The most frequently asked questions concerning our gardens are about the tree ferns. They are startling and unusual plants and we have devised a few methods at the zoo to keep them flourishing.

There are 2 species of Dicksonia available; Dicksonia squamosa (New Zealand Tree Fern) which, if you are lucky enough to find one, will require all year round glasshouse protection, and Dicksonia antarctica (Tasmanian/Australian Tree Fern), this species we grow here.

Dicksonia antarctica can be grown outside in Britain in the milder weathered counties as long as the plant is placed in a sheltered area with adequate shade and ventilation plus the opportunity to enjoy the heat from the sun during our far too short summer. The soil needs to be richly fertilised and well aerated so as to allow good drainage. The addition of well-rotted compost should do this.

During the winter months (September to March) no watering is required if the tree ferns are left outside and only moderately if kept inside. They will need frost protection for the crown of the fern. At the zoo we have found that a pile of autumn leaves will do this but straw would be a good alternative.

From the end of March or the last frosts, watering should be increased and because the roots of tree ferns actually travel down the trunks of the plants internally, the trunks need to be sprayed. At the zoo, for those that are not positioned near one of our sprinkler systems, we have found the best method is to pour a bucket of water gently over the crown so that the water trickles slowly down the trunk. This is best done either in the early morning or late evening to avoid evaporation. They must be watered daily without fail, especially during the hot, dry summer months as these plants come from a humid climate. New fronds will push through winter frost protection so it is not necessary to remove this.

Propagation is by spores. These can be sown at any time on the surface of finely sifted loam and peat in well-drained pots which are kept moist and covered with a sheet of glass.

CUSTOMS SEIZURES

The tree ferns you can see at the zoo are all customs seizures. The importation of these plants is controlled by CITES regulations and when, in 2000, over 300 tree ferns were imported without the appropriate paperwork they were confiscated at the docks by Customs. As it was not possible to return them to their native homeland they have been placed in the care of Zoo Federation members for visitors to enjoy. Other confiscated plants donated to us by Customs include several Cycads, Macrozonia moorei.