How to Plant, Grow, and Care for Pennsylvania Sedge

Sedges are unique, grass-like plants that thrive worldwide. Some are invasive weeds, while others are well-behaved native species that fill our forests, riversides, and meadows with grassy green growth. The Pennsylvania sedge is one of the most popular, as it has a wide range in the eastern U.S. and grows well in dry shade.

I learned to tell sedges apart from grasses with the simple phrase, “Sedges have edges.” This phrase points to the triangular shape of the leaf blade. Sedges have triangular blades, while grasses have flat ones. Rushes, another group of grass-like plants, have round leaf blades. These identifiers can help you tell a sedge apart from grasses or rushes.

Native Area

This sedge originates from eastern and central Canada and the northern, eastern, and central parts of the U.S. It grows wild in many different environments, from sunny, exposed sites to shady, forested areas. It’s most common near oak trees, hence its other name, “oak sedge.”

Though this perennial prefers moist soil, it can tolerate dry or wet sites with poor soil. It’ll grow large in the shade and short and squat in the sun. The more moisture it has, the quicker it’ll grow, while the less moisture it has, the slower it’ll mature. 

Characteristics

Oak sedge sprouts thin, grassy blades and flower spikes in spring. The flowers are monoecious, meaning there are separate male and female flowers. Pollen must travel from the male flowers to the female ones for pollination to occur and seeds to form. 

When left to grow, Pennsylvania sedges form vast colonies over time. They’re perfect for shady, dry sites where other plants struggle to survive. Though they don’t tolerate a lot of foot traffic, they’re perfect for open spaces beneath trees, shrubs, and tall perennials.

Underground, sedges use creeping rhizomes to spread. Aboveground, they have seeds that sprout readily each year. They use both propagation methods to outperform other grasses and perennials. 

Planting

There are two options for sourcing: starting seeds or buying potted plants. Starts are often available at local native plant nurseries, while seeds are easy to source from online shops and retailers. Ensure you’re buying Carex pensylvanica, not another Carex species, as they’re difficult to tell apart. 

Growing From Seed

Sedges are challenging to grow from seeds! They’re slow to sprout and variable in their success rates, making it difficult to reliably use them for starts. If you’re up for the challenge, consider starting this plant by planting seeds in pots or outdoors in the dirt. 

The seeds benefit from a warm stratification period before sowing. This period helps the seeds break down and begin to grow. Place them in a sandy mix inside a plastic or glass container, and wet the sand so it’s moist, but not soggy. 

Place the containers in an area where they’ll have temperatures between 60-70°F (16-21°C). Keep them there for 12 weeks, then plant them a quarter inch deep in pots or in the ground. Thickly sow the seeds to account for their low germination rates, and keep them moist. Seedlings may be slow to sprout, so practice patience!

Transplanting

Potted plants are easy to transplant during the growing season. Early spring and fall are the best times for transplanting. In regions with mild winters, like Southern California, you may plant them over the winter. So long as temperatures are mild, frost-free, and regular, you may begin the transplanting process. 

Start by loosening the plants from their pots. Rough up the bottom of their roots, then set them aside. Prepare holes for planting by digging twice as wide and as deep as the plants’ rootballs. Place their roots inside, then cover them with the soil you dug out earlier. 

Water the transplants well, and maintain consistent moisture levels while they’re establishing themselves. Add some mulch, like compost or leaf mold, on top of the soil after planting. It’ll insulate the ground and feed it with nutrients for the betterment of your garden specimens. 

How to Grow

These native plants are incredibly adaptable and work well in many states across the country. Grant them what they need, and they’ll thrive for years to come. Happy plants will spread, forming colonies throughout your yard with lush, graceful foliage. 

Light

How much light this species tolerates depends on your climate. In hot, dry regions near the southern U.S., they’ll benefit from more shade. In colder, northern climates, they’ll tolerate more sun. They’ll thrive in a wide range of exposures, from full sun to full shade, though partial shade is best for most growing zones. 

Water

Unlike most sedges, the Pennsylvania variety prefers a dry culture in the shade. After it establishes itself in your garden, it’ll require infrequent watering to look its best. Watch for yellowing or browning leaves as a signal of excessive dryness. The more sunlight the plants receive, the more water they’ll require.

Soil

Well-drained, loamy soil is key to growing sedges successfully. They appreciate ample drainage and a loose structure. The rhizomes tolerate sandy loam, though they’ll struggle in dense clay. Amend poor sites with compost to improve drainage, structure, and fertility. 

Temperature

Extremely cold-hardy, Pennsylvania sedges grow well in USDA hardiness zones 3 through 8. They’re more tolerant of cold than they are of heat—they’ll struggle in warm zones 9 and above! The warmer your climate, the more shade the sedges will require. 

The plants enter a dormancy period for the winter in the coldest regions with recurring frosts. They’re evergreen in most regions, though they’ll die back in extremely frosty sites. Don’t worry! They’ll pop back up in the spring. 

Fertilizing

Relatively low-maintenance, these perennials rarely require fertilizer. Instead of fertilizing them, amend them with annual helpings of compost. Add a layer two to three inches thick, and water it well to help the nutrients leach out into the soil. 

Maintenance

Aside from pulling up unruly runners, you’ll have to do little else to maintain healthy sedges. New sprouts will pop up in healthy crops. Let them grow if you’d like, or dig them up and transplant them elsewhere. 

Pennsylvania sedge is a perfect lawn substitute in lieu of weak, non-native grasses. Mow them once every week or two to keep them short. They’re intolerant of frequent foot traffic, but they’re a beautiful native replacement for lawn grasses in eastern states. 

Propagation

Though seed starting is often a difficult task, dividing and potting up runners is simple! You can easily multiply your sedge supply once you establish a healthy colony. 

Division

You may divide small or large plants to turn one specimen into many. Divide them in fall or spring, or in winter in mild, frost-free climates. Start the process by digging up healthy sedges. Dig a few inches from the base of the plant to ensure you get a healthy amount of roots.

The roots will have dirt clinging to them, and it may be difficult to inspect them. Rinse or brush the dirt off to take a good look at the plant. Using pruners or a sharp knife, separate it into multiple portions with roots and shoots.

Pot up the shoots in containers with fresh potting soil, or transplant them elsewhere in your garden. After a few years of sufficient growth, you can divide the plants again for another round of propagation.

Potting Up Runners

Rather than digging up and separating individual plants, you can select runners that sprout for easy transplanting. This sedge sprouts new plants from underground rhizomes, or fleshy, thick root structures. As the new plants pop up away from the original, you can dig them up and propagate them.

Pot up runners in spring or fall while the weather is cool and mild. Sever the runners with a sharp spade shovel, or dig them up and prune them off. After unburying them, plant them in pots or the ground and keep them moist while they adapt to their new environments. 

Saving Seeds

If you’re up for the challenge of starting seeds, you can collect them off the flowering heads after their blossoms fade. They’ll sit on the flower spikes before falling to the ground from spring through summer. 

Collect them by picking them off the plant, or prune the heads off and place them in brown paper bags. The seeds will fall to the bottom of the bags for easy collecting. Store them in a cool, dry location like a pantry until you’re ready to sow them. 

Common Problems

Sedges are relatively issue-free and perfect for low-maintenance gardens. They have few pests and diseases and require less watering and mowing than lawn grasses. Keep your sedges happy and healthy to prevent problems during the growing season. 

Pests

Aphids are the main sedge pests. They eat the tender foliage, especially on weak plants in early spring. Keep them off your sedges by spraying them with strong streams of water from a hose or watering can. If the site is already moist, consider squishing or brushing them off. 

Fungus gnat larvae may eat at sedge roots in wet locations. Prevent infestations by growing these perennials in well-drained and relatively dry soil.

Diseases

A few diseases may infect unhealthy sedge colonies. Watch out for smut, rust, anthracnose, and leaf spot. Rust and leaf spot affect the appearance of the plants, though they’re rarely fatal. They’re common in humid, warm, and moist conditions; prevent them by planting in well-drained soil and watering less often. They’ll appear during moist seasons, and they’ll likely disappear the rest of the year. 

Smut can be deadly if it infests the site. It’s a fungal condition that commonly infects grasses and sedges. Galls form that spread black, sooty spores throughout the garden. Remove galls as you see them, and avoid overwatering to prevent the infection from occurring. 

Anthracnose is not as deadly as smut. Prolonged periods with excessive moisture invite it into the site. Black, dead spots occur on the leaves that crinkle and dry as they die. Prevent the condition by maintaining proper moisture levels, and consider planting your sedges in a new site if the disease is persistent. 

Frequently Asked Questions