Flowering Perennials: Characteristics and Culture
Reviewed by David H. Trinklein
Division of Plant Sciences
Missouri Master Gardener Program
Flowering perennials represent a large group of garden plants with roots that persist from year to year. Stems and leaves of some may remain, but in most, the tops die back to the soil each winter.
Perennials are suitable for many locations. Most frequently, they are incorporated in a flower border that they share with annual flowers and shrubs. Perennials with similar cultural requirements are grouped into plantings known as rock gardens, wildflower gardens, bog gardens or perennial flower borders.
The pages of this guide list some major perennial plants and their important characteristics and cultural preferences.
Space is not available here to fully describe the plants and flowers. Reviewing garden catalogs or visiting a nursery, garden center or botanic garden will help you become familiar with available plants.
Mixed borders of both perennials and herbaceous perennials can provide an interesting landscape year-round.
The height range, given in inches, helps to determine whether a plant is suitable for an edging (1–12 inches), for the middle of a bed (12–36 inches), or for a background plant (more than 36 inches). Where a very wide range is given (such as Bellflower, 8–36 inches), some dwarf varieties are indicated.
The month or months of peak bloom are listed. Time of flowering varies with exposure and climatic area. These listings are primarily for central Missouri.
Plant are keyed with their most common colors. Many blends, shades and tints exist.
- Blue (B)
- Green (G)
- Lavender (L)
- Orange (O)
- Pink (P)
- Red (R)
- Violet (V)
- White (W)
- Yellow (Y)
- Full sun (FS)
Locate plant away from the shade of buildings, large trees or other objects that will not allow at least six hours of direct sunlight each day.
- Semi-shade (SS)
Give partial shade either as a long period of light shade or as more dense shade during the afternoon. Most plants in this category must have shade during the hottest part of the day.
- Shade (S)
These plants must have continuous shade with no direct sun. In heavy shade, other necessary cultural requirements must be carefully fulfilled.
- Well drained (WD)
Periods of standing water on the soil are damaging to perennials in both summer and winter. In heavy soils, add liberal amounts of organic matter to ensure good internal soil drainage. If external drainage is poor, consider raised beds or drain tile below. For information on improving soils, see MU Extension publication G6955, Improving Lawn and Landscape Soils.
- Dry (D)
These plants will not tolerate moist conditions very long, but they will withstand considerable dryness.
- Moist, but well drained (M)
Plants in this category do not tolerate drying, but they also do not tolerate any water standing around their roots. In the garden, they need regular watering during dry periods.
- Wet (W)
Plants will tolerate boggy conditions or even standing water. However, they are not the aquatics, such as waterlilies. Aquatic plants are not included in this publication.
- Loam (L)
Any good well-kept garden soil fits this category. Yearly additions of organic matter help develop a good loam. Where a poor soil is to be planted for the first time, amend it by mixing in at least 4 inches of organic matter.
- Sandy loam (SL)
This type of soil is required mainly by plants that need excellent drainage. If the original soil is a tight clay, large amounts (at least 50 percent) of sand will have to be added to achieve this type of soil.
- Organic soil (OS)
Some plants require a soil very high in organic materials that have an acid reaction. Where soils are not naturally this way, liberal amounts (up to 33 percent) of peat moss mixed thoroughly with the soil can achieve this condition, and annual applications of sulphur may be necessary for maintenance.
- Woodland soil (WS)
Such a soil is usually required for the wildflower garden. It results from decomposition of leaves and is fairly high in organic matter. It is not necessarily very acid soil. Add liberal quantities of leaf compost or peat to prepare this type of soil.
- Easy (E)
- Moderate (M)
- Challenging (C)
Unusual or outstanding plant and cultural characteristics are listed briefly. Included are notes on cultural ease, winter hardiness, or special uses, or emphasis of an extremely important cultural requirement.
Table 1. Characteristics and culture of flowering perennials.
|18–30||Sept.–frost||W, P||SS||WD||L||M||Dislikes transplanting. Spring plant only.|
|Anthemis, Golden Marguerite,|
|12–24||Aug.–frost||Y||FS||WD||L||M||Attractive fine-cut leaves. Divide every 3 to 4 years. Self-seeds readily.|
|9–36||Aug.–Sept.||W, Y||FS||WD||L, S||E||Many species and varieties. Includes Silver King and Silver Mound.|
|Aster, Michaelmas daisy,|
|12–72||July–frost||W, R, B, L, V, P||FS||M, WD||L||M||Many varieties of differing growth habit. Divide every other year.|
|12–24||May–June||W, P||FS||M, WD||L||E||Easy to grow. Sometimes incorrectly called spirea.|
|18–30||June–July||W, P||FS||WD||L||E||Easy to grow. Avoid acid soil. Add lime if necessary.|
|18–24||May–Aug.||B, W, P||FS||WD||S||M||Weak-stemmed plant, may need staking. Avoid wet places.|
|12–18||May||Y||FS||WD||S||M||Foliage gray. Suitable for rock garden.|
|6–28||June–July||P, R, L||FS||WD||S||M||Avoid acid soil. Fairly short-lived. Some good as cut flower.|
|18–24||July–Aug.||R, P, L, W||FS||WD, D||L||M||Other species available. Useful for hot, dry places. Also endures light shade.|
|8–36||May–July||W, B||FS, SS||WD||S||M||Needs excellent drainage. Avoid clay. Mulch in winter. Species vary in height.|
|12–15||May–June||P, W||SS||M||L||M||Waxy foliage remains green in winter.|
|24–36||July–Aug.||O||FS||WD||L||E||Flowers followed by blackberry-like seed clusters.|
|24–36||June–July||Y, O||FS||WD||L||E||Very tolerant. Good for bold splash of color.|
|Bleeding heart, Old-fashioned,|
|18–24||May||P, R||FS, SS||WD||L||M||Easy to grow. Should be fall planted.|
|Blue false indigo,|
|36–48||May–June||B||FS||WD||S, L||E||Also called rattlebush. Missouri native.|
|12–28||June–Aug.||B||FS||WD||L||E||Likes poor soil. Lasts about 3 years. Easily grown from seeds planted in spring.|
|24–48||Aug.–Sept.||W, P||FS||WD||L||E||Choose named cultivars. Species gets too tall for most gardens.|
|Brunnera, Siberian bugloss,|
|12–18||May–June||B||SS||M, WD||L||M||Resembles forget-me-not.|
|12–20||Aug.||O, Y, R||FS||WD||S||E||Difficult to transplant. Suited to hot, dry sites.|
|8–12||April||W||FS||WD||L||M||For rock garden and stone walls, or groundcover.|
|10–36||July–frost||W, R, O, V, L, P||FS||WD||L||E||Varieties determine growth. Pinch tips of tall types in early summer for bushiness.|
|6–36||April–June||W, R, P, V, B, L, Y||FS, SS||WD||S, L||E||Fairly short-lived. Reseeds easily. Sow seeds in early summer.|
|24–36||Aug.–Oct.||P||FS||WD||L||E||Tolerates very poor soil. Flower “petals” drooping.|
|18–24||June||W, P, R||FS, SS||WD||L||M||Divide every 3 years. Good cut flower.|
|Coreopsis, Thread-leaf tickseed,|
|18–30||June–Aug.||Y||FS, SS||WD, M||L||E||Easy to grow. Blends well with other perennials. Blooms all summer.|
|15–36||June–Sept.||R, O, Y, L, P||FS, SS||WD, M, D||L||E||Easily grown. Adapts to many conditions. Excellent hybrids available.|
|36–60||July–Aug.||W, B, L||SS||WD||L||M||Likes cool weather. Give afternoon shade. Needs excellent drainage.|
|8–36||July–Aug.||Y, P||FS||WD||S, L||M||Flowers open in evenings. Good rock garden plant. Some are invasive.|
|18–48||July–Sept.||P, W||FS, SS||M, WD||L||E||Also called obedient plant. A vigorous grower.|
|36||July–Sept.||Y, O||FS||WD||L||M||Flowers good for cutting.|
|10–12||May–June||W, P||SS, S||WD||L||M||Compact, spreading growth habit. Flowers similar to Astilbe.|
|24–28||June||V, P, W||SS||M, WD||L||M||Grow as biennial. Sow seed in coldframe in Aug. or Sept. A cool-climate plant.|
Gaillardia x grandiflora
|24–30||July–Sept.||Y, R||FS||WD||L||M||Easy to grow. Good cut flower.|
|12–20||July||R, O, Y||FS||WD||S||M||Divide every 3 years. Provide winter mulch.|
|24–48||July–Sept.||B||FS, SS||WD||S, L||E||Tolerates poor soil. Replant every 3 to 4 years.|
|12–18||May||Y, O||FS, SS||M, WD||L||M||Do not let dry out. Good beside pools.|
|24–36||July–Aug.||W||FS||WD||L||E||Very aggressive. May become invasive.|
|36–48||Aug.–Oct.||Y, R||FS||M, WD||L||E||Good cut flower. Divide and replant every 3 years.|
|24–60||July–Sept.||W,P, R||FS||M, WD||L||M||Also called H. moscheutos. Flowers very large.|
|48–72||July–Aug.||W,P, R||FS||WD||L||E||Best grown as biennial. Seed outdoors in July.|
|Hosta, Plantain lily,|
|6–36||July–Aug.||W, L||SS, S||M, WD||L||E||Useful as groundcover. Leaves large in some types.|
|12–36||April–June||B, V, R, P, W, Y, L, O||FS||WD||L||E||Easy to grow. Many varieties available.|
|18–36||June–July||B, W, Y, L, P||FS, SS||M, WD||L||M||Suitable at the edge of ponds. Replant every 4 to 5 years.|
|18–24||May–June||W, B||FS, SS||M, WD||L||E||Likes rich soil. Never let dry out.|
|12–18||June||P||FS, SS||WD||S, L||M||Will grow in dry, poor soils. Woolly grayish leaves.|
|10–12||June–July||Y||FS, SS||M||L||M||Compact, spreading habit. Prefers a cool, moist location.|
|12–20||July–Aug.||L||FS||WD||S||M||Likes poor soil. Very fragrant foliage.|
|8–12||Aug.–frost||B||FS||WD||S||E||Sometimes called plumbago. Semiwoody groundcover.|
|5–8||Feb.–March||W||SS||M, WD||L||C||Needs rich soil. Do not transplant or cultivate.|
|12–18||April||Y||FS, SS||M, WD||L||E||Dormant in July–Aug. Plant among spring bulbs.|
|24–48||July–Sept.||W, L||FS||WD||S||E||Adapts well to dry locations. Spike flowers open from top downward.|
|6–10||Aug.||V, W||FS, SS, S||WD||S, L||E||Evergreen border plant or groundcover. Cut back old growth in spring.|
|6–8||May||W, P||SS||M, WD||L||E||Used for groundcover and cutting of flowers.|
|18–30||July–Sept.||Y||FS, SS||M, W||L||E||Needs semishade in dry soils.|
|8–12||May–June||B||SS, S||M||L||M||Very distinctive foliage with unusual variegation.|
|24–40||June–July||B, W, P, Y||FS, SS||WD||S||C||Dislike hot summers. Short-lived in Midwest.|
|24–30||June–July||P, V, W||FS, SS||M, WD||L||M||Foliage like columbine. Male and female plants.|
|24–36||June–July||W, P||FS, SS||WD||L||E||Fleecy, graceful flowers. Prefers humusenriched soil.|
|Painted daisy, Pyrethrum,|
|12–24||June–July||P, R, W||FS||WD||L||C||Will not tolerate wet soils. Replant every 3 years.|
|6–10||April||B, W||FS||WD||S||M||For rock garden. Needs good drainage. No acid soil.|
|18–36||May–June||W, P, R||FS, SS||WD||L||E||Transplant in Sept. Plant 2 to 3 inches deep in rich soil.|
Salvia x superba
|18–24||June–July||B, V||FS||WD||L||E||Effective blue flower color.|
|3–5||April–May||P, L, W||FS||WD||S||M||Also called ground pink or thrift. Tolerates poor soil.|
|18–48||June–Sept.||R, P, L, W||FS, SS||WD||L||M||Many varieties available. Sometimes listed as P. decussata.|
|18–24||June–July||B||FS||WD||L||M||Unique flower with conspicuous stamens.|
|10–15||May–July||R, W, P||FS||WD||L||M||Very fragrant. Bluish gray foliage. Edging plant.|
|4–9||May||R, P, W||FS||WD||S||M||Dwarf pink. Gradually spreads to form a green mat.|
|8–12||June||R, O, P, W||FS, SS||WD||S||M||Often grown as annual. Seeds started indoors will flower in first season.|
|24–40||May–July||O, R, P, W||FS||WD||S||E||Needs good drainage. Place in protected spot, or mulch in winter.|
|8–12||May||B, O, Y, R||SS||WD||S||M||Must be kept moist. Cannot survive summer heat and drought.|
|Red-hot poker, Tritoma,|
|36–48||July–Sept.||O, Y, P, W||FS||WD||S||E||Needs excellent drainage. Mulch in winter.|
|5–10||June–July||P, W||FS||WD||S||M||Pruning back helps retain compact form. Needs good drainage.|
|36–48||June–July||B||FS||WD||L||E||Uniquely colored, aromatic foliage. Good companion for plants with yellow flowers.|
|15–24||Aug.–Sept.||B, W||FS||WD||S||M||Sometimes called statice. Large decorative foliage.|
|4–24||June–frost||P, R, Y, W||FS||WD||S||E||Many species available with differing growth habit and flower color.|
Leucanthemum x superbum
|12–36||June–Aug.||W||FS||WD||L||M||Needs replanting every 2 to 3 years. Dwarf and tall forms available.|
|3–5||May–June||W||FS||WD||S||M||Small gray woolly leaves. Forms dense carpet. Needs excellent drainage.|
|8–24||May–Aug.||B, V, W||SS, S||M, WD||L||E||Easily grown. Roots easily from the nodes.|
|12–30||Aug.–Sept.||B, W, P||FS||WD||S||M||Needs good drainage. Mulch in winter.|
|Sweet pea, Perennial,|
|60–96||June–Aug.||P, R, W||FS, SS||M, WD, D||L||E||Very easy to grow. May crowd out other plants.|
|6–15||May–June||R, P, W||FS||WD||S||E||Biennial that self-sows easily. An “old-fashioned” favorite.|
|8–12||June–July||P, V, W||FS||WD||S||E||Needs good drainage. Mulch in winter. An everlasting.|
|24–36||June–July||Y, O||FS||WD||L||E||Tolerant of dry soils. Good for low maintenance areas.|
|2–36||May–Sept.||B, W||FS||WD||L||E||Easy to grow. Species differ in growth habit.|
|6–8||April–May||V, L, W, Y||FS, SS||WD, M||L||E||Forms a dense mat. Reseeds easily.|
|2–36||June–Aug.||Y, P, R, W||FS||WD||L||E||Easy to grow, but should be replanted every 3 to 4 years.|