Patricia Fisher tosses a limb from the roof of her home in Tybee Island, Ga., after an oak tree uprooted during the recent Hurricane Matthew. Experts say tree maintenance could help prevent or minimize such weather-related problems. (Kathleen Foody/AP)

It’s easy to think that trees are among the few great things in life that are free. They increase our property values, provide shade, give us autumn scenery and help create the air we breathe. But sometimes there may be a price.

To keep your trees healthy or to get rid of dying ones, you may want the benefit of professional advice, skill and labor. That is especially important as winter approaches. Falling tree limbs can cause great damage to your home.

To help you find this help, nonprofit consumer group Washington Consumers’ Checkbook magazine and Checkbook.org have surveyed their members and Consumer Reports subscribers about their experiences with area tree-care services. For the next month, Checkbook is offering free access to its ratings of tree care services to Washington Post readers via this link: www.checkbook.org/washingtonpost/tree-care.

You don’t have to be an expert to spot many potential tree problems. Examine your trees several times a year for the following:

  • Discolored leaves and thinning in the tree’s crown;
  • Roots pulled loose from the ground and fungal growth on roots and main trunk;
  • Dead and fallen branches more than two inches in diameter;
  • Deep vertical cracks on opposite sides of the main trunk;
  • Sawdust on the trunk from wood-boring insects;
  • A trunk that noticeably leans in one direction and a branch canopy that is not roughly balanced;
  • And other unusual deformations and deposits on leaves, limbs or bark.

Other reasons for tree work include eliminating the risk to your house or to electrical or other utility wires from rubbing limbs or precarious overhanging limbs; letting light and breezes more readily reach your house, garden or lawn; and protecting foundations and drainage systems from invading roots.

In many cases, the problem and the solution will be obvious — removing specific limbs, for example. But sometimes it’s difficult to diagnose and treat trees. At those times, you need expert advice. But don’t assume that all estimators from tree-care companies can determine what’s wrong and prescribe the correct treatment.

Checkbook’s evaluation of local tree-care services found big company-to-company differences in the quality of advice and work performed. The good news is that many area companies were rated quite high for the quality of their work. But the news is not all good. Some companies received favorable ratings from only 60 percent or fewer of their surveyed customers. Common consumer complaints included charging more than promised, producing bad results and even property damage caused by careless or untrained workers.

If you need tree care work, the best strategy is to get more than one opinion. Invite representatives of several companies to your home to offer estimates. Ask them to explain what they plan to do and why.

Along with several opinions, you’ll get comparative pricing. Checkbook’s undercover shoppers found big differences in prices for tree care work. For example, for a large tree removal job, companies quoted prices ranging from $1,825 to $6,600.

Typically, you don’t have to be home when bidders are looking at the job — but do include a thorough description of the work in a written contract that specifies who cleans up afterward, hauls away debris and wood and removes the stump. What is not specified in writing is very unlikely to get done.

If a job can wait, consider having the work done in winter, when companies are less busy and there is less debris to haul away.

Check whether a company’s liability insurance and workers’ compensation insurance are currently in effect. Ask to see certificates of insurance, and call the company’s insurance carrier to verify. This is a serious concern because high-powered equipment, heavy branches and trunks, lofty heights and proximity to power lines make tree work dangerous.

If you live in Maryland, also check that companies are licensed. Companies operating in Maryland must be licensed to perform virtually any tree care work — including removal — for trees taller than 20 feet. To check on a company’s licensure status, search the state’s online list at http://dnr.maryland.gov/forests/Pages/programapps/newtreeexpert.aspx or call 877-620-8367. Neither the District nor Virginia requires tree care companies to be licensed.

Finally, ask about the company’s payment policy to see how much of the total cost is payable upon completion of the job or later. Paying after the work is completed gives you leverage to ensure that work is carried out properly and on time.

Kevin Brasler is executive editor for Washington Consumers’ Checkbook and Checkbook.org. The nonprofit Washington Consumers’ Checkbook magazine and Checkbook.org rate service companies and professionals. See ratings of area tree care services free of charge until Nov. 15 at www.checkbook.org/washingtonpost/tree-care.