As someone who spends a lot of time working outside, I'm always looking for ways to make dealing with the weather more tolerable. One thing I'm always looking to improve is my wardrobe, as what you wear can be the difference between good day and a brutal one.
Surprisingly, there don't seem to be many clothes designed for landscaping/yard work, at least not that I've found. Most folks just wear jeans, a cotton t-shirt, and some old sneakers- and if that works for you then that's fine. For me, jeans are too hot and heavy in the summer; they restrict movement, and all the sweating I do leads to chaffing. Likewise the cotton t-shirt gets soaked with sweat early on and stays wet all day- not to mention the fact that being out in the sun all day means you probably don't want your arms exposed the whole time, so you'll have to add another layer of something long-sleeved on top. Finally, heavy-duty work requires heavy duty footwear. The last time I tried to work in sneakers they only lasted a month. By the end they were almost unrecognizable and smelled awful.
Over the years, through the process of trial and error, I've settled on a wardrobe that works pretty well.
HAT - I suggest a wide-brimmed hat of some sort. They don't always look great, but this isn't the time to be fashionable- this is the time to not get skin cancer. Many garden centers sell hats designed just for this purpose. Fishing hats are a good option too. You can also tuck a bandana into the back of a baseball caps to protect the back of your neck. Regardless of the headwear you choose, I highly recommend using sunscreen as well, and you'll often find yourself looking up, head tilted back and squinting into the sun, completely defeating the purpose of your hat.
SHIRT - This was my most recent discovery. I used to wear a cotton shirt with a long-sleeved Dickies work shirt over it. The compounded layers got hot and wet quickly and stayed like that all day. It wasn't until this past winter when I was cleaning out my dresser that I realized how many tech shirts I'd acquired from participating in foot races. I had way more than I'd ever need for running.
Tech shirts are designed for vigorous physical activity in a number of ways: they wick sweat away from your skin, they dry out quickly, and they don't rub your skin raw. You can also get long-sleeved ones for running in cold weather. So I decided to start wearing long-sleeved tech shirts while working outside and lo and behold they've worked out great so far! The only trick here is that tech shirts can be outrageously expensive. Mine have all come as part of my race packages, but in stores they seem to range in price from $25-$50+ each. I have found a few run clubs who sell tech shirts with their logos for as little as $15 each, so this would be a good time to brush up on your bargain-hunting skills.
PANTS - Shorts may be fine if all you're doing is mowing your lawn, but if you're going to be outside doing serious work for extended periods of time you'll want long pants to protect your legs from sunburn, thorns and splinters, sharp metal edges, exposed nails, etc. As I mentioned earlier, I'm not a fan of jeans as work pants. Instead I wear khakis. They're lighter, dry out faster, and can often be found cheaper at places like Kohl's.
SHOES - If you're serious about working outdoors, I recommend investing in a good pair of boots. Not a cheap pair from Walmart. Find a farm supply store like Agri Supply where they carry high quality footwear. They'll last longer and fit better, which is important because good footwear isn't just about comfort, it's also about preventing injury (I can't tell you how many blisters and ankle injuries I've gotten as a result of bad boots). Also (for me), steel toes are a must. Stuff falling on your feet is an inevitability when you're working outside, and this is another area where protection in key.
So that's my wardrobe advice for working outside for extended periods of time. What clothing solutions have you discovered?