Most home gardeners propagate ferns by division, but it is also possible to grow new ferns from spores. Fern spores are similar to seeds in that they produce new plants, but the process is quite different and takes considerably longer. Growing ferns from spores can be a fun project for patient gardeners who want to observe the unique life cycle of these fascinating plants.

young fern growing on forest floor — Propagating ferns from spores is a fun project for gardeners with patience. ⁽¹⁾

How Ferns Reproduce

Unlike flowering plants, ferns do not produce seeds. Instead, they produce tiny spores in clusters called sori on the undersides of their fronds or on specialized fertile fronds. When mature, the sori turn dark brown or black and release microscopic spores.

After a spore germinates, it does not immediately become a fern plant. Instead, it develops into a tiny, heart-shaped structure called a prothallus (or gametophyte). This stage produces eggs and sperm. Because fern sperm must swim through a thin film of water to reach the egg, moisture is essential. Once fertilization occurs, a young fern plant develops. This new plant, called a sporophyte, is the fern that eventually grows in the garden.

A Project for Patient Gardeners

Spore propagation is not the fastest way to grow ferns, but it offers gardeners the opportunity to observe a remarkable plant life cycle from start to finish. It requires careful attention to cleanliness, moisture, and humidity. For gardeners who enjoy propagation and experimentation, it can be one of the most rewarding ways to grow ferns.

Timeline at a Glance

Spore germination: 2 to 8 weeks
First visible fern plants: 2 to 6 months
Ready for individual pots: Several months after sporophytes appear
Ready for the garden: Typically 1 to 2 years

Growing Ferns From Spores

Collect Fern Spores

Begin by selecting a healthy fern with mature sori on the underside of the fronds. Mature sori are typically brown or black rather than green.

Cut a fertile frond and place it on a sheet of white paper in a draftless and dry room. After several days, a fine dust-like powder will collect on the paper. This powder contains the spores.

Prepare the Growing Container

One of the biggest challenges in spore propagation is preventing mold and fungal growth. Starting with clean materials greatly improves success.

Use a shallow plastic container with a clear lid. Wash the container thoroughly, then sterilize it by soaking it in a 10 percent bleach solution for at least 10 minutes.

Fill the container with a moist growing medium such as peat moss, fine vermiculite, or a seed-starting mix. To reduce disease problems, sterilize the medium. Place moist media in the microwave for three to five minutes until it is steaming. A clean covered casserole dish works well. Steam is important to kill the pathogens. Allow it to cool to room temperature before sowing the spores.

The medium should be evenly moist, but not soggy.

Sow the Spores

Sprinkle the spores thinly over the surface of the growing medium.

Do not cover the spores with soil. They need light to germinate and are too small to emerge if buried.

Provide the Right Environment

Place the lid on the container or cover it with clear plastic wrap to maintain high humidity. Damp, but not soggy, conditions are needed for successful fertilization. This makes humidity a key component.

Set the container in a location with bright, indirect light. Avoid direct sunlight, which can quickly overheat the covered container.

Temperatures between 65°F and 75°F are ideal for most fern species. The growing medium should remain consistently moist throughout the process.

Watch for Germination

Patience is important. Depending on the species, spores may take two to eight weeks to germinate.

The first growth will not look like a fern. Instead, a thin green layer will develop across the surface of the medium. This green mat on the soil surface is made up of small, heart-shaped prothalli (sg. prothallus). These structures represent the reproductive stage of the fern life cycle. If the mat is too dense or layered, it may benefit from a thinning to allow the sperm to more readily travel from one prothallus to another.

Keep the Surface Moist

During this stage, constant moisture is essential. Fern sperm require a film of water to reach the eggs on neighboring prothalli and complete fertilization.

Check the container regularly and mist lightly if needed. Do not allow the growing medium to dry out.

Wait for Fern Plants to Appear

After fertilization occurs, tiny fern plants begin to emerge from the prothalli. The first true fronds usually appear two to six months later.

At this point, the young plants begin to resemble miniature versions of mature ferns. As these young ferns grow, the prothallus will die back.

Pot Up Young Ferns

Once the young ferns have developed several small fronds, carefully transplant small clusters of fronds into individual pots.

Use a well-drained potting mix rich in organic matter. Continue providing consistent moisture and bright, indirect light while the plants become established.

Acclimate Young Plants

As the ferns grow, gradually reduce humidity over several weeks by slightly opening the container or removing the cover for increasing periods of time.

Protect young plants from direct sun and drying conditions. Continue growing them in pots until they are sturdy and well rooted.

Plant Outdoors

Growing ferns from spores is a slow process. Depending on the species, plants often require one to two years before they are ready for the garden.

Once they are well established, transplant them into a suitable location outdoors. With time and proper care, these home-grown ferns will become attractive additions to shade gardens and woodland plantings.

Troubleshooting Common Problems

Mold or Fungal Growth

Mold is one of the most common reasons fern spore propagation fails. White, gray, or fuzzy growth on the medium usually indicates contamination.

To reduce problems:

Always use sterilized containers and growing media.
Keep the container covered to prevent airborne contaminants from entering.
Avoid excessive moisture or standing water in the container.
If mold appears in a small area, carefully remove the affected portion of the medium and improve air circulation slightly.

Severe contamination often requires starting over with fresh, sterilized materials.

Growing Medium Drying Out

Fern spores, gametophytes, and young sporophytes are very sensitive to drying. Even a brief period of drought can kill developing plants.

To prevent drying:

Keep the container covered with a clear lid or plastic wrap.
Check moisture levels regularly.
Mist lightly if the surface begins to dry.
Keep the container out of direct sunlight, which can quickly dry the medium and overheat the container.

The medium should remain consistently moist but never waterlogged.

Poor Germination

If few or no spores germinate after several weeks, one or more factors may be limiting success.

Common causes include:

Immature spores collected before the sori were fully developed.
Old spores that have lost viability.
Spores covered with growing medium after sowing.
Insufficient light.
Temperatures outside the recommended 65°F to 75°F range.
Dry growing conditions.

Remember that fern spores germinate slowly. Depending on the species, it may take two to eight weeks before any visible growth appears.

Quick Reference: Growing Ferns from Spores

Use this checklist as a simple guide to the process:

Collect mature spores from dark brown or black sori.
Allow spores to fall onto white paper and collect the dust-like spores.
Sterilize containers and growing media.
Fill a shallow container with moist, sterile medium.
Sprinkle spores on the surface and do not cover them.
Cover the container to maintain high humidity.
Place in bright, indirect light at 65°F to 75°F.
Keep the surface consistently moist.
Wait for the green prothalli (gametophyte) to develop.
Maintain moisture for fertilization.
Watch for tiny fern plants and their first fronds (sporophyte).
Transplant seedlings into individual pots when several fronds have formed.
Gradually reduce humidity and continue growing plants in containers.
Grow young ferns for one to two years until well-rooted and sturdy.
Transplant established plants into the garden.

More Information

Photo credits: 1: Aaron Steil

Authors:

Aaron Steil

Last reviewed:

September 2026