Hardy ferns are tolerant of cold winter temperatures and can be grown outdoors year-round. Many ferns are both cold and heat tolerant — these make the best garden plants for the South.
Height/Spread
While most ferns average between one and three feet tall and wide, some, such as resurrection fern, grow only a few inches tall. Others, like royal and ostrich ferns, can tower to six feet. Most ferns are slow growing and can take several years to reach their mature size.
Culture
All ferns prefer well-drained soil high in organic matter. For heavy clay soil, mix a 2-inch layer of composted pine bark or other organic material into the top 10 inches before planting to improve drainage. Poultry grit (crushed granite) also works well to improve drainage and should be used in addition to organic material, not as a substitute. Sandy soils also benefit from mixing in a 2-inch layer of organic material tilled in because it helps them retain moisture. It is wise to prepare a large area for ferns before planting, not just individual holes. This will help prevent water from filling the holes and rotting the roots. Ferns may also be grown in raised beds, which provide good drainage.
Most ferns require a moist, shady spot to grow — either in a wooded area or near the north side of a building. Many need plenty of moisture during the growing season and should be given an inch or more of water per week if not supplied by rains.
While most of the ferns discussed here prefer acidic soils with a pH of 4 to 7, both southern and northern maidenhairs as well as ebony spleenwort prefer a more alkaline soil with a pH of 7 to 8. Have a soil test done to check the pH, and mix ground limestone or crushed oyster shells at recommended rates into the planting area if your soil is acidic.
Fertilizing should be done in spring, just after new growth has begun. Ferns are very sensitive to over fertilizing, so it is best to use a slow release fertilizer, such as Osmocote 14-14-14. Complete organic fertilizers also work very well. Always follow package instructions for fertilizer rates.
A 2- to 3-inch layer of leaves or pine straw, applied in the spring and in the fall, is an excellent mulch for ferns. Ferns grown in wooded areas benefit from the falling leaves and pine needles in the fall. See the chart below for cultural requirements of specific ferns
Fact sheet:Cinnamon Fern
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