its pretty simple actually..you quote , the customer accepts...your invoice provides supply and plant or lay and thats it ...the important thing is that customer receives information from you that the job will entail a list of things that you will do ....eg supply and lay much to the existing garden beds after they have been weeded , no need to specify the volume of materials , all they want is a good job...evryone looks at the bottom line...customer gets a great looking job and you get a fat reward.....