ward off evil spells, cure illness, ensure fertility, bring good luck and serve as an antidote for poisons. Of course, it is most known for its role in kissing rituals. The Druids admired the plant’s mystical properties, as it was commonly found to grow on oak trees, also sacred. Despite no roots to sustain or support it, it remained evergreen. Norse legends attribute the plant’s white berries to the tears Frigga shed for her slain son, prior to his resurrection and her creation of a decidedly popular “good luck through kissing ritual.” This once again brings us to numerous layers of symbolism found in a single evergreen plant, ranging from resurrection myths to notions of fertility. Early Christians banned the use of mistletoe due to these associations, but the Victorians later gave the ritual another opportunity to adorn the holiday season.

Many other plants continue to play a diverse role in holiday celebrations. Some are ancient, like strewing fragrant branches of the evergreen rosemary upon the floor in winter; others are modern additions like the poinsettia, a Latin American native that plays a holiday role, mostly because of the red and green symbolism. Even purely decorative plants, such as paperwhite narcissus, while they simply provide fragrance and flowers in Occidental homes, have a brighter significance in Chinese dwellings: bulbs planted in midwinter serve as a harbinger of the New Year.

Across time and continents, these plants and many others have continued to play a significant role in world mythology and symbolism, bringing life and color and traces of understanding to both our rituals and our daily lives.

Copyright 2009, Joseph M. Keyser