On almost all my projects, I ask for 50% of the overall price first, 25% at the halfway mark, and the remaining 25% on a satisfactory completion. Many projects, however, are not that long or large and the 50% up front stays that way until the end. This would be anything taking less than, say two weeks. Some projects are heavily front-loaded with materials prices. And, in truth, landscaping itself is just that: heavily front-loaded in the contractor’s costs.
Take your typical $15,000 project consisting of a waterfall, a sod lawn with concrete edging, plants, boulders and a small creek bed to act as a draingae aid. The costs amount to a bit less than 40% of the project, yet almost everything comes early. $800 for a truckload of boulders, $600 irrigation supplies, up to $1,500 for parts for the water feature, $600 for any machine rentals, perhaps $2,000 for plants, $600 for sod, the cement edging $400. As you can see, it mounts up, especially when labor is factored in. Landscaping requires the single most materials-driven advances of any trade I know of.
Larger and more complex problems present another scale and formula. On projects which will last more than a month, anything, say, from $60,000 and up, I will still ask for the 50% up front. I may also ask for something prorated later, say, 3 payments of $10,000. Other projects even larger and usually commercial are not as tidy. One usually goes on an estimate of percentage of progress.