Garden Detective

Why did fiber optic grass lose its sparkle?

Garden Detective: Fiber optic grass, actually a sedge, gets its nickname from its distinctive seed heads.
Garden Detective: Fiber optic grass, actually a sedge, gets its nickname from its distinctive seed heads. Bee File Photo

Experts tackle readers’ garden questions.

Q: I had a new patio garden installed in late March. I have a very narrow yard around three sides of my urban home. Most of the plants – gardenia, camellia, citrus, feijoa, rosemary, mondo grass and herbs – are all doing very well. However, I also had quite a few fiber optic grass plants put in. Some are doing well, but some are very brown, stressed and struggling. I’m not sure if it’s overwatering, underwatering or some other factor. The most beautiful of these plants is right next to some that are struggling. Any ideas appreciated!

Michele McCormick, Sacramento

Bee garden writer Debbie Arrington: Fiber optic grass (Isolepsis cernua) is actually a sedge, not a true grass. And it’s a “water plant”; it needs a lot more moisture than your other selections (except for maybe the gardenia).

Fiber optic grass gets its nickname because of its look. It produces small round seed heads at the end of its long blades, giving this sedge the look of a fiber-optic novelty lamp.

Isolepsis grows naturally in bogs and along streams or ponds. It needs soil that’s always moist, never completely dry. If the soil dries out, the plant quickly turns brown and goes dormant (or dies). It also needs full sun; if shaded, it becomes thin and lanky – and brown, too. Isolepsis is considered a tender perennial and needs protection from heavy frost, which also will cause it to brown.

Is your garden on drip irrigation? If so, the failing plants may not be getting enough water. You may need to hand water those struggling plants (every other day in summer) until they bounce back. The brown plants may be trimmed back to encourage new growth.

If they don’t respond to more irrigation, then it’s time to replace them with something else.

The Bee’s Debbie Arrington is a consulting rosarian and lifelong gardener., 916-321-1075, @debarrington

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