Hello. Since mold on the surface of the substrate is an indicator of high and/or constant humidity, it is recommended that watering be done moderately, with optimal amounts of water, only when the surface layer of the substrate is dry. Water should not stagnate at the base of the pot or in the tray. Double pots can limit the optimal air circulation in the substrate, thus creating conditions for fungal growth. Therefore, you may consider placing the palm on a saucer or in a larger flowerpot.
Given the existence of mold on the surface of the substrate, it is recommended to change the first few centimeters of the substrate with a new, fresh one (e.g. ), followed by a treatment with a bio fungicide, such as . This is applied by watering at the roots, in a dose of 10 g/ 10 L water. It is important to prepare a volume of solution corresponding to a single treatment (respecting the mentioned dosage), as the already prepared mixture has a shelf life of no more than 24 hours.
Subsequently, it is important to ensure the optimal environmental conditions for this species (Palm trees, plant care and growing guide and Chamaedorea, plant care and growing guide). In order to stimulate its healthy growth, from spring onwards you can consider using a specific fertilizer such as , applied by watering or foliar spraying, according to the information on the label.