Why do Boston ferns drop sticky sap?
Why do my ferns drop sticky sap all under the fronds of the plants? Usually it is tiny dots of orange splattered all over. Only the one has been doing it until the past month. Now both of them have a sticky floor under the plants.
Certified GKH Gardening Expert
The plant has pests. There are several it could be, such as aphids, mealybug or scale. All give off a substance called honeydew that will be clear, sticky and drippy. Treat the plant with a pesticide, such as neem oil, and this problem should clear up.
Ferns can be very sensitive to insecticide - be sure you use only horticultural oil, or soap, or a mix of the two. For DIY, mix a tsp. of mild dish detergent and a tsp of light cooking oil (canola is good) in an ordinary spray bottle. Spray fern thoroughly, especially the undersides of the leaves, until the plant is dripping. Do this weekly for 3 or 4 weeks. And wipe the sticky off the floor so you can monitor the effect of your treatment.