Which palms do you grow from seed?
My favorite from seed are Phoenix canariensis and Washingtonia robusta--haven't had luck though with the true date nor Washingtonia filifera (though one I have may be a hybrid). The one in the photo is six feet tall and has a diameter of 8 inches. I have four other canariensis palms (about half this guy's size)--all originally from seed.
Here is a link that might be useful: