What Types of Ferns Prefer Acidic Soil?

Ferns generally prefer shady gardens using acidic soil. Soil with a pH of 7 is considered neutral. A pH below 7 is acidic, while a pH above 7 is alkaline. Different kinds of ferns have particular soil pH conditions within the acidic selection, however. Some types of ferns need acidic soil with a lower pH, but some prefer soil that is just slightly acidic. Still others are going to grow in acidic, neutral or slightly alkaline soils. Your soil pH can be determined with a simple pH test. It’s worth determining before deciding which kind of fern will thrive in your garden soil.

Low pH Soil

Boston ferns (Nephrolepis exaltata), also known as sword ferns, and flowering ferns (Osmunda regalis), also called royal ferns, prefer a lower pH. Boston ferns are hardy in U.S. Department of Agriculture (USDA) plant hardiness zones 9 to 11. This kind of fern grows in soil with a pH of 5.0 to 5.5. They do best in humid conditions in partial to full shade where the land is high in organic matter. Its bright-green fronds grow to a height of 3 feet and width of 6 inches. Flowering ferns are hardy in USDA zones 3 to 10. They grow in soil with a pH of 4.3 to 5.2. This kind of fern has brown, leafless fertile fronds and infertile, leafy fronds that can be up to 6 feet tall. The 2-inch extended leaflets are spaced slightly apart along the frond, giving the fern an open, airy look. It favors organically rich soil in full shade but will tolerate up to six hours of direct sunlight so long as the soil is kept moist.

Low to Moderately Acidic Soil

American climbing ferns (Lygodium palmatum) and Japanese tassel ferns (Polystichum polyblepharum) prefer a soil pH of 5.1 to 6.5 and are hardy in USDA zones 5 to 9. American growing ferns, also known as creeping, Hartford and Windsor ferns, grow long, 3- to 4-foot tall twining fronds that will climb nearby plants. Its leaflets are palmate or shaped like an open palm with fingers outstretched. They’ll grow in partial or full shade. Japanese tassel ferns, also called Japanese lace ferns and Korean tassel ferns, grow to a height of two to three feet with dark, glossy green fronds and finely dissected or serrated leaflets. Dappled or full shade with rich soil that is kept uniformly moist is most effective for this kind of fern.

Moderately Acidic Soil

Cinnamon ferns (Osmunda cinnemonea) and Ostrich ferns (Matteuccia struthiopteris) prefer soil with a pH of 5.5 to 6.5. Cinnamon ferns grow to between 5 and 3 feet tall with light green fronds. This kind of fern has sterile and fertile fronds. The sterile fronds are cinnamon brown when they first emerge but change graduallyto green as they mature. The fertile fronds remain cinnamon brown and do not develop green leaflets. They are hardy in USDA zones 3 to 10. A planting website with visually rich, moist soil in partial shade is ideal for the fern, but it is going to grow with as much as six hours of direct sun exposure or dappled shade. Ostrich ferns grow to a height of 2 to 6 feet with dark green, finely dissected fronds. They are hardy in USDA zones 2 to 8. In warm Mediterranean climates, they need to be planted in a shady place with rich soil that stays uniformly moist.

Acidic to Alkaline Soil

Holly ferns, Japanese holly ferns or Asian net-vein holly ferns (Cyrtomium falcatum), and Christmas or dagger ferns (Polystichum acrostichoides) prefer a soil pH of 5.6 to 7.8. Holly ferns are hardy in USDA zones 6 to 11. They grow to a height of two feet with dark green, pointed leaflets that resemble holly tree leaves. This kind of fern prefers organically rich soil in partial or full shade, but will grow with as much as six hours of direct sunlight. Christmas ferns are hardy in USDA zones 3 to 9. They grow to a height of two feet with leathery green leaflets that resemble small Christmas stockings. Fast-draining soil that is high in organic matter in partial or full shade is ideal for this kind of fern.

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