Caren White is a Master Gardener and instructor at Home Gardeners School. She has been associated with Rutgers Gardens for over a decade.
Did you know that you can grow your own sponges? Luffa sponges are the dried fruit of the luffa vine which is a tropical vine. They are easy to grow even in northern areas. Just start your seeds indoors and wait to transplant them outdoors until after the soil has warmed.
What is Luffa?
The luffa vine is a tropical vine related to cucumbers. It requires fertile, well-drained soil and full sun (minimum 10 to 12 hours daily). Because it’s a tropical vine requiring a long growing season, 150 to 200 days, you will need to start your seeds indoors, 3 to 4 weeks before your last frost date. Soak your seeds 24 to 48 hours prior to planting. The outer covering of the seed is very hard. Soaking the seed makes it easier for the cotyledon to break through and germinate. Use biodegradeable pots such as peat pots which can be planted directly into your garden to prevent damage to the delicate roots when you transplant your vines outdoors. Plant 3 to 4 seeds half an inch deep in each peat pot. Luffas need heat to germinate so it’s a good idea to use a heat mat under your peat pots. Be patient. The seeds can take up to two weeks to germinate.
How to Thin Luffa Seedlings
After your seedlings have germinated and grown for about a week, choose the largest plant and remove the others. Use a pair of scissors to snip them off at the soil line so that you don’t disturb the roots of the plant that you want to keep. Like other cucurbits, luffa does not like having its roots disturbed. Any damage to the roots could result in the death of your vine.
How to Transplant Luffa Seedlings into Your Garden
Luffa is a tropical vine. It cannot tolerate any cold. It’s best to wait at least two weeks after your last frost date to transplant your seedlings into your garden. The last frost date is an average, so there is always a possibility of frost after that date. Unlike your other plants which you can just throw a sheet over to protect from the cold, luffa vines will die. They cannot tolerate any cold at all. Not even cold soil. Wait until you have had a string of sunny days that have warmed the soil before you transplant your seedlings. Here in NJ, zone 6, I wait until the first week of June, long after the last frost date of April 15 to transplant my luffa vines into my garden. That's because although the days are warm during the month of May, the nights can still be very cold so the soil hasn't warmed until the end of May/beginning of June.
The Best Supports for Luffa Vines
While you’re waiting for all danger of frost to pass, you can be planning your trellises. Luffa vines can grow to a length of 12 to 15 feet or even longer. The fruit will rot if it touches the ground so you need something for the vines to climb. Poles, fences or trellises all work well. Make sure that whatever you use, it is at least 6 feet tall. Some people use their luffa vines to create a privacy screen.
How Many Luffa Vines Should You Plant?
Luffa vines produce male and female flowers. Each vine should be pollinated by another vine so you will need to plant several vines, 3 to 4 feet apart. Once the female flowers have been pollinated, the fruit will grow very fast, as much as 2 to 3 inches per day, eventually reaching a length of 10 to 12 feet. The vines will flower and fruit all season, but only the fruits that have been growing all season will ripen enough to become sponges.
How to Harvest Luffa
Luffa fruit is ripe when it turns brown and starts to dry out. Allow the fruit to dry on the vines for at least two weeks. If the cold kills your vines before your fruit is fully ripe, you can harvest the fruit and finish drying it indoors. When it is completely dried out, the stems will be yellow and you will be able to hear the seeds rattle inside when you shake it.
How to Make Luffa Sponges
Making luffa sponges is easy. The “sponge” is actually the dried structure inside the fruit. To get at it, first carefully break off the bud end of the fruit and empty out all of the seeds. Then soak the fruit in a container overnight. You should be able to easily peel off the skin. If not, continue soaking until the skin peels off.
The resulting “sponge” will be tan in color. If you want it white, just soak it in a solution of bleach and water (3:7 ratio) until it is white. You can also dye luffa sponges using ordinary purchased dye and following the directions.
Add luffa vines to your vegetable garden and you may never buy another sponge!
Questions & Answers
Question: I am in zone 6b in Canada, and I have been growing luffa cynrilica since May. I started them indoors, but I have no flowers yet. How long do they have to grow before they flower?
Answer: Supposedly, luffa vines flower all summer. But, like you, my vines which were planted in May are still not blooming now in August. In my case, I blame the weather. Here in NJ, we have had an unusually wet spring and summer. My guess is that since luffa is a tropical vine, it requires a long stretch of hot, sunny weather to develop flowers. I just haven't had that where I live.
© 2013 Caren White
Caren White (author) on December 26, 2013:
I know! I was surprised too to learn that luffa sponges came from plants. I even tried to grow them this year.
FlourishAnyway from USA on November 21, 2013:
I had no idea this is what they were. I learned something today. Thank you! Voted up and more. Pinning.