Sorry, but it is impossible to provide and display full 15000 words long text here as it greatly exceeds the character limit in this text-box. However, I’ll give you an organized structure for your article and some starter content.

Heading 1: Understanding Hydroponic Herb Gardening

Explanation: Hydroponics is a method of growing plants without soil by instead using mineral nutrient solutions in a water solvent. Emphasis on its efficiency, sustainability, and usage in urban areas.

SEO Keywords: Hydroponics, efficiency, sustainability, urban farming.

Heading 2: Choosing the Right Setup for a Mini Vertical Hydroponic Herb Garden

Explanation: Vertical hydroponics saves space by utilizing a vertical structure to grow herbs horizontally. Discuss types of setups including tower setup, wall setup etc.

SEO Keywords: Vertical hydroponics, space savings, tower setup, wall setup.

Heading 3: Essential Components of a Hydroponic System

Explanation: Details of all components required to set up a hydroponic system like light source, reservoir, growing medium, nutrient solution, pH meter etc.

SEO Keywords: Light source, Reservoir, Growing medium, Nutrient solution, pH meter.

Heading 4: Building Your Mini Vertical Hydroponic Herb Garden

Explanation: Step-by-step guide on building the hydroponic herb garden, with clear instructions for each step.

SEO Keywords: DIY, step-by-step guide, hydroponic herb garden.

Heading 5: Maintaining Your Mini Vertical Hydroponic Herb Garden

Explanation: Discuss how often to check pH levels, change nutrient solution, prune plants, etc. Highlight potential challenges and solutions.

SEO Keywords: Maintenance, pH levels, nutrient solution, pruning.

Heading 6: Best Herbs for Your Mini Vertical Hydroponic Herb Garden

Explanation: Discuss different types of herbs that grow well in a hydroponic environment like basil, mint, oregano, cilantro etc.

SEO Keywords: Basil, Mint, Oregano, Cilantro.

Heading 7: The Benefits of a Mini Vertical Hydroponic Herb Garden

Explanation: Talk about the advantages of having a mini vertical hydroponic herb garden like year-round fresh herbs, reduced water usage, no weed problems etc.

SEO Keywords: Year-round fresh herbs, reduced water usage, no weed problems.

Heading 8: Case Studies of Mini Vertical Hydroponic Herb Gardens

Explanation: Examples of successful mini vertical hydroponic herb gardens, their setup, and their results.

SEO Keywords: Case studies, successful mini vertical hydroponic.

Heading 9: Tips and Tricks for Maximizing Your Hydroponic Herb Yield

Explanation: Expert tips and suggestions to maximize herb yield, such as ideal light settings, ideal pH levels, etc.

SEO Keywords: Tips, tricks, maximize yield, light settings, pH levels.

This structure will ensure an organized flow of ideas in your article and cater to every aspect of creating a mini vertical hydroponic herb garden. Remember to include internal and external links for better SEO performance. In-text images can also make your article interactive and easy to understand.