Now's the time to retrieve that rusty old putter from the closet and get into the swing of things. Miniature-golf fans are already practicing their strokes, determined to master that elusive hole in one.

By this weekend most area courses will be open, offering an increasingly popular way to spend a warm spring day or night out of doors.

Miniature golf is a sport for the entire family; as one course owner put it, "Anyone from a young child to an older person, including the handicapped, can play it - and become good at it, if they want to."

The game has two divisions: Putt-Putt and miniature golf. Putt-Putt is a franchise operation that features a standard layout and lighting fixtures; each hole is a par two. Miniature golf courses, not part of a franchise, have varied layouts, and par varies from hole to hole.

Either way, the game's the same. Mini-golfers are faced with 18 holes of various obstacles ranging from windmills to small rivers. To complicate matters further, some holes are placed on sloping carpets, forcing the putter to shoot from odd angles.

L.J. Bruton, manager at Arlington Putt-Putt, spends the winter as a real-estate agent and comes up from North Carolina each spring to run his course. He was cementing down rubber tees when I talked to him, shortly before he opened for the season; he said that he replaces the carpets for each hole of his two-course setup every year because the putters "really beat the greens to pieces." Bruton charges a dollar per game and hopes that if business remains good, he won't have to raise his rates. For groups of seven or more such as birthday parties, one round cost only 75 cents.

In Alexandra, Mount Vernon Putt-Putt's three courses opened March 1; they'll be open daily until the end of the fall. Manager Neil Frandson charges $1.75 per game, $3.50 for three games any time during the week, and $9.50 for ten games.

Frandson, a student at the University of Maryland, says that Mount Vernon Putt-Putt aims at bringing out the entire family, so he has special summer discount rates for children - first game $1.75, second game 50 cents.

"Since Mount Vernon Putt-Putt is located in the Mount Vernon Plaza Shopping Center, Mom can drop the kids off while she does her shopping," Frandon says.In addition, he says, businessmen often stop off during lunch breaks to play a few rounds.

Frandson says his three-year-old business has been so popular, mainly because of the discount rates, that he will probably build a fourth couse this summer.

Like Arlington Putt-Putt, there are lower rates for large groups. But for each day of the week, with the exception of Sunday and Wednesday, there are "special." On Monday, putters can play from 9 to 6 for $2.50; Tuesday is junior putters' league day; Thursday is bumper-sticker night; and Saturdays, children (5 to 14) play for 50 cents a round.

In Rockville, owner Chip Linville, who is also a partner at the Mount Vernon course, opened his doors several weeks ago; he would have opened even earlier, but the course went through a face-lift that involved replacing several holes and rebuilding the clubhouse.

The Rockville Putt-Putt stays open until December 1. Linville, who has been in the business 11 years, predicts that more people will be playing Putt-Putt this year than ever before. Why? Because, says Linville, Putt-Putt has increased its promotional efforts and there's a growing awareness that the game is not just for kiddies.

"Putt-Putt," claims Linville, "is for the masses. We're a novelty sport that is increasing in popularity. On any given weekend, we attract as many fans as do the Redskins games."

All three area Putt-Putt courses have what they call "Moonlight Madness," which take places Friday and Saturday nights in Rockville and Alexandra and Saturdays only in Arlington. It's a putters' tournament that begins at midnight and lasts until at least 4 in the morning.

Winners usually receive trophies and discounts on future games, gift certificates from local merchants and T-shirts; and at the Arlington Putt-Putt, a picture of the Moonlight Madness winner is posted on the clubhouse for the following week.

Moonlight Madness usually begins in May at all three courses, depending on the weather. To qualify for the tournaments you need only show up. One veteran Moonlight Madness contender warns, "Don't plan on beating out the competition by playing the course ten times a day, because managers have been known to tighten or loosen the boards of a course prior to the tournament, just to throw you off."

But Putt-Putt isn't the only game in town. There are also the various un-standardized miniature golf courses in the area.

The Spring Mall Golf Center opened at the end of March after the obstacles were repainted for the new season. Manager Bill Salyer charges $1 per round, and the usual free game is obtained if the putter makes a hole-in-one on the 18th. Salyer claims that his course "is a little different from others around here. We offer a driving range and pro shop, in addition to the course. Plus we have electrical obstacles, which very few miniature gold courses have. Our obstacles move. For example, we have moving bowling pins that must be avoided to reach one of the holes."

The East Potomac Miniature Golf course is to open this Saturday at noon, weekends only. Once school lets out it will remain open seven days a week until Labor Day. General Manager Jack Rogers said that he had a lot of repair work to do since the snow damaged many of his carpets. Rain doesn't do much harm to the course, Rogers continued, because the courses are built with small cracks in the cement that provide drainage. Rogers says he doesn't get involved in the competitive aspect of miniature golf: "My course is run strictly for the public's enjoyment," at a dollar a round.

Jim Kennedy, owner of the Arnold Palmer Putting Course, said that "Some of our ferris wheels and windmills still need painting, but we're officially open for business now."

The course will be open weekends only at first, but later this month it will open full time. Kennedy also charges one dollar a game fro adults, but for kids it's 90 cents. Discounts are available too: A three-game pass costs $2.50, a five-game pass $4.

Kennedy says tournaments are held every Wednesday night for all age groups. The contestants play three rounds and the winner receives a trophy, while the second and third runners-up receive a discount pass for future games. On Saturdays from noon to 5 putters can play all day for $1.50. "Most business we do is with families and young adults," Kennedy said. And carpet-lovers beware: At the Arnold Palmer course the course is made of Astroturf, which Kennedy claims, is more durable.

The Rocky Gorge 4 Seasons Golf Fairway, as the name indicates, is open all year round. Owners Gus Novotny and Fran Robinson primarily operate a driving range in the winter, but Novotny says, "Since it doesn't cost any more to keep the miniature course open we're not going to turn anyone away who wants to play bundled up in a scarf, hat and mittens."

Now that the days are longer, Rocky Gorge, which is about nine miles off the Beltway in Laurel, will be open day and night, again depending on how many warm nights there are. One game costs $1.25 for adults and kids alike. Novotny says Rocky Gorge does not hold tournaments because "We have only one course and don't want to tie it up with a tournament."

Novotny, himself, is a designer and builder of golf course, which comes as no surprise once his obstacles are seen: an eight-foot totem pole and an 18-foot Washington Monument.

Here's a list of area miniature courses; except as noted, they're all open. CAPTION: Picture, LINING UP CAREFULLY, TO HIT THE BARN-DOOR. By Doug Chevalier.