At a glance
| Annual | Completes its life cycle in one growing season; replant yearly unless it self-sows |
|---|---|
| Biennial | Two seasons: leaves and roots in year one, flowers and seed in year two, then dies |
| Perennial | Lives more than two years; herbaceous types die back in winter, woody types keep stems |
| Tender perennial | Perennial in warm climates but killed by frost, so grown as an annual in cold zones |
| What decides it in your yard | The plant's cold hardiness compared with your USDA zone |
| Bloom length | Annuals: most of the season. Perennials: often a few weeks each year |
| Replanting | Annuals: every year. Perennials: occasional division or replacement |
| Check your zone | Zone finder by ZIP code |
Definitions: annual, biennial and perennial
Oregon State University Extension, University of Illinois Extension and the NC State Extension Gardener Handbook define the three life cycles the same way:
- Annual: a plant that germinates, grows, flowers, produces seed and dies within one growing season. Zinnias and marigolds are familiar examples, along with crops such as corn and beans (NC State Extension). The next generation comes only from seed.
- Biennial: a plant that needs two growing seasons. In the first year it makes leaves (often a low rosette) and food storage organs, and the rosette persists through winter. In the second year it flowers, sets seed and dies. Foxglove, hollyhock, sweet William and parsley are common garden biennials (NC State and Oregon State Extension). Carrots, beets, Swiss chard and celery are also biennials, but they are harvested in year one, before they flower.
- Perennial: a plant that lives more than two years; NC State Extension notes some live for decades or even centuries. Herbaceous perennials such as peonies, hostas, daylilies and coneflowers (Echinacea) die back to the ground each winter and regrow from their crowns and roots. Woody perennials, meaning trees, shrubs and woody vines, keep living stems above ground all year.
The word "perennial" on a plant tag usually means herbaceous perennial. Trees and shrubs are technically perennials too, but they are sold and discussed separately.
Annuals vs perennials compared
| Annuals | Perennials | |
|---|---|---|
| Lifespan | One season | More than two years; some for decades |
| Bloom season | Long; many flower from planting until frost | Usually a defined window of a few weeks, varying by species |
| First-year show | Full size and bloom the first summer | Clemson HGIC notes many won't bloom the first year |
| Replanting | Every year (except self-sowers) | Rarely; divide crowded clumps every few years |
| Best uses | Containers, seasonal color, filling gaps, cut flowers | Long-term beds, borders, pollinator gardens, groundcovers |
| Soil preparation | Yearly, light | Once, thoroughly, because the plants stay put for years |
| Winter | Killed by frost (tender) or by finishing their life cycle | Dormant underground (herbaceous) or leafless/evergreen above ground (woody) |
Neither is better. Clemson HGIC's perennial guide stresses thorough soil preparation because perennials may stay in place for many years. University of Georgia Extension notes that many annuals, properly cared for, brighten the landscape continuously from spring until frost. Most gardens use both: perennials for structure that returns each year, and annuals to carry color between perennial bloom times.
Types of annuals: cool-season, warm-season and self-sowing
University of Georgia Extension's guide to flowering annuals divides them by temperature tolerance (hardy, half-hardy and tender), which tells you when to plant them:
| Group | Frost tolerance | When to plant | Examples |
|---|---|---|---|
| Hardy and half-hardy (cool-season) annuals | Hardy types withstand freezing; half-hardy types may withstand light frost | Early spring, or fall in mild-winter regions | Pansies (hardy); calendula, annual phlox and snapdragons (half-hardy) |
| Tender (summer) annuals | Not frost-tolerant | After the danger of frost has passed | Zinnias, vinca, impatiens, sunflowers, cleome |
| Self-seeding annuals | Varies | Once; seedlings may return on their own | Cleome, larkspur, California poppy, alyssum |
Several popular "annuals" are technically perennials in their native climates and are simply grown as annuals. The site answers the most-searched cases one by one: marigolds, petunias, and impatiens, along with snapdragons, pansies and others.
Biennials: the two-year plants
Biennials confuse gardeners because the plant you buy in bloom is usually in its second and final year. After it sets seed, it dies. Many biennials self-sow heavily, though, so a patch of foxglove or hollyhock can look perennial: new seedlings replace the plants that died each year.
- Year 1: sow seed in late spring or summer. The plant forms a leafy rosette and no flowers.
- Winter: the rosette needs a cold period to trigger flowering.
- Year 2: it sends up flower stalks, sets seed and dies.
To keep biennials blooming every year, sow seed two years in a row, or let plants drop seed and leave the seedlings where they come up. The two-year cycle for one of the best-known biennials is laid out in hollyhock care.
Why your zone decides whether a plant comes back
"Perennial" describes a plant's life cycle. Whether it survives your winter is a separate question. The USDA Plant Hardiness Zone Map (2023 edition) is based on the average annual extreme minimum winter temperature, shown as 10°F zones and 5°F half zones (such as 7a vs. 7b). A plant rated for zones 8–11 is a perennial in Gulf Coast gardens but dies in a zone 5 winter, so in zone 5 it behaves as an annual.
These tender perennials account for many of the plants that are "annuals" in the North:
- Begonias, impatiens and geraniums, which University of Georgia Extension lists as tender perennials killed by frost when left outdoors
- Many other bedding plants: NC State Extension notes that many are perennial in the wild but treated as annuals in the garden
- Plants with tender tubers or rhizomes, which can be dug and stored indoors (see how to overwinter tender perennials)
Before buying a perennial, compare its zone rating with yours. Look up your zone with the zone finder. A plant hardy only to your exact zone is marginal: it may come through mild winters and die in a hard one.
Do perennials come back every year?
Perennials that are hardy in your zone and planted in conditions they like come back every year. A few things to know:
- Lifespans vary a lot. Iowa State University Extension notes 50- to 60-year-old peonies are not uncommon in older Iowa neighborhoods, and University of Missouri Extension says peonies can last decades or even a century when undisturbed. Iowa State lists columbine, lupine, delphinium and tickseed (Coreopsis grandiflora) among short-lived perennials that usually disappear within 10 years; some, like columbine, persist by reseeding. Long-lived perennials include hosta, daylily, Siberian iris and black-eyed Susan 'Goldsturm'; see black-eyed Susan care.
- They start slowly. Gardeners sum up a new perennial's first three years as "sleep, creep, leap": little top growth the first year while roots establish, more the second, and full size by about the third. It's a rule of thumb, not botany, but it explains why a new bed often looks sparse at first.
- Late risers aren't dead. Some perennials emerge weeks after others in spring. Mark their locations so you don't dig them up.
- Common reasons a perennial doesn't return: it wasn't hardy in your zone, the crown rotted in wet winter soil, it reached the end of a short natural lifespan, or voles or other animals ate the roots.
Choosing between annuals and perennials
| If you want… | Choose |
|---|---|
| Color from late spring to frost | Warm-season annuals, or perennials with annuals mixed in |
| A bed you plant once and maintain | Perennials hardy to at least your zone |
| Containers and window boxes | Annuals (perennials in pots need extra winter protection) |
| Pollinator habitat year after year | Native perennials suited to your region |
| Quick results in a new garden | Annuals the first year while perennials establish |
| Early spring and fall color in mild climates | Cool-season annuals such as pansies |
Common mistakes
| Mistake | Why it matters | Do this instead |
|---|---|---|
| Mistake | Why it matters | Do this instead |
| Buying a "perennial" without checking its zone | Tender perennials die the first winter in colder zones | Match the plant's zone rating to yours |
| Deadheading every biennial and self-sowing annual | No seed means no plants next year | Leave some flowers to set seed |
| Pulling a perennial that hasn't emerged by April | Some perennials are late risers | Mark perennials and wait until late spring |
| Judging a perennial by its first summer | Roots establish before top growth | Give it until the third season |
| Skimping on soil prep for a perennial bed | Plants stay in place for years | Amend thoroughly before planting |
Frequently asked
What is a perennial?
A perennial is a plant that lives more than two years. Herbaceous perennials, such as peonies, hostas and daylilies, die back to the ground in winter and regrow from their roots each spring. Woody perennials, such as trees and shrubs, keep their stems year-round.
What is the difference between an annual and a perennial?
An annual completes its whole life cycle in one growing season and dies, so it has to be replanted. A perennial survives winter and comes back for several years from the same roots. Annuals usually bloom longer each year, while perennials bloom for a shorter window but return.
Do annuals come back every year?
No. The plant itself dies at the end of the season or at frost. Some annuals, such as cleome, larkspur and California poppy, drop seed that sprouts the next year, so they appear to return (University of Georgia Extension). Tender perennials sold as annuals can also survive winters in warm zones.
What are annual flowers?
Annual flowers complete their life cycle in one season and typically bloom from planting until frost. Zinnias, marigolds and sunflowers are true annuals. Many other bedding plants, including impatiens, begonias and geraniums, are tender perennials grown as annuals, per University of Georgia Extension.
What does biennial mean?
A biennial plant takes two growing seasons to complete its life cycle. It grows leaves the first year, overwinters, then flowers, sets seed and dies in the second year. Foxglove, hollyhock, sweet William and parsley are common examples.
What is the 3-year perennial rule?
It's the gardener's saying "sleep, creep, leap": a new perennial puts most of its first-year growth into roots, grows more in year two, and reaches full size and bloom by year three. It's a rule of thumb rather than a botanical law, but it's a good guide to patience with new perennial beds.
Do perennials come back every year?
Yes, if they are hardy in your USDA zone and grown in suitable conditions. Some are short-lived and fade within several years, and plants rated only for warmer zones die in a cold winter. Poor drainage and animal damage are other common reasons a perennial doesn't return.
Which is better, annuals or perennials?
Neither is better; they do different jobs. Perennials give a permanent framework that returns every year, while annuals provide long-season color, fill gaps and suit containers. Most gardens combine the two.
Sources
- Know the life cycles of plants: annuals, biennials and perennials, Oregon State University Extension
- Extension Gardener Handbook, Chapter 3: Botany, NC State Extension
- Gardening Terms Defined, University of Illinois Extension
- Flowering Annuals for Georgia Gardens (B954), University of Georgia Extension
- Landscape Basics: Success with Herbaceous Perennials (B1424), University of Georgia Extension
- Growing Perennials, Clemson Cooperative Extension HGIC
- Longevity of Perennials, Iowa State University Extension and Outreach
- Peonies thrive on neglect, can live more than 100 years, University of Missouri Extension
- USDA Plant Hardiness Zone Map (2023), USDA Agricultural Research Service
- Digitalis purpurea (Extension Gardener Plant Toolbox), NC State Extension