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How to Grow Northern Sea Oats, a Native Grass

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 was once tasked with tending a garden that was filled with plants whose flowers were dried and used in wreaths and arrangements. A fellow gardener suggested I plant northern sea oats. It is small enough to not overpower the other plants and the seed heads are lovely.

It grew well for me, but I didn’t harvest the seed heads quite on time and it prolifically reseeded itself the following year.

What is Northern Sea Oats?

Northern sea oats (Chasmanthium latifolium) is a perennial grass that is native to North America. Its range is from Canada to Mexico. It is hardy in zones 3 – 9. Northern sea oats is popular because it is one of the few native grasses that will grow in partial shade.

The plants grow in clumps from underground rhizomes. Unlike a lot of grasses which spread quickly, northern sea oats spreads at a rate of only a few inches per year.

The plants reach a height of 2 – 3 feet tall and a width of 1 – 2 feet, making it a rather small grass. It can easily fit into your garden unlike the large ornamental grasses that are usually planted in their own beds.

The leaves are bright green and shorter than most grasses. They grow along the stem much like bamboo, which is also a grass. The foliage turns a copper color in the fall. It remains standing throughout the winter adding color to an otherwise dull landscape.

The leaves grow from the stems similar to bamboo.

The leaves grow from the stems similar to bamboo.

The flowers look like the seeds of oat plants (hence the name) and hang from stalks that bend in graceful arcs from the weight of the flowers. Bloom time is July and August. The flowers start out green and then mature into a light tan. They are sensitive to the slightest breeze, making a pleasant rustling sound as they move.

The seed heads will stay on the plants throughout the winter adding interest to your garden as well as an important food source for the local birds.

If you want to use the seed heads in dried arrangements, harvest them as soon as they start to turn tan. If you wait too long as I did, the dried flowers will shatter, spraying seeds all over your garden. Finish drying them somewhere dark and well-ventilated.

The flowers grow from stems that bend in graceful arches from their weight.

The flowers grow from stems that bend in graceful arches from their weight.

How to Grow Northern Sea Oats

Northern sea oats will grow in both full sun and partial shade making it a great candidate for anyone whose yard includes mature trees that shade different parts of the yard throughout the day. You can even plant them under the trees. Once established, northern sea oats grown in the shade are drought tolerant so they won’t mind competition for water from the tree roots.

If you prefer to grow yours in full sun, be sure to keep them watered. Don’t let them dry out. The plants will also be shorter and the leaves lighter in color than plants that are grown in the shade.

Most gardeners purchase their northern sea oats as plants from their local nursery. Plant them 12 – 18 inches apart in moist, rich, well-drained soil.

There is no need to fertilize northern sea oats because it is a native plant that is adapted to growing in our conditions.

Remember to remove the seed heads before they mature to prevent your plants from reseeding in the spring. These plants are aggressive reseeders if you don’t remove the seed heads in the fall. The seedlings are easy to remove in the spring if you forget or if you leave the seed heads on for fall and winter interest.

The foliage turns a lovely copper color in the fall and remains throughout the winter.

The foliage turns a lovely copper color in the fall and remains throughout the winter.

The foliage does not die in the fall. It’s a good idea to leave the leaves over the winter, rather than cutting them down as is normally done with ornamental grasses. The foliage will protect the crown of the plant from the cold winter weather. In the spring, you can trim the leaves back to 2 – 3 inches. New growth will replace them, starting in April.

How to Divide Northern Sea Oats

Northern sea oats don’t spread quickly enough to need regular division, but if you would like to divide your plants, it’s best done in the spring. Use a garden spade to carefully dig up the rhizomes. Then use a pair of heavy shears to cut the rhizomes into pieces. Discard any dead or diseased rhizomes. Replant the healthy divisions 12 – 18 inches apart.

© 2020 Caren White

Comments

Caren White (author) on December 02, 2020:

I love plants that have multiple uses.

Peggy Woods from Houston, Texas on December 02, 2020:

I like seeing many of the ornamental grasses. These sea oats would make for lovely dried flower arrangements.

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