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How to Grow Cinnamon Fern, a Native Plant

Caren White is a Master Gardener and instructor at Home Gardeners School. She has been associated with Rutgers Gardens for over a decade.

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I love ferns and one of my favorites is the cinnamon fern. It’s called the cinnamon fern not because it tastes like cinnamon, but because the fertile fronds (the ones that produce the spores) are dark brown, the same color as cinnamon.

What are Cinnamon Ferns?

Cinnamon ferns (Osmundastrum cinnamomeum) are deciduous ferns that are native to the Northeastern United States and Canada. They are among the hardiest of the native ferns, growing in zones 3 – 9. They prefer wet soil so they are commonly found along stream beds and in marshy areas.

The fibrous root masses of these ferns grow large and dense. They can be harvested and used for growing orchids and other epiphytic plants that do not grow in soil. The fibrous root mass is known as osmunda fiber after it is dried.

Cinnamon ferns are slightly smaller than ostrich ferns, another moisture loving native fern. They grow only 2 – 4 feet tall and 2 – 4 feet tall. Like most ferns, they have two types of fronds, fertile and sterile.

The fertile fronds appear first in the spring. They are green and skinny, and slightly shorter than the green sterile fronds, only growing 2 – 3 feet tall. As the spores develop, the fertile fronds turn their characteristic brown color. They remain throughout the winter.

Ferns reproduce via spores rather than seeds. Seeds are newer way for plants to reproduce. Ferns still use the ancient method of spores. Cinnamon ferns are considered a living fossil. They have been identified in fossils from 75 million years ago.

Very soon after the fertile fronds start to grow, the sterile fronds appear as fiddleheads which then uncurl to reveal the bright green of the mature fronds. A distinguishing characteristic of cinnamon ferns is that the sterile fronds turn yellow in the fall adding color to the landscape. These fronds die to the ground after the frost.

The fiddleheads of the cinnamon fern are not eaten. The entire plant is carcinogenic. The Native Americans used cinnamon ferns medicinally but only externally for things like rheumatism and joint pain.

The fertile fronds are dark brown, the same color as cinnamon, giving the plants their name.

The fertile fronds are dark brown, the same color as cinnamon, giving the plants their name.

How to Grow Cinnamon Ferns

Gardeners purchase their ferns as plants, usually from nurseries that specialize in native plants. It’s better to purchase native plants from reputable local nurseries than harvesting them from the wild. We are losing many of our native plants to habitat destruction and climate change. Leave the plants in the wild and purchase from local nurseries who either grow them themselves or sustainably harvest them from the wild.

These ferns prefer shade or partial shade and wet soil. That wet, shady spot in your yard is perfect for them. Another good spot for them is in a shady rain garden. Plant them 2 – 3 feet apart. Spread a thick layer of mulch around your plants to help keep the soil moist and prevent weeds from growing that will compete with your ferns for water. Add a thick layer of mulch around your plants each spring after your last frost.

Keep your ferns well-watered as they settle into their new home. Misting the fronds a few times a week will also help.

Because these are native plants, they are adapted to our growing conditions so they don’t need to be fertilized. If you want to fertilize them, use a slow-release balanced fertilizer once in the spring as the fronds are emerging from the soil.

In the fall after the first hard frost, remove the dead sterile fronds. You can remove the fertile fronds also or leave them for winter interest.

The sterile fronds turn yellow in the fall, adding color to the landscape.

The sterile fronds turn yellow in the fall, adding color to the landscape.

How to Divide Cinnamon Ferns

If your clump of cinnamon ferns is getting too big for its space in your garden, you can divide it. The best time to do that is in the spring as the fronds are emerging. Use a garden fork to carefully dig up the rhizomes. Then use a sharp knife or pruners to cut the rhizome into pieces making sure that each piece has a root system. The plants will not grow if they have no roots.

Replant your divisions 2 – 3 feet apart and water well. Keep the divisions well-watered as they settle into their new homes. Spread a thick layer of mulch around the bases of your divisions to keep the soil moist and discourage the growth of weeds that will compete with your plants for water and nutrients.

© 2021 Caren White

Comments

Caren White (author) on January 19, 2021:

They are very eye-catching in the fall.

Caren White (author) on January 19, 2021:

I saw them growing in a local woods and was really struck in the fall when they turned yellow. They became a must-have in my shady garden for their fall color.

Peggy Woods from Houston, Texas on January 19, 2021:

I like the yellow color in the fall when growing these cinnamon ferns. Thanks for another informative plant article.

BRENDA ARLEDGE from Washington Court House on January 19, 2021:

Interesting article and pictures.

I have never seen a fern with such a beautiful golden color.

I love gardening and ferns bring a great aspect to other flowers.

Nice write.

Caren White (author) on January 19, 2021:

Just make sure that they are well-watered. I don't think that you will have to worry about having enough humidity!

Pamela Oglesby from Sunny Florida on January 18, 2021:

This is a very detailed and informative article about growing cinnamon ferns. I love growing most anything, so I appreciate this information, Caren. I don't have a lot of shade in northern FL, but I do have a few areas of shade, so I may try to grow these ferns.