Salvia farinacea 'Victoria Blue'
Flowers are the horticulturist’s reward for hard work. Flowers and flower borders, those accents that enliven the landscape, provide color against the bulk of green. They complement conventional landscaping features such as trees and shrubs. They visually alter heights and slopes, adding depth and dimension, form and texture.
An herbaceous perennial is a hardy plant that will remain in the garden summer and winter for years, although the top portion dies back each winter. It seldom blooms for more than a few weeks.
Not all herbaceous perennials are created equal. Some have very specific requirements whereas others thrive across a broad range of conditions. Some are relatively short lived, dying out in three to four years, while others will live 30, 40, 50 years or more!
The herbaceous annual blooms all season, but is killed by freezing temperatures. It remains in the garden for only one growing season, although it may self-seed and return to your garden as a “volunteer.” Like the annual, a biennial is a short-lived plant, but it completes its life cycle in two years. Like the perennial, it blooms for a limited period of time.
- In choosing a site, consider sunlight (full sun to heavy shade), slope (which affects temperature and drainage), soil type, and the role the plants will play in your garden.
- Locate a traditional herbaceous garden in front of a suitable background, such as a fence, row of tall flowers, shrubbery, or a building. Take advantage of the shape and topography of the land in laying out lines. More contemporary designs include the island bed and the incorporation of flower beds with architectural features such as pools, decks, and paths.
- Avoid a ruler-straight front edge. Edge the garden with a curve, easily laid out with a garden hose. The deeper the curve, the slower the eye moves, and the greater the visual enjoyment. Outline the border with bricks or flat stones set flush with the soil to minimize trimming after mowing.
- Select key plants for:
- Line—the silhouette or outline of a plant.
- Mass—the shape or denseness of the plant.
- Dependability—the plant’s ability to remain attractive with a minimum of problems.
- Establish plants in groups large enough to form irregularly shaped masses of color or texture. Five or so small plants or a single large plant, such as a peony, will create the desired effect. A random collection of different small to medium-sized plants will present a disorganized, checkerboard appearance. Don’t set in rows but in groups, as they would grow in nature.
- Allow enough space for each group to grow comfortably, but manipulate the space for effect. Reduce the spacing if you want a solid mass of plants for an “instant” garden. Increase it if you want individual plants to be conspicuous as specimens.
- Place tall flowers in the back part of the bed, medium-height species in the middle, and dwarf varieties along the front. Limit plant height to two-thirds the width of the bed. For example, no plants taller than four feet in a bed six feet wide. Break up height lines by letting some tall plants extend into the medium-height groups, giving a more natural effect.
- Consider each plant’s period of bloom. The longer the bed has flowers in bloom, the more you will enjoy it. Vary the blooming season for a steady succession of color.
- Too often, planning tends to focus on bloom time and flower color. Consideration should also be made for plant structure, habit, and foliage characteristics. Foliage is typically present on herbaceous plants throughout the growing season, whereas bloom is seldom expressed for more than a few weeks.
- Put the plan to scale on graph paper. It’s far easier to move plants using an eraser than to physically shift them with a shovel. You might make a plan for each season, indicating which plants will be actively blooming during that time.
Publications: HG 94 - IPM Series: Annuals and Perennials
HG 20 - Introduction to Herbaceous Perennials
HG 89 - Ground Covers