Sending your kid off to college might result in sudden loneliness, especially if you've had a close relationship. You might fool yourself into thinking that you are worried about them when, in reality, you just miss them. When it comes down to it, that umbilical cord, never emotionally cut, could stand some more loosening. Daily contact, appropriate in high school, becomes a new delicate issue: What is too little? What is too much? You're back to Goldilocks trying to get it just right.
To start, acknowledge your own needs -- not always pretty, but pretty universal -- and try to separate them from your child's. You will hate admitting to yourself your co-dependency on them, but it leads to a courageous discovery. Then you can have a conversation about what you both consider to be an appropriate level of communication -- daily, weekly, bi-weekly. Once you agree on how often to connect, stick with it and learn not to nag, but instead to gather information during these check-in times that will satisfy your real need to know as well as allow them to mature on their own. Topics to ask and advise about might include class schedule and workload, grade expectations, budgeting vs. bailouts, roommate compatibility and friends. Encourage engagement in co-curricular activities and clubs that lead to developing meaningful friendships, furthering self-exploration, and promoting leadership.
Negotiate home visits that can range from monthly to only on major holidays. Be aware that coming home too often keeps both you and your child dependent, so discourage regular weekly visits. On the other hand, cutting children off cold (no matter how old they are), that old sink-or-swim method, may be too harsh. Forge a reasonable middle ground. When the shoe is on the other foot and your kid is expressing feelings of homesickness or having chosen the wrong college, be brave and give suggestions of ways to participate more and learn how to belong. Don't give in until they have done their part and really tried.
It's a given that going off to college should be a step in maturation for your child, but it's also going to be one for you. Use your newfound free time along with your own anxieties to fuel the next stage of personal development for yourself: to advance your own career, find new hobbies and activities that fulfill you, even mentor younger children. In the absence of the responsibility of day-to-day parenting, use that empty space -- called the "empty nest" for good reason -- in far more profound ways than you had expected to. It will be a win-win.
Help them make their luck happen.