Flowering Perennials: Characteristics and Culture

Reviewed by David H. Trinklein
Division of Plant Sciences

Mary Kroening
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.

Figure 1
Mixed borders of both perennials and herbaceous perennials can provide an interesting landscape year-round.
 

Description of terms and codes

Height

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.

Bloom period

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.

Color(s)

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)

Cultural requirements

Light

• 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.

Moisture

• 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.

Soil

• 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.

Relative ease of care

• Easy (E)
• Moderate (M)
• Challenging (C)

Remarks

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.