how fast do king palms grow

[Mr.SamuraiSword]

anyone know?

[Stethoscope]

I know this doesn't answer your specific question but have a look at this document from Fairchild Tropical Botanic Gardens that quantifies the growth rate of a variety of palm trees with good accuracy. They don't have Archontophoenix species listed but it can give you a general idea of growth based on similar palms. 

Fairchild Palm growth rates.pdf

[Ben in Norcal]

You'd need to specify growing conditions and species.  A pot-bound A purpurea kept mostly indoors in CT will be a very different situation from an A alexandre in Hilo!

[NorCalKing]

Mine, in-ground, has put on about a couple of feet per year.

[pigafetta]

Depends on your climate but in a subtropical to tropical climate basically the more water you give them the faster they grow almost impossible to over water and extremely fast when well watered and fertilised.

[tim_brissy_13]

A cunninghamiana here in Melbourne well cared for can get to 3m tall in 4 years from seed. If neglected and not watered though, I've got some from the same seed batch that are less than knee height. Water and nutritious soil are the keys.

[palmfriend]

Hello there,

this is one of my alexander palms...

in May 2015 and the same one...

...a few days ago.

I would say, this is fast growing species under our local conditions.

best regards