Staghorn fern care guide

Two kinds of fronds, and why it lives on a board

In the wild the staghorn fern grows on tree trunks and branches, with no soil at all. It has two kinds of fronds. The flat, rounded shield fronds at the base hold it to its support, cover the roots and catch water and fallen leaves. They turn brown and papery as they age, which is normal, so leave them in place. The gray-green, forked fronds that give it its name reach outward or hang down, and the brown, felty patches under their tips carry spores. They are not a disease.

That is why it grows best mounted. Shape a mound of sphagnum moss on a wooden board, a slab of bark or a wire basket, set the fern on it with the shield fronds touching the moss, and tie it on with fishing line, plastic strips or nylon. Never use copper wire. Young plants are often sold in pots, which works while they are small if the mix is an airy orchid or sphagnum mix that drains well.

Move it to a larger mount when the shield fronds reach the edges, although it copes with being crowded. Small plantlets, called pups, grow from the base. You can separate them with their roots and mount each one on its own board.

Water by soaking. Take the fern down and put the board or basket in a sink or tub of water until the moss is soaked through. Let it drain before you hang it back up. A fern in a pot can be watered from below.

Soak it again when the moss feels almost dry and the fronds look slightly limp. In warm, dry weather that is usually about once a week, in cool or cloudy weather less often. Let it dry a little between soaks, but never completely. Too much water is the most common way to lose a staghorn fern, because a base that stays wet rots.

Give it bright, indirect or filtered light, close to a window but out of strong direct sun. A north window works well. In very low light it grows weakly and is more prone to pests and disease.

Feed it with a balanced liquid fertilizer, with equal parts nitrogen, phosphorus and potassium, at the strength on the label. A young fern can have it once a month in the warm months and every other month in the cool months. A large, mature fern needs only one or two feeds a year. For a mounted fern, add the fertilizer to the soaking water.

It grows best at about 20 °C (68 °F) by day, with nights a few degrees cooler. Keep it between 16 and 28 °C (61⁠–⁠82 °F) indoors and away from radiators. It can survive a short cold spell close to freezing outdoors, but it does not tolerate frost.

It likes humid air and takes in water through its fronds as well as its roots. In a warm, heated room, mist it about every two days. A bright bathroom also suits it. Air that stays very damp can cause black spots on the fronds, so misting every two days is enough.