The toughest part in putting together a sustainable landscape is selecting and grouping the plants. Plants need to be arranged based on soil, sun, and water requirements with an eye to their mature size. Fortunately there are some great resources available. FYI Pasadena / Altadena are in Sunset zone 20 and USDA zone 9
The primary reference is Bob Perry’s new book – you can download the first three sections that are lists of plants organized by multiple criteria (e.g. Mediterranean, drought tolerant, ground cover, Sunset zone, etc.). The book is in the Reference section of the Pasadena Library.
Other great resources include:
BeWaterWise – a web site published by the Southern California Water District:
The Garden Spot – http://www.bewaterwise.com/knowledge01.html
Native Plant Guide: http://www.bewaterwise.com/great_native.html#Anchor-Groundcover-63546
The California Friendly Garden Guide providing access to a great plant directory:
the Theodore Payne Foundation promotes the understanding and preservation of
California native flora. They offer a great plant wiki and are local
El Nativo – mostly wholesale nursery, covers Mediterranean climate plants beyond CA natives. Has some valuable resources – link to documents detail usage of drought tolerant plants.
Las Pilitas – great native plant nursery in San Diego county.
Monrovia Nursery – has nice how to section – link to plants selected for low water needs that grow in Pasadena area – USDA zone 9