Water-Wise Landscapes

During the hottest summer months, our lawns and gardens face a number of environmental challenges which threaten their health and beauty. Wilting and discoloration of lawns and foliage is a common example, as are flowers dropping buds, or tomatoes succumbing to blossom-end rot. And yet these symptoms also herald additional complications, as voracious insect pests and fungal diseases find an easy prey in plants under stress. The root of the problem is soil moisture and whether plants are getting enough to drink during cloudless, 90 degree days.

The solution to dry soils and drought, however, is not simply to run a hose and run up a huge water bill. Watering is very often the most wasteful and expensive of solutions -- with improper watering or overwatering leading to even more short and long-term problems for the landscape. To keep your corner of the globe green, it is best to become water-wise.

Liquid Lawn Care

Lawns are the dominant part of most landscapes. Grass is easy to put in, especially over a large area, but keeping grass green and lush is another story. Lawns are notorious water hogs, with most doting homeowners applying much more water than a lawn really needs, often squandering as much as 100,000 gallons on a typical quarter-acre suburban lot. Fortunately, there are a number of simple water-wise practices that can actually improve the health of your lawn, while saving money, time, and tens of thousands of gallons of precious water.

Stop watering. Although it sounds like lawn care heresy, most grasses (except bluegrass) can safely be allowed to enter a period of dormancy during the driest part of the summer. In fact, dormancy is a natural mechanism to help grass survive drought and heat. Your lawn will recover with the return of rain and cooler temperatures.

Stop fertilizing. The worst possible time in the year to apply fertilizer is in the summer. That jolt of nutrient pushes grass plants to grow unsustainably, risking health and vigor, and interrupting root development when it is most needed. Wait until fall before even thinking about fertilizing.

Grasscycle. Let grass clippings remain on the lawn when you mow, and cut your grass no lower than 3 inches. Clippings are over 90 percent water, and, as they filter to the soil surface, they provide a temporary layer of mulch to conserve soil moisture; taller grass also shades the soil, reducing surface heat and evaporation.

Watering do's and don'ts. If you must water, do it right. Water only in the early morning, never during the day or in the evening; improper watering can lead to fungal diseases or scalded foliage. Do not water on windy days, as breezes only hasten evaporation. Do not water driveways, streets or sidewalks; in addition to wasting water, runoff entering stormdrains can elevate stream temperatures and harm or kill sensitive fish and other aquatic life.

Water lawns only when they need it, normally when foliage appears dull, bluish-grey, or when walking on grass leaves footprints. Avoid frequent and shallow waterings which can cause thatch and shallow, drought-sensitive roots. Lawns require about one inch of water, although no more than once a week. To measure, place a flat pan under the sprinkler until one inch of water has accumulated, then move to a new location. Ensure that soil is moistened to a depth of four to six inches by pushing a screwdriver into the ground as your indicator. Turn off your hose if water starts to spill onto paved areas; wait 30 minutes, and resume watering.

The Water-Wise Landscape

As lawns require about five times more water than other plants in the landscape, the best water-wise practice is to reduce the amount of space dedicated to turfgrass, while also improving the quality of the soil and its moisture-holding ability.

Eliminate the competition. Lawns often run right up to and under trees and shrubs. However, grass roots easily "steal" water from these other plants, while still struggling to survive in the shade. Instead of grass, substitute an organic mulch, such as wood chips, shredded leaves or leaf mold, or plant ground covers -- you can even combine the both options for a low-water, low-maintenance, and attractive planting area. [See the posting: Ground Covers: Made in the Shade, August 25, 2007.]

Expand planting beds. Increase privacy and landscape value by developing "planting islands" in your sea of grass. Plant trees and shrubs in spacious, sweeping beds, rather than individually. Existing trees and shrubs can also be linked together as planting islands by adding an additional tree or two and replacing the lawn area between them with mulch or ground covers. In sunnier spots, "mulch islands" can be established, utilizing ornamental grasses, showy perennials, and hardy native plants. Eventually, over a period of time, these individual "islands" can become the dominant landscape feature, with lawn areas now serving as easily-managed green lakes and open spaces among a more natural, graceful, and beautiful setting.

Mass plantings. Similar to planting islands for trees, it is best to mass plants together, rather than spreading them across a broad area. Massed plantings have a stronger visual impact than a row of annuals dotted in front of shrubbery. Moreover, by grouping plants together according to similar water needs, they can be cared for much more easily, and can more readily care for themselves. A thick, established group of plants will keep out weeds and will shade the soil around their root zones, thereby conserving precious moisture and reducing drastic changes in soil temperature.

Xeriscaping. Although xeriscaping (xeros = dry) originally related to landscaping in extremely dry climates, its principles, which include using water-efficient and drought-tolerant plants, fit well with our water-wise goals. For example, using regionally adapted plants, such as the growing variety of natives, ensures that the plant can handle this area's seasonal temperatures and rainfall, along with other environmental and soil conditions. But non-natives can also be used to add color and texture to the garden, especially those which are suited for dry, sunny locations, like many of the Mediterranean herbs: rosemary, thyme, etc. Generally speaking, silver-grey plants, such as Dusty Miller, Artemisia, Santolina, and so, feature foliage which reflect sunlight, thereby keeping the plant cool and reducing water loss. However, xeriscaping does not mean using only colorless plants, Yuccas and Prickly pear cactus -- it does mean using the right plant in the right place. See below.

Mulch, mulch, mulch. Mulching with organic materials is one of the easiest methods for conserving soil moisture and providing long-term soil improvement. Mulches can be placed on soil up to four inches deep, except over shallow-rooted plants like azaleas. After applying mulch, especially when using wood chips or materials which appears dry, it is advisable to water both mulch and plants thoroughly at first. Dry mulch might otherwise keep moisture from percolating into the soil. Woody mulches are best used around permanent plantings, like trees and shrubs, while finer textured mulches, such as untreated grass clippings, compost, shredded leaves and leaf mold, are preferable for tender plantings, such as annual and perennial flowers and vegetables.

Compost, aerating, topdressing. Improving soil quality will also improve its soil retention ability. Garden beds can be amended by adding compost, either by digging it in manually or rototilling it into the soil, which is best done in autumn or early spring. Existing beds can be improved by using compost as a mulch or sidedressing anytime of year. Aerating a lawn allows air to reach grass roots, helps microorganisms break down organic matter to feed the lawn naturally, and facilitates water penetration. Topdressing is the practice of applying compost to the surface of the lawn up to one-half inch deep, increasing the soil's organic content, enhancing earthworm activity, and serving as a mulch to protect shallow grassroots.

Becoming water-wise can be as simple as changing some everyday practices -- or as involved and comprehensive as changing the face of your landscape. Like most endeavors, your success depends upon a program which matches your interests, abilities, and available resources -- although the ultimate goal of the water-wise landscape is to safeguard our existing water resources, and to provide more time for your other interests.

Copyright 2010, Joseph M. Keyser

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.