1. Tidy up

My No. 1 fall gardening task is cleaning up borders and ornamental plantings. Start by deadheading flowering perennials. Remove spent warm season annual bedding plants and refresh tired containers with chrysanthemums, snapdragons, pansies and ornamental grasses to echo the colors of fall.

Hand pull weeds if they are sparse. Tame extra-weedy areas by covering them with newspaper or cardboard, then add compost and mulch. Overzealous shrubs can be lightly trimmed to manageable limits, but leave hard pruning until late winter.

Finally, apply 1-2 inches of compost around perennials, shrubs and trees, leaving a 3-5 inch space around trunks and stems.

The icing on the cake is a 1-2 inch layer of pine straw or bark mulch. 2. Let lawns languish

Despite the barrage of national ad campaigns, resist the siren song to “winterize” lawns. This practice is not recommended for Lowcountry yards because warm season turf grasses such as Bermuda, St. Augustine, Zoysia and Centipede enter dormancy in the fall, signaled by environmental cues such as longer nights and cooler evening temperatures.

Applying fertilizers with large amounts of nitrogen at this time, like those advertised for winterizing, won’t be useful to dormant plants, and excessive nitrogen pollutes our waterways. This practice may ultimately damage or even kill lawns.

Fertilizing in the late summer spurs new growth that is susceptible to cold damage, when temperatures dip below freezing and pesky winter weeds will grow quickly with the extra nitrogen.

The weeds will out-compete grass for water and nutrients, leaving the grass stressed and weak.

Lawns plagued by annual winter weeds last year can be treated with pre-emergence herbicides when nighttime lows reach 55-60 degrees for four consecutive nights, typically between Sept. 15 and Oct. 1. Be sure to read labels carefully. For specific weed control information go to: http://bit.ly/4MLWbY

Begin winterizing warm season grasses by slightly raising mowing height as summer wanes. Over the winter months, keep leaves from accumulating over the grass.

Finally, since the best way to keep a healthy lawn is to manage it properly while it is actively growing, test soil now for next spring.

3. Do garden math

Perennials plus a shovel equals exponential blooms!

Dividing perennials is an easy and inexpensive way to get more plants. The rule of thumb is to divide spring and summer blooming perennials in the fall, and fall bloomers in spring.

In order to conserve energy necessary for root and leaf growth, do not divide perennials while they are in bloom. Dig and divide daylilies, hosta, bee balm, garden phlox, coneflowers, and yarrow now through mid-October. If you don’t have room for the extras, share with neighbors and gardening friends.

For more information see: http://bit.ly/c5wLhK

Another inexpensive way to multiply flower power is by sowing seeds now for spring flowers. For just a few dollars or less, you can start many popular perennials and biennials from seed this fall.

In nature, many flowers “reseed” or drop seeds that lie dormant over the winter waiting for spring to sprout. Mimic “Mother Nature” by sowing seeds of purple coneflower, black-eyed Susan, columbine, alliums, and foxgloves. Sow seeds directly in the garden or in flats filled with seed starting mix. If you start in seeds in flats, be sure to keep them moist (but not wet) over the winter.

4. Navigate the nursery

Fall is a great time to plant trees and shrubs, but without a planting plan, these landscape purchases can become costly and lead to disappointment. Take your time determining your personal garden style and explore what will grow well in your landscape to avoid long-term mistakes made from impulsive purchases.

Creating a list of well-researched plants that fit your site will help ensure long-term garden success. Measure landscape areas and keep notes to determine how many plants you will need. Remember to think long term and buy based on the ultimate size at maturity. Note the plant’s genus, species and cultivar to ensure you purchase the correct plant at the nursery.

When shopping for plants, choose nurseries with an informed sales staff, since they are often great gardeners themselves and can discuss care and maintenance tips with you.

Smart phone apps and QR code readers on plant tags that launch links to informational websites can also be helpful in deciding if an unfamiliar plant will work in our region. The key is knowing your cold and heat hardiness zones, soil type and amount of sunlight in each area of your yard.

Be gentle with newly purchased trees and shrubs. Transport them home in a covered vehicle, if possible, to avoid damaging and drying them out.

If you must bring them home in a pickup truck bed, lay plants down and cover with a tarp that is securely battened down to avoid damaging winds on the ride home. Think about what happens to trees in 60 mph winds! Water plants well as soon as you arrive home, prior to planting.

5. Plant cool crops

Between battling weeds, swatting mosquitoes and dodging diseases, summer gardening can be quite a hassle. That’s why I love fall gardening. Vegetables that do well in other areas in spring thrive in our warm fall weather. The cooler temperatures also mean I’m more willing to spend time tending a fall garden.

Sanitation is key in vegetable patches and will help keep future pest and disease outbreaks at bay.

Pull up and discard warm season vegetable plants. Refresh soil with chopped leaves, compost, or grass clippings. Directly sow seeds of lettuce, kale, Swiss chard and collards in prepared soil.

Set out transplants of broccoli and cabbage and mulch with straw to keep them moist on these last warm days. For added crunch in your salad, sprinkle in radish and mustard seeds at two to three week intervals throughout the fall.

Root crops such as beets, turnips and rutabagas also can be started from seed now for hearty winter meals.

Purchase garlic bulbs now for planting between Oct. 1 and Nov. 30. Garlic grows best over the winter, and is harvested in spring as the days lengthen. Be sure to prepare soil using the results from a soil test as garlic thrives in rich soils with a pH between 6-7.

Mulch garlic plants well to prevent soil from drying out and harvest next spring when the tops begin to turn yellow.

For tips on choosing the best cultivars go to: http://bit.ly/17W5U5z.html.

Native Plant sale set for Sept. 28

The Lowcountry Chapter of the S.C. Native Plant Society, in partnership with Charles Towne Landing, will hold a Native Plant Sale from 9 a.m. to 12 p.m. Sept. 28 in the parking lot of Charles Towne Landing, 1500 Old Towne Road, Charleston.

Admission to the plant sale is free. The sale will include: colorful perennials, trees, shrubs, ferns, native grasses and edibles.

Cash or check only for all purchases.

Contact Colette DeGarady for more information: cdegarady@tnc.org, 937-8807, ext.15, or visit our website at www.scnps.org/.

Supper, tree seminar at Magnolia

Supper & Seminar — Twilight in the Trees will be offered by Clemson Extension, Magnolia Plantation & Gardens and Natural Directions Tree Care Company. Join us for an evening rooted in growing beautiful landscape trees.

Identify the best trees for the Lowcountry landscape, discover the secrets to planting, pruning and caring for landscape trees and protect valuable trees by learning about common insect and disease problems.

Twilight in the Trees will be 5:30-8:30 p.m. Oct. 15 at Magnolia Plantation & Gardens. Dinner and educational materials are provided. Registration is $50. Discounts for couples and Master Gardeners.

Learn more at http://calendar.clemson.edu/event/twilight_in_the_trees_seminar_supper#.UjDGF7wpfMM

Amy L. Dabbs is the urban horticulture extension agent and Tri-County Master Gardener coordinator for the Clemson University Cooperative Extension. Send questions to gardening@postandcourier.com.