How to Overwinter Purple Fountain Grass
Burgundy foliage and soft, feathery plumes make purple fountain grass a landscaper's dream. Adding texture and movement to the garden, it's among the most popular ornamental grasses. Join gardening expert Melissa Strauss to find out how you can overwinter this beauty.
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Soft, shimmery, and vibrant, purple fountain grass is a stunning addition to any garden. Its graceful, fountain-like shape is excellent for adding texture and movement to borders, containers, and focal points. It’s lovely enough to hold its own, but it mixes incredibly well with many other plants.
Purple fountain grass appreciates full sun exposure and needs well-drained soil. It will thrive in this environment, showing off its most vivid color and fullest display of plumes. It tolerates heat and drought excellently, so it’s easy to maintain in warmer climates, where it acts as a perennial.
You will enjoy the softness and drama this plant brings to the garden from spring until fall. But when winter comes around, there are some issues to address, as the roots are not entirely cold-hardy. Depending on your climate, purple fountain grass will require different treatments if you want to overwinter it.
Let’s talk about how to overwinter purple fountain grass to best carry your plants from fall to spring.
General Cold Tolerance
For all of its virtues, purple fountain grass is, sadly, not very cold-tolerant. It’s a tender perennial that loves warm climates similar to its native range of Africa, Southeast Asia, and the Middle East. It grows best and is perennial only in zones 9 to 11. Here, it either remains evergreen or dies back lightly and grows back in the spring.
Ultimately, in zones 8 to 10, you can overwinter this plant outdoors (with more protection in zone 8). It’s tolerant of temperatures between 25 and 30°F (-3 to -1°C), but the crown will typically die in a hard freeze. A prolonged period of 20°F (-7°C) weather or lower will be the death of it.
Because of its tropical origins, many Northern gardeners treat this plant as an annual, replanting in the spring. However, you can overwinter purple fountain grass indoors. With proper care, you can overwinter this plant in most climates. It just takes a bit more work in regions with cold winters.
Zones 8-10
I’m going to include zone 8 in both categories, but know that purple fountain grass isn’t considered perennial here. It’s indicated for zones 9 through 11, but with some additional care and planning, you can probably overwinter it outdoors.
In warm climates, purple fountain grass is easy to overwinter. It is a true perennial in zones 9 through 11, and extra insulation can typically save the crown from freezing in zone 8. The key is to protect it from cold snaps and wet soil while it is semi-dormant.
Here are some steps you can take to help overwinter your purple fountain grass in warm climates.
Leave the foliage until after frost
Resist the urge to cut the foliage back during fall and winter. It helps to insulate the crown of the plant, which is the most vital part to its survival. Wait until spring. The dried leaves and plumes add beauty to the winter landscape. Then cut the foliage back to about four to six inches to make way for new growth.
Mulch the base
Even in zones 9 through 11, mulch is a valuable resource for overwintering your purple fountain grass. It’s likely to survive without it, but you’ll almost certainly lose portions of the perimeter. Add a two to three-inch layer of light mulch, like pine needles or shredded leaves, around the root zone. This helps protect the roots and crown from rapid shifts in temperature.
Scale back watering
This plant likes a dry environment. Even when it is actively growing, it doesn’t need much supplemental moisture. In the winter, it’s semi-dormant, so it needs even less. Water only enough to prevent the roots from drying out entirely. Too much water mixed with cold weather is a recipe for root rot.
Plant in shelter
This one probably won’t help if you already have your purple fountain grass planted, but it bears mentioning. If you’re planting one, aim for a location where it has some shelter from the wind. Near a South-facing wall is ideal. A well-drained raised bed is another good spot for this ornamental grass.
Reduce fertilizing
Don’t fertilize your purple fountain grass in the fall. This will produce new growth, which will not overwinter well. It can also burn the roots as the plant enters semi-dormancy. Resume fertilizing in the spring after new shoots appear.
In zones 9 through 11, your plant may remain evergreen, especially if it’s planted in a sheltered spot. If this is the case, you don’t have to cut it back entirely in the spring. Just give it a trim to clean things up, and it will bounce back beautifully in the spring.
Zones 8 and Below
Though we make some exceptions for zone 8, purple fountain grass is really only meant to overwinter outdoors in zones 9 through 11. North of these, it’s not reliably cold-tolerant and will likely die back. In zones 8 and sometimes even 7, you can overwinter it outdoors with considerable protection. There are two main methods for overwintering purple fountain grass, indoors and outdoors.
Method 1: Overwintering Indoors
- You want to preserve as much of the plant as possible if you’re going to overwinter it indoors. If you keep it warm enough, it will behave as an evergreen. Make sure you make a plan and dig it up well before your first anticipated frost date. Dig a hearty clump, as much of the rootball as possible, and put it in a large pot with a light potting mix.
- If you want to make it easier to handle, you can trim back the foliage to about four to six inches tall. This is optional.
- Choose a location for your pot that is cool and brightly lit. You don’t want it cold, but a temperature of around 50°F (10°C) will keep it in a semi-dormant state and make it easier to care for.
- Water sparingly throughout the winter. The soil should stay almost dry, just moist enough to support the roots while they’re dormant.
- You can move your purple fountain grass back outdoors when the temperature stays above 50-60°F (10-16°C) at night. Gradually acclimate it back into full sun over the course of a week.
Method 2: Overwintering Outdoors with Protection
In zone 8, this should work well. If you’re in zone 7 and want to give it a try, it might be effective, but I can’t give you a guarantee. I would say that if you’re not going to be heartbroken if you lose it, it’s worth a try. If you’re attached to the plant, it’s better to overwinter it indoors.
- After the first frost, cut the grass back to about four to six inches.
- Mulch heavily around the base, use pine straw, shredded leaves, straw, or shredded wood mulch. Pile an additional four to six inches of mulch on and around the crown to insulate it from temperature shifts.
- Cover the stump, mulch and all, with frost cloth during any particularly cold spells. Again, if it’s not already planted, consider planting your purple fountain grass in a sheltered location where it will get plenty of sun, first thing in the morning.
Key Takeaways
If you’re a warm-weather gardener, it should be easy to overwinter purple fountain grass. It may even remain evergreen. In cooler climates, purple fountain grass is typically planted as an annual and replanted in the spring. However, it can be successfully overwintered indoors.
