Polypodium

polypodium

( pol - ee - POH - dee - um )

At-A-Glance Information

This genus, commonly called Rockcap Fern or Polypody, includes species of ferns which need partial to full shade to do well in the garden. They are native to mainly cool temperate regions of the Americas, Eurasia, and Africa, Rockcap Ferns are suited well for wild landscapes and in woodland areas; they normally grow on mossy rocks or logs amongst leaf litter. All species have creeping rhizomes and shed fronds cleanly when new growth appears. Use these ferns as shady-area no-traffic groundcover, in rock gardens, or as an underplanting for trees and shrubs.

polypodium Species and Varietals

Polypodium is a genus in the plant family Polypodiaceae and includes 47 distinct species. Ferns in this genus are related to those in Microsorum (Musk Fern). The best growing zones for Polypodium vary depending on the species. For more information, see the species descriptions below. To find your zone, click here: Zone Map.

Polypodium aureum (Phlebodium aureum) (Hare's Foot Fern, Golden Polypody, Gold-Foot Fern, Blue Star Fern)
This species grows well in USDA hardiness zones 8-12 or Sunset growing zones 15-17, 19-24, H1 and H2. They are native to tropical America and reach 2.5 feet tall and 5 feet wide with arching, blue-green fronds. This species needs regular water to do well in the garden. Cultivars include 'Davana' (compact with ruffled fronds), 'Blue Star' (with deeply lobed fronds and fuzzy golden rhizomes to 2-3 feet tall) and 'Mandaianum' (also called 'Lettuce Fern', with wavy fronds). This species is considered invasive in Hawai'i, Australia, southern Africa, and Portugal (Madeira).

Polypodium californicum (California Polypody)
Best in USDA hardiness zones 7-10 or Sunset growing zones 4-9, 14-17 and 22-24, this species is native to California and northwestern Mexico. It produces bright green fronds and is summer dormant. California Polypody reaches up to 1-2 feet tall and 2-3 feet wide, spreading slowly to form colonies. Great for slopes or under trees, this fern needs good drainage to perform well. The main cultivar of this species is 'Sarah Lyman', which has finely cut fronds.

Polypodium glycyrrhiza (Licorice Fern, Many-Footed Fern, Sweet Root)
This fern does well in USDA hardiness zones 5-9 or Sunset growing zones A3, 4-6, and 14-24, forming a mat a foot tall and spreading indefinitely in the landscape. This fern is native to Alaska down through California and inhabits rocky, forested coastlines. Fronds are dark green and delicate. The species makes a solid groundcover in woodland areas and also performs well in rock gardens. They can take full sun in coastal conditions and are drought-tolerant.

Polypodium scouleri (Leathery Polypody, Scouler's Polypody, Coast Polypody, Leather-Leaf Fern)
This species is native along coastlines from British Columbia down through Southern California. It does well in USDA hardiness zones 8-10 or Sunset growing zones 4-6, 15-17 and 24. It is a slow grower, eventually reaching 6 inches tall and spreading indefinitely. Fronds are thick, glossy, and deep green and are often found growing on trees or rocks. This species can tolerate salt spray.

Polypodium vulgare (Common Polypody, Adder's Fern, Wall Fern)
This native of Europe and Asia grows well in USDA hardiness zones 5-9 or Sunset growing zones A2, A3, 2-9, and 14-17. It is found in woodlands on rocks and trees, and reaches a foot tall, spreading indefinitely. Fronds are medium green. Common Polypody is considered invasive in New Zealand.

Caring for Polypodium

Polypodium ferns do well in partial to full shade, thriving best in a spot that gets bright shade or 2 or fewer hours of direct morning sunlight per day. Space plants between 12 and 30 inches apart for best coverage and airflow. Ensure that soil is well-draining, rich in nutrients and humus, and has a pH of between 4.5 and 7.5 (acidic to neutral). If local soils are particularly poor in nutrients or do not drain well, make sure to amend the planting area with plenty of organic compost before installing. Apply a layer of mulch around the planting area to suppress weed growth, maintain consistent soil temperatures, and to increase soil moisture retention. Water new plantings regularly as they establish a strong root system in their new home. At maturity, these ferns perform well in consistently moist soils. Avoid letting them sit in standing water or dry out completely.

Fertilize yearly in early springtime with an application of 2 inches of compost around the base of plants. Pull mulch back before applying, work the compost gently into the soil a bit, water it in, and then replace mulch. These plants are not heavy feeders, and this should be sufficient to provide the necessary nutrients for the active growing season. Pruning is simple; remove any damaged, diseased, or dead foliage at any time during the growing season. Every few years, these ferns will need to be divided (especially if they are being grown in a cramped border or container). For instructions on how to successfully divide these ferns, see the Propagation section below. Under ideal conditions, these ferns can survive for 10 to 20 years or more in the landscape before needing to be replaced.

Growing Polypodium Indoors
Choose a container for the fern that is about 2 inches wider than its original nursery pot. Ensure that the container has adequate drainage holes before planting. These ferns do well in a well-draining, organically rich soil. After planting, set the container in a space that is sheltered from dry, cool drafts. They prefer a humidity of between 50% and 70%, which can be imitated by misting twice daily. They require bright indirect light, but avoid placing them in direct sun as this exposure can scorch foliage. Water whenever the top inch of soil feels dry to the touch. Withhold feedings and lessen waterings in fall and winter when these ferns are dormant. Every few years, these ferns will need to be divided. For instructions on how to successfully divide Polypodium ferns, see the Propagation section below.

Propagation

Polypodium, or Polypody, are best propagated through division of existing plants. Spores can be used to propagate as well, though doing so requires more specialized knowledge, previous experience, and a suitable medium. To learn more about propagating ferns via spores, see the Propagation module. To propagate your Polypodium, follow the directions below:

Propagating Polypodium by Division
This type of propagation is relatively simple; you will need a clean shovel, mulch, fresh soil, compost and pots (only necessary if you will be saving divided plants for transporting elsewhere). Division is best done in early spring. To propagate by division, follow these steps:

Using a shovel, dig up your existing plant. Start from the outside and work your way in to avoid damaging the root(s). Once you have worked it up out of the ground, lay it out.
Start to tease apart the roots with your fingers. Once the roots are untangled, separate your plant into segments, ensuring that each one has at least one thick root section attached.
Prepare your pot(s) or new planting site(s) with amended, well-draining soil. You can either bring in new soil or simply amend your existing soil with compost to complete this task. Then, plant your divisions and water thoroughly.
Apply a thick layer of mulch over the new planting to protect it from cold weather as it acclimates to its new home. Then, enjoy watching it sprout in the next growing season.

Problems and Pests

Certain Polypodium species are considered invasive in some regions; see the species descriptions above for more information. Check with local authorities before planting. Polypodium ferns are generally tough, trouble-free plants, but can suffer from the following from time to time: