LSU AgCenter Horticulturist
Luckily, we’ve gotten a reprieve from cutting grass and the extreme, hot weather. Time to put away the mowers and weed trimmers. The winter months provide us an opportunity to focus on landscape planning, planting and maintenance.
Winter is the perfect time for planting trees and shrubs in the landscape when the temperatures have cooled. Although deciduous trees experience a winter dormancy, the roots are still active and do not enter full dormancy. This time of year is more of a resting phase.
The resting period and dormancy are broken once spring arrives. Tree roots are respiring structures, so they need to breathe and continue to function through the winter.
All types of trees can be planted in the wintertime, including fruit trees. However, tropical and subtropical trees such as avocados, citrus and olives should not be planted, as they are evergreen and susceptible to damage — even death — in temperatures in the lower 30s and 20s.
Hardy shrubs also can be planted this time of year. Some great Louisiana Super Plants Program selections include Belinda’s Dream roses, Drift roses, ShiShi Gashira camellias, Henry’s Garnet Sweetspire, Conversation Piece azaleas and Leslie Ann sasanquas. Also consider natives such as American beautyberry, dwarf yaupon holly, dwarf palmetto, star anise, Virginia sweetspire, inkberry and other native viburnums.
Besides planting, winter also is a great time for equipment maintenance. Now that landscape equipment is effectively retired for the season, it’s time to sharpen mower blades and take care of any mower or weed trimmer maintenance. Check spark plugs and change the oil in equipment. Sharpen and oil tools to prevent rusting.
Here are some suggestions for a winter planting and maintenance checklist.
In the landscape beds, plant tulip and hyacinth bulbs in late December or early January. Remember, tulip and hyacinth bulbs must be refrigerated for six to eight weeks before planting. Many retail garden centers sell prechilled, ready-to-go bulbs. Some hardy perennials that can still be planted in winter are delphinium, foxglove and French hollyhocks.
Cool-season annual bedding plants that are blooming this time of year are alyssum, calendula, dianthus, hollyhock, lobelia, flowering cabbage and kales, pansies, snapdragons and violas.
Some of the Louisiana Super Plants cool-season annuals are swan columbines, Redbor kale, Camelot foxgloves, Amazon dianthus, jolt series dianthus, sorbet violas, Supertunia vista bubblegum petunia and Supertunia mini vista indigo petunia.
Transplants will provide instant color and bloom best in well-drained areas with six or more hours of sun daily. You will get the most blooms with more sun. For shadier spots with dappled light use cyclamen, foxglove, nicotiana, forget-me-nots, lobelia and primrose.
Some maintenance duties for winter are rake and keep fallen leaves of deciduous plants and trees to use as a mulch or to compost. Prune landscape trees, shrubs and evergreen plants that do not flower in the spring (do not prune spring blooming azaleas, hydrangeas and spireas). Prune everblooming roses in late January or early February. Landscape roses like the popular Knock-Out roses should be cut back by about one-half their height (do not cut back lower than 2 feet from the ground). The end of January is a great time to trim your ever-blooming roses to flush out new blooms for the spring.
Mulch to protect the roots and rhizomes of tropical landscape plants, citrus and other cold sensitive plants. Spread a 4-to-6-inch layer of pine straw, pine bark, leaves or straw mulch around the base of the plant or cover the entire landscape bed. Be sure to bring in any tropical plants in containers to protect them from freezing temperatures.
Deadhead or remove old flowers from your cool-season bedding plants to extend the bloom period and improve flower performance. Begin planning your spring annuals and perennial garden selections.
January and February are also the ideal time to fertilize young trees and shrubs in preparation of rapid spring growth. Fertilize shrubs with 1/4 pound of complete fertilizer per square yard, and fertilize trees, using 1 to 2 pounds per year of age.
For trees, use a granular fertilizer with a 3-1-2 ratio such as 15-5-10. The amount you apply is based on the square footage of tree roots. For example, apply 20 pounds of fertilizer per 1,000 square feet.
Begin a preventative spray program alternating fungicides for blackspot and powdery mildew on roses.
Watch azaleas in February for lace bugs. They cause the foliage to have numerous small white spots, and they feed underneath lower foliage. Control them with horticultural oil sprays or a systemic pesticide. Always remember that a healthy plant can ward off insects and disease, minimizing the need to use pesticides, so always give them the best environment, water and nutrients.
Winter is the perfect time to get things growing. Don’t get caught with your plants down.
Cool-season annuals such as pansies, kale and foxglove grow well in the winter and can tolerate temperatures in the lower 20s. Photo by Bob Mirabello/LSU AgCenter
Bald cypress needles are an attractive, natural mulch that can be raked and used to reduce weeds and insulate winter soils. Photo by Heather Kirk-Ballard/LSU AgCenter