1. Introduction to Sustainable Urban Gardening
– Overview of urban gardening and its benefits.
– Basics of choosing the right location and containers.
– Starting with easy-to-grow plants for beginners.
– Tips for soil selection and composting.
2. Container Gardening for Small Spaces
– Detailed guide on container gardening.
– Types of containers and suitable plants.
– Watering, fertilizing, and pest control in containers.
– Creative ideas for maximizing small spaces.
3. Composting 101: Turning Waste into Garden Gold
– Introduction to composting and its environmental benefits.
– Composting methods and bin selection.
– What to compost and what to avoid.
– How to use compost to enrich your garden soil.
4. Vertical Gardening Mastery
– Advanced techniques for vertical gardening.
– Building vertical structures and trellises.
– Selecting and caring for climbing plants.
– Designing visually appealing vertical gardens.
5. Advanced Pest Control in Sustainable Gardening
– In-depth pest identification and prevention.
– Organic and eco-friendly pest control methods.
– Integrated pest management strategies.
– Troubleshooting common pest issues.
6. Seasonal Gardening for Year-round Harvest
– Planning a four-season garden.
– Crop selection and planting schedules.
– Extending the growing season with cold frames and hoop houses.
– Harvesting and preserving crops throughout the year.
7. Permaculture Principles for Urban Gardens
– Introduction to permaculture and its principles.
– Designing a permaculture-inspired garden.
– Creating sustainable ecosystems within your garden.
– Regenerative gardening practices.
8. Advanced Soil Health and Nutrient Management
– Soil testing and analysis.
– Amending soil for optimal plant growth.
– Nutrient deficiencies and remedies.
– Soil conservation and erosion control.
9. Hydroponics and Aquaponics for Urban Agriculture
– Hydroponic and aquaponic system design.
– Growing without soil: nutrient solutions and water quality.
– Managing fish and aquatic systems in aquaponics.
– Troubleshooting and maintaining hydroponic and aquaponic setups.
10. Urban Beekeeping and Pollinator Gardens
– The importance of pollinators in sustainable gardening.
– Setting up and managing a beehive in an urban environment.
– Creating pollinator-friendly gardens.
– Beekeeping ethics and best practices.
11. Advanced Garden Design and Landscaping
– Landscape planning and design principles.
– Incorporating aesthetics and functionality.
– Hardscaping and garden structures.
– Sustainable plant selection and placement.
12. Advanced Seed Starting and Propagation Techniques
– Mastering seed starting indoors and outdoors.
– Cuttings, divisions, and grafting.
– Saving and storing seeds.
  – Hybridization and breeding for unique plant varieties.
These courses can offer in-depth knowledge and specialized skills to those who are truly passionate about sustainable urban gardening, while the free courses serve as an introduction and encourage users to explore further. Pricing for premium courses can be based on their complexity and the value they provide.