When growing banana plants (Musa spp., U.S. Department of Agriculture plant hardiness zones 9 through 11), the most important thing to keep in mind is that they originate from the tropics. That means banana plants prefer lots of bright sunlight, high humidity and consistently warm temperatures. Of course, taking care of a banana leaf plant involves some other basics, like water and fertilizer, but banana plants are particularly sensitive to low humidity and low temperature.
Sunlight, Humidity and Temperature
Choose a full-sun location for your banana leaf plant. It will thrive if it can get at least 12 hours of sunlight each day, which can be difficult to attain even with a bright south-facing window. However, bananas are also known to grow as understory plants in their native habitat, so less light or partial shade may be sufficient as long as all other conditions remain ideal. Provide an artificial grow light if you don't have a suitable window in your home.
Keep humidity levels above 50 percent by running a humidifier in the same room as the banana plant or by setting up an evaporation tray. You can also mist the leaves with water from a spray bottle. Finally, try not to expose it to temperatures less than 57 degrees Fahrenheit; otherwise, its growth will slow down significantly.
Water and Fertilizer Requirements
In the tropics, banana plants enjoy consistent rainfall and virtually never have to suffer through a drought. To keep your banana plant healthy, give it small amounts of water every day if it's growing in a container. Banana plants grown outside should be watered deeply every two or three days. If you lose track, a good rule of thumb is to water banana plants when the top half inch of soil is dry.
Banana plants should always be planted in rich, dark humus to provide them with plenty of macronutrients and micronutrients right away. When the plant's leaves are actively growing, it can be given a balanced N-P-K fertilizer. Once it starts to flower, switch to a high-potassium fertilizer, like potash, especially if you plan to harvest fruits from your banana plant.
Container-grown banana plants should be fed on a "little and often" schedule since nutrients leach out of containers much faster than in the ground. Liquid fertilizer is often used for container-grown plants since it is immediately available for the plant to absorb. Granular or slow-release fertilizer is better for banana plants that aren't suffering from a nutrient deficiency and are grown in the ground.
Overwintering Banana Leaf Plants Indoors
If you can provide ideal growing conditions year-round whether indoors or outdoors, you can keep your banana leaf plant growing at all times. However, the climate in most of the United States simply isn't tropical enough for bananas to survive outdoors. Fortunately, they don't require much pampering during the winter because they stop growing and enter a period of dormancy. As long as the temperature always remains above freezing, your banana plants can spend the winter in a garage, basement or closet with no water, fertilizer or sunlight.
When it's time to prepare your banana plants for winter, remove all leaves from the plant. Dig up outdoor banana plants and make the root ball small enough to fit inside your chosen bucket or container. You don't need to plant the banana in fresh soil at this time; that can wait until spring. Indoor plants don't need to be dug up; just move their pot into your chosen overwintering room.
When spring arrives, water the banana plant deeply and let it sit in front of a sunny window. Once a few leaves sprout, you can transplant the banana outdoors with plenty of rich, organic humus. If it's destined to be an indoor banana plant, give it fertilizer along with its first drink of water.