First and foremost, it needs to be stated that tips are optional not obligatory. Tips should not be given out willy nilly; they should be earned by hard work. The customer reserves the right to withhold a tip if they have good reason to believe that the work was subpar. Valid reasons for refusing to tip are as follows: workers show up late, check their phone often, take too many breaks, pull out your plants, damage your current landscaping, cut corners, use profane language, etc. That said, if the yard work performed exceeds expectations, then a 10% to 20% tip is a reasonable amount. In this regard, the landscape industry is similar to the restaurant industry. Working outside through rainy weather or scorching heat warrant a higher than average tip.