Can you advise on the ideal height for a planter box used for seating as well?

Ah, the delightful dilemma of creating a planter box that also invites you to sit and stay awhile. It's not just a box for your petunias; it's a potential throne for garden contemplation. So, let's talk height—the most critical measurement for comfort and function.

For a planter box meant for seating, the ideal height typically ranges from 18 to 20 inches (45 to 50 cm). This is the sweet spot that mirrors standard chair and bench heights, allowing most adults to sit with their feet flat on the ground and their knees at a comfortable, roughly 90-degree angle. It's a height that says, "Relax," rather than "Perch precariously."

But why this range? A box shallower than 18 inches might leave you feeling like you're rising from a deep squat, while anything much taller than 20 inches could have your legs dangling uncomfortably. This 18-20 inch zone provides the necessary soil depth for a variety of popular plants—from vibrant annuals to hearty herbs and shallow-rooted shrubs—while ensuring the structural integrity needed to safely support human weight.

Remember, your personal comfort is the ultimate judge. Consider the primary users' average height. Also, factor in the planned cushion or seat top thickness; a 3-inch cushion on a 20-inch box creates a 23-inch seated height. The material matters, too. Sturdy, rot-resistant woods like cedar or redwood, or durable composite materials, are your best allies here, ensuring your beautiful bench doesn't bow under pressure.

So, aim for that 18-20 inch foundation. It transforms a simple garden vessel into a versatile haven where both your plants and your spirit can root down and thrive. Build it right, and you'll have crafted not just a planter, but a destination.