Get It Growing for 12/06/24

Citrus trees are abundant at retail garden centers during fall and early winter. They make beautiful holiday gifts, and they are one of the most popular types of fruit to grow in Louisiana home gardens. However, our occasional — but exceptionally cold — arctic air blasts can make success with these tropical and subtropical trees a bit tricky.

Because citrus trees are sensitive to the cold, special care is needed when choosing cultivars to grow and when deciding whether to plant them in the ground or in containers.

There is a lot of conflicting information out there about the best times and strategies for planting citrus. Our advice? It’s all about location, location, location — and even within Louisiana, recommendations vary by region.

To get started, take a look at the U.S. Department of Agriculture Plant Hardiness Zone Map and see where your garden sits. When this map was updated in 2023, most locations in Louisiana became one zone warmer. Northern Louisiana moved to zone 8b, where average minimum temperatures are still 15 to 20 degrees Fahrenheit. That’s pretty cold for citrus trees, which can suffer severe damage and even die in subfreezing temperatures.

Even in extreme southern Louisiana and the New Orleans area, which are now in zone 9b, average minimum temperatures fall between 25 and 30 degrees. These lighter freezes can still take a toll on citrus, especially more cold-sensitive cultivars and very young trees.

Keep in mind that these are average low temperatures. Cold snaps with even chillier temperatures are always a possibility!

So, depending on where you live, you may want to stick to growing satsumas, calamondins and kumquats, which have the most cold tolerance. Limes and lemons — the least cold-tolerant types of citrus — are a safer bet in warmer southern parishes. Navel oranges, sweet oranges, blood oranges and grapefruits fall somewhere in the middle of the cold tolerance spectrum.

“Several new satsuma cultivars are hardy down to the low 20s once established,” said Anna Timmerman, an LSU AgCenter horticulture agent in Plaquemines and St. Bernard parishes. “Artic Frost and Orange Frost satsumas may be a good choice for northern growers.”

Wherever you live, growing citrus in large containers is a great option. This way, you can move your trees to protected areas when a freeze approaches. As long as you keep up with periodic root pruning and regular fertilization, all citrus can be successfully grown in containers.

“You can plant citrus trees in containers at any time,” Timmerman said. “Newly purchased citrus trees can stay in the nursery pot for several months with regular watering until you are ready to plant them. They can be left outdoors and brought in if freezing temperatures are predicted. There is a slow-release fertilizer in the nursery pot, so additional fertilizer is not needed for several months.”

The best time to purchase a citrus tree is when the varieties you want are available, Timmerman said.

“These trees can be successfully held in their containers until the right time to plant,” she said.

If you’d rather plant in the ground, you need to consider your location, USDA hardiness zone and last frost date, which can be found easily via internet search.

Timmerman offered a few additional guidelines:

— In New Orleans and south of Lake Pontchartrain: Plant any time from November through February, as winters are generally mild. Waiting until March this far south can be a bit too late because citrus trees tend to flower in early January or early February in this part of the state. The trees should be given adequate time to root in and establish before the extreme summer heat and dry conditions.

— North of Lake Pontchartrain, in the River Parishes outside of New Orleans and in southwestern and south-central Louisiana: It’s best to wait to plant until March or the local last frost date. If planting earlier, be sure to cover the young, newly planted trees completely using a windproof sheet or tarp in the event of a frost. Wrapping the trees with old, non-LED Christmas lights also can generate enough heat under a covering to keep the trees above freezing. Watering the soil around the root ball ahead of a frost is another method that can help increase temperatures by a few degrees.

— For the Alexandria area and points north: Wait to plant until the last frost date, which can be as late as April 1 in the far northern parishes. In this region of the state, planting citrus in the ground will require cold protection structures or thick coverings paired with a heat source, especially while the trees are young. Growing citrus in containers makes it much easier to protect them in the winter.

To learn more about growing citrus in Louisiana, go to www.LSUAgCenter.com and search for “Louisiana Home Citrus Production,” a helpful guide with information on varieties, growing practices, pests, fertilization and more.

LSU AgCenter horticulturists Jason Stagg and Anna Timmerman talk about when to plant citrus trees.

Ripe fruit on a citrus tree. Photo by Randy LaBauve/LSU AgCenter

Citrus trees such as this kumquat can be grown in large containers. LSU AgCenter file photo by Mary Helen Ferguson

Citrus trees in containers. LSU AgCenter file photo by Johnny Morgan

Satsuma trees planted in the ground. LSU AgCenter file photo by Olivia McClure

Anna Timmerman, left, an LSU AgCenter horticulture agent in Plaquemines and St. Bernard parishes, recently was a guest on a Get It Growing TV segment about citrus. Get It Growing is hosted by AgCenter horticulturist Jason Stagg, right. Photo by Randy LaBauve/LSU AgCenter