Your advice on subing out a landscape/turf install

One of our customers will soon be finishing construction on a new bldg.
Based on what is already on our plate for this spring, I may have to sub it a larger company here who does very good work and I know the owner.

I have never sub'd a large landscape install and want to make sure I cover all the bases for my customer. One part of the job is the installatiom of 60 6 ft pines and thats only about half the job. The local township rules give him only X number of days to get the landscape in which is where the problem lies for us doing it.

Would you be willing to share with me a sample bid/work order you use of have used in a sub situation?

Other things you want to mention to watch out for would be much appreciated ...thanks for your advice