Dr. Larry Costello is retired after 30 years as an Environmental Horticulture Advisor for San Francisco and San Mateo Counties. He is currently is a horticultural consultant and nurseryman, co-owner of Oracle Oak Nursery in Hopland, CA.

Ellyn Shea wears a number of hats as a Certified Arborist, Certified Tree Risk Assessor, Registered Consulting Arborist, gardener and horticultural educator. Her checkered professional experience includes landscape gardening, bookkeeping, teaching abroad, community urban forestry and arboricultural consulting. Ellyn is also known as the go-to girl for passing the Certified Arborist Exam in the San Francisco Bay Area, after putting on several "Arboriculture Boot Camp" workshop series. Visit her at www.garden-guidance.com