Make sure that you stand your tree fern upright outside (do not be tempted to put in a greenhouse)
and plant 1/5 to 1/4 either in the ground or in a pot in John Innes 2 or similar in a shady position
if possible- less shade more water.
Water at least 1 gallon (approx. 5 litres) per foot per day – 3 foot tree fern 15 litres / 3 gallons- making sure that most of the water enters the crown.
Where it will stand down to minus 5 degrees C quite comfortably. If it is colder than this then use the fleece to make a ball shape and wedge this in the crown. This can be done on a longer term basis in winter – do not use straw or bubble wrap.
Do not cut the fronds back from previous years but pull out from the crown and if they are at the right stage (often feb/ march depending on the season) they will pull out. By not cutting back you are preserving the aperture of the crown to ensure healthy future growth and more emerging fronds.