I planted this the year the greenhouse was built as a seedling about 10 inches tall. That was almost 17 years ago. The crown is at about 12 feet now and the fronds are huge and king of lay partially flat on the ceiling of the GH at its highest point (which is almost 20 feet). I am hoping it does;t get too much taller, they are said to normally max out at 20 feet height.
The smaller one I have in the back I think is the 'non-watermelon' form but its still too early to tell.