- Describe seasonal plants common to the horticulture industry.
Planning combinations of woody and herbaceous plants with different life cycles and high visual impact generates year round interest in exterior and interior plantings. When visual interest is planned for one period such as early summer, borders and containers can have a poor appearance the rest of the year. Optimizing the use of grasses, bulbs, perennials, annuals, biennials, shrubs, climbers, and trees can provide a succession of plant forms, colours, textures, and habits throughout the seasons. In temperate regions, year round interest is maximized by selecting plants with at least two, and even three or four seasons of interest.
Conifers and broadleaf evergreens shrubs are often used for year round colour and spatial structure. For example, Taxus cuspidata ‘Capitata’ (upright yew) provides reliable winter colour and a framework that can be enhanced with other shapes, textures, and colours. On the other hand, a planting of broadleaf evergreens such as Skimmia japonica (Japanese skimmia) offers winter colour and structure as well as showy spring flowers and colourful fruit in the autumn. Distinctive plant shapes and the bark of trees such as Cryptomeria japonica (Japanese cedar) and Morus alba ‘Pendula’ or species with persistent fruit like Sorbus aucuparia (European mountain ash) also contribute structure and winter interest.
Some deciduous shrubs and trees like Caryopteris x clandonensis (bluebeard), Cercidiphyllum japonicum (katsura), and Rhus typhina (staghorn sumac) have interesting branching patterns throughout all seasons. The bark and buds of Ribes sanguineum (flowering currant, winter currant), Magnolia x soulangeana (saucer magnolia), Liriodendron tulipifera, and Styrax japonicus (Japanese snowbell, Japanese snowcone) provide winter interest and interesting buds forecast the appearance of foliage and flowers. Climbers with variegated or textured foliage and colourful flowers like Actinidia kolomikta (actinitdia) and Campsis radicans (trumpet vine) also contribute vertical structure. View the images seasonal plant characteristics available at this link to the KPU Plant Database [New Tab]
The appearance of plants before, during, and after flowering is an important consideration for planning seasonal interest. For example, the herbaceous specimen plant Gunnera manicata (gunnera, giant rhubarb) provides a bold shape and texture for at least half to perhaps three quarters of the year. With planning, the eye catching winter stems and seed heads of grasses and perennial species such as Pennisetum alopecuroides (fountain grass), Pennisetum setaceum ‘Rubrum’ (red fountain grass), and Perovskia atriplicifolia (Russian sage) can serve as distractions from seasonal voids. Layering various heights of ground covers, bulbs, annuals and perennials under and around woody shrubs and trees allows a succession of foliage shapes, sizes, textures, and colours to become prominent as the year progresses. In this way, emphasis is placed on year round interest and not only the seasonal show of flowers. A planting calendar is a useful tool for working out the succession of flowers and colour palettes as well as other planting design features. Figure 8.1 shows an example of a basic planting calendar that allows the planner to visualize the times of the year that are most colourful and interesting and those that could use additional development.
As the succession of spring bulbs like Anemone blanda (Greek windflower, blue wood) and Hyacinthus cvs. (hyacinth) finish flowering and foliage fades, deciduous shrubs such as Spiraea x vanhouttei (bridal wreath spirea) and an array of herbaceous annuals, biennials and perennials come into flower in early and mid spring. Examples of spring blooming perennials include Aubrieta x cultorum (common rock cress), Brunnera macrophylla (Siberian bugloss), Papaver orientale (oriental poppy), Pulmonaria saccharata (lungwort), and Dicentra spectabilis (bleeding heart). From late spring and early to mid summer, the flowers and foliage of broadleaf evergreen shrubs such as Daphne cneorum (garland daphne) and herbaceous species like Thymus pseudolanuginosus (woolly thyme), Heuchera cvs. (coralbells, alumroot), and Phlox paniculata (common phlox) take prominence. The progression of seasonal foliage and bloom continues in mid to late summer and through autumn with perennials such as Actaea simplex Atropurpurea Group (cimicifuga), Aster spp. (common aster), Astrantia major (masterwort, astrantia), Coreopsis spp. & cvs. ( coreopsis), Geranium spp. & cvs. (geranium), and Gaillardia cvs. (blanket flower). The texture and seed heads of perennials like Hylotelephium spectabile (autumn joy sedum, stonecrop), and grasses such as Andropogon gerardii (big bluestem), Calamagrostis x acutiflora (feather reed grass), and Molinia arundinacea ‘Skyracer’ (tall moor grass) extend the visual interest from late autumn into winter. Year round interest is fulfilled by evergreens and the flowers of winter blooming shrubs and perennials. View images of the seasonal plant characteristics available at this link to the KPU Plant Database [New Tab]. Read more about seasonal plant combinations at this link to Gardenia Seasonal Garden Ideas [New Tab].