This Month in Your Garden – September 2024

Coastal Region – Glen Payne

Obedient Plant (Physostegia viginiana) being pollinated by a bumble bee.
Glen Payne, ©2024, Clemson Extension

• Tropical Storm Debby left over 16″ of rainfall in the Lowcountry at the end of August. Irrigation systems can be checked, and watering days and run times can be dialed back as the nights become longer. High temperatures and too much water with excess nitrogen will cause turf to start to show signs of fungus. Management is key to a good-looking yard in the late summer.
• Late summer weeds that have been overlooked may be overtaking planting beds during the summer heat. Shady areas under trees may have colonies of basketgrass (Osplismenus) taking over. Coffeeweed (Sesbania herbacia) can also be seen taking over areas of fallow pastureland and is best removed by hand this late in the weed growing season.
  
• Pollinators are busy, busy as late summer flowers bloom and begin putting on a show, as is seen by this photo of Obedient Plant (Physostegia viginiana) being pollinated by a bumble bee.
• Take a few minutes to review soil sample results from earlier in the spring. If potassium is recommended, be sure to install it at the rates prescribed for maximum root growth before turf starts to go dormant. Healthy deep roots will allow for maximum uptake of fertilizer & micronutrients after correcting potassium deficiencies. 
• Lime turf now, if needed, according to soil sample results, as it will take 2-3 months to start to change soil pH. And will have turf ready to grow and look its best just in time for spring fertilization.

Midlands Region – Jackie Jordan

September is a period of transition in the garden.

• Take cuttings of warm-season annuals like basil, coleus, and geraniums to overwinter.
• Plant seeds of hardy annual flowers like calendula, sweet alyssum, foxglove, larkspur, and poppies.
• Freshen up containers and flowerbeds. Pull out warm-season annuals and set out pansies, violas, snapdragons, ornamental cabbage, and kale once they become available.
• Start shopping for spring flowering bulbs for the best selection. Bulbs can be stored in the refrigerator for several weeks until ready to plant. Just avoid storing bulbs near ripening fruit or vegetables.
• There are a few fall-blooming bulbs, like colchicum and autumn crocus, that are planted immediately and will bloom that season.
• Add fall-blooming perennials such as ginger lilies, goldenrod, Mexican sage, pineapple sage, asters, and ‘Autumn Joy’ sedum to sunny areas.
• Toad lilies, Japanese anemones, and autumn ferns perform well in shade.
• It’s time to plant collards, arugula, kale, mesclun, mustard and Swiss chard, broccoli, cauliflower, cabbage, and many other vegetables.
• Plant cool-season herbs like chives, cilantro, dill, and parsley towards the end of the month.
• Fertilize Tall fescue lawns at a rate of 1 lb. of actual nitrogen per 1,000 sq. ft. If your tall fescue lawn has become patchy from heat stress, make plans to seed at a rate of 6lbs. per 1,000 sq. ft.
• Continue to scout for armyworms about every 15 days. They have a 30-day lifecycle, and we have four generations a year.
• Apply preemergent herbicides this month to control annual bluegrass. For preemergent herbicides to be effective, they must be applied before the weeds start actively growing. Annual bluegrass begins to germinatewhen we receive four consecutive days with daytime highs at or below 75 °F.
• Another great way to prevent a lot of annual winter weeds is to freshen up mulch in your flower beds and maintain a 3-inch layer.
• If you want to overseed your warm-season lawn with ryegrass, the middle of the month is a great time to do this, but be careful.
• Early fall is a great time to divide perennials like daylilies, daisies, and hostas.
• Fall is a great time to plant trees and shrubs. The plants have a chance to become established in the cooler weather and can take advantage of higher rainfall. If you have room in your garden, consider adding a native tree or shrub. One of my favorites is beautyberry. It has purple berries that add interest to the garden in fall and are great in arrangements. Hearts-a-Busting is a native shrub with showy scarlet fruit in September and October. A variety of viburnums have showy berries in the fall and offer beautiful autumn leaf colors. If you have room for a tree consider adding an autumn blooming cherry. They bloom in the spring but will rebloom in the fall with warm weather.

Upstate Region- LayLa Burgess

• Go green, “green manures,” that is. Consider planting a cool season cover crop in late September when soil temperature begins to drop. There are a variety of cover crops, both leguminous and non-leguminous, to choose from. Cover crops are planted not with the intent of harvesting but rather terminating the plants at an appropriate time to return nitrogen or biomass to the soil. Cover crops help improve the soil by recycling nutrients, adding organic matter, retaining soil moisture, suppressing weeds, and more. Do you think a raised bed is too small to grow cover crops? On the contrary, you can do it!
• It’s time to think about planting those fall vegetables. Leafy greens like kale, lettuce, Swiss chard, spinach, turnips, and collards are all good choices. Mix in some radishes, carrots, broccoli, and onion-sets to round out the harvest. End-of-summer herbs like summer savory, sage, oregano, basil, and tarragon are harvestable for drying and storage. Use the herbs in winter meal preparations with fall-planted vegetables.
• Bermudagrass lawns can be over-seeded with cool-season perennial or annual ryegrass. Perennial ryegrass will provide a high-quality, green cover to the dormant, warm-season grass, but it may persist longer into the spring than desired. Annual ryegrass is less expensive but may not tolerate cold temperatures or drought, unlike perennial ryegrass.
• Warm-season turfgrasses still need adequate water through the fall and winter months, at least 1 inch of water after three weeks of no rainfall. Install a trusty rain gauge to capture and monitor weekly precipitation. Properly irrigate when rainfall does not meet the water demand, especially when over-seeding with actively growing ryegrass on a dormant, brown bermudagrass lawn or with cool season, tall fescue.
• It’s time to prep and fill those perennial flower beds. Clean out the old to make room for the new. For beds that have become overcrowded, get started on digging, dividing, replanting, and sharing the leftovers. Add an organic soil amendment to the beds to improve the soil fertility and plant growth for the upcoming spring season. Consider establishing new ornamental grasses or perennials among old perennial favorites in the refreshed landscape bed.
• Establish new, woody shrubs and trees in the fall to early winter, dormant season. Give attention to the proper planting method and irrigation during this time. If you are considering transplanting established shrubs and trees to a different location in the landscape, begin making plans now for the move. Appropriate root pruning may need proper timing.