With Thanksgiving behind us, it's time to prepare for winter in earnest. Bed down the lawn and cut it for the final time; some of the work will be hand-digging chickweed and henbit, other will be liming the lawn. Neglected lawns will need dethatching so you're able to overseed in the next two weeks. This is also time for last-minute planting of spring bulbs; otherwise, you'll have to freeze the bulbs for the winter. You need to plant potted mums, too.

First, if you've shepherded your lawn well this fall after the late summer renovation, make your final cut of the turfgrass this weekend. Bring down the cut to 1 1/2 inches for fine fescue, tall fescue and perennial rye; bluegrass should be cut at an inch or slightly higher. Chances are that you won't have to cut the grass again this year.

Incidentally, if you cut the lawn short, you will virtually eliminate chances of "snow mold" disease attacking your lawn during the winter.

When you cut the lawn, don't put a lot of gasoline in the mower's fuel tank. When you're through mowing, you want the barest amount of fuel in the tank. Use an old kitchen basting tool to remove any fuel remaining in the tank, then start the engine and let it run until all fuel is consumed. When the engine dies, the carburetor and fuel lines have been purged. Next week's column will tell you how to winterize the mower so it's in perfect condition next April.

On lawns that were neglected during the fall and treated with weed killers during the past two weeks, plan on dethatching in the next week. On small lawns, raking with the bamboo rake will be acceptable as long as the tines are digging into the surface; if they don't, raking serves no purpose. For large lawns, rent a power rake.

Adjust the front of the rake so the steel nails dig into the top half-inch of soil; make several trial passes on different parts of the lawn until the tines comb the soil to the half-inch depth, then dethatch north-south and east-west. Rake the debris from the top of the lawn and thrown it away. Shop for seed so you can be overseeding during the Dec. 12-13 weekend.

Beyond the lawn, a lengthening roster of garden chores are on tap. Here are some of the priorities:

Fruiting fig trees should be protected. With container trees, remove any foliage clinging to branches, water the soil thoroughly with warm water, let it drain for 20 minutes, then move the plant into an enclosed garage for temporary storage this weekend. Next, jot down the dates Dec. 26 and Jan. 23 on a sheet of paper and pin it to the garage wall. On these dates, pour about 20 ounces of lukewarm water into the soil of the container. On the last weekend of January, you will move the container plant to the basement for a week before moving it into full sun in an upstairs room where it will resume growing. In January, you'll check the limbs and trunk for egg masses, then spray with dormant oil to destroy the eggs.

For in-ground fig trees, get your fence out of storage and wrap it around the tree trunk to leave about 4 to 6 inches of free space on all sides of the trunk. If you don't have fencing from last year, buy some at the building supply store (chicken wire will do, about 5 to 6 feet high and 3 feet long).

Surround the trunk with the fence, tied into place, then backfill in the crevace with fallen leaves packed firmly in place; scatter moth balls intermittently among the leaves to keep rodents from overwintering in the leaves and gnawing at the trunk. Spray unprotected upper limbs with an antidessicant to minimize dieback on branches over the winter. Spade caladium, dahlia and tuberous begonias from the garden this weekend, massage the soil off the tubers with your hands, then let them dry for a week or two in a warm spot indoors. Afterward, put the tubers in a brown bag, add 2 tablespoons of powdered Captan, close the top of the bag with your hand and shake the bag a few times to coat the tubers with the Captan. Next, insert the tubers in an old onion bag, separating them with sheets of newspaper rolled into tennis-ball sized wads; then hang the bag from a rafter in the basement. Tubers will store nicely, but you'll need to check them in late January for rot.

Cut chrysanthemums now, pruning everything above the bottom 4 or 5 inches. Leave the plants unmulched for now. Indoor potted mums should be planted now in a location with full sun. Dig a hole 8 inches deep by 6 inches wide, discard all the soil, put down a two-inch layer of sharp sand, then backfill with a 50-50 mix of sharp sand and peat humus. Bang your potted mums from the pot and plant right away. Apply a teaspoon of lime over the top of the soil, then water to remove the air pockets. Mulch the plants in January.

If you plan to use a live, balled and burlapped Christmas tree for the holidays and then want to plant it outside, dig the hole now while the ground is soft. First, choose the site with the tree in mind. It will need full, unobstructed sun all day long and perfect drainage with no wet spots when it rains.

If you've already chosen the tree, measure the root ball right away. Dig a hole 1 1/2 times the height and twice the width of the root ball. For example, a root ball 12 inches high and 18 inches wide calls for a hole 18 inches deep and 36 inches wide. Fill your wheelbarrow with the soil, then resort to large containers, all of which should be promptly stored in the garage. Afterward, pile leaves in the hole up to the soil line to reduce frost penetration.

You want the tree delivered the weekend of Dec. 12-13. Meanwhile, shop for a large tub (3 feet in diameter) to house the tree during the holidays. An old rubber tire will come in handy for holding the tree erect in the tub. Jack Eden hosts "Over the Garden Fence" Sundays from 10 a.m. to 1 p.m. on WTOP Radio (1500 AM).