Are Ferns Annuals or Perennials? The Answer Explained

Many gardeners wonder if ferns are annuals that last one season or perennials that return year after year. The confusion is understandable, as how a fern behaves in a garden can vary. While there is a straightforward botanical answer, factors like climate and the specific type of fern influence its longevity in any given location.

The Botanical Classification of Ferns

An annual is a plant that completes its entire life cycle within a single growing season and then dies. A perennial, conversely, is a plant that lives for more than two years, often for many seasons.

From a botanical perspective, nearly all of the 10,500 known fern species are perennials. Their perennial nature is centered in their specialized underground stem structures, known as rhizomes. These rhizomes persist in the soil year after year, even when the visible foliage, or fronds, dies back.

This underground stem is responsible for storing energy and nutrients, allowing the fern to endure unfavorable conditions. Each spring, new fronds, often called fiddleheads, unfurl from this persistent rhizome. This ensures the fern’s return and confirms its classification as a perennial.

How Climate Impacts a Fern’s Lifespan

While ferns are botanically perennial, their ability to survive year-round in a garden is heavily dependent on the local climate. This introduces the distinction between “hardy” and “tender” perennials. Hardy ferns can withstand freezing winter temperatures, while tender ferns, often native to tropical areas, cannot tolerate frost.

The United States Department of Agriculture (USDA) Plant Hardiness Zone map helps gardeners determine which plants will likely survive winter in their area. For instance, the Ostrich Fern (Matteuccia struthiopteris) is considered very hardy and can survive in zones 3 through 8. In contrast, the Boston Fern (Nephrolepis exaltata) is only hardy in the warm climates of zones 9 through 11.

When a tender fern like the Boston Fern is planted outdoors in a colder region, such as zone 5, it will not survive the winter. Gardeners in these areas often treat these ferns as annuals, enjoying them for one season and replacing them the following year.

Evergreen Versus Deciduous Ferns

Even among the hardy ferns that survive cold winters, there is another classification based on their winter foliage. These perennials are categorized as either evergreen or deciduous, which describes whether they retain their fronds through the winter.

Evergreen ferns, as their name suggests, keep their green fronds throughout the winter, providing year-round color and texture. A common example is the Christmas Fern (Polystichum acrostichoides), which maintains its leathery foliage even under snow. These ferns may look weathered by spring, but the foliage remains largely intact.

Deciduous ferns have a different winter strategy. Their fronds die back completely to the ground after the first hard frost. In the spring, they send up new growth from the same root system. The Ostrich Fern and the Lady Fern (Athyrium filix-femina) are well-known examples that offer a lush appearance during the growing season before disappearing for the winter.

Caring for Perennial Ferns Through the Seasons

Caring for ferns properly depends on whether they are deciduous, evergreen, or tender varieties being overwintered. For deciduous ferns, the dead fronds can be cleaned up in the fall to maintain a tidy garden bed. Alternatively, they can be left in place over winter to provide a natural mulch that protects the plant’s crown and then removed in early spring before new fiddleheads emerge.

Evergreen ferns require less maintenance but still benefit from a spring cleanup. Any fronds that have become brown or damaged by winter weather can be trimmed at the base. This makes way for fresh growth and improves the plant’s appearance.

For tender ferns grown in containers in colder climates, it is possible to help them live out their perennial lifecycle. Bring plants like the Blue Star Fern (Phlebodium aureum) indoors before the first frost to be cared for as houseplants. Placed in a location with indirect light and consistent moisture, they can survive the winter and be moved back outdoors once the danger of frost has passed.