If you're buying a home, you're probably already feeling strapped for cash, and might not be eager to add another cost to your list. And if you're already hiring a home inspector, you may think that will cover your needs; the home inspector is a generalist, who should be able to flag any issues with the home that might reduce its value or warrant ongoing negotiations with the seller, right?
Maybe yes and maybe no. The standard home inspection does cover both the inside and outside of the home you'll be buying: its structure, systems, and physical components, such as the roof, plumbing, electrical and heating/cooling systems, floor surfaces, paint, windows and doors, and foundation. The inspector will look for pest infestations (termites, rodents, and other critters) as well as dry rot, mold, and similar damage.
A good inspector will also examine the land that the house sits on, for issues concerning soil grading, drainage, and retaining walls, and note issues concerning plants that affect the house, such as through root intrusion or falling branches.
That's a lot on the inspector's plate already. (And it's worth finding out where your inspector's particular strengths and weaknesses lie; almost all inspectors are stronger in some areas than in others.)
But even the best home inspection typically doesn't cover everything that you might care about with a house, nor everything that adds to its value.
If the house has extensive grounds, or landscaping in place; or if you're hoping to have it landscaped, and would like to know the limits and possibilities; you might want to hire a separate professional to evaluate issues relating to outdoor hardscape and structures, plants, soil quality, irrigation system, and other aspects of the landscape.
While no official "landscape inspector" profession exists yet, this term is being used more and more to describe a landscape professional who will, for a fee, examine a piece of land and prepare an evaluation. A thorough landscape inspection should include:
Don't be put off by the fact that the standard purchase contract has no box to check for a "landscape inspection." As with any other aspect of buying a house, you can ask to include conditions, referred to as "contingencies," to your closing the sale. If you'd like to make the deal contingent on being satisfied with the results of a landscape inspection, you can certainly ask.
If your real estate agent can't recommend someone for this job, do an online search for "landscape inspection" and the name of your town. Be sure to research the inspector's background, check personal references, and ask exactly what will be included in the inspection.
For detailed information on all aspects of house buying, including more information on inspections and negotiations, get Nolo's Essential Guide to Buying Your First Home, by Ilona Bray, Ann O'Connell, and Marcia Stewart (Nolo).