Annual, Perennial, Biennial, Ephemeral: Explaining Common Garden Terms
For the newbie gardener, there are lots of garden terms to come to terms with. Have you ever wondered what makes a perennial a perennial? And what makes an annual an annual? And what in the world are biennials and ephemerals!? Garden expert Christina Conner breaks down what each of these terms means and what some common examples of each.
Contents
In the world of gardening, there are many terms to become comfortable with. For the novice gardener, this can feel overwhelming! One family of terms that refers to the growing cycle of plants can be particularly challenging. What the heck do the words annual, perennial, biennial, and ephemeral mean!?
In short – annuals live for only one season, perennials and ephemerals last many, while biennials live for two years. This might also be a good time to differentiate the terms die versus die back. This distinction can also be challenging for many new gardeners. When an annual dies, it’s dead dead. It will not come back in spring, though it may spread seeds. For perennials, their foliage will die back before pushing out new growth in spring.
It can get a little confusing if you’ve moved from significantly different climates. Many perennial plants in Miami would likely be annual in Northern Colorado. A South Floridian invasive species might even be considered a harmless houseplant in colder climates. This is when consulting with the USDA heat zone map and your local extension office is especially important.
If this is getting over your head, fear not. Here are the differences between the terms annual, perennial, biennial, and ephemeral:
Annual
Many of the colorful flowering plants that we see exploding from planters, window boxes, and hanging baskets in summer are annuals. They’re called annuals because they last a single season before dying during the first frost. Generally speaking, they will not return the following season and will need to be replanted.
There are several types of annuals. Some hail from tropical locales where they may be perennial, while others are “true annuals” that complete their life cycle in one season, such as zinnias, sunflowers, and marigolds. No matter what climate they’re in, they will grow, flower, set seed, and die in a single season.
Three Types of Annuals:
- Hardy annuals: These are commonly called fall or winter annuals. They dislike scorching hot summer days and tolerate cooler temperatures down to the low 40s (~4°C) and even the occasional frost or freeze once established. They can be planted earlier in spring or later in summer. Pansies and snapdragons are two common flowers. That said—they are still annuals. Once temperatures are consistently below freezing, they likely won’t survive. In mild winters, however, they may resurge in spring.
- Semi-hardy annuals: These are similar to hardy annuals in what they can handle but aren’t quite so tough. They tolerate cool temperatures but will be damaged by frost. They’re slower-growing than other types, so if starting these from seed, do so about a month in advance of the first anticipated frost. Examples include baby’s breath and strawflower.
- Tender annuals: These plants unequivocally hate cold weather and will not survive a frost. They thrive in heat. These are tropical plants that love the summer! Examples include begonia, coleus, and marigold.
What about summer vegetables? Yes—most are considered annuals, and new plants will need to be planted in spring. A few, like rhubarb and asparagus, are biennial or perennial.
Common annual species include (note that these are sometimes perennial or biennial depending on the climate they’re grown in):
| Petunia | Petunia spp. |
| Viola | Viola cornuta |
| Impatiens | Impatiens walleriana |
| Celosia | Celosia argentea |
| Snapdragon | Antirrhinum majus |
| Zinnia | Zinnia elegans |
Biennial
Biennials are a little bit more complex. They complete their life cycle over two years instead of just one. The first year a biennial is planted from seed, it will grow foliage, and develop a root and food storage system, but you won’t see any flowers. The next year, the biennial will produce a longer stalk and flower, producing fruit and seeds before dying at the end of the season.
But sometimes, a biennial can go from germination to setting seed in one season! This is what’s known as bolting—just to throw another horticultural term at you. Bolting is when a biennial is exposed to temperatures that signal it’s time to reproduce. The plant then quickly accelerates its growing season. This is essentially the plant jumping ship and giving its seeds a chance of survival. I could give more metaphors—the pilot of a fighter jet jumping out in a parachute, the SOS signal of the Titanic, but you get the point. The plant starts to put its energy toward seed production because it thinks it’s dying.
Biennials aren’t quite as common as perennials and biennials, but that doesn’t mean they’re anything short of exquisite. Again, climate is the determining factor as to whether or not these plants are biennial, but in most regions of North America, these are.
| Foxglove | Digitalis purpurea |
| Hollyhock | Alcea rosea |
| Swiss Chard | Beta vulgaris subsp. vulgaris |
| Dame’s rocket | Hesperis matronalis |
| Sweet William | Dianthus spp. |
Perennial
In short, perennials come back year after year. Some may stay evergreen through winter, while some will die back to the ground after frost. The operative word here is “die back.” While the foliage above ground may drop, the root system survives underground. In spring, the plant will come back and grow bigger each year. Perennials can live for years and years, be divided, or even be passed down through generations.
While annual species offer a quick way to add color to the garden, perennials require more patience, but the payoff is worth it. Once they’ve established themselves in the garden, they tend to be lower maintenance and don’t need to be replanted each year. As some perennials grow, their roots will grow deep into the soil and thrive on neglect, unlike shallow-rooted species.
That said, when planting perennials, you need to keep their full-grown size at maturity in mind. Provide plenty of space between plants to prevent overcrowding and let them grow big and strong! At first, there may be an awkward amount of unnatural-looking space between plants. Over time, they will grow and fill in the spaces.
Interspersing the perennial bed with annuals in their first few seasons can be a great strategy to fill in gaps. They may even self seed and grow new plants the following season.
Two Types of Perennials:
- Herbaceous perennials are soft-stemmed plants that will die back to the ground in winter. They typically benefit from being pruned. In spring, new growth will appear from the plant’s crown. Yarrow, hostas, and catmint are examples of herbaceous perennials.
- Woody perennials include trees and shrubs and anything else with a woody stem. These stems withstand the cold, so don’t prune them. Flowering maple and wormwood are examples of woody perennials.
You may have also heard the term “tender perennial.” This is a type of perennial that cannot survive frosts and will only act as a perennial in mild or warm climates. Tender perennials may be considered annuals in colder climes.
It’s especially important to do your research and pay attention to the USDA heat zone map when selecting perennials. A perennial in Zone 8 may not be able to withstand the cold winters of Zone 4. Big box stores aren’t always the best at properly labeling annuals and perennials based on the local climate, so I recommend sourcing perennials from smaller, more knowledgeable plant nurseries or plant societies.
| Yarrow | Achillea millefolium |
| Coneflower | Echinacea spp. |
| Hostas | Hosta spp. |
| Catmint | Nepeta spp. |
| Shasta Daisy | Leucanthemum x superbum |
| Blanket Flower | Gaillardia spp. |
Ephemeral
Think of ephemerals as the early birds of the plant world. Meaning “existing briefly,” ephemerals appear and disappear before all of the other forest plants. Their strategy? Before the forest canopy shades out the forest understory, ephemerals have evolved to soak up all the sunlight and warmth that they can. This evolutionary trait allows them to then sail through summer without needing to compete for resources. For ephemerals, the early bird really does get the worm.
Ephemerals are usually native plants and are especially abundant in the southeast and mountains of Appalachia. Generally speaking, ephemerals are perennials with a tuber, rhizome, or other bulbous underground structure. They provide a food source for animals emerging from hibernation and nectar for pollinators like bumblebees, wasps, and flies.
Many ephemerals are natives and may already be in your yard! Sadly, many are rare, threatened, or endangered. Because they’re less common, sourcing them from a rare or native plant nursery or botanical garden is your best bet for obtaining some of these plants.
| Lady Slipper Orchid | Cypripedium reginae |
| Bloodroot | Sanguinaria canadensis |
| Trout Lily | Erythronium americanum |
| Trillium | Trillium spp. |
| Mayapple | Podophyllum peltatum |
| Virginia Bluebells | Mertensia virginica |
