Average Salary: $26,000
Expected Lifetime Earnings: $1,085,448
Gardeners see quite a bit of green at work—but most of it isn't in their paychecks. Landscape maintenance isn't really a great way to get rich, or even to get not-poor. That said, a few landscaping companies do rather well, raking in the cash while they're raking up the leaves.
These successful businesses often provide benefits for their employees. Unfortunately, most landscape maintenance companies aren't that successful, so you'll have to take what they give you.
The industry is loaded with cheap competition. It's hard to compete with those who settle for minimum wage without benefits. Those who take their work seriously and want to get paid adequately for it are at a serious disadvantage for the average yard-trimming job.
Those just starting out must often settle for minimum wage until they get through their probationary period, at which point they get a small pay raise. After gaining enough experience and a few long-term clients, gardeners with a decent reputation can average $25,000 or so annually (source).
To make any more than that on your average groundskeeping crew, the best way is to become a specialist (such as an arborist) and get paid extra for those extra talents.
The most desirable jobs are at big gardens and parks, or working for municipalities. They earn the best rates of pay, often exceeding $55,000 for college graduates with a few years of experience. The benefits are also much better in these jobs.
Outside of the traditional routes, there are landscape maintenance companies out there trying to capitalize on all sorts of trends. Drought tolerant landscapes, xeriscaping, sustainable gardening, and other alien-sounding gardening advances are all ways in which companies can moon jump into the landscapes of the future—and maybe earn a little extra money doing it.