Figure 1
Mixed borders of both perennials and herbaceous perennials can provide an interesting landscape year-round.
Flowering perennials: Characteristics and Culture
David H. Trinklein
Department of Horticulture
Flowering perennials represent a large group of garden plants. Their common
characteristic is that their roots 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 the perennial flower border.
Below is a list of some of the major perennial plants, their important characteristics
and cultural preferences.
Space is not available in G6650 to fully describe the plants and flowers. Garden
catalogs or a visit to a nursery, garden center, or botanic garden will all help
to familiarize you with available plants.
Description
of terms and cultural requirements
Height
The height range, given in inches, helps to determine whether a plant
is suitable for an edging (1 to 12 inches), for the middle of a bed (12 to 36
inches), or for a background plant (more than 36 inches). Where a very wide range
is given (such as Bellflower, 8 to 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.
Colors
Each plant is keyed with its most common color or colors. Many blends,
shades and tints exist.
Light
- Full sun
Locate the plant away from the shade of buildings, large trees, or other
objects that will not allow the plant at least six hours of direct sunlight each
day.
- Semi-shade
Give partial shade either as a long period of light shade, or more dense
shade during the afternoon. Most plants in this category must have shade during
the hottest part of the day.
- Shade
These plants must have continuous shade with no direct sun. In heavy
shade, other necessary cultural requirements must be carefully fulfilled.
Moisture
- Well drained
Periods of standing water on the soil are damaging to perennials both
in 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.
- Dry
These plants will not tolerate moist conditions very long, but they
will withstand considerable dryness.
- Moist, but well drained
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
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
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, it should be amended by mixing in at least 4 inches of organic
matter.
- Sandy loam
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
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 can be mixed thoroughly with the soil to achieve this
condition, and annual applications of sulphur may be necessary for maintenance.
- Woodland soil
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
- Moderate
- Challenging
Remarks
Unusual or outstanding plant and cultural characteristics have been
listed briefly. Included are notes on cultural ease, winter hardiness, special
uses, or emphasis of an extremely important cultural requirement.
G6650, revised May 2002
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