Probably the oldest form of spiritual renewal is to go on retreat. Getting away from the worries of a noisy, busy world into a peaceful country setting creates the solitude necessary for communion with the soul. Traditionally, retreats were reserved for monks, masters, prophets, world-renouncers and religious zealots. Now they're open to everyday seekers.

Just north of Baltimore on 45 acres of woods and meadows in the Greenspring Valley, Koinonia is a community of about 40 people who share the belief that, to change the world, you must first change yourself. Room and board is $13 a day, you can design your own schedule. You can work in the organic garden or remain completely alone in your search for inner space. Koinonia calls itself a "greenhouse for people." Special workshops, classes and group rereats are held regularly. For details, write to PO Box 5744, 1400 Greenspring Valley Road, Baltimore, Md. 2120S.

Ana and John Kohne opened the Dharma Center just over a year ago on a 225-acre working farm in the foothills of the Blue Ridge. Dharma offers private retreats at $25 a day. You are welcome to participate in farm activities or explore rolling hills, woods and streams while you explore yourself. Guests stay in a separate house but share meals with the Kohnes and their staff at the main farmhouse. All meals are vegetarian, with much of the food coming from Dharma's own organic gardens. If you desire, yoga instruction is available as well as sessions on polarity balancing and foot massage. For details, write to RFD Box 113-AA, Shipman, Va. 22971.

Waterfarm is on the upper Eastern Shore, two hours drive. For $15 a day, you can unwind by youself or with a friend. Guests stay in a three-story glass treehouse in the woods at the water's edge. The day begins with relaxation excersis and mediation. Breakfast is followed by workshops and seminars or you can plan your own schedule of quite recreation. Guests are asked to contribute an hour or two of chopping wood, mowing the lawn or sweeping the floor. Meals are usually vegetarian. Waterfarm also offers rebirthing, special weekend workshops and something called a "delight intensive, which, for $115 a day, must truly be something special. For retreat reservations, call 301/778-159S, collect.

At Missionhurst retreat house in Arlington poustina retreats can be arranged. Poustina means "to be alone with God." You stay in a room with a board for a bed and a blanket, consuming only bread and water. Missionhurst also offers regular Roman Catholic retreats for $15 a day room and board. You can keep to youself or seek out a spiritual counselor. Reservations are needed far in advance, especially for weekends. Call Father Wynant at 528-3800.

In the next few weeks, several special retreats are scheduled.

Yes, Inc. sponsors "Recharging: A Yoga Retreat" at Camp Fraizer in Great Falls, Va., the weekend of Nov.18-20. For beginners as well as advanced yoga students. Hatha yoga, chanting, mediation and do-in are scheduled to allow free time and silence. The champ is on a lovely site along the Potomac and accomodations are bunk-style rustic. A $45 fee includes buffet vegetarian meals with a pot-luck supper on Saturday to which each guest is asked to contribute. To reserve, call Yes, Inc. at 338-7676.

The Integral Yoga Society is scheduling a retreat the weekend of Oct. 223. At the edge of Rock Creek Park, the Porter Street house is an oasis of peace and quiet in the middle of the city. Room and board for the weekend will be $30. For those who can afford to travel to Connecticut for a weekend, the integral Yoga Society offers retreats at Yogaville East in Pomfret Center. There, students of the Swami Satchidananda, the principal popularizer of yoga in the United States, practice the variety of forms of yoga in beautiful surroundings. Guests are always welcome.The swami is in residence six months of the year, when he's there, he leads the Saturday evening satsang (a gathering of good company for spiritual sharing and discussion). Fee for a guest weekend is $30, $45 for a silent retreat. For details, call the Integral Yoga Society at 244-5538.

Another retreat within the city is scheduled for this weekend. The 3HO Foundation (Golden Temple, Golden Temple Emporium) is sposoring a course in Tantric Yoga to taught by the Yogi Bhajan. Tantric yoga is recommended for married couples, lovers or any two people who seek a deepened communication. The workshop will be held at the Quality Inn-Central on Arlington Boulevard in Arlington. Overnight accommodations are not included in the price of the weekend, $54 per person or $90 for married couples. For reservations, call 483-6660.