Staghorn ferns (Platycerium spp.) are challenging houseplants that enjoy warmer temperatures. Most species of staghorn ferns originated from tropical or semi-tropical regions, where frosts and freezing temperatures are rare. How much cold a staghorn fern can ultimately withstand may depend on the exact species, however, because a few varieties can tolerate much lower temperatures than others.
Because staghorn ferns are native to tropical areas in the Philippines, South America, Africa, Southeast Asia, Australia and Madagascar, they cannot tolerate much cold. Most staghorn ferns are classified as "tender" or "semi-tender." In fact, staghorn ferns will begin to suffer cold injury when temperatures drop below 55 degrees Fahrenheit. If you're growing your staghorn ferns outdoors, they will need cold protection in winter.
Although staghorn ferns are generally cold-tender, some species are slightly more tolerant of lower temperatures than others. For example, the most common species -- P. bifurcatum -- can tolerate temperatures as cold as 30 degrees. The species P. vassei and P. veitchii can tolerate temperatures as low as 40 degrees. There are also some staghorn fern species originating from mountainous regions in Australia that can survive freezing temperatures down to 10 degrees. Most staghorn ferns sold today are not this cold-hardy and usually come from more tropical climates, however.
Other staghorn fern species include P. stemaria, which is hardy down to only 50 degrees; P. superbum, which is hardy down to 30 degrees; and P. grande, P. andinum, P. angolense and P. wandae, which are hardy down to 60 degrees.
The ideal temperature for staghorn ferns is in the range of 60 to 80 degrees. Staghorn ferns are epiphytes, meaning that they grow without soil. Instead, their roots hang in the open air while the ferns grow mounted onto trees or rocks. Rainfall onto the roots provides staghorn ferns with moisture and nutrients. You can mount staghorn ferns onto wooden boards, tree fern fiber or wire baskets, but not in pots of soil. Position the staghorn fern in partial shade or in the dappled light beneath a shade tree. Ensure that the fern gets some indirect light, but not direct or full sun.
To grow a staghorn fern, water the plant when the mounting medium dries out completely. To ensure that the fern has dried out entirely, you can wait until the plant begins to wilt slightly before watering. During hot, dry conditions, you may need to water the staghorn fern no more frequently than once each week. You can also feed the staghorn fern once each month while it's actively growing with a 10-10-10 or 20-20-20 NPK water-soluble fertilizer. Fertilize the staghorn fern once every two months during the season when it's growing slowly. If you have a large, mature staghorn fern, you can provide just one or two yearly applications of slow-release fertilizer.