Fall weather is in the air and its arrival to the Cape Fear region is much-appreciated! But the work isn’t over. Cooler weather means that deciduous landscape plants and warm-season turfgrass will soon be going into dormancy, a period of inactivity when plants store energy for the colder months ahead. As you reclaim the outdoors and get back to your garden you will still find there is plenty of work to do in order to get your landscape ready for winter.
Divide and conquer
Not only does this apply to your fall cleanup and maintenance chores, but also to your perennial plantings. Fall is a great time to divide and relocate perennials such as daylilies, iris, hosta, and liriope. Fall is also the best time of the year to plant landscape trees and shrubs because it gives plants time to acclimate to their new environment; and watering, although important, is less critical.
When temperatures approach freezing, you can cut down the stems on your perennials to an inch or two from the ground, but leave the ground level cluster of green leaves that form on some perennials. Remove only older, brown stems that remain from spent flowers. Keep in mind that certain plants, like Black eyed Susans, asters, and coreopsis will provide food for birds in the winter months and should only be removed after the seed heads have been eaten.
Raking and mulching
As trees begin to shed their leaves remove leaf debris from the lawn. Large piles of leaves left on the lawn will not break down quickly and can kill turfgrass. Dead leaves can be mulched with a lawn mower. Mulched leaf debris used in beds to create a top layer of organic material that will supply nutrients to the soil or added to the compost pile.
As nights become colder and temperatures approach freezing, it is a good idea to add a layer of mulch around landscape trees and shrubs. Instead of mulching with dense, heavy mulch consider adding a 3-4 inch layer of straw, pine needles, or pine bark since they won’t pack or suffocate roots, but will protect exposed roots from freezing damage in the winter months.
Fertilization and irrigation
A common misconception is that you need to add fertilizer to your lawn in the winter months; this does not apply to warm season turf commonly grown in this region. As turfgrass begins to go dormant, it is no longer taking any nutrients and applying certain nutrients such as nitrogen, will only encourage weed growth and the spread of turfgrass diseases like large patch. If you do apply fertilizer, focus on potassium (K), also referred to as potash; this will help improve drought tolerance and plant hardiness in the upcoming winter months, but must be applied at least six weeks before the first frost. Remember: the only way to be sure of what nutrients your lawn or garden needs is to have your soil analyzed.
If you have an irrigation system for your yard, start decreasing the amount of water you apply to your lawn and landscape plants. An inch of water per week is recommended for summer, but this time of year you should decrease to a ½” to ¾” per week. Plants still need water in cooler months, but not as much, so apply less frequently. You should only water when temperatures are above freezing. Over watering in the fall can be just as harmful as it is in the summer because it can increase plant injury, encourage plant diseases, and weed growth.
Fall weed control
Just as in summer, we have to do deal with an onslaught of weeds in fall. Some common fall weeds include: Florida betony, annual bluegrass, gray cudweed, and chickweed. A good preventative measure for fall weed control is to apply a pre-emergent herbicide to your lawn in mid to late September. Effective application of pre-emergent products depends on your turfgrass type and which weeds have been problematic in the past. To determine which weeds you have, bring a sample to your local Extension center to receive specific control recommendations.
For help interpreting soil reports, weed identification and control and other fall gardening advice, visit ces.ncsu.edu, where you can submit questions via the ‘Ask an Expert’ link, or contact us: If you live in Pender County, call 910-259-1238. In New Hanover County, call 910-798-7660. In Brunswick County call 910-253-2610.
Sam Marshall is the horticulture agent with the Brunswick County Center of the Cooperative Extension of NC State University, College of Agriculture & Life Sciences.