The virtual work force is growing fast and bringing many benefits to companies. According to Chris Ducker, an expert on virtual staffing and author of the book Virtual Freedom, a typical business saves $11,000 a year for each virtual worker it hires. Beyond that, the ability to hire the best people you can find, regardless of whether they work from your office, can produce immeasurable benefits.

But although that's all well and good, managing virtual employees brings challenges that you just don't have in a standard office environment. The good news is that these challenges can be conquered with just a bit of effort on your part. Here are five tips for managing your virtual employees more effectively than you ever thought possible.

1. Increase communication as you increase distance

The old saying "Out of sight, out of mind" really applies when it comes to virtual workers. It's easy to forget that they're out there--at least until something really good or really bad happens that involves them. Make a point of reaching out to your virtual employees regularly, even if it's just to say hello and ask how things are going. The farther away you are from your virtual workers, the more important it is to keep in touch. Put a weekly call on your calendar to each of your virtual employees, and make sure you follow through on it.

2. Bring your virtual employees into meetings

Technology now makes it easy to include your virtual employees in regular business meetings. Invest some money in getting a quality speakerphone system for your conference room that allows everyone to hear and be heard clearly, or set up a PC or laptop with a camera that you can use to make calls on Google Hangouts, Skype, or a platform like GoToMeeting. There's no reason to leave anyone out of your meetings, regardless of where he or she may be.

3. Schedule periodic team-building events

People naturally build strong relationships when they work together as a team. It's much harder for virtual employees to build these strong relationships with co-workers--especially co-workers whom they never meet in person. You can help your virtual employees build strong bonds with their co-workers, both virtual and nonvirtual, by hiring a facilitator and scheduling periodic team-building sessions with all of your employees. Not only will these employees enjoy meeting one another in person, but you will help them build better working relationships and bridges of trust that will make them more effective and productive.

4. Make your expectations crystal clear

Because virtual employees don't work in the office, they are not subject to the standard rules that your other employees have to adhere to. If they work at home, every day may be Casual Day, and you may find them working at a Starbucks in the evening or on a schedule that has little relationship to the one your business runs on. Although some amount of independence in your virtual workers is usually a good thing, if you have specific expectations for them--for example, that they will work during normal business hours or that they will always be available by phone--then you need to make those expectations perfectly clear. If everyone's expectations are in sync, you can avoid a lot of misunderstandings and potential conflict.

5. Celebrate their successes

All your employees need to be recognized and rewarded when they do good things for your company, and this includes your virtual workers. Make sure you take time to reward your virtual employees, and publicize this recognition widely throughout your organization. Though you may not be able to bring your virtual employees into the office for recognition, you can send them thank-you notes and recognition items such as gift cards, coffee mugs, flowers, or any number of other items to celebrate their success.