Learn how to grow foxtail ferns (Asparagus densiflorus "Sprengeri"), also known as asparagus ferns, to enjoy low-maintenance greenery indoors or out. Bright yellow-green needle-like leaves on cone-shaped, partially upright fronds can extend 2 to 3 feet in length. Foxtail ferns produce tiny thorns and 1/4-inch diameter red berries. They bloom sporadically with tiny white flowers. A native of South Africa, foxtail ferns are evergreen perennials in USDA zones 9a and warmer and are a popular potted annual and houseplant in colder regions. Foxtail ferns are not generally bothered by insects or disease.
Select a pot for planting that is slightly larger than the pot in which your foxtail fern was sold.
Fill the pot with enough potting soil so that when you rest the tuber of the fern on top of the soil, the base of the fern is about 1/2 inch from the top of the pot. A tuber is a root system that resembles a very thick bulb or a small potato.
Place the fern in the pot on the soil and fill around it with additional soil to cover the tuber. The soil should reach within 1/2 inch of the top of the pot.
Soak the fern with water. This helps it to become accustomed to its new environment. Tap the pot a few times against a table or the ground to help the soil settle and remove any air pockets. Keep the soil moderately moist but not soaked, checking with your finger for dryness to determine when to water.
Place the potted fern in a sunny window. Foxtail ferns prefer partial sun and relative warmth but can adapt to a range of light and temperatures that fit those conditions, making them easy houseplants. Alternatively, place the potted fern in a sunny spot outdoors during warm weather. However, do not expose the fern to freezing temperatures. In USDA zones 9a and warmer, the fern may remain outdoors through the winter. In colder areas, bring the fern indoors and place it in a sunny window until the risk of frost has passed.
Fertilise the fern with an organic water-soluble fertiliser after several weeks.
After several years, the plant's woody root system, which may become 3 to 6 inches long and 1 inch in diameter, may fill the container and impede with drainage. Repot the plant in a container about 1 inch larger using the same method.