Question
I moved from Chicago to Texas and am building in the hill country (just outside of San Antonio). I need to find a landscape designer & have little knowledge of Texas landscape options.  What are the best questions and areas to cover with potential designers with respect to design, timing, cost, hidden expenses, etc.  Is there an "average" cost to gauge what is reasonable for design cost alone?

Answer
The question/s you have posed require a lot more understanding of your program than you have provided. Design(only) Fees are typically either hourly, lump sum, or based on a percentage of the installation costs. The latter is primarily used when the designer will administer the contract and assist with reviewing the work during installation. In general hourly rates vary widely from city to city and designer based on demand and credentials. A junior landscape designer may charge as little as $25 to $45/hr for residential design and will typically have only limited scholastic credentials and experience. A more qualified designer with significant schooling and perhaps even a horticulture or landscape design degree will typically charge $45 to$75/hr. And finally a registered and/or well credentialed designer who may or may not be a registered Landscape Architect or some one with significant professional experiences and local knowledge will typically charge $65 to $200/hr. Most charging around $85 to $100/hr. Only senior and very well known designers charge more than $125/hr. for Residential designs.

As a general rule on projects under 25,000 you should expect to spend 8-10% on design fees. This percentage typically drops as the budget increases. For example on a million dollar project, the fee might only be 3% and on a $200-500K project expect about 5-7%.
If you are not planning to spend at least 10K on your install, then you probably don't need and can not justify the expense of a professional designer...consider instead using a design/build firm.

When interviewing designers I would suggest asking question about elements of your program. By that I mean to be sure they are familiar with the types of plants and major features you would like to install in your yard. Ask if they have a personal "design style". If they do, be sure it is congruent with your tastes. Many good designers will easily be able to mold their design to meet your style not their own.
In design there are no hidden fees that are typical, but I can't speak for every designer. I charge a fuel surcharge on sites that are more than 30 miles from my office.

You can begin your search fro designers on the www.ASLA.org web site if you want a registered Landscape Architect.

I hope this helps,

Best of Luck

Sean J Murphy, RLA, ISA
www.amenityarchitects.com
www.seengineering.com