Tony Dickerson answers your gardening questions
Has tree fern died in early cold spell?
Q Can I revive my tree fern? Hazel Dyke, by email
A The cold spell in February has killed a lot of tree ferns and I fear that is the case with yours. By now there should have been some new fronds. Put your hand down in the crown and feel for the croziers, which are the curled frond shoots, and break one away. You’ll probably find that it’s black where you have broken it off, indicating that the plant is dead. Often, in milder areas, simply protecting the crown of a tree fern is sufficient, but in very cold spells this is risky. As we can never predict the severity of the winter it pays to be cautious by going to some trouble to protect tree ferns. The smaller they are the more likely they are to suffer cold damage, but it’s good practice to protect all tree ferns regardless of size. The protection needs to be put in place at the first warnings of frost, usually between September and November, depending where you are in the country. First, pack some straw in the crown and cover with a circle of polystyrene. Gather the fronds up and tie them around with twine above the polystyrene disk before cutting off the surplus growth. Then, using wire netting, create a tube at least 40cm (1¼ft) wider and higher than the trunk and put this over the plant. Pack straw down to the bottom inside the tube – barley straw, available from farms or pet stores, is ideal.
Cut a large square of polythene and place this over the top of the wire netting tube and tie it down securely. This will protect the crown from excess winter wet that might subsequently freeze, but leaves the sides open so excess condensation doesn’t build up. Finally, put a 15cm (6in) mulch of bark or coarse garden compost around the tree fern to protect the rhizoids (roots).
Straw-packed, wire netting tubes are the best way to protect a range of tender plants, such as bananas. In spring the protection can be removed once all danger of severe frost has passed and stored away for the summer to reuse the next autumn.