The second garden has plants from temperate and subtropical regions. There is an extensive collection of palm trees, although a number of Phoenix canariensis have been destroyed by the red palm beetle (Rhynchophorus ferrugineus), which is ravaging many palms around the Mediterranean. A project is underway to evaluate the use of nematodes to combat the pest, while currently electronic sensors are plugged into the top of the stem. When the movement of larvae is detected, a mobile phone alarm is sent to alert staff who treat them with neem oil.
A concoction made from nettles, larkspur and equisetum, grown in the garden, has been successfully used as a plant stimulant and pesticide, and there is now a research project to understand its effectiveness.
The whole garden is run on ecological principles, without the use of chemicals, and the bug hotel was popular with a range of different insects.
Both here and at the Barcelona Botanic Garden, many of the palms are left untrimmed as they would be when growing in the wild: the dead fronds up the stem providing protection and also a habitat for wildlife. The palms are often interplanted with Strelitzia nicolai and S. reginae growing to impressive heights.