Late fall and winter weather this year has created more “plant confusion” than normal, says LSU AgCenter horticulturist Allen Owings.
November and December were much warmer than normal, which lessened the accumulation of chilling hours.
Many plants went into the dormant season very slowly. Foliage retention lasted longer on plants this winter, and the unseasonably warm late fall and early winter resulted in December and January blooms on plants that normally bloom in March and April.
During the dormant season, many fruit trees and some landscape plants require a certain number of chilling hours — the amount of time when temperatures are below 45 degrees — in order for them to properly produce fruit or flowers.
The most important months for chilling hours are November through February in Louisiana.
Chilling hours are offset by the amount of time temperatures are above 70 degrees.
Chilling hour accumulations are slightly lower than average through mid-February, Owings says. The Baton Rouge area has had around 350 hours with slightly fewer hours in other parts of south Louisiana.
Many mid- to late- winter-flowering trees — such as ornamental cherries, Oriental magnolias, swamp red maples and more — are blooming now, which is about normal, Owings says.
Azaleas began showing signs of blooms opening in January and February, although normal peak bloom in south Louisiana is March 20-25.
Indian hawthorns and liriope are also showing their spring foliage. Loropetalums have also been flowering, which will result in fewer overall flowers later in the spring.
Some pansies and violas along with some other cool-season flowers struggled because of rainfall this winter, but others will last until mid- to late-April in most landscapes.
More traditional spring-flowering cool-season bedding plants, such as columbine, foxglove and dianthus, are flowering on time, Owings says.
“As we approach the end of winter and the beginning of spring, monitor the 10-day forecast prior to planting warm-season bedding plants that are not frost-hardy,” Owings says.
Gardeners can continue planting frost-hardy bedding plants, such as petunias and snapdragons, through March.
Weather patterns are highly variable, and plant performance is highly variable.
“Simply follow your usual practices, and realize that many horticulture happenings in the landscape do not ‘follow the calendar’ from year to year,” Owings says.
Knowing frost dates, recommended planting times and winter/summer hardiness of your landscape plants are keys to successful gardening, he says.
Got a gardening question? Write to GardenNews@agcenter.lsu.edu.