How to Grow Blechnum – Deer Fern

Sharing is caring!

Blechnum is a woodland fern with leathery, usually once-pinnate or deeply lobed, ladder-like fronds. Blechnum is sometimes known as hard fern or deer fern.

Blechnum is a genus of 150 to 200 species of usually evergreen, rhizomatous, terrestrial ferns found mostly in moist, sheltered, acidic soils in temperate or tropical regions.

Grow Blechnum in a shady border or woodland garden. Blechnum can be grown indoors in regions where it is not hardy.

Get to know Blechnum

  • Plant Type: Fern
  • Growing Zones And Range: Zones 8-11
  • Hardiness: Hardy to Zone 8
  • Height And Width: 9 inches (22cm) to 6 feet (1.8m) tall and 9 inches to 3 feet (1m) wide depending on the variety
  • Foliage: Pinnate usually leathery fronds
  • Uses: Grow in woodland, in shady herbaceous border, or in rock garden
  • Common Name: Hard fern, deer fern
  • Botanical Name: Blechnum
  • Family Name: Blechnaceae
  • Origin: Temperate and tropical regions worldwide
Hard Fern - Blechnum spicant
Hard Fern – Blechnum spicant

Where to plant Blechnum

  • Light outdoors: Grow Blechnum in deep shade outdoors.
  • Soil outdoors: Grow in moist, humus-rich, acidic soil.
  • Light indoors: Provide bright filtered or indirect light.
  • Soil indoors: Grow Blechnum indoors in a mix of 1 part each acidic loam, medium-grade bark, and charcoal; 2 parts sharp sand; and 3 parts coarse leaf mold.
  • Where not hardy, grow Blechnum in a greenhouse or conservatory.

When to plant Blechnum

  • Set Blechnum outdoors after all danger of frost is past.

Planting and spacing Blechnum

  • Space Blechnum 9 inches to 3 feet (1m) apart depending on the variety.

How to water and feed Blechnum

  • Water Blechnum freely to keep the soil evenly moist during the growth period; water moderately in winter.
  • Fertilize Blechnum with an organic fertilizer formulated for ferns.

Blechnum care

  • Frond discolor if air circulation is poor, and in a dry atmosphere.
  • Blechnum fronds may scorch in full sun.

Growing Blechnum as a houseplant

  • Grow Blechnum indoors in a mix of 1 part each acidic loam, medium-grade bark, and charcoal; 2 parts sharp sand; and 3 parts coarse leaf mold.
  • Provide bright filtered light indoor and moderate to high humidity and good ventilation.

Blechnum pests and diseases

  • Blechum is prone to leaf spot and rust.
  • Scaled insects, mealybugs, and caterpillar can be a problem.

Blechnum propagation

  • Sow spores in late summer.
  • Divide in spring; divisions can take time to re-establish.

Blechnum varieties to grow

  • Blechnum alpinum, see B. pennamarina.
  • B. appendiculatum. Slightly arching; lance-shaped pinnate dark green fronds; grows to 15 inches tall; Zone 10-11.
  • B. australe. Slightly arching fern; linnear pinnate midgreen fronds; grows to 15 inches tall; Zones 10-11.
  • B. brasiliense. Evergreen, upright, trunk-like rhizones; oblong-lance-shaped pinnate mid to dark green fronds; grows 3 to 5 feet; Zone 11.
  • B. chilense. Evergreen, creeping rhizomes; ovate to lance-shaped pinnate, dark green fronds; grows 3 to 6 feet; Zone 10-11.
  • B. gibbum. Evergreen with upright trunk-like rhizome; black-scaled, bright green fronds grows to 3 feet tall and wide; Zones 12-15.
  • B, nudum. Evergreen, ovate-lance-shaped fronds; grows to 3 feet tall and wide; Zones 8-10.
  • B. occidentale, hammock fern. Evergreen with erect or ascending rhizomes; lance-shaped, mid-green fronds, grows 9 to 18 inches tall and wide; Zones 9-11.
  • B. penna-marina, syn. B. alpinum. Evergren with linear, pinnate fronds, grow 4 to 8 inches tall and wide; Zones 10-15.
  • B. spicant, deer fern. Evergrene with creeping rhizoes; narrow lance-shaped , pinnate, dark green fronds; grows 8 to 10 inches tall and 24 inches wide; cultivars include ‘Crispum’, ‘Cristatum’, and ‘Richard’s Serrate’; Zones 10-11.
  • B. wattsii. Arching, braodly ovate pinnate dark green blades with bronzy red new growth; grows to 12 inches tall; Zones 9-11.

Written by Stephen Albert

Stephen Albert is a horticulturist, master gardener, and certified nurseryman who has taught at the University of California for more than 25 years. He holds graduate degrees from the University of California and the University of Iowa. His books include Vegetable Garden Grower’s Guide, Vegetable Garden Almanac & Planner, Tomato Grower’s Answer Book, and Kitchen Garden Grower’s Guide. His Vegetable Garden Grower’s Masterclass is available online. has more than 10 million visitors each year.

How To Grow Tips

How To Grow Tomatoes

How To Grow Peppers

How To Grow Broccoli

How To Grow Carrots

How To Grow Beans

How To Grow Corn

How To Grow Peas

How To Grow Lettuce

How To Grow Cucumbers

How To Grow Zucchini and Summer Squash

How To Grow Onions

How To Grow Potatoes

How to Grow Bishop’s Weed — Aegopodium

Greenhouse for growing vegetables

Vegetable Garden Season Extension