HOW TO PROTECT TREE FERNS OVER WINTER

When it comes to tree ferns you should always lean to the safe side. Consider the worst weather that the winter climate is likely to throw at you, and protect your plant against that. You can do this in one of two ways.

1. Protect you fern for the entire winter period or
2. Only protect your fern when temperatures get close to the limits that it can survive at.

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Which parts of the tree fern will need protecting?

Although it’s the fronds that are most susceptible to the cold, they are also in fact the most expendable. It is the crown of the trunk that is the most important part as this is where the meristems exist which will produce the following years growth. Next in line is the trunk because this protects the thick, bootstrap like roots which – if the crown dies – may be able to produce new meristematic tissue from dormant buds which will in turn produce new fronds – but don't hold your breath. Coming in third in the hierarchy of importance is the thick, fibrous root system at the base of the plants. If the root system dies - but the crown and the thick roots within the truck survive - there is nothing to worry about as these will re-grow over the following season. I would still protect them just to be on the safe side as less hardy species - such as Dicksonia squarrosa - can form multiple crowns and will grow back from the base if the crown is cold damaged – but only if it is mature enough.

Methods of protection

In their native habitat the crowns of tree ferns will normally be protected by leaf litter that has fallen down from the tree canopy above.

You can easily mimic this with leaves collected from around the garden, and this will work quite effectively down to temperatures of between 1 or 2 degrees below freezing.

However the best method is to plant the tree fern in the ground but with the root-ball still contained in some type of pot. That way it can be lifted before the cold depths of winter arrive without disturbing the root-ball. Remember that - come the spring - the tree fern will need to be hardened off again. Unfortunately this will be dependent on the size and weight of the tree fern, and whether suitable overwintering space is available, otherwise the yearly lifting of your tree fern may not be a viable option.

The most popular method used for protecting tree ferns is to surround the entire plant – excluding the fronds as these will grow back – with a simple structure filled with a natural insulation. The structure can be made of anything that is sturdy enough such as wood, plastic tubing or a firm wire mesh.

This can be covered with clear polyethylene sheeting, bubble wrap, loft insulation – again, use whatever is suitably appropriate and close to hand. This in itself may be perfectly adequate, but for extra protection you can backfill the structure with a good layer of straw or woollen fleece. I would recommend putting on some kind of a water-proof lid above the structure but make sure there is a good air gap between the top and the sides to prevent the buildup of condensation on sunny days. At all times the crown must be kept moist especially if the weather picks up, but try not to have it wet during the cold spells as freezing will damage the crown.

As an additional precaution for the cautious, you can build up a mound of soil around the base of the trunk to help protect the root system and the lower body of the trunk from the cold.

For related articles click onto the following links:
Grow Tree Fern Spores
HOW TO FEED TREE FERNS
HOW TO GROW TREE FERNS
HOW TO OVERWINTER DAHLIA TUBERS
HOW TO OVERWINTER GUNNERA MANICATA
HOW TO OVERWINTER TREE FERNS
HOW TO WATER TREE FERNS
KELWAY: Making the Most of Your Fern
WHEN DO TREE FERNS PUT OUT NEW FRONDS?
WHY IS MY TREE FERN DEAD?