Made up of 38,000 specially grown plants, planted outdoors and exposed to high temperatures, rain, wind, etc., Puppy is carefully tended to every day of the year. Inside the 12-meter high, 15-ton sculpture is a metallic structure comprising five floors of scaffolding that houses the watering system.
The walls are made of boxes of soil covered by metallic mesh and a green geotextile membrane. The soil is changed every four years, a task that takes 20 days to complete. The flowers themselves are replaced every six months in a process that usually takes 10 days and involves 25 gardeners.
The plants are grown specifically for Ferrovial Services at a nursery in Navarra, since they must be supplied in a format that is not commercially available. The root balls must be very small. All 38,000 plants are introduced one by one through the mesh and the geotextile. Although some patches of geotextile may be visible when the flowers are newly planted, it is soon covered when the plants grow. In summer, Puppy wears impatiens, marigolds, lobelias, begonias and ageratums. In winter he always wears pansies as they tolerate the cold.