Temperature and Light Requirements

Keep fishtail palm trees at a nightly temperature of 60 degrees Fahrenheit and a daily temperature of 70 to 80 degrees Fahrenheit. Maintain a lower temperature of 55 to 60 degrees Fahrenheit during winter to induce a resting period. Fishtail palm trees cannot survive in temperatures below 45 degrees Fahrenheit without suffering permanent damage.

Place your fishtail palm tree in a south-, east- or west-facing window to provide plenty of sunlight. Fishtail palm trees can survive in any amount of light from deep shade to full sun. They thrive, however, in bright, indirect sunlight. Keep them in a shady location outdoors during warm months, but never place directly into the sun or the trees will undergo shock.

Humidity and Watering

Mist fishtail palm trees each day with a spray bottle filled with lukewarm water to raise the relative humidity. Alternatively, place a humidifier near the plant to permanently increase the humidity and alleviate the need for misting. Low humidity will cause the foliage to yellow and reduce the rate of growth.

Water fishtail palms once every seven to 10 days, allowing the soil to dry partially between applications. The soil should never be allowed to dry out completely or the plant will begin to drop foliage. Apply water once every 14 days during winter when the plant is dormant. Be careful not to splash water on the leaves during applications, as moist foliage is more susceptible to diseases.

Fertilizing and Repotting

Feed fishtail palms once per month using an all-purpose liquid houseplant fertilizer. Apply the fertilizer immediately after watering to prevent root burn, which can permanently damage the plant. Excessive fertilization can cause the foliage to wither. If this occurs, remove any damaged leaves and cease fertilizing for two months.

Repot fishtail palms once every two years to prevent them from becoming completely root bound. Transplant them into a container that is about 3 inches larger in diameter than the previous container to allow plenty of room for growth. An all-purpose houseplant-potting soil will provide proper drainage and fertility for fishtail palm trees.

Pests and Diseases

Red spider mites can become a problem when fishtail palm trees are grown indoors. These pests are visible to the human eye and usually appear on the underside of the plant's leaves. They look like tiny red spiders and are typically easily controlled. If you find spider mites on your fishtail palm, take it outdoors and spray with a stream of water from your water hose to dislodge the pests. Miticide, which is found at your local home and garden center or home-improvement store, may be necessary if you have a particularly bad infestation.