How fast does a whiffletree grow?

A whiffletree, also known as a whippletree, doesn't refer to a specific plant or tree species, but rather a mechanical device used in various applications, such as in horse-drawn carriages. If you meant a different type of tree or plant, please specify so I can provide accurate growth information. If you are referring to a specific tree species, growth rates can vary significantly based on the species, environmental conditions, and care provided.