Selecting Trees and Shrubs Pahrump NV
Las Vegas, NV
Las Vegas, NV
Selecting Trees and Shrubs
Tree vs. Shrub The terms tree and shrub can at times seem arbitrary because there are treelike shrubs and shrublike trees, both naturally occurring and in cultivated varieties. Yet the terms generally help in visualizing distinctions. Although trees and shrubs both have hard, woody stems that increase in girth annually, trees tend to develop one main trunk or just a few trunks from the same base, as birches do. Instead, a shrub develops numerous stems from the same base and remains less than 20 feet tall. So even though short trees remain shorter than tall shrubs, their trunks distinguish them.
Plant Prices You can buy two- to three-year-old bare-root seedlings and young transplants for as little as $1 or $2 each, whether locally from organizations that promote woody plants or through mail order. For $10 to $50 each at garden centers, you can buy young trees and shrubs with roots well established in soil containers. For $50 to $1,000 or more, you can buy older trees and shrubs with heavy root balls wrapped in burlap. Depending on unit cost and quantity, a nursery may agree to plant for free. But if they do the planting, insist on a one-year warrantee. Is bigger better? Even though large costly plants seem to offer instant gratification, they can suffer from transplant shock for several years while their cut-back roots regain their former mass and vigor.
Selection Criteria Like clothes shopping, shopping for trees and shrubs involves trade-offs between personal taste (color, style, features) and practical considerations (size, durability, suitability for climate). Although clothes may be suitable for just one season, trees and shrubs need to be suitable in all four. Trees and shrubs can improve in appearance and value each year, but only if placed in conditions they like. It's fairly easy to determine your region's growing conditions. The least alterable condition is your climate's temperature range, especially summer highs and winter lows. Yet even temperature can be moderated by a "microclimate" created by buildings and stonework that serve as heat sinks and wind screens. Other vital conditions include sunlight, soil and precipitation. As to personal taste, you'll likely find hundreds of appealing trees and shrubs suitable for your local growing conditions.
Growing Conditions It's smart to postpone selection and planting until you've had a year or so to evaluate your planting sites in all seasons. Particularly on recently purchased property, wait at least full year before moving existing plants. You might discover that certain drab summer "bushes" outside your living-room window display striking fall color and gorgeous, fragrant spring flowers. Sunlight. Note how the sun's daily path and its high summer angle and lower angle in spring and fall affect sunlight and shade. You might find it helpful to record seasonal sunlight patterns in a logbook or on a property drawing. With that record, you can match new plants to your planting sites, based on published sunlight preferences of each tree and shrub. Sunlight preferences are usually expressed as full sun (six or more hours direct sun); partial sun (four to six hours of sun), light or dappled shade (sunlight through sparse foliage); shade (no direct sun, as found on the north side of buildings and under dense tree canopies). Cold Hardiness. Before selecting a plant, you need to know whether it can survive your winters. Begin by consulting the Cold-Hardiness Zone Map on page xx. Caution: The zone numbers are based on estimates for your region and may not be precise enough for your site. For example, cold air settles at night into low pockets where temperatures may be 5° to 10° F colder than on nearby hillsides. Heat Hardiness. In the late 1990s, the American Horticultural Society introduced its Heat Zone Map. Its zones indicate the average annual number of days that exceed 86° F. As field tests of plants catch up with the Heat Zone system, commercial growers will increasingly publish pairs of hardiness numbers - one for cold tolerance, one for heat.
For now though, if you lack the heat-hardiness number for a given plant, it's prudent to give summer's dog days a thought. Of course, plants native to your region are likely to do well in summer, and local nurseries can suggest other trees and shrubs that have proven successful. Also, you could search around your neighborhood for attractive plants and inquire about their hardiness, source and maintenance needs. Soil. Given appropriate climate and sunlight, plants fail more often from inappropriate soil than any other cause. Of course, you could take a chance and simply select plants that tolerate a wide range of soils. But you'll have better results if you select plants that are specifically suitable to your soil. Key considerations are soil acidity and soil texture (whether predominantly clay, sand or loam). Relative acidity determines how well plants can use water-soluble soil nutrients, as explained in the pH chart on page xx. Each plant has its own range of pH preferences, a pH range in which the nutrients it needs are available. Most trees and shrubs thrive in slightly acid soils, those with pH of 5.5 to 6.8. (A pH of 7.0 is considered neutral.) Some plants, such as rhododendrons and certain oaks, prefer especially acid soils of 4.5 to 5.5. Others, such as apples, boxwoods and junipers, prefer neutral soils of 6.5 to 7.5. But rather than battling soil pH by applying lime to sweeten acidity or sulfur to reduce alkalinity, you'll have better long-term results with plants that like the pH where you planted them. You can conduct rough pH tests inexpensively by using either an electronic meter or a simple soil-testing kit and a color-matching chart. However, for a more complete analysis, especially if you plan to invest in costly plants, it's wise to submit soil samples to a soil-testing lab. These labs are listed in your yellow pages and on the Internet. Local agricultural extension offices may perform simpler tests and forward soil to affiliated university labs. In addition to pH, a lab analysis will tell you whether the soil is deficient in any major or minor minerals. Basic tests run about $7 to $15. Elaborate tests from commercial labs, including tests for heavy metals (recommended if you plan to grow fruit trees and vegetables) can run $100 or more. Although the U.S. Department of Agriculture publishes soil maps (indicating soil types), the map for your locale may not apply to your specific site if a developer hauled off your topsoil, imported fill or dumped clay from basement excavation where you plan to plant.
Drainage is another key concern. Although all plants need moist soil to make minerals soluble for uptake by their roots, the roots can literally drown (suffocate) if the soil remains too wet for too long. For best use of moisture, roots need well-aerated soil - soil that is porous enough for water to drain away, yet absorbent enough to retain moisture. Ideal porosity literally lets roots breathe and conduct gas exchanges with underground air. If aeration is poor, roots may grow too shallowly, near the surface where they find it easier to breathe. Shallow root systems are more susceptible to drought and don't adequately anchor trees and shrubs in wind. If your soil doesn't drain well, you'll need to improve drainage by installing drain tubing or tiles, or else use plants that like "wet feet," such as willows and bald cypress. Compost can improve soil aeration and provide slow-release nutrition. Still, the latest research suggests that woody plants fare better when planting holes are backfilled with unamended original soil. Over time, however, it's helpful to use compost and well-decomposed wood chips as a top dressing, or mulch. Design Options It's far easier to select a plant that will do well in your particular conditions rather than trying to integrate it into a pleasing design. Still, there's no need to install a fully designed garden all at once. Patience hath its rewards. You can begin by selecting just a few trees and shrubs each year and supplement as time and budget allow. Unlike fall-planted narcissus and tulip bulbs that provide stunning displays the next spring, young trees and shrubs may remain wimpy ugly ducklings for years before beginning to show their mature form and sending forth flower and fruit. Even the bark of a tree celebrated for its winter beauty won't begin to impress until the trunk gains some girth. As for design, there are whole books by and about landscape designers who are truly artists with form, color and texture.
If you have a flair for drawing and painting, you'll have an advantage in visualizing and sketching design combinations. Many excellent garden designers can't draw worth a hoot, but they know plants and can visualize how they'll look five and 10 years out - through all seasons. Knowing little about trees and shrubs, many people settle for the year-round green of juniper hedges, a spring-blooming rhododendron or two, and simply mow the rest. But your options between that and hiring a costly design firm are many, requiring varying amounts of research and commitment. As for research, some of the better books on design and selection are listed at the end of this article. They illustrate and explain concepts, while suggesting reliance on your own taste. The best books for this purpose also profile hundreds of trees and shrubs, addressing the full range of North American growing conditions. Although photos and descriptions can be valuable, they're not as valuable as seeing the plants themselves. For this, consider visiting public gardens and arboreta in your region. They usually feature stunning tree and shrub combinations, often in association with nonwoody plants. As a bonus, these plant "museums" contain woody plants likely to do well in your climate.
If you visit on weekdays, you'll have a chance of encountering garden staff willing to discuss their plants and perhaps offer suggestions for your situation. Also visit at least a few local nurseries that specialize heavily in trees and shrubs. Larger nurseries usually offer design consultations that may be free or at nominal cost if you purchase their plants.
Shopping Locally Although local nurseries carry proven trees and shrubs for your climate, also consider your property's soil and other growing conditions. You may have heard the joke about the dentist who commented to a young patient, "Your teeth look great, kid, but your gums have to go." Such a lesson applies to young trees and shrubs that look good but have damaged or otherwise troubled root systems.
In a nursery, trees and shrubs with roots in containers and those that are balled-and-burlapped (B&B) can look good for a year or more if watered well. The key here is size of the root mass in relation to plant size. Under natural growing conditions, tree and shrub roots will have approximately the same mass below ground as aboveground. Such roots usually spread well beyond the dripline of outermost branches. If young seedlings are carefully removed from planting soil with all roots intact and if the roots are then gently spread within a container large enough to accommodate them, with extra growing room, the roots will absorb water and nutrients better than roots cut and ripped from the soil. In your aboveground inspection, favor healthy-looking plants with stout twigs, suggesting good reserves of carbohydrates needed for resumed growth after planting. Avoid plants with withered or diseased branches or leaves. Then try to determine how the roots are doing.
Recommended Reading - Complete Book of Shrubs by Kim Tripp & Allen Coombes (Reader's Digest, 1998). - Home Landscaping a series of six books by Roger Holmes, Rita Buchanan, and others, each devoted to a distinct region: Northeastern United States & southern Canada; Mid-Atlantic states; Southeastern United States; Midwest United States & southern Canada; Northwestern United States & southwest Canada (Creative Homeowner). - Pirone's Tree Maintenance (7th edition) by John Richard Hartman, Thomas P. Pirone & Mary Ann Sall (Oxford University Press, 2000) - Trees, Shrubs & Hedges for Home Landscaping by Jacqueline H�riteau (Creative Homeowner, 1999).