Annual Flowers for Northern Arizona Above 6,000 Foot Elevations
Cooperative
Extension, College of Agriculture & Life Sciences, The University of Arizona
Written by
Tom DeGomez, Associate Agent, Agriculture and Natural Resources
Hattie Braun, Master Gardener
Annual flowers are plants that grow, flower, set seed and
die in one growing season. Their single goal is to reproduce often resulting
in an abundance of flowers. Annuals therefore offer a quick easy way to
add color and excitement to the landscape. You can select from a wide
range of flower color, size, shape and bloom period. Not only do many
annuals provide color for weeks or even months, some have showy foliage
that provides contrast to bright flowers.
Annuals are often separated into three groups based on their
cold tolerance. Knowing which group an annual falls into helps the gardener
determine when they can safely plant annuals. The first group includes
the frost resistant, cool weather types; the most common are the pansies.
These plants can tolerate a few degrees of freezing. They are usually
planted in early spring for late spring color. A second group, known as
half-hardy annuals, can handle just a touch of frost. Most annuals fall
into this category. It may be possible to set these plants out before
the last spring frost but a severe frost will damage the foliage unless
they are covered. The third group includes the frost sensitive, heat tolerant
types and are usually called tender annuals. These are planted after the
last spring frost and may not be suitable for cooler locations because
they usually perform poorly under cold conditions. They bloom in the summer
and fall until killed by frost.
Many plants grown as annuals are actually tender perennials that in milder climates will over winter and survive for many years. As long as these tender perennials flower in the first year, they make suitable annuals for colder climates. Biennials can also be grown as annuals and many have very attractive flowers. These plants require two years to mature, producing foliage the first season and flowering the second season.
The short growing season and late spring frosts experienced by much of northern Arizona makes careful plant selection a must. Choosing the hardiest plants for early planting and waiting until late spring or early summer to plant the more tender annuals may afford a more successful gardening experience.
Ways to use annuals
Probably the greatest use of annuals is in individual flowerbeds and borders. If possible, locate the garden against a background such as a fence, wall, or shrub planting. This shows off the colors of annuals most effectively.
Dwarf and low-growing annuals make excellent ground covers, borders,
or edging plants. For a continuous supply of fresh flowers for use in
the home, plant a row or two of the cutting varieties in your vegetable
garden or as a border in a perennial flower bed. Some kinds are also useful
when dried. Annuals are also invaluable for starting a new garden or for
filling in gaps until perennials and shrubs can mature.
Most annuals grow well in containers and may be used in hanging plants. Many water conscious gardeners limit their annuals to containers so that they can carefully control the amount of water they use. Growing annuals in containers also allows northern Arizona gardeners to extend the short growing season; plants that can be placed near buildings may have enough protection to survive late spring and early fall frosts.
Planning the garden
Plan the garden on paper before you plant. This will help you select
the right location for each kind of annual and the number of plants needed.
Choose varieties that are best suited to the soil and sun light that your
garden has to offer. Many gardeners return home from the nursery with
more plants than suitable places to plant them. This limits your success
and perpetuates the notion that it is too hard to garden in cold climates.
Height is an important consideration. Use the tallest varieties at the
back of the bed and dwarf or low growing types toward the front of the
planting. A minimum of five or more hours of sunlight per day is essential
to successfully grow most types and varieties of annual flowers.
The choice of flower colors and color combinations is largely a matter
of personal taste. Small gardens are most attractive when only a few colors
or shades of one color are used. The larger the garden the wider the range
of colors that may be successfully combined. Regardless of size, a garden
will have its greatest visual impact when each kind of annual is grouped
for a mass effect. A good rule is to plant in groups of three, five, seven
or more depending on the size of the plant. Combining just a few plants
of many kinds of annuals each with a different flower color often results
in a confused disorganized garden picture.
Consider the microclimate of the site and the plants cultural requirements
when selecting a garden location. South facing walls and under east and
west overhangs are generally the warmest spring and fall locations. In
summer, a garden planted in front of a west wall will be subjected to
high heat and high light intensities. Against an east wall, however, a
summer garden will be protected from afternoon heat and light reflection.
North walls are the coolest and shadiest year round.
Give some thought to maintenance when you decide how large your garden will be. How much time and energy are you willing to commit to garden maintenance? You will enjoy your flower garden most if garden chores are a pleasure rather than an unending tedious job.
Soil Preparation
Annuals grow best in a well-drained soil rich in plant nutrients. If
the soil is rocky or is a heavy clay, remove it to a depth of 1 1/2 to
2 ft. and replace with good soil.
Organic matter should be added to the flowerbed every year. Spread a 2 to 4 inch layer of wood residue material, compost, or well-rotted manure over the garden area and about 1 lb. of ammonium phosphate (16-20-0) per 1,000 square feet. A complete lawn and garden fertilizer may be used in place of the ammonium phosphate if desired. Thoroughly mix these materials into the soil 1 to 2 feet deep. (For alternative fertilizers contact your county Extension office.)
Planting
Water the garden area 2 or 3 days in advance of planting so the soil
will be moist but not too wet when annuals are set out. Harden-off the
plants prior to planting. Harden-off annuals by slowly exposing them to
the environment where they will be planted. Water the plants several hours
before planting to prevent sudden wilting once they are removed from containers.
If the weather is hot, plant late in the day so that the transplants will
be less subject to moisture stress.
If the plants are in a grow-pack or nursery flat, gently separate the
root clump of each plant with your fingers. This causes less transplant
shock and injury than using a knife or trowel to separate plant root clumps.
Transplants can dry out quickly be sure to water them shortly after planting. Annuals need watering daily until established, especially if the weather is hot or windy. As the plants begin to grow, water less often but apply more water each time to promote deeper rooting.
Care of established beds and borders
Established annuals should be watered at 3 to 6 day intervals depending
on soil characteristics and weather conditions. More frequent watering
is necessary on sandy soils that do not retain much water, and during
dry hot weather regardless of soil type. To determine when it’s time
to irrigate check the moisture content of the soil an inch deep and watch
plants for the first sign of wilting.
Because of the abundance of flowers produced, most annuals benefit from
additional application of fertilizer. Monthly applications of about 1
pound of ammonium phosphate (16-20-0) or similar analysis fertilizers
per 1,000 square feet of bed area should maintain adequate growth and
promote flowering.
Organic mulch material helps conserve soil moisture, prevents soil crusting
and helps control weeds. In small beds and borders and in containers,
remove faded flowers to encourage continued flowering. Insect pests or
diseases may become a problem in planting annual flowers. Contact the
nearest Cooperative Extension office for current control recommendations.
The following Tables describe many of the common annual plants that perform well at the high elevations in Arizona.
Tables:
1. FROST RESISTANT HARDY AND HALF-HARDY ANNUALS AND PERENNIALS GROWN AS
ANNUALS.
Table1
Table2
Table3
FROST TENDER ANNUALS AND PERENNIALS GROWN AS ANNUALS
Table4
Table5
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by the University of Arizona.
Document located http://cals.arizona.edu/pubs/garden/az1255/
Published January 2002
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