Luffa sections can be a backyard-sourced organic alternative to store-bought rooting cubes and plugs. The fibers of the luffa provide structure, allowing each round to be free-standing with excellent drainage.
They also promote the air pruning of side roots. Being organic, they will eventually compost completely, without leaving behind plastics or artificial binders. Luffa sponges can even be used for their original purpose, which is to start more luffa plants.
What is a Luffa?
Luffas, which are also commonly called “loofahs,” are in the cucurbit (gourd) family. As such, they are related to (but cannot cross pollinate with) gourds, squashes, melons, and cucumbers. The three most popular species are luffa acutangula (angled luffa), which has noticeable ridges; the smooth-sided luffa aegyptiaca or luffa cylindrica; and the small, round, and spiky luffa operculata (wild luffa).
How to Make Luffa Starters
Step One: Grow a Couple of Luffa Plants
They can be started indoors before the last frost, but care must be taken not to set them outside too early as they are not frost tolerant. Harden transplants slowly and handle them carefully as they are susceptible to transplant shock and growth may stall if their environment changes too dramatically. Plant in mounds of one to three plants.
A healthy luffa vine can grow quite long over the course of the season, and a sturdy trellis is recommended as fruits on the ground tend to curl.
Water and feed like squash and cucumbers. Keep soil from drying out, but avoid overwatering. Use a mild application of a balanced fertilizer monthly.
Luffas are monoecious and have male flowers that form in clusters that bloom along a stem length and female flowers that can be identified by the miniature luffa fruits at their base that will develop into full-sized fruits if pollinated. Luffa flowers attract a variety of pollinators and are a bee favorite.
Step Two: Harvest Luffas After They Have Dried on the Vines
As the fruits mature, the xylem (which transports water from the roots upward to the rest of the plant) becomes fibrous and more rigid.
Collect the luffa fruits after they have turned from green to yellow or black, have lost most of their weight, and rattle when shaken (or before an impending frost). Some fruits with green remaining may have developed enough fiber to be useful, but it is safest to wait until they have started to dry on the vine to be sure.
Fun fact: Immature luffas are edible, but those intended for the cooking pot should be harvested when they are small and before the fruit turns fibrous.
Step Three: Prepare the Luffas for Drying
Peel away the outer skin from the fiber beneath. Collect the seeds and keep those from the best luffas for replanting. Luffas produce many seeds per fruit, but select only the black, mature seeds for saving.
Rinse away any remaining pulp from the fiber in fresh water. Soak a few minutes in a dilute bleach solution to whiten the fibers if desired, and rinse a final time before setting out to dry.
Step Four: Drying and Storage
Once the luffa sponges have dried, they can be kept whole for storage or cut into chunks to use for either sprouting seeds or starting cuttings. Dried luffa sponges can be kept almost indefinitely if kept free from moisture and dust.
Step Five: Use as Starter Rounds
Fill the natural voids in the cross section of a cut luffa with cut pieces of luffa fiber or with a potting mix or other grow medium. Place the prepared luffa sponges in trays, and plant the seeds or cuttings into the luffa rounds.
What to do With Leftovers
If there are leftover luffa sponges after planting needs are budgeted, they can either be kept for the following year or used in other ways.
Two other common uses for luffa sponges include using them to wash dishes with (which is how they earned the name “dishrag gourds”) or to wash and exfoliate skin in the shower. Sponges used on dishes or skin should be allowed to dry between uses, so rotating between multiple sponges may be helpful.
Thankfully, a successful harvest should produce a plethora of homegrown sponges, allowing the frequent replacement of sponges. If there are still luffa sponges left over, they can be woven into mats, be used to line pith helmets, or to filter diesel fuel.
Luffas can be fun to grow, are bee friendly, and produce a useful sponge that can be used in a variety of ways. Growing luffas at home tends to be very cost effective compared to purchasing them.
An individual luffa sponge from a specialty beauty shop may well cost more than an entire packet of luffa seeds, and it wouldn’t take many to offset the other gardening expenses such as the cost of water and a little fertilizer.
While their need for a long growing season puts them out of reach for some gardeners, they grow in a much wider range than the peat moss and coconut tree alternatives for homegrown starter round material.