How to Grow Amorphophallus Titanum Indoors

Measure the diameter of the titan arum's tuberous corm with a yardstick or long ruler. Choose a container that is three times wider than the tuber's diameter. The container must have drainage holes in the bottom.

Fill the container with a quality, houseplant peat-based potting mix. Alternatively, blend your own potting soil that is four parts fresh peat to one part washed sand and grit. Do not use topsoil, as it will compact and harden in a container. Topsoil also contains microorganisms and pathogens that can harm the titan arum.

Plant the corm 1 to 2 inches deep in the container. Orient the corm with the central depression upward, as this is where the leaf sprout originates. Tamp down the soil atop the corm and then water with room temperature water to evenly moisten the soil and remove any air pockets.

Place the container in a very brightly lit area of the greenhouse or sun room. Do not let intense midday sun rays reach the plant. Bright, diffused light through opaque glass or a white curtain sheer ensure that sun rays do not scald the plant. Maintain an ambient temperature between 78 and 90 degrees Fahrenheit, with humidity above 50 percent.

Water only when growth appears from the corm, and then only to maintain an evenly moist soil. Avoid soggy wet and bone dry conditions when the leaf or flower stalk is present. Once the leaf naturally yellows and collapses in autumn or winter, reduce watering significantly. Keep the soil slightly dry, but never bone dry, during the time when the plant is seasonally dormant. Resume increased watering when a new growth shoot again emerges.

Fertilize with a balanced formula of water-soluble fertilizer as part of regular watering when the leaf is present. Follow product label directions for dosage and repeated application based on the container and plant size. Do not fertilize once the leaf naturally withers and the plant is dormant.