LSU AgCenter Horticulturist
(03/09/19) Despite the cold weather the past few early-March days here in Louisiana, the evidence of spring is all around us. Gardening March Madness begins!
This is one of the busiest times of year for the home gardener in the South. Outside, we see Japanese magnolias and eastern redbuds have bloomed. The azaleas and Indian hawthorn are beginning their bloom. Lawns are beginning to green up, and leaves are popping out on our deciduous trees in the landscape. And the pollen? Well, it’s everywhere! Ahchoo! Gesundheit!
Get ready because it’s time to mark your calendars for spring weekend gardening plans. You can get started now in south Louisiana. But north Louisiana is on a three-week delayed start for all of these activities because the average last frost date is April 1. So keep this in mind as you begin your spring gardening and planning.
First week, you want to begin preparing warm-season bedding and vegetable beds. Pull any weeds and turn the soil to loosen it. Remove any old plant roots and apply compost and mulch. This is also a good time to apply dormant oils to camellias, citrus, sweet bay magnolias, banana shrub, gardenias and other shrubs or trees susceptible to scale, whitefly and other types of sucking insects.
Go ahead and fertilize established perennials and other landscape plants at this time to encourage vigorous spring growth as they begin to take off with the longer days and hopefully warming temperatures. Black spot, powdery mildew and stem canker can be problems on roses along with pesky insects such as aphids, cucumber beetles, spider mites and thrips this time of year. Use a preventive spray program for pests and diseases on your roses, and treat them every week in the early morning or late in the evenings to prevent foliage burn by chemicals.
Second week, you can begin mowing your lawns on the lowest setting and remove the clippings. This is a great time to start herbs in both containers and beds with still-cooler temperatures. Some great annual herbs are basil, cilantro, dill and mint. Go ahead and get your warm-season vegetable seeds such as cucumber, corn, cantaloupe, summer squash, snap beans, Southern peas, radishes and so on started.
Additionally, it is still a good time to plant hardy spring-flowering shrubs, container roses and flowering trees. Be sure that all new plantings are watered in adequately and mulched to prevent weeds and help retain soil moisture.
Third week, or after March 15 in south Louisiana when the threat of a late frost is less likely, go hog wild and plant those warm-season bedding plants and vegetables. You can plant tomatoes, peppers, eggplant transplants at this time. Hold off on okra transplants for a couple more weeks.
Warm-season bedding plants such as alyssum, begonia, blue daze, coleus, cosmos, dahlias, geraniums, impatiens, periwinkle, verbena and zinnia can go in the ground. Again, be sure to water these new plantings well and add mulch. And you can go ahead and use half-strength water-soluble fertilizer to give them a boost to start.
Fourth week, March and early April in south Louisiana, you can fertilize St. Augustine grass and centipede grass. Work with garden center experts and consult manufacturers’ recommendations for application. According to one AgCenter expert, Ron Strahan, “fertilizing too early with high nitrogen lawn fertilizer or weed and feed can contribute to winter kill with a late-season freeze and bring on brown patch disease.” So timing is important.
Some folks like to use a weed and feed combination that both fertilizes lawns while killing weeds for the convenience of application. However, this is not always the most effective for weed control. Up north, you want to wait until mid-April to do anything with lawns.
In addition to these recommendations, March is also a good time to do a few other gardening tasks such as moving houseplants outside into a shady location when temperatures are warm enough. And you can go ahead and set out hummingbird feeders at this time.
Enjoy all of those flowering shrubs and hold off on any pruning until the blooming period is over. Control the urge to prune growth damaged by winter freezes. Wait until the shrub has begun to grow again before pruning.
You can prune summer-flowering shrubs such as althea, oleander and crape myrtle by the end of the month along with camellias that have completed their winter bloom. Be sure not to wait any later than May to prune camellias because new buds set in the summertime for the next winter bloom.
Get out there and enjoy this beautiful and brief season in Louisiana — you know, that short time between winter and our soon-to-be-hot summer! Watch your landscapes come to life.
Remember, the AgCenter website www.lsuagcenter.com has many great resources with lawn and garden tips for spring. Stop by the site for plenty of sound advice.
A hop hornbeam leafs out in early spring. Photo by Heather Kirk-Ballard/LSU AgCenter
An Indian hawthorn displays its spring blooms on the LSU Baton Rouge campus. Photo by Heather Kirk-Ballard/LSU AgCenter
Azaleas bloom under a cow oak as spring weather encourages new growth. Photo by Heather Kirk-Ballard/LSU AgCenter