What Is a Good Fertilizer for Maidenhair Fern?

Types of Maidenhair Ferns

• Whether maidenhair ferns are grown indoors as houseplants or outdoors in the landscape affects the fertilizing methods. For outdoor growing in cold climates, try the northern maidenhair. It grows in U.S. Department of Agriculture plant hardiness zones 3 through 8. Adapted to cold weather, the northern Maidenhair does not grow well indoors. For mild climates and indoor growing, try evergreen maidenhair, hardy in zones 9 through 10, or Delta maidenhair, hardy in zones 8 through 10. California maidenhair, rosy maidenhair and southern maidenhair are all hardy in zones 7 through 10.

Container Grown Ferns

• Indoor ferns and outdoor ferns growing in containers live in the limited environment of the pot. Once the nutrients in the potting soil are exhausted, the fern does not have access to more on its own. Fertilize maidenhair ferns every four to six weeks. Use a slow-release fertilizer, reducing the application to one-quarter the amount indicated on the package label. Apply a 10-20-10 fertilizer for container-grown maidenhair ferns. Apply the fertilizer during spring, summer and early fall. Hold off fertilizing in winter, when growth slows.

Natural Fern Care

• Outdoors, maidenhair ferns have better access to nutrients in the soil. As they are already low feeders, meaning they don't require a lot of extra nutrients, these ferns can get by with little additional fertilizer. Spreading a layer of compost or seasoned manure 1 to 2 inches deep over the area provides ferns with sufficient nutrients. When the dead fronds are trimmed off, cut them up and leave them at the base of the plant. As the material breaks down, it returns nutrients to the soil.

Fertilizer for Outdoor Ferns

• Sometimes a little extra fertilizer is required. In poor soil conditions, or when maidenhair ferns don't display sufficient growth, use a slow release 10-20-10 fertilizer. Apply one application in spring as new growth begins to appear. When growing ferns in the landscape, avoid planting them near lawns and heavy feeding plants. Excessive fertilizer in the soil damages maidenhair ferns. Too much fertilizer burns the roots, compromising the overall health of the plant.