Question
QUESTION: We have a 7 foot tree fern in the backyard, but we're wondering, since it's getting too tall, and touching the patio rooftop, we wanted to know if we are able to cut the trunk, and then replant it that way.. Or will that cause too much of a shock?
ANSWER: Mat, your title says "repotting", is it in a pot now? or in the ground by the house? follow-up with that info and when you say cut the trunk, do mean to try to replant the crown, devoid of roots? let me know..Nick

---------- FOLLOW-UP ----------

QUESTION: Sorry, it's in the ground, along the backyard window garden.  I thought maybe, as how you buy the tree fern, without any root system, you can just cut the trunk off half way between the crown, and the soil, and plant it that way.  It's about 7 feet high, I want it so it's about half that size.  
Hope that's better for ya.  
Thanx, Matthew.

Answer
Mat, even though it seems like there is no root system in the tree fern, there actually is; the base has the roots that are intended for support and nutritional collection (surface feeders). Tricky as it may be, if necessary, you can do what you intend, and over time it will regenerate from the bottom of the cut (there being roots all the way up the trunk), but patience is the virtue here, it will take time for this to happen, and the tree may decline because of its size, and the depletion of its existing root system. Bottom line, if you have to do this, then you will be tossing the dice; fern trees need good moisture and dappled shade (being rain forest denizens in their natural habitat) and this may be a difficult endeavor to accomplish without their root system intact. I would attempt to move the entire fern with as much of the root system as possible to a more suited spot...good luck Nick