Perennials are plants that persist for many growing seasons. This category includes trees, shrubs and many herbaceous plants. Plants are classified as herbaceous if the top dies back to the ground each winter and new stems grow from the roots each spring.
When perennial plants die back in the fall, they experience dormancy with the first hard frost. The roots persist through the winter, and every spring new plant tops arise. Any plant that lives through the winter is said to be hardy. There are many advantages to perennials, the most obvious being that they do not have to be planted every year, like annuals. Another advantage is that with careful planning, a perennial flower bed will change colors as one type of plant finishes, and another variety begins to bloom. Also, since perennials have a limited blooming period of an average of 2 to 3 weeks, deadheading, or removal of old blooms, is not as frequently necessary to keep them blooming. However, they do require pruning, and dividing to keep them attractive and healthy. Their relatively short bloom period is a disadvantage, but by combining early, mid-season, and late-blooming perennials, a continuous colorful show can be displayed.
Annual flowers live only for one growing season, during which they grow, flower, and produce seed, thereby completing their life cycle. Annuals must be planted or seeded every year. Some varieties will self-sow, or naturally reseed themselves. This may be undesirable in many flowers because the parents of this seed are unknown and hybrid characteristics will be lost and may scatter everywhere instead of growing in their designated spot. Some perennials, which are plants that live from year to year, are classed with annuals because they are not winter-hardy and must be set out every year; begonias and snapdragons are examples. Annuals have many positive features. They are versatile, sturdy, and relatively inexpensive. Plant breeders have produced many new and improved varieties. Annuals are easy to grow, produce instant color, and, most important, they bloom for most of the growing season.
“Bulb” is a term sometimes used loosely to include corms, tubers, tuberous roots, and rhizomes as well as true bulbs. True bulbs, such as daffodils have internal layers filled with carbohydrates with a flower stored inside. It has a basal plate where roots grow, and fleshy scales or layers
The foliage must die back to build next year’s flower. A tuber is propagated by division and “eyes” form on the surface (e.g. potato). A rhizome is a modified stem with food storage capacity. Its roots grow along the ground. A corm is a fleshy, starchy underground stem that produce “cormlets” around the mature portion.
Some Best Management Practices for Annuals, Perennials and Bulbs
- Test the soil to learn pH and nutrients already present; then select plants that will grow in the conditions in the landscape
- Determine soil drainage capacity before planting
- Avoid planting invasive species; instead choose plants, especially native plants, that minimize maintenance and increase habitat http://www.dcr.virginia.gov/natural-heritage/invsppdflist, https://www.plantnovanatives.org/
- Group plants with similar needs (water, fertilizer, sun…) for easier maintenance
- Use plants or mulch to conserve water, suppress weeds and prevent soil erosion
- In times of low precipitation, irrigate the plants deeply and infrequently at a rate of one inch per week
- Irrigate early in the morning, rather than late at night, to minimize evaporation losses and allow plants to dry off before evening. Avoid overhead watering.
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Perennials: Culture, Maintenance and Propagation VT Publication 426-200. See https://pubs.ext.vt.edu/426/426-203/426-203_pdf.pdf
Annuals – Culture and Maintenance VT Publication 426-200. See www.pubs.ext.vt.edu/426/426-200/426-200.html
Flowering Bulbs: Culture and Maintenance VT Publication 426-201. See www.pubs.ext.vt.edu/426/426-201/426-201.html