This is a blog by Thomas Wang, gardener and professor at City College of San Francisco.  Each post is a nature story with teaching diagrams.   The posts range the gamut of Thomas’ research interests from the qualities of soil and water to food and drug plants; from butterflies around San Francisco to the caterpillar within.

The goal is a stronger bond to the world that surrounds us, and an inner metamorphosis.  Good luck in your journey!

Note regarding City College of San Francisco Horticulture online class curriculum:

In addition to, or sometimes in lieu of, the text book and reader assignments, students are asked to read selected entries here.  There are also a handful of youtube videos. Due dates will be assigned in class.  These entries are grouped according to the classes taught.

Granted, there is some repetition from one class to another, and there is also material which builds upon the foundation of introductory classes.  As students, you are welcome to ‘jump ahead’ or read up on any topic, no matter what classes you are enrolled in.  The following sections are organized by Class, Topic, Numbered blog entry at, and Youtube link.

OH50 Introduction to Horticulture
This class is the first class any student ought to take in our department. It gives a good overall introduction to the science and art of plant work. The topics are listed in the order we follow based on the contents of the California Master Gardener Handbook.

Work opportunities:

Climate and weather:

Taxonomy and origins:
Centers of diversity

Structure, function, & processes:
CMGH Chapter 2 supplement
Flower parts:
Hormones and alkaloids:
Roots stem leaves flowers seeds:
Abscisic acid, pollination, fertilization:
Plant parts:
Seeds, stilt roots 10

Soil and compost
Composition and function
Cation exchange capacity & colloids
Food webs and organic matter
Basics and chemistry
Profiles etc
Serpentine soils etc 8

Fertilizer and amendments:

Water & irrigation:
Soil water and tree relations
Irrigation notes

Vectors viruses & bacteria
Fungus basics


Entomology and invertebrates:
Bee love 32; Larvae 31; Invertebrates rule 29; Insect pests 9

Pesticides: Nerves & acetylcholine, poisons & horticulture

Integrated Pest Management

Indoor plants

Lawns and turf

Woody plants

Vegetables and fruits: Challenges 20; Day length etc 13

Vegetables and fruits:



Poisons and medicines::

Golden Gate Park field trip

OH53 Landscape Horticulture
The notes here are from two classes I have been teaching with Gus Broucaret for the past dozen years +. Landscape horticulture class concerns basic maintenance in the garden. Gus has owned his own landscaping business for over forty years – planting tulips, doing fine pruning, and mowing lawns in gardens all over town.  The class focus is primarily hands on and practical – to help and guide gardeners and landscapers in their day to day work. The class is significant in our emphasis on safety and small machines.

Fall semester:

Work opportunities

Safety, insects & fungi

Pruning trees and woody plants
Tree pruning and planting 46

Herbaceous perennials

Drainage, erosion control, and mulches

Field propagation

Drip irrigation

Compost and recycling in the garden

Humans and small engines
Part I:
Part II:

Part I:
Part II:

Fixing irrigation
Part I:
Part II:

Erosion & drainage

Building rock walls

Tool final fall semester:

Spring semester:

Gardener conduct:

Fences and hedges:

Grasses and turf:

Working as a gardener

Body mechanics and injuries

Gardening approaches

Irrigation valves:

Tool handles:

Mammalian and bird pests:  

Maintenance schedule

Safety and injuries:

Tool final:

OH55 Tree Care:
Tree basic vocabulary

Tree selection

People are walking trees

Tree death and disease

OH58 Greenhouse production 

This class, along with the following class OH65 Propagation, are taught by Tom Perlite and myself.  Tom is the owner of Golden Gate Orchids, and runs the last and only commercial greenhouses left in San Francisco.  He is awesome, and shares a wealth of knowledge with the students about growing orchids, vireya rhododendrons, cycads, ferns, and on and on.  A fountain of spring water he is!

Greenhouse history

Greenhouse location

Day length and plants:


Poinsettia crop
Crop update
Another update

Potting soil ingredients


Conservatory of Flowers tour

Park Nursery tour

Heating and cooling systems

Humidity & poinsettias update

EC Meter and the Dosatron


OH65 Propagation

Society and plant use:

Society and plant use

Life cycle and genetics

Growing environment


California natives:



Mimic natural habitats



OH70 Landscape design
If you want to design gardens or landscapes, this is a good series (two classes) to take. Some people who have design experience from interior or industrial or art related realms jump right in. Others wait till the end to take the design classes – learning plant Identification, construction, characteristics of soil and water – before committing. Either way, you will learn how to draw a good set of plans. Afterwards, students tackle either residential yards and public spaces, or go on to graduate school if they want to become a landscape architect. We focus on the importance of knowing your plants and their ecology in relation to the overall design. We teach you to see the garden as a dynamic multi dimensional creature that requires care and maintenance over time. Heres the reading list according to our curricula itinerary:

OH 70A Beginning design:

Site inventory and basic drafting
Site survey
Site survey

Garden styles
Miscellaneous styles

Hardscape materials

187. DESIGN: Hardscape and edges

Section elevation


Plant selection and placement

San Bruno Mountain field trip

Drawing plants

Basic principles

Gondwanaland designs

SFBG field trip

Isometric drawing

One point perspective drawing

Hand drawn plans

Filoli field trip:

182. DESIGN: Field trip to Filoli

OH70B Advanced design:

Water features:

Chinese gardens

Plant ecology and community


Maintenance and design

Sacred gardens:

OH76 Plant Identification
These notes have little to do with the actual plant identification classes offered at CCSF.   Plant ID (OH 76 & 77) teach another set of about 300 commonly planted ornamental plants around here.  Nevertheless, this seemed like the best heading to place the following entries. Observing plants and learning their names and habits will make the world come alive for you, and sharpen your senses and mind.








Tree identification and classification

Xeriscape gardens

This concerns dry land gardening.  How to select proper plants, when to plant, and how to plant in seasonally dry and drought prone regions such as ours here in California.

162. XERISCAPING: Introduction

163. XERISCAPING: Succulent and cacti

164. XERISCAPING: How to plant

165. XERISCAPING: Plants from down south

166. XERISCAPING: Local plants and butterfly plants

167. XERISCAPING: Planting for wildlife

168. XERISCAPING: Hedges & lawns. Irrigate like rain.

Miscellaneous garden posts

School gardens

Story cards

Basic curriculum

Botanical gardens

115. GARDENING: More changes at the botanical garden

Glen Canyon, San Francisco