Flowering Perennials for Georgia Gardens (B 944) University of Georgia Extension This publication is devoted specifically to covering everything you need to know about growing herbaceous perennials, primarily to those that persist from crowns and/or fleshy roots. 2017-04-19 15:31:28.02 2006-06-02 14:26:45.0 https://secure.caes.uga.edu/extension/publications/images/primary-pub-images/B944-primary.jpg Flowering Perennials for Georgia Gardens | Publications | UGA Extension Skip to content

Flowering Perennials for Georgia Gardens (B 944)

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pink daisy

Paul A. Thomas, Extension Horticulturist

Plants are classed according to their growth cycle as annuals, biennials or perennials. Annuals are short-lived plants that complete their entire life cycle within one growing season. Biennials normally do not bloom until the second season, form seeds and then die. Perennials live from year to year, with varying bloom times.

Perennials are also classed as woody (trees and shrubs that produce woody above-ground stems and branches that live from year to year) or herbaceous (plants that produce comparatively soft tissues which often die back to ground level at the end of the growing season). Herbaceous perennials persist by means of various underground storage structures—bulbs, corms, tubers, tuberous stems, tuberous roots and crowns.

The distinction between annuals and perennials, woody and herbaceous, is not always sharply defined because climate influences growth potential. Further, those biennials and perennials that bloom the first year along with tender perennials (those actually killed by frost) are often treated as annuals in the landscape.

This publication is devoted specifically to herbaceous perennials (subsequently referred to simply as perennials), primarily to those that persist from crowns and/or fleshy roots. For information on bulbous-type herbaceous perennials (daffodil, canna, dahlia, etc.), refer to Extension bulletin 918, Flowering Bulbs for Georgia Gardens.

Use

There has been a resurgence of interest in perennials. Home gardeners are becoming more aware of perennials and so are commercial landscapers.

Because perennials live from year to year, they offer a certain permanency to the landscape. They are virtually unequaled in providing year-round color and interest; variations in colors, sizes, habits and time of bloom are almost endless. Although many gardens and garden borders feature perennials exclusively—the classic English perennial border is legend—most often their best use comes in the skillful combination with other plants in the total landscape.

Some sources have suggested that perennials are not well suited to the Southeast. This simply is not true. Many perennials perform exceedingly well in Georgia and the Southeast in general. Not all perennials perform well here, but then not all perennials perform well in the Northeast or even in England. Remember, much of the existing literature regarding perennials is based on conditions where cooler summer climates prevail. So exercise care in choosing plants well adapted for your particular area.

Most perennials are completely winter hardy, although there are a few so-called tender perennials that are sometimes injured by low temperatures. The limiting factors in perennial adaptability in the Southeast are often heat tolerance and diseases that prevail in hot, humid climates.

Selection

In addition to climatic adaptation, perennials should be selected based on their ability to perform well and contribute to specific landscape needs. Height, spread, color, time and length of bloom, and plant habit should be given careful consideration. Some perennials are tolerant of poor drainage, others totally intolerant. Sun and shade tolerance varies. All these factors are important in selecting and using perennials correctly.

In most cases, a given species has many varieties available, which greatly extends the size and/or color range of the species. Commercial catalogs are a good source of information on varieties. Purchasing plants by botanical name and variety is a good idea because common names vary from region to region.

Bed Preparation

Good bed preparation is extremely important for perennials. Remember that you are making a long-term planting; it is much easier and much less disruptive to improve the soil and correct drainage problems before planting.

Beds should be deeply spaded, to a depth of at least 8 to 10 inches if possible. Many perennials are deep-rooted. Some perennials grow well in sandy soils, but most prefer soils higher in organic matter and with better water-holding capacity. Heavy clay soils should be amended with sand, perlite or coarse bark to improve drainage. Good drainage is critical to the success of many perennials. To test for drainage, dig a hole about 10 inches deep and fill with water. The next day, fill the hole again and see how long the water remains in the hole; if it drains away in eight to 10 hours or less, drainage is satisfactory for most perennials. In some situations, it may be necessary to install underground drainage lines or construct raised beds.

Have the soil tested. A pH of 6.0 to 6.5 is optimal for most perennials. Most Georgia soils are acid and require the addition of lime to correct pH. In the absence of a soil test, add a complete fertilizer such as 8-8-8 or 10-10-10 at the rate of a 1½ pounds per 100 square feet. Incorporate the fertilizer and lime, and rake the soil surface smooth.

Planting

Many perennials can be seed propagated, but most home gardeners prefer to start with established plants. Most perennials can be planted in fall or early spring. Many perennials are now produced in containers, which aid in transplanting and establishment, but many are still field grown and shipped bare root and dormant. Fall planting is often better because it gives the plant more time to become established before the start of active growth.

Unless instructed otherwise, position the crown of the plant at or just below the soil surface. Planting depth is critical; if the crown is planted too deeply, it may develop crown rot. Untangle and spread the roots. Fill the planting hole with soil, gently firm it around the roots and water thoroughly. You may want to mark or protect the plants, since when dormant they may be forgotten or stepped on accidentally.

Care and Maintenance

It is a misconception that because perennials last from year to year they require little maintenance and care. While some perennials survive with little care, more require some attention to look their best. In many cases perennial beds require more work than annual beds, which can be completely renovated rather easily each year. But the rewards of perennials make the added maintenance worthwhile.

Perennials vary in their drought tolerance, but more require an ample moisture supply at least during periods of active growth. Do not rely on normal rainfall; irrigate if necessary. Allow the water to penetrate deeply. Frequent light waterings are not advisable because they wet only the upper soil depths and result in shallow root growth and wet foliage and flowers, an invitation to many diseases. Soaker hoses and drip irrigation systems work well with perennials.

Mulching helps conserve moisture, control weeds and improve the overall appearance of the garden. Mulches also tend to prevent soil crusting, which retards water penetration, and prevent soil from splashing on lower leaves and flowers. Mulches also provide an added degree of winter protection. A word of caution: Heavy mulches that hold moisture can be detrimental, particularly to plants subject to crown rot. Pine bark, pine straw, wood chips and a variety of other materials are used successfully.

Maintenance fertilization is essential to the continued growth of perennials. An application of 8-8-8 or 10-10-10 (1½ pounds per 100 square feet) should be applied in early spring and once or twice again during the growing season. Maintenance fertilization practices should be based on soil tests; application of phosphorus is frequently unnecessary once adequate soil levels become established. Water the bed after application so that the fertilizer enters the soil and is available to the plant. Wash any fertilizer off the foliage to prevent fertilizer burn.

A well-prepared bed requires little cultivation. Deep cultivation is likely to injure roots and often uncovers weed seeds, which can then germinate. Weed control should usually be done by hand weeding or with the use of herbicides. Exercise extreme caution when using a herbicide. Very few are suitable for use around perennials. Read the label carefully to be sure it will not injure desirable plants.

Figure 1. Tie the plant securely to the stake but not so tight as to cause girdling.Figure 1. Tie the plant securely to the stake but not so tight as to cause girdling.

Many perennials are top heavy and require support to prevent them from bending or falling over during wind and rain. A number of methods can be used to lend support, but simple wire, plastic or bamboo stakes are often the easiest. Done correctly, the plants grow to cover the stakes so that they need not detract from the appearance of the plant. Be careful not to twist the ties too tightly because girdling may result.

To maintain vigorous growth, remove mature flowers; do not allow seeds to form. Removal will often stimulate growth of side shoots on which additional flowers will form.

Remove dead foliage and stems in the fall. Remember that it is natural for the tops of many perennials to be killed to the ground by frost. Some herbaceous perennials have evergreen foliage.

Division and Propagation

While the length of time varies, most perennials eventually become overcrowded and require division. Mature clumps can be cut or pulled apart. Divisions should usually contain three to five shoots or growing points. Discard any weak or diseased divisions. The time to divide perennials varies somewhat, but is most often fall or early spring, coinciding with desired planting dates. Many perennials are easily propagated in this way.

Figure 2. Perennials like daylily and liriope, which cannot be pulled apart easily, may be cut or pried apart.Figure 2. Perennials like daylily and liriope, which cannot be pulled apart easily, may be cut or pried apart.
Figure 3. Plants like bearded iris are easily propagated by cutting through the rhizome, leaving at least one growing point on each section.Figure 3. Plants like bearded iris are easily propagated by cutting through the rhizome, leaving at least one growing point on each section.

Many perennials can also be propagated by stem cuttings; garden phlox is a good example. Cuttings should be 3 to 6 inches long. Strip the lower foliage and insert the cuttings into the rooting medium. Cuttings should be protected against drying (a plastic tent or large glass jar works well) until roots form, at which time they can be transplanted to pots or beds. Most such cuttings are taken in late spring or early summer to allow plenty of time for rooting and establishment before cold weather.

Some perennials can be propagated from root cuttings, which are taken when the plant is dormant. Oriental poppy is an example.

Many perennials can also be seed propagated. In many cases, however, vegetation propagation is preferred because the desirable characteristics of the parent plant are retained in the new plants. Some variation is to be expected in seed propagated plants; resulting seedlings can be inferior to parent plants.

Seed propagation techniques are essentially like those used with annuals. Seeds of many perennials, however, do have special requirements, often a need for chilling, before germination can occur. Be sure you know these specific requirements before attempting to propagate perennials by seeds.

Diseases and Insects

No plant is completely immune to insects and diseases; perennials are no exception. A wide spectrum of insects and diseases can attack perennials and may require control measures. Quite often, proper site selection and good cultural practices will prevent many disease problems.

For the identification and recommended control of specific insect and disease pests, consult your county Extension agent.

Recommended Perennials

The following is a list of commonly grown perennials satisfactory for most areas of Georgia. It is by no means comprehensive—many other lesser-known perennials also grow well. The plants are listed alphabetically by common name with additional common names in parentheses.

For quick navigation:

Achillea

Achillea millefolium (common yarrow)
A filipendulina (fernleaf yarrow)

Yarrow blooms from mid- to late summer. Common yarrow grows 2 to 3 feet tall, while fernleaf yarrow may grow to 4 feet. Both are easily grown in sunny locations. Colors range from white to pink to red in common yarrow; fernleaf yarrows are yellow or gold. Both dry well. Several other species and hybrids are also available.

Ajuga

Ajuga reptans (bugleflower)

Generally used as an evergreen ground cover, ajuga is a spreading perennial only a few inches tall. It grows well in moist, shady areas. It will tolerate sun if adequate moisture is provided. Attractive blue flower spikes cover the plants in mid-spring. Several varieties are available with pink and white flowers and some with variegated or bronze foliage.

Alyssum and candytuftAlyssum and candytuft

Alyssum

Aurinia saxatile (gold alyssum)

Gold alyssum is frequently used in rock gardens and for edging. In early spring it blooms, producing a dense mat of yellow flowers 9 to 12 inches high. Full sun and excellent drainage are essential.

Anemone

Anemone x hybrida (Japanese anemone)

Unlike the tuberous, spring-flowering anemones, Japanese anemone flowers later on tall, wiry stems to 3 feet in height. Single and semi-double flowers range from white to deep pink. Moist, rich soils are best. Other species are also available.

Artemisia

Artemisia schmidtiana ?Silver Mound? (silver mound artemisia)
A. ludoviciana ?Silver King? (silver king artemisia)

These two varieties are perhaps the best known of the artemisias, most of which are grown for their silvery gray foliage. ?Silver Mound? is dwarf and compact, about 1 foot in height; ?Silver King? may grow 2 to 3½ feet tall.

Asclepias

Asclepias tuberosa (butterfly weed, chigger weed)

Asclepias is native to Georgia and easy to grow. It prefers full sun and is tolerant of poor soils and drought once established. The familiar orange flowers are produced on plants 1 to 2 feet tall. Established plants do not transplant well.

Aster

Aster species and hybrids

Numerous species and varieties of asters are cultivated. Blooming from late summer to fall, height ranges from 1 to 5 feet. Almost all colors are represented. Many are so vigorous they require restraint. The Michaelmas daisies (A. novae-belgii) are common and easy to grow. A. X frikartii, a lavender-blue, flowers from June until frost. Mildew is a common problem with asters, but can be controlled.

Astilbe

Astilbe japonica and hybrids (false spirea)

Astilbe grows 1 to 3 feet high, producing clumps of fernlike foliage and feathery flower spikes. A variety of colors are available as a result of aggressive plant breeding and selection programs in recent years. The plant grows best in shade to partial shade and prefers moist, rich soils.

Baptisia

Baptisia australis (blue indigo)

A member of the pea family, baptisia is adapted to poorer, low-fertility soils. A single clump spreads about 3 feet and grows 4 to 6 feet tall. It is a good substitute for lupine in the South.

Begonia

Begonia grandis (hardy begonia)

Growing to about 12 inches, it is best in shady flowerbeds. The species is pink, but a white variety is available. The plant can be propagated from bulbils that develop in the axils of leaves. This plant should not be confused with the wax begonias and tuberous begonias, which are not hardy in Georgia.

Buddleia

Buddleia davidii

Known for its ability to attract butterflies, this hardy woody perennial now comes in many colors. Plants grow to 6 feet wide and 5 feet tall, require some pruning and require full sun. The cultivar ?Black Knight? is one of the most popular for beginners due to its dark lilaclike flower clusters and wonderful fragrance.

Candytuft

Iberis sempervirens

Candytuft is frequently used in rock gardens, for edging and as a ground cover. Growing to a height of 10 to 12 inches, it produces a mass of white flowers in late spring. It is best in full sun, but will tolerate light shade, and is fairly drought tolerant once established. Do not confuse perennial candytuft with annual candytuft.

Carnation

Dianthus caryophyllus (hardy garden carnation)

This is the same species as the florist?s carnation. Garden varieties are selected for dwarf compact habits; most of them grow to a height of about 12 inches. Many colors are available. Carnation is very fragrant and an excellent garden cut flower.

Caryopteris

Caryopteris clandonensis

This plant makes a 4-foot mound of light blue flowers late July through September. Excellent for cut flowers or for attracting butterflies. The semi-woody plant may die back to the base in cold winters. Caryopteris requires full sun and good drainage; tolerates drought well.

Centaurea

Centaurea montana (perennial bachelor?s button)

Blue flowers about 2 inches in diameter are held erect 12 inches or more above the basal foliage. Blooming in early summer, full sun and light soils are best. Do not confuse C. Montana with C. cyanus (cornflower, bachelor?s button), an annual that grows wild in Georgia.

Ceratostigma

Ceratostigma plumbaginoides

This plant is a low-growing perennial ground cover for full sun. The dime-size flowers are the deepest blue imaginable and provide color from July through September and beyond. It spreads by runners and does well in poor soils once established. This plant has few pests.

Chrysanthemum

Chrysanthemum X morifolium

Garden chrysanthemums perform well in all parts of Georgia, although not all varieties are cold hardy. Many colors and varieties are available. The shorter cushio types, ranging in height from 1 to 3 feet, are generally preferred for landscape use. Taller types usually require staking. C. coccineum (painted daisy) grows well in most parts of the state, as does C. X superbum (Shasta daisy). C. zawadskii (C. X rubellum) cv. Clara Curtis, a pink daisy type, is also common in the fall landscape.

Columbine

Aquilegia hybrida

Growing 2 to 3 feet tall, they are often used in borders and for cut flowers. Columbine blooms in late spring or early summer. It needs a fairly rich and well-drained soil, and will grow in sun or partial shade. The foliage frequently declines in midsummer. Plants are usually seed propagated but can be carefully divided in August or September. Leaf miner is a common pest.

Coreopsis

Coreopsis grandiflora
C. lanceolata
C. verticillata
(threadleaf coreopsis)

Coreopsis grows from 1 to 3 feet high and bloom from May to fall if the old flowers are removed. It grows best in full sun and is fairly drought tolerant. Coreopsis is often treated as a biennial. Yellow and gold predominate in the flower color range. Coreopsis is among the easiest perennials to grow.

Chrysogonum

Chrysogonum virginianum (green-and-gold)

Low growing and spreading, chrysogonum forms a dense ground cover. Small yellow flowers are produced over a period of several weeks from spring to early summer. Chrysogonum is tolerant of a range of cultural conditions but seems to grow best in moist soils and under light shade.

Delphinium

Delphinium species (larkspur)

The larkspur types grow well, acting as reseeding annuals. The delicate airy spikes, in a wide range of colors, are attractive in perennial borders and make good cut flowers. The

Status and Revision History
Published on Sep 1, 1999
Re-published on Feb 24, 2009
Reviewed on Jun 26, 2012
Reviewed on Feb 1, 2016