I don't wear denim as I'd sweat like a sieve, but I wouldn't wear shorts working around my area either (brambles, poison ivy, thick brush, mosquitos, etc). Instead I wear loose hiker's pants which have elastic cinch strings around the cuffs that can be tightened or loosened, which makes them easy to pull up to my knees to act as quick shorts. Also, the bottom parts of these type of pants zip out at the knee, turning them into actual shorts (though it'll take a minute to fiddle with the zippers). However if I want the protection of the pants but I start to get hot, I sometimes open the zippers halfway around the back of the knee, allowing them to act like air vents.