It would be comfortable in cooler and warmer weather, made of a breathable fabric so that sweat will not be trapped against the skin.
Let's start with the perfect pair of gardening pants...
the pants should be comfortable and loosely fitting with an elastic waist with a wide elastic. The fabric should be infused with bug repellent, and be stain and wrinkle resistant. It should block all UV rays so the wearer does not need to wear sunblock under the pants.
Step 1: Bottom of the Pant Legs
Step 2: Padded Knees
Step 3: Pockets, Pockets, Pockets...
There would be the standard jeans style pockets by the waist for car keys and such, loops just below those pockets for handing clippers or trowels on a carabiner, large cargo pockets on the sides of the leg with flaps that close with velcro, and flat pockets on the bottom of the leg for carrying light items like seed packets and signs to mark rows of vegetables.