The Difference Between Annuals, Perennials and Biennials
The label annual, perennial or biennial appears on plant tags at the local nursery, but it never hurts to remind ourselves what these familiar gardening terms actually mean.
If you understand the growing habits of existing plants in your yard–basically, which of these three types they are–then you can add blooms accordingly for year-round interest to maximize your garden’s potential.
However, a plant’s status as one of these three types largely depends on the location and climate it’s grown in. For example, extreme climates can drastically shorten the life span of parsley, normally a biennial, so some gardeners may treat it in the garden as an annual.
We’ve also included several examples of annuals, perennials and biennials that thrive in Southern California gardens.
All About Annuals
While the name is somewhat deceiving, annuals are plants that seed, grow and die all in one cycle. They are typically more inexpensive than perennials because of the need to completely replace them each year.
Some annuals are self-seeding, meaning that seeds from your plant could blow to other parts of the yard and sprout the following season. You won’t have total control over where the next batch of annuals appears but it works with many garden styles.
A common mistake made is pairing annuals with high water needs with succulents and other plants requiring less watering so be sure to group like plants. Here are some easy-to-care-for suggestions.
While marigolds can be grown from seed, they are very cheap to buy as young plants in local nurseries. Colors range from yellow to burnt red with even multicolored varieties available. They are edible (though be sure to use organic pest control and compost if you intend to consume them) and some varieties are thought to ward off some pests. Deadhead them for best results.
Big on color and low on maintenance zinnias are easy to grow as border plants, in containers and basically anywhere you’d like to add color. In fact, your kids could even plant them by seed (they do need a little sun to germinate so don’t plant them too deep). They need sun and well-draining soil. If you deadhead them, which can be quite a chore on these little robust plants, you’ll be rewarded with even more blooms. Zinnias are perfect choices for beginning gardeners.
It’s all in the striking leaves, big and small. Coleus plants that have red and purple pigments can handle lots of sun, while those with yellow and green colorations prefer less. Read the pots while shopping for them to verify growing conditions but they are extremely rewarding to grow as a year-round color alternative. They also do well in containers and don’t always need yearly replacing in our climate if cared for properly.
Perennials typically live for multiple growing seasons. You can plant them from seed or bulb, but they are often found for sale as young plants. Because they don’t bloom as long as annuals do, it’s common for gardeners to stagger perennials with different blooming seasons in order to maintain color throughout the yard. The species below are low-maintenance Southern California favorites.
These days, agapanthus (lily of the nile) comes in a a variety of blues and purples as well as white. Agapanthus lasts for years in Southern California, shooting up tall stalks of flowers up to 3′. When not in bloom, the leaves grow in small clumps which can be divided once the plant is mature enough.
Kangaroo paw —
A native of Australia and common feature in San Diego water-wise gardens, Kangaroo paw come in dwarf and full sizes with blooms ranging from pink to yellow. Shades of red are the most popular. Kangaroo paw need sun and will not tolerate overwatering. Blooms are at their fullest in the spring and summer. They earn their name from the fuzzy flowers that are shaped like kangaroo paws.
Bird of paradise —
Known for its striking orange flower, bird of paradise grow extremely well in San Diego with very little care. They grow up to 6′ tall (usually less in Southern California) and 4′ wide. These perennials require sun and look great on their own or in large groupings. Contrast the striking foliage with water-wise agave and other succulents.
Hens and chicks —
Often used as a water-wise ground cover or lawn replacement, hens and chicks are striking little succulent rosettes that shoot off smaller rosettes as they spread. Hens and chicks come in a wide range of leave shape and colors. They do need occasional water to thrive as not much is stored in their small leaves.
Southern California Biennials
A biennial plant takes usually two growing seasons to complete its life cycle. During the first year, the plant grows its support system–roots, leaves and stems–and may go dormant in cold weather. During the second year, the plant grows dramatically and may produce fruit or seeds before it dies.
While dahlias are technically perennials, gardeners in Southern California grow them as biennials, replacing them annually as they die back. Occasionally, if the tuber is removed and stored properly or (in rare cases) left happily in temperate ground, they’ll rebloom annually. From 12″ dinnerplate dahlias to smaller, single petal varieties, these stunning plants are a great way to add color to your yard.
If you’ve ever felt the disappointment of buying a young herb plant and having it immediately flower off and die (we’re looking at you, cilantro), you’re not alone. In Southern California parsley is a biennial which means it usually lives for up to two years which is a long time for normally short-lived herb plants. When flowers appear, that is when you know it’s time for a new plant.
Sweet William —
While the name might not ring a bell, the flower is recognizable and its easy to find at local nurseries. Sweet William provides single or double blooms in a variety of color. Some are short-lived perennials but many are biennials that can even provide year-round color. Professionals say that there is a Sweet William (pictured above) for virtually every type of yard and growing condition so ask your local nursery to help you find one to suit your outdoor living space.
Which annuals, perennials and biennials do particularly well in your yard?
Photo credit: Marigolds, Flickr/pfsullivan_1056; hens and chicks, Flickr/27398485@N08; Sweet William, Flickr/duncanh1