Answer: Cyathea cooperi, the tree fern, is a relatively hardy plant and will eventually grow to about 20' in height. The fronds are sensitive to dry air and to winds, which dessicate them. They grow to huge proportions in humid places such as Hawaii. Since you're near the ocean I suspect the humidity is adequate for your trees, but you may be overwatering them. While they like to be watered regularly, one 15 minute session per week is probably adequate for them. Try reducing the frequency of watering this growing season and see if that doesn't improve the situation. Best wishes!
Q&A Library Searching Tips