General Information

• Vegetable Gardening Guide (Penn State Extension)

Calendar

• Plant Hardiness Zones (USDA)
• Pennsylvania Calendar (Urban Farmer)
• Lancaster Calendar (All Things Plants)

Companion Planting

• Companion Planting Guide (Mother Earth News)
• Companion Planting Information and Chart (Permaculture News)
• Companion Plant List (Wikipedia)

Organic Pest Control

• Organic Pest Control: What Works, What Doesn't (Mother Earth News)
• Organic Pest Control Guide (Extremely Green)
• Natural Garden Pest Control (EarthEasy)

Please suggest other links that have been useful for you or might be useful for others!