Just as different animals have different life cycles, so too do plants. Understanding the basic life cycles of plants, their differences as well as their similarities, can make you a better gardener by preparing you for each life cycle's unique aspects. Without understanding the differences in basic plant life cycles, you may misdiagnose what is happening with your plants and make inappropriate decisions pertaining to their care.
Plant life cycles are based on the length of time it takes them to reach reproductive maturity. The plants that complete this process in a single year or growing season are called annuals. Many plants are unable to produce flowers, fruits or seeds until the second year. These are called biennials. Plants that die back each year, generating new vegetative growth annually are known as herbaceous perennials. Those plants that have woody stems and survive cold temperatures fall into the woody perennial category.
Most plants begin from a seed which contains an embryonic version of the plant and the food necessary to sustain it through the first part of its life. When temperatures become warm enough and moisture is present, the seed begins to send out both a root and a main stem. These will form the main support for the plant throughout its life. Once the stem has emerged from beneath the soil, it begins to develop foliage. This can include leaves and more stems or branches.
Annual plants reach full maturity in one growing season. Once the plant has reached maturity, it develops flowers. The flowers attract pollinators such as bees. This triggers the production of fruit which ultimately will house the new seeds. Once the fruit has developed, it is dispersed in order to spread the seeds. This can happen through human or animal intervention or because of wind and other elements dislodging the fruit or seeds. Annual plants die each year and new seeds generate new plants the following year. Examples of annuals are tomatoes and zinnias.
Biennial plants spend the first year producing only the vegetative parts of their structure, leaves and stems. These will store food and allow the plant to overwinter. The second season biennial plants will follow the same pattern as annual plants, developing flowers followed by fruit which eventually releases new seeds. Biennial plants generally die off after the second year. Examples of biennial plants are blackberries and raspberries.
Herbaceous perennials grow new stems each year. These stems produce flowers, fruits and seeds as well. Once seed production is complete for the season, the stem dies back down to the ground. In subsequent years, these plants will send up new stems and the process will continue. These plants can live for many years. Some examples of herbaceous perennials are peonies and hydrangeas.
Woody perennials are the large shrub and tree plants. Many of these plants can take several years before they reach maturity. Each year they continue to grow in height and width until they reach sexual maturity. At this point the process of flower, fruit and seed production commences. Woody perennials do not die back each but rather become dormant during winter months and then continue growing when the spring temperatures are warm enough.