You don't sound like the expert that you should be as the contractor.
Who uses round up? A glysophate from JDL or something of the like, is what you should be buying. Why is she buying plants? If a client says they want to buy materials or w/e, they're gone. That p!sses me off when they want to buy materials for a job YOU are doing. If they want to be the DIY homeowner, direct them to Home Depot and DIY Network.
Also, if you use fabric (it is useless for mulch, any weed seed that sprouts, lands in the mulch and then grows, making that $50 worth of fabric pretty much a waste).
This person sounds like a complete cheap a$$ and is not worth any contractor's time.
Charging (not hourly but figuring) only $45 an hour (gross, but even netting that isn't very much), regardless of your situation within life, will not be enough.
As for the guy that thinks you don't have to figure $100+ for fuel. I did an rock removal/install & several plantings installed & some sod, 6 houses away from me, I burned about $75 in fuel between getting material and dumping the removed stuff.
Depending on the task at hand for a job, I figure a minimum of $100 in fuel for my truck. Usually one tank, fuel prices are a bit lower than they were last summer so a full tank is only about $75-$80 so it makes things easier and profits are higher.
*Just because you already have said material that is going to be used does not mean you charge less!!!*
Having material (pavers, retaining wall block, etc.) leftover and keeping it at your shop is a great advantage as you don't have to purchase as much, meaning more profit.
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