Question: I’m embarrassed to admit this, but I just found out that luffa is a plant, not a sponge from the ocean. Is it possible to grow them in Western Pennsylvania? I don’t have a lot of space but was wondering how to grow them. What type of soil do they prefer? Where can I find them (as plants or seeds)? Any other information you can provide would be appreciated.
Answer: Luffa gourds (also spelled loofa) are grown for their fibrous inner tissue which is dried and used as a bath or kitchen sponge.
Luffa is quite easy to grow, and when the fruits are still young, they’re actually quite delicious. They can be cooked and eaten like zucchini. But, for gardeners interested in growing luffa as a sponge, the fruits need to mature on the vine.
A vining plant, closely related to cucumbers, melons and squash, luffa takes up quite a bit of room in the garden. The vines can reach 10 to 20 feet in length, so most gardeners will want to grow them up a trellis or fence. They are fast growers, so make sure a sturdy support trellis is in place before you even plant the seeds.
Pick a site that receives a minimum of six to eight hours of full sun per day and work some compost or other organic matter into the planting area before sowing the seeds.
Because luffa seeds sometimes take a long time to germinate, soak them in warm water for a day or two before planting to speed germination.
Seeds can be planted directly into the garden soon after the danger of frost has passed, usually in mid May. But, for the best results, and to get a jump on the growing season, you may want to start your luffa seeds indoors in mid-April, under grow lights and in plantable peat pots. They’ll be ready to transplant outside just a few weeks later. Luffa takes a long time to reach maturity, between 90 and 100 days; starting the seeds indoors gives the fruits plenty of time to fully ripen before frost arrives.
Plant two or three luffa vines close together and allow them to climb the trellis. Water the vines regularly throughout the growing season and mulch with a 2-inch layer of straw or untreated grass clippings.
The green, cucumberlike gourds will begin to develop in mid- to late-summer and will eventually reach up to 2 feet in length. Expect one to two dozen luffas per plant. You’ll know they’re ripe when their green skin shrivels and turns yellow and dry. Still-green fruits do not make good sponges. The fruits must be allowed to fully ripen on the vine.
There are two ways to harvest the gourds for sponges.
First, you can pick the gourds late in the season, soon after their skin dries. After it is off the plant, put the gourds in a tub of water and use your hands or a brush to remove the skin. Inside, you’ll find a tangle of fibers, full of seeds. Cut the sponge to the desired length and shake out the seeds. Let the sponge pieces dry outside for a few sunny days before using them.
Or, you can let the gourds stay on the vine for a bit longer, and harvest them when they’re dry and yellow. Place the harvested fruits on a screen in a garage or dry basement area for about two or three weeks. When the skin hardens and turns brown, peel open the large end of the gourd and give it a few good shakes to dislodge and remove the seeds. Soak the whole thing in water overnight, then peel off the skin. Let the fibrous tissue dry in the sun for a few days before using.
Horticulturist Jessica Walliser co-hosts “The Organic Gardeners” at 7 a.m. Sundays on KDKA Radio with Doug Oster. She is the author of several gardening books, including “Attracting Beneficial Bugs to Your Garden: A Natural Approach to Pest Control” and “Good Bug, Bad Bug.” Her website is jessicawalliser.com.
Send your gardening or landscaping questions to [email protected] or The Good Earth, 503 Martindale St., Third Floor, Pittsburgh, PA 15212.