A well-designed landscape should start with a plan, or rather, a series of plans. The first plan is a base plan which shows the major elements of the current landscape, including the footprint of the house, driveway, patios, walkways and all existing trees, shrubs and garden beds. The base plan should also show directions (indicate which way is north), and should include the location of spigots, downspouts and external electrical outlets.
A base plan needs to be drawn to scale. The easiest way to do this is to use graph paper with eight or ten squares per inch (1:8 or 1:10 scale). You'll probably also need a friend or spouse to help hold the tape measure as you work your way around the yard. Once the base plan is complete, the next step is to make a bubble diagram. This involves taking a copy of the base plan and adding descriptive notations ("bubbles") to indicate such things as views that need to be enhanced, areas that need screening for privacy, and areas that have specific uses. This is the time to decide how you want to use various areas in your yard. For instance, if you like to barbecue, you'll need to include an outdoor cooking area. If you have children or pets you'll need a play area.
The final step is to use the bubble diagram to come up with a well-defined landscape plan, identifying specific site details (fences, trellises, decks, etc.) and a planting scheme. The landscape plan serves as the blueprint for constructing the finished Xeriscape, so you'll want to be as specific as possible when it comes to the type and number of plants. Group plants according to their light and water requirements - don't put plants that like dry conditions in the same area as plants that need frequent watering. Put taller plants in the back of the garden bed, and shorter plants near the front. When designing plant lacement on slopes, place lower-water demand plants at the tops of slopes and higher-demand plants at the bottom.
Soil is the foundation of every landscape. The better the soil, the more successful a Xeriscape will be. Soil is made up of three main types of particles -sand, silt and clay. The soils in northern Arizona tend to be shallow andclayey. Clay soil has a high moisture retention capacity, but it is slow to absorbwater and slow to release it. When water is applied too quickly to clay soil, the soil can't absorb it and most of it runs off. Clay soil also tends to be heavily compacted, making it difficult for plants to establish the deep root systems ecessary to survive a drought. Sandy soil has the exact opposite characteristics. It has excellent drainage and lots of air space for root growth, but does a poor job of retaining moisture and nutrients. Water applied to sandy soil tends to percolate quickly down to the water table. This limits the amount of time plant roots have access to the water. Fortunately there's a way to improve both clay and sandy soil. That's to amend it by adding lots of organic material, such as aged compost and/or manure. The ideal way to do this is to spread three to five inches of organic material over the top of the existing soil, and rototill as deeply as possible (a depth of six inches is considered sufficient.)
Once a landscape has become established it is much harder to improve the soil. Organic material can be applied to garden beds and worked in by hand. Existing lawns can be top-dressed. This involves spreading a very thin layer of compost (no more than 1/4 inch) over the lawn and letting it slowly sink to the soil level. Over the course of several years regular top-dressing will help build an organic base.
Strip and stockpile existing topsoil prior to site-regrading. Following completion of grading, replace topsoil and improve soil for planting with suitable soil amendments. Improve soil as suitable before planting and installing the irrigation system. Soil improvements promote better absorption of water, improved water-holding capacity and drainage of the soils. It also allows for better oxygen transfer within the root zone. Add organic material to the plant hydrozones, but only as needed. This typically means adding organic material for High and Moderation water zones, but not for Low and Very Low water zones. PH-balanced examples of organic materials are compost, sphagnum peat, and animal manure.
Soil preparation should include the breaking up and loosening, or scarification, of soil to 6 inches, with the incorporation of organic amendments, fertilizers, etc. as specified by a landscape designer, landscape architect or soil analysis (see Figure 3).
Converting your yard to Xeriscape does NOT mean you have to get rid of all the grass. It does requires identifying practical areas of grass, rather than just putting turf everywhere. For instance, areas that get considerable of foot traffic might do better with walkways, decks or patios instead of turf. Heavily shaded areas would do better with a groundcover such as vinca or sweet woodruff, which are more shade-tolerant than turf. Narrow strips such as the tree lawn between the sidewalk and the street are difficult to irrigate with spray heads without also watering the sidewalk and street. Replacing the turf in these areas with drought-hardy plants and drip irrigation will eliminate water waste.
In areas where turf is appropriate, select the type of grass that best suits the
site. For instance, warm-season grasses such as buffalograss and blue grama
are very water-conserving, but not very tolerant of heavy foot traffic during
their long dormant periods. A good spot for a warm-season grass might be a
sunny front yard where most of the foot traffic is confined to the sidewalk. Cool-season grasses like Kentucky bluegrass are more traffic tolerant but require
considerably more water to stay green during the summer. Cool-season grasses
would do well in a back yard where children or pets will play.
Mulch is an essential component of gardening in a semi-arid climate like ours, for several reasons. Mulching minimizes evaporation. It cools plant root zones, which reduces the amount of water plants lose through evapotranspiration. It reduces weed growth, and it helps control erosion. Mulch also adds a finished look to the garden.
There are two basic types of mulch - organic and inorganic. Organic mulch is
wood-based, such as pole peelings, chipper chips, cedar chips, and deco bark.
Organic mulch will decompose over time and improve soil texture, but it will
need to be replaced periodically. It's an ideal choice in new gardens, where
plants are much smaller than their mature size. The mulch will fill in the
empty spaces and slow weed growth. As the plants mature and spread, they'll
cover the mulched area so you won't have to keep replacing the mulch.
Inorganic mulch is stone-based. Types of inorganic mulch include cobblestone, river rock, pea gravel and lava rock. Inorganic mulch rarely needs to be replaced, but it tends to retain and radiate heat so it's not the best choice to go along the sunny side of a house. It works best in a more formal setting where the rock will remain visible even when plants are mature.
Organic mulch should be applied directly on top of the soil in a three to four
inch layer. Inorganic mulch may be applied on top of the soil or over a weed
barrier fabric, and should be layered two to four inches deep. [NOTE: Never
apply mulch over black plastic. Plastic doesn't allow moisture or air to
penetrate, and can kill beneficial organisms.}
No garden is completely maintenance-free. Like more traditional landscape, Xeriscapes require regular maintenance to look their best. This includes pruning shrubs and trees, deadheading perennials, aerating, mowing and fertilizing lawns, and controlling pests.
Pruning Regular pruning keeps plants looking good and promotes plant vigor. Also, many shrubs bloom on new wood, so pruning is necessary in order to have flowers. The best time to prune most shrubs and trees is in the winter to early spring. Prune dead or unwanted branches slightly away from the trunk, on the outer edge of the branch collar (a ring of compressed bark at the branch crotch). Leave the entire branch collar in tact, to allow new bark to form over the cut.
Deadheading means removing spent flowers before they mature into seed heads. Deadheading makes the garden look more attractive, helps prevent unwanted, self-sown seedlings, and encourages the plant to produce more flowers. Many plants, including valerian, catmint and salvia, will bloom repeatedly during the summer if deadheaded.
Aerating Regular core aeration will reduce thatch buildup and loosen the soil. This promotes better root growth, and allows water and fertilizer to move into the root zone. Core aeration can be done with a core aeration machine or a manual aeration device. The plugs can be left on the lawn to disintegrate or can be added to compost piles. Core aeration is best done twice a year, in spring and late summer.
Mowing and fertilizing lawns should be mowed to a height of 2-3", and should
be mowed frequently enough so that no more than 1/3 of the grass height is
removed at any one time. Make sure the mower blades are sharp, and don't
water when the grass is wet. Fertilization schedules will vary according to the
type of grass involved. For more information on fertilization the University of
Arizona's Turfgrass web page.
Controlling pests The most effective way to control garden pests is through
Integrated Pest Management (IPM). There are four steps to IPM - discovering
the problem, identifying the cause, monitoring the situation, and managing the
problem through a variety of techniques, including using disease-resistant
plant, spraying insects with water, using sprays of BT bacteria to manage
caterpillars, and using pesticides or herbicides.
Where possible preserve existing native remnant plant communities and site conditions that support them.
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Where possible preserve healthy tree. Established plants have often developed a root system that can adapt to lower water conditions
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Controlling pests
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Local native plants and plants with documented lower water requirements should be given priority in landscape design. A native plant species “that occurs naturally in a particular region, state, ecosystem, and habitat without direct or indirect human action” Federal Native Plant Conservation Committee, 1994).
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Use of native plants in the landscape supports local biodiversity, helps sustain local wildlife, enhances recreation experience, supports remnant native plant community and reduces water consumption.
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All landscapes have the potential to impact native plant communities through transport of seeds and plant propagules by wind and storm drainage.
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Landscapes adjacent to native sites are particularly critical due to the potential direct spread, but all project (public or private) should not harbor or install exotic horticultural plant species that are known to be invasive and therefore threaten natural areas. A complete list of threatening plants to avoid is provided by the Colorado Native Plant Society.
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Landscapes adjacent to native areas should emphasize the use of species with low fuel volume with low flammability. Mowing management can be used to limit build up of flammable plant materials. Information on the fire-resistance of some native plants can be found at Colorado State's Cooperative Extension webpage.
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Remove species that are designated as noxious weeds, especially ornamental species such as loosestrife, oxeye daisy, tamarisk, myrtle spurge, and yellow toadflax. See the State of Colorado's noxious weeds list. |
Newly transplanted native or drought tolerant vegetation requires more frequent irrigation to allow new plants to establish their roots. Once established, you can cut back on the amount of water. Apply the water efficiently with a hose-end sprinkler or with an automatic sprinkler system.
The keys to either method are:
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Keep water close to the ground. Avoid the oscillating type of sprinkler that sends water high into the air. Stationary sprinkler heads that keep the water fairly low or sprinklers that move horizontally from side to side (like rotary heads) are less prone to evaporation. Drip, micro-sprays or bubbler emitters are the most efficient for watering flowers, shrubs and trees.
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Know how much water your sprinkler puts out in a given amount of time
so you can calculate how long to water for each zone. The easiest way to
measure sprinkler output is to place three identical empty cans at various
distances from the sprinkler within a given zone. Turn the sprinkler on for
15 minutes, and then turn it off and pour the collected water into one can.
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Design your sprinkler system (or plan your hose placement) so that a given zone or hose placement waters plants with similar watering requirements. Don't try to water low and moderate-water-requiring plants at the same time -- you'll end up either over watering some plants or under watering others.
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If you have an automatic sprinkler system, change the watering times per zone at least once a month to reflect the different water requirements. Plants need more applied irrigation in the heat of the summer than in the spring or fall.
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Check your system regularly for leaks, broken or misaligned heads, and make repairs promptly.
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A well-designed landscape should start with a plan, or rather, a series of plans. The first plan is a base plan which shows the major elements of the current landscape, including the footprint of the house, driveway, patios, walkways and all existing trees, shrubs and garden beds. The base plan should also show directions (indicate which way is north), and should include the location of spigots, downspouts and external electrical outlets.
A base plan needs to be drawn to scale. The easiest way to do this is to use graph paper with eight or ten squares per inch (1:8 or 1:10 scale). You'll probably also need a friend or spouse to help hold the tape measure as you work your way around the yard.
Once the base plan is complete, the next step is to make a bubble diagram. This involves taking a copy of the base plan and adding descriptive notations ("bubbles") to indicate such things as views that need to be enhanced, areas that need screening for privacy, and areas that have specific uses. This is the time to decide how you want to use various areas in your yard. For instance, if you like to barbecue, you'll need to include an outdoor cooking area. If you have children or pets you'll need a play area.
The final step is to use the bubble diagram to come up with a well-defined landscape plan, identifying specific site details (fences, trellises, decks, etc.) and a planting scheme. The landscape plan serves as the blueprint for constructing the finished Xeriscape, so you'll want to be as specific as possible when it comes to the type and number of plants. Group plants according to their light and water requirements - don't put plants that like dry conditions in the same area as plants that need frequent watering. Put taller plants in the back of the garden bed, and shorter plants near the front. When designing plant lacement on slopes, place lower-water demand plants at the tops of slopes and higher-demand plants at the bottom.
