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Dr. Mary Helen Ferguson

Let’s Get Growing

I’m partial to plants that I can plant once and enjoy for multiple years. It’s one reason that I like fruit crops and prefer perennial flowering plants over annual beddings plants.

Most vegetables that we grow are annuals in our climate. Some that are perennials in other places are either heat sensitive (e.g., rhubarb and globe artichokes) or too cold sensitive (e.g., chaya, Malabar spinach, and a number of vegetables commonly grown here as annuals, including tomatoes, peppers, and sweet potatoes) to be reliably perennial here. However, we can grow some perennial vegetables.

Perhaps the thing that most often comes to people’s minds when someone mentions perennial vegetables is asparagus. We eat the plant’s young vegetative shoots, called spears. They’re harvested as they emerge from the ground, when about 6 to 10 inches tall, in late winter and spring.

Asparagus should be planted in a well-drained and well-prepared bed. In much of Louisiana, lime will be needed to raise soil pH above pH 6. Weed management and adequate fertility are important.

Asparagus crowns are planted in winter or spring, and plants should be allowed to grow for at least one year before any spears are harvested. In the second year, a few spears can be cut or snapped off during a 3 to 4 week period in the spring. Once plants are well-established, spears can be harvested for 6 to 8 weeks. Each year, plants must be allowed to produce enough foliage to continue to sustain themselves.

Here’s a fun fact: One of the United States’ best-known asparagus breeders, Howard Ellison, worked at the US Department of Agriculture’s US Field Laboratory for Tung Investigations, which was housed in what is now the Bogalusa Post Office, before becoming a professor at Rutgers University in the 1950s. He was instrumental in developing hybrid all-male asparagus cultivars, such as Jersey Giant and Jersey Knight.

The plant that we in Louisiana call mirlitons or vegetable pears – often called chayote in other parts of the world – is another perennial. The top of the plant is frost-sensitive, but roots can survive with protection from a thick, loose layer of mulch. Like other root-hardy tropical plants, mirlitons should be planted in the spring, after the last frost. We typically eat the fruit, but one can also eat the tuberous roots, young shoots, and other parts of the plant. Choose varieties from Louisiana to increase thae likelihood that they will be suited to our climate.

While globe artichokes (those from which we get artichoke hearts, etc.) tend to die in the summer in Louisiana, Jerusalem artichokes or sunchokes are aster family cousins that perennialize here. They’re closely related to sunflowers and likewise have ornamental value, but unlike annual sunflowers, they make an edible tuber (underground stem) that can be eaten as a substitute for white potatoes. This is one of relatively few vegetables that’s native to North America.

Plant sunchoke tubers or pieces of tubers in the spring. Once plants are established, tubers can be dug as needed in the fall and winter. When deciding where to place them, consider that plants can reach 6 to 10 feet tall and spread to the extent that they’re considered weedy. They tend to be less productive in the Deep South than in more northerly locations.

The final plants I’ll mention are cacti. The fruit and pads or cladodes (called “nopales” as a food) of prickly pear cacti (Opuntia spp.) are edible. Elsewhere, fruit is most often cultivated from a species called Barbary fig (O. ficus-indica), and it appears that varieties of this species vary in their cold hardiness. Some may be suited to Louisiana, while others likely are not cold hardy enough. The fruit of the eastern prickly pear (O. humifusa), which is native to Louisiana, is also edible. Great care must be taken when handling and preparing either the fruit or pads of prickly pear cacti, since both have hair-like spines called glochids, in addition to the more obvious spines found on the pads.

Let me know if you have questions.

Dr. Mary Helen Ferguson is an Extension Agent with the LSU AgCenter, with horticulture responsibilities in Washington and Tangipahoa Parishes. Contact Mary Helen at mhferguson@agcenter.lsu.edu or 985-277-1850 (Hammond) or 985-839-7855 (Franklinton).