TREE FERNS
These giants of the fern world add majesty and architectural form to any garden. In Britain the new fronds begin to unfurl in mid to late spring from the tops of stout fibrous or woody stems. The stems contain masses of old leaf bases and compressed roots, which can be most clearly seen in Dicksonia antarctica. The tree ferns we offer are all hardy providing they are adequately sited and given some modicum of winter protection. However, we do strongly advise that smaller specimens under 90cm in height be over wintered in a frost-free environment. With tree ferns, size matters!
CULTIVATION
Unless stated otherwise all tree ferns require a position in full or dappled shade with some protection or filtering of cold, desiccating winds from the north and east. They thrive in moist but well-drained neutral to acid soil enriched with leafmould and/or well rotted horse manure.
Bare rooted tree ferns need only to be planted quite shallowly in the ground, 4-6" being adequate. Obviously with tall specimens this poses a problem with stability and the best method of securing them is to wedge them in with wooden stakes for the first two years until the roots have grown and anchored them naturally. They should be kept moist during hot dry periods by watering the crown (which acts as a natural reservoir) and by watering the trunk. Eventually the fronds will be affected by winter winds and frost when they begin to turn brown (in frost free areas they will remain more or less green). We leave the old fronds on if they are still capable of photosynthesis, i.e. if they are still fairly green, cutting them off in mid-spring just as the new fronds are emerging.
OVERWINTERING
Here in Norfolk we get by with placing two to three heaped handfuls of straw or bracken in the crown, pushing it well in. This is done in November or December. If winters are likely to be very severe straw or bracken is also packed around the trunk, held in by canes and finished off with two or three layers of bubble-wrap or horticultural fleece. The protection is removed in the spring, usually in late April or early May. Our techniques have worked successfully here but this is given as a guide only. Tree ferns grown in different parts of the country may need less or more protection, depending on local conditions.
POT CULTURE
We advise pot culture for smaller (3ft and less) specimens unless you have a particularly sheltered site or are prepared to protect your tree ferns really well.
A good all-round potting mix is one part each of John Innes No.3, composted bark and charcoal to two parts sharp sand and leafmould. Water regularly during late spring to autumn, applying a liquid feed (tomato food is excellent) once a month. In mid-late autumn bring pots under cover (frost free) and water sparingly over the winter months keeping the compost just moist. Pot on in spring.
