Hi mate, how are you? One of my previous businesses was a landscape business, I had to wind it back due to the body just not keeping up. Luckily I had digital marketing to fall back on.
The #1 marketing tool that you have is word of mouth, if we could bottle it and sell it - we would be millionaires. In a digital sense, its all about imagery - highlighting that focus on quality that you mention. What we can do is work together on compiling images of your best projects over the journey, then put them together into a website that addresses key search criteria for jobs that you want to concentrate on. If you have videos - even better and you may want to think about doing some "how to" videos for basic jobs as an extra source of income.
Then we can look at simple social media such as Facebook, Youtube, Linked in. And target sites that are looking for contract workers in your space.
That's a starting point of what comes to mind, but I'm sure there is so much more that will come up if we get a chance to chat.
Best Regards
Jon