Q. What can cause the leaves of a in house grown cacao plant to turn yellow and fall off?
Cacao plants are not easy in-home plants, particularly because of their humidity requirements. They are plants from warm and humid places, so think about that as you care for the plant. It is accustomed to stable warmth and humidity and you should try to reproduce those things at home. This plant must never drop below 60° and needs considerably higher daytime temperatures to thrive – 70° and higher. It should not be placed too near an air conditioning or heating vent or an open window in the colder months; the blast of hot or cold will shock it and result in leaf drop and ill health. Temperature, shock or a lack of humidity could be what led it to drop its leaves.
A cacao plant needs humidity above 70% to stay healthy, which is hard to achieve in a home in our area. Humidity can be provided by placing the pot in a tray of pebbles with some water, allowing the water vapor to rise up to the canopy. In the dry winter months, you can put a clear plastic bag over the leaf canopy to hold in that rising moisture. Alternatively, you could use a humidifier or mist the plant very frequently.
Another reason it may have yellowing leaves drop from the plant is over-watering or allowing the plant to sit in a run-off dish of water after it has been watered. If the plant does not have enough humidity around it, it is more difficult to regulate watering needs properly. You should be watering the plant thoroughly (until water runs out the bottom) and re-water after the surface soil is dried during the growing season. Less water is needed in the winter months. Empty the dish underneath after the plant has drained for ten minutes so it does not sit in the wet. (This is different than having it sit on the wet rocks as the rocks prevent direct contact with the water).
In their native locations, these are understory plants and they will do well in dappled light in your home. If you can move it outside to a filtered sun position in the warmest months of the year it will benefit enormously.
Should you need to repot this plant, wait until you have it stabilized. When you do, early spring is the best timing, using a clay pot, one size up, with good drainage. A standard potting mixture with a pH of 5 to 6 is ideal. During the growing season fertilize every two weeks with a balanced, organic fertilizer.
Good luck with your plant! Please let us know if we can offer any additional help.