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Annuals in the Landscape
by Sandy Turico, Master Gardener

They're easy to grow, come in an endless range of sizes and colors, are versatile and relatively inexpensive. Annuals are a simple and enjoyable way to liven up your garden. Here and gone in just one growing season; the seed of an annual plant germinates, grows to maturity, blooms, reproduces itself by forming seed and then dies.

Year-round color can be achieved with annuals. In Maricopa County cool-season annuals planted in the fall thrive until spring, a time when the days are warm and the nights cool. Warm-season annuals are usually planted from around February until May, flourishing through our long, hot summers. The list of warm-season annuals may be shorter, but there are still many that do well during the more intense heat of late spring and summer.


Gaillardia grandiflora

Are you ready to add some pizzazz to your landscape? Annuals can be incorporated into your landscape in numerous ways adding instant appeal to your yard. Use them as a focal point in the landscape or blend them with other landscape plantings. Containers, raised beds, hanging baskets and window boxes filled with colorful annuals are an ideal way to provide exciting accents to your home and garden.

Welcome guests to your home by edging pathways leading to entryways; enhance patio and pool settings where you entertain or unwind after a hard day. Interplant annuals with perennials to extend bloom in the garden or utilize them to fill in empty spaces until newly-planted trees and shrubs grow to maturity.


Dianthus chinensis

Create a cutting garden to help bring the beautiful outdoors into your home. Design an island bed or perhaps a spiral garden. Have some fun with annuals in your vegetable or herb garden. They not only will offer some extra attraction with their lively hues, but may also repel insect pests or attract beneficial insects.

Consider an annual's color, size, and blooming time when making choices for your landscape. Sketching out your ideas on graph paper might help you to better visualize an attractive design. Curving lines and simple, asymmetrical shapes in your design will contribute to a more natural look. Use taller plants in back and lower ones in the foreground but don't be too rigid in your planning. Consider the size of an annual flowerbed when planning. You will appreciate having easy access to the bed in order to attend to weeding and other gardening chores. Try to rotate the varieties of flowers you use from season to season to discourage disease.

Color should flow naturally through the landscape. Experiment with flower and foliage colors. Masses of flowers in one color will create a bigger impact; using too many different colors or too many plant varieties may result in a jumbled, confused appearance. If you want to achieve a lively look in your garden, try utilizing complementary colors such as blue and orange or yellow and purple. To visually open up space use the calm, cool colors of green, blue, and purple. The warm hues of red, yellow and orange are stimulating and will draw in the eye and help to define an area. White and pastels sparkle in the dark. Make use of them in the shade and around areas where you relax or entertain guests in the evening. Finally, be aware of the background colors of fences, walls or other plants when choosing colors.

Keep in mind that most annuals require a sunny location although there are those that will tolerate some shade. Well-draining, fertile soil will give your annual plants or seedbed a healthy start and make your gardening chores easier in the long run.

Flower beds may be prepared months ahead of time or right before planting. Loosen your garden soil twelve to eighteen inches and mix in four to six inches of organic material such as compost. Some gardeners choose to add soil sulfur or gypsum to alleviate salt build-up in our alkaline soils while others skip this step.

When it comes to fertilizing, most gardeners have their own preferences and methods. Whether you choose to use organic or chemical fertilizers remember that nitrogen and phosphorous are needed to produce healthy annuals in our desert soils. The exception to this rule is wildflowers, which do well in native soil and do not appreciate soil amendments or fertilizer.

Organic fertilizers such as bonemeal, fish emulsion and manure contribute to the health of your garden soil and are less likely to burn your plants but may be more costly. Nitrogen is essential for foliar growth. Phosphorus will guarantee a healthy root system and assure bloom, but does not easily move through soil, so work it into the soil before you plant where it will reach the root zone. Be sure to follow directions regardless of what kind of fertilizer you decide to use.

Keep a journal of the type and amount of fertilizer used, and the frequency of applications; note how your annual plants respond. Be aware that container plants will need a more regular fertilization schedule.

Think about the type of irrigation you will use; annuals need regular watering. Since it is best to avoid wetting the foliage when irrigating, consider using soaker hoses or a drip system. Moisten the planting area to a depth of one foot. Let the soil dry out reasonably well before the next watering. Winter annuals may go a week or more between irrigations while your summer annuals may need to be watered every couple of days. Note that container plants dry out faster than those in the ground.

Pull weeds regularly as they compete with landscape plants for sun, moisture, and nutrients. Using mulch around you plants will deter weed growth. Organic mulches such as compost, grass clippings, and shredded bark will actually contribute to the health of your soil. Just be sure to avoid placing mulch right next to the stems of the plants. The end of the blooming period will signal the annual to go to seed and then die. "Deadheading" or removing depleted blooms once a week will encourage continued flowering.

Because of their short life cycle annuals must be reseeded or transplanted seasonally. Many annuals self-seed. These "volunteers" may be a delight to some gardeners, an annoyance to others. Using transplants will assure color in your landscape more quickly than growing annuals from seed. When picking out transplants at a nursery try to choose those just beginning to bloom so you will be sure that you get the flower color you desire. Check for healthy foliage and insect damage. If you decide to start your plants from scratch, be sure to purchase seeds packed for the current year.

Here is a list of some popular annuals and wildflower annuals to try out in your garden. Note that some of these plants are actually perennials but are grown in our area as annuals

Cool-Season Annuals Ageratum houstonianum (Ageratum)*
Antirrhinum majus (Snapdragon)
Calendula officinalis (Calendula)
Callistephus chinensis (Asters)
Centaurea cyanus (Cornflower)
Centaurea moschata (Sweet Sultan)
Chrysanthemum coccineum (Painted Daisy)
Chrysanthemum maximum (Shasta daisy) *
Cleome spinosa (Spider Flower)
Consolida ambigua (Larkspur)
Centaurea cyanus (Cornflower)
Centaurea moschata (Sweet Sultan)
Delphinium x cultorum (Delphinium) *
Dianthus barbatus (Sweet William) *
Digitalis purpurea (Foxglove) *
Dimorphotheca sinuata (African Daisy)
Echinacea purpurea (Purple Coneflower)
Gypsophila elegans (Baby's Breath)
Helichrysum bracteatum (Strawflower)
Heuchera sanguinea (Coral Bells) **
Iberis amara (Candytuft) *
Iberis sempervirens (Candytuft) *
Lathyrus odoratus (Sweet Pea) *
Limonium sinuatum (Statice)
Lobelia erinus (Lobelia) *
Lobularia maritima (Sweet Alyssum) *
Matthiola incana (Stock)
Moluccella laevis (Bells of Ireland)
Myosotis sylvatica (Forget-Me-Not) *
Nicotiana alata (Flowering Tobacco) *
Papaver rhoeas (Shirley Poppy)
Pentas lanceolata (Star Clusters) **
Petunia x hybrida (Petunia) *
Phlox drummondii (Phlox) *
Primula malacoides (Fairy Primrose) **
Primula polyantha (Primrose) **
Reseda odorata (Mignonette) *
Scabiosa spp. (Pincushion Flower)
Tropaeolum majus (Nasturtium)
Verbena peruviana (Verbena)
Viola x wittrockiana (Pansy) *
Viola tricolor (Johnny-Jump-Up) *
Viola spp. (Violet) *

Warm-Season Annuals

Capsicum annum (Ornamental Pepper) *
Catharanthus roseus (Periwinkle)
Celosia cristata (Celosia)
Coleus x hybridus (Coleus) **
Cosmos bipinnatus (Cosmos)
Dahlia x hybrida (Dahlia) *
Eustoma grandiflorum (Lisianthus)
Gomphrena globosa (Globe Amaranth)
Helichrysum bracteatum (Strawflower)
Impatiens balsamina (Balsam)*
Kochia scoparia (Kochia)
Limonium sinuatum (Statice)
Mirabilis jalapa (Four O'Clock) *
Portulaca grandiflora (Moss Rose)
Portulaca x hybrida (Purslane)
Sanvitalia procumbens (Creeping Zinnia)
Tagetes erecta (Marigold, American & African)
Zinnia elegans (Zinnia)

* Annuals that tolerate partial sun or partial shade
** Annuals that tolerate shade Photos by Candice Sherrill




Maricopa County Master Gardener Volunteer Information
Last Updated November 21, 2004
Author: Lucy K. Bradley, Extension Agent Urban Horticulture, University of Arizona Cooperative Extension, Maricopa County
© 1997 The University of Arizona, College of Agriculture and Life Sciences, Cooperative Extension in Maricopa County
Comments to Maricopa-hort@ag.arizona.edu 4341 E. Broadway Road, Phoenix, AZ 85040,
Voice: (602) 470-8086 ext. 301, Fax (602) 470-8092