Often found growing in wet or peaty areas near the sea, fiber-optic grass is a cosmopolitan grass. It is native to western and southern Europe, British Isles, North Africa, the west coast of North America, and Australia, as well as New Zealand. Although it looks like a grass, fiber-optic grass is an evergreen species in the sedge family. This bright green, grass-like plant gets its name from its resemblance to a fiber-optic lamp—multiple stems with tiny flower spikes at the tips. The flowers are cone-shaped and start out as white or silver, eventually turning tan or brown.
This low-maintenance plant grows upright when it is young, then spills gracefully over the edges of containers or garden walls as it matures. It has a slow to moderate growth rate.
Fiber-optic grass is toxic to humans and pets.
Fiber-Optic Grass Overview
Where to Plant Fiber-Optic Grass
Select a location with full sun that has slightly acidic soil and ample moisture, such as along a pond, a boggy area, or a rain garden.
With its verdant green color all season long, the plant adds a soft texture to containers and garden borders. Its small stature makes it a perfect choice for miniature or fairy gardens. Fiber-optic grass also works well when grown as a houseplant in a sunny window.
How and When to Plant Fiber-Optic Grass
Plant potted nursery plants in the spring after all danger of frost has passed. Dig a hole that is about 1.5 times as wide as the root ball and about as deep. Set the plant in the hole and backfill it with original soil.
Fiber-optic grass can have its crown covered with water up to 2 inches but if the plant was merely grown in damp and not wet conditions before, the sudden extreme change in soil moisture can make the roots rot. If you intend to plant it in standing water, such as in a wetland or near a garden pond, it’s best to keep fiber-optic grass in its pot for a few weeks and gradually increase the soil moisture through watering before planting it in the ground.
Space plants 10 to 12 inches apart.
Fiber-Optic Grass Care Tips
Light
Fiber-optic grass prefers full sun. It can handle some shade but will develop a much looser growth habit.
Soil and Water
Plenty of moisture is key. Fiber-optic grass turns brown if allowed to dry out. When planting it in a water garden, gradually adjust the plant to being constantly submerged as described above under the planting instructions.
The ideal soil pH is slightly acidic, between 5.8 and 6.2.
Temperature and Humidity
Fiber-optic grass is very heat-tolerant but doesn’t survive temperatures below 20 degrees F. If you live below zone 9, grow it as an annual or overwinter it indoors. Bring the pot inside when the foliage changes color and before freezing temperatures start. Place the pot in a sunny window and keep it well watered (placing the pot on a tray filled with water helps to keep it constantly moist).
Fertilizer
Especially when grown in a water garden, fiber-optic grass needs regular fertilizer as water does not retain nutrients like soil does. At the same time, plants submerged in water are also susceptible to overfertilization. Use balanced water-soluble fertilizer diluted to half of the strength indicated on the label. Apply it once a month from spring through early fall.
Pruning
It is not necessary to deadhead the plant, but you can give it a haircut if it gets too long and lanky over the summer. It also benefits from a springtime shearing to remove the old seedheads and brown foliage to make room for the new growth. Avoid cutting the plant back in the winter when it is not growing.
Potting and Repotting Fiber-Optic Grass
Fiber-optic grass lends itself to being grown in containers, especially if your climate is too cold to overwinter it outdoors and you need to bring it inside. Choose a container with large drainage holes and large enough to fit the roots plus about 2 inches extra for future growth. Fill it with a mixture of potting mix and compost and place the container in a location where it sits partially in the water, such as along the edge of a garden pond. Alternatively, you can also place the container on a tray or saucer filled with water but keep in mind that you will need to replenish the water regularly.
Repot it in a larger pot when it has outgrown its container.
Pest and Problems
Fiber-optic grass does not typically have pest or disease issues. It is deer-resistant.
How to Propagate Fiber-Optic Grass
Fiber-optic grass can be propagated from seed or by division. When grown in the garden, it also self-seeds.
Start the seeds indoors in small pots filled with damp potting mix. Gently press them into the soil, they need light to germinate. Place the pots in a bright windowsill or under grow lights in a warm room and keep the soil evenly moist. The seeds germinate in 14 to 21 days.
The plant can also be divided. This should only be done in the spring, as it can injure the roots. By doing it at the beginning of the growing season, the plant has time to recover and is less susceptible to winter damage. To divide, dig up the plant and cut or break the clump into smaller sections with leaves and roots attached. Plant these into the garden at the same depth as the original plant and water well.
Frequently Asked Questions
- Is fiber-optic grass a perennial or an annual?In warm climates, the plant is grown as an perennial and blooms potentially year-round. In cooler climates, it is grown as an annual, blooming from early to late summer. It can also be grown as a houseplant.
In warm climates, the plant is grown as an perennial and blooms potentially year-round. In cooler climates, it is grown as an annual, blooming from early to late summer. It can also be grown as a houseplant.
- Why is my fiber-optic grass turning brown?The change in foliage color may be seasonal. When temperatures drop, the foliage may change from the bright green to yellow or brown. The inflorescences at the tip of each leaf also turn tan or brown in the fall. If you can rule out these two natural occurrences, the brown foliage could also mean that your plant needs watering.
The change in foliage color may be seasonal. When temperatures drop, the foliage may change from the bright green to yellow or brown. The inflorescences at the tip of each leaf also turn tan or brown in the fall. If you can rule out these two natural occurrences, the brown foliage could also mean that your plant needs watering.