I agree with what Curtis James says above.
I'm also a landscape designer that is contracted to install some of my creations and depending upon the job, two to three weeks of time can be taken up at a single residence. Quite often the material costs are high when taking into account the plant material, stone and brick work, and/or other hardscape items. As a result, I don't see anything wrong with progress invoicing, say on a weekly basis or when the materials arrive. I typically don't worry too much about the labour, but I can't afford to be stuck with thousands of dollars of materials. I look at the majority of landscaping and tree-related work as non-necessity, so if the homeowners can't afford the work, they shouldn't be getting it done! When I am doing a tree removal or even a contract job, I just stick it out, get it done, then invoice. This is because the majority of these jobs are in and out in a day or two, not weeks. Being out your time is one thing, but once materials are involved, you've got to look after yourself. (Just my feeling!)
