Luffa in the Garden

Luffa vines bring a tropical feel to the garden and make excellent summertime privacy screens.

Luffa is exceptionally easy to grow, requiring only warm temperatures, full sunlight and average garden soil.  In our USDA zone 7a garden, here in Virginia, it helps to start the luffa seeds a bit early, indoors, and transplant them outside once the danger of frost is past.  The seedlings are frost-tender and cannot survive cold temperatures, so we wait until May 12th to transplant (our late frost risk begins to diminish by April 28th, and by May 12th, the chance of frost drops to almost zero).  For luffa, seeds should ideally be sown 25 days prior to the target transplanting date, and should be actually transplanted once they have 2 true leaves.  Thus, if you live in zone 7, plan to start luffa seeds indoors, in mid-April.

Trellising

Seedlings send up tendrils to climb strings and trellis supports very early on, so make sure to plan ahead and build your BIG, STURDY trellis first!  Luffa will grow to epic proportions and can easy break small or weak trellises.  Either you must prune aggressively throughout the growing season, or you must build a trellis that can handle the weight.  If growing luffa along a fenceline or up a tree in a food forest, or on a pergola or arbor, check the stability and strength of that structure first.

Training luffa is almost unnecessary, if the seedling is planted below the structure and a line or two are anchored next to the seedling to guide it aloft.  You may need to gently teach the vine to find this upward line at first, but it should follow it aggressively.  Tendrils grip well and ties are rarely needed.  Once it reaches the top of the trellis, the vine will sprawl outward along the supports and fill in the available space.  Horizontal growth is sturdier and receives more nutrients, compared to vertical growth, so a curtain-style of wire trellis, a table-top style trellis, or an arbor will all yield better gourds than straight vertical wires extending upward indefinitely, like hop trellises or greenhouse cucumber bobbin-trellis systems.  A vertical height of 4-10 feet is more than sufficient, if there is room in your garden for horizontal supports.

Use strong posts for luffa trellis.

Prune off shoots that head in other directions, whether they attempt to escape from the trellis or just threaten to cover and strangle the existing, older vines.  Do not feel bad about pruning, especially once the vine is established and growing vigorously.  It is generally easier to just prune off the errant vines rather than trying to tie or train them back onto the trellis.  Prune any shoots that try to grow along the ground rather than up the trellis.  Fruits growing on the ground are likely to be discolored and rotten.  Your goal in pruning should be to contain the growth to only the designated area, and prevent such overlapping and tangling of the vines that the interior leaves end up choked, starved for sunlight, or rotting from trapped moisture.  Good airflow and good exposure to sunlight are the keys to health.

Be warned: happy, healthy luffa vines in summer can grow 8" to a foot EVERY DAY, along numerous tendrils.  Do not plant this vine too closely next to other garden plants, for it will happily overtake them and outcompete them for sunlight.  It is not a good idea to let other vines, such as grapes, share the same trellis with luffa, unless you can dedicate time to pruning back the vines every other day throughout the warm months.  Instead, plan ahead for these aggressive vines: give them plenty of room.  One vine, planted at the center, can fill a 15' long straight-wire trellis with evenly spaced wires up to 10' high.  A sturdy arbor or pergola can accommodate one, or perhaps two, luffa vines.  The less space you provide for this growth, the more often you will need to prune.

Trellis management for commercial production focuses upon maximizing harvest yields per acre, and consequently provides less space per plant--trading increased labor requirements for increased size and production of mature gourds per area.  However, a single sprawling, healthy luffa vine in a homestead garden can produce shocking quantities of gourds, usually in excess of even the most demanding household's annual need for sponges and veggies, so there is no need to follow commercial planting and trellis guidelines in spacing the luffas at home.  Prioritize time savings, prune less, and enjoy the beauty of the vigorous vines filling larger trellises.  You will still get plenty of gourds.

Watering

Luffa responds very quickly to dry conditions, especially when young; as the vine matures, the roots eventually grow enough to weather short droughts without irrigation.  Just make sure that the young vine receives adequate water to prevent stress.  The leaves will wilt rapidly when the plant is thirsty, so it is easy to visually monitor when it is time to water the young plant.  This can actually be a helpful indicator for water stress in the surrounding garden, if other water-sensitive plants are growing in the same conditions but do not provide such visual cues for when to irrigate them.  Happily, luffa bounces back almost instantly from its wilting, when water is provided (the leaves rebound almost quickly enough to watch!).

Flowering

Flowers decorate the vine all summer.

Luffa is self-fertile and does not require cross-pollination from other vines or varieties.  The flowers typically appear in late June in our climate.  Luffa flowers are large and brilliantly yellow, so attractive that a gardener could choose to grow luffa exclusively for its ornamental value (especially as a privacy screen along a fenceline or as a trellised summer hedge).  Usually, one female flower will grow for every ten male flowers, almost guaranteeing fertilization of the female flower by the insect pollinators (mostly bees) that visit the vine.  The male flowers open every morning that the temperature is above 65 degrees F, and remain open until the afternoon.  By evening, these flowers close and fall off, so there is no need to deadhead or clean debris from the vine.  The female flowers, once pollinated, develop the fruit: a cylindrical, green gourd that forms like a cucumber behind the flower.  The used female flower does not always fall off, but since the gourds will be peeled before use, there is no problem arising from discoloration where the flower stuck to the end of the fruit.

Pollinators

Bumblebees adore luffa flowers and will visit the vines throughout the daylight hours, from early summer through late fall, cruising for open blooms.  Other bees, butterflies, moths, beneficial wasps and even the occasional hummingbird will enjoy the flowers, although the vine particularly benefits from bees.  The luffa is a fantastic nectar source for feeding pollinators long-term, especially if the garden contains other, short-term-blooming plants that will require the presence of pollinators in a specific, brief window.  Luffa is a great support plant for orchards and stationary beekeepers to consider growing near their bee yards, since it provides such a consistent food supply from June through October/November.

Luffa Ant Guild

Red ants protecting luffa gourds and drinking from EFNs.

 
Herbivorous insects can be a serious problem for growing some garden plants, especially annual vines like squash, cucumbers and tomatoes.  Insects may eat the leaves, burrow into the fruits, bite and suck out the juices of the vines, or even outsource the feeding (farmer ants will herd aphids on plants, moving the aphids around and protecting them while they eat the garden plant, and 'milking' the aphids for sugar in exchange).

Some garden plants resist such insect damage, either by producing chemicals to discourage the bugs from eating them, or by camouflaging their scent to confuse the insects, or by growing hard bark or thick skins on the fruit to keep insects out.  However, there is another, and by far more entertaining strategy which only a few garden plants employ: they hire "bouncers!"

Luffa vines are one of the best in the garden at hiring protection.  To do this, luffa produces Extra-Floral Nectaries (EFNs), tiny button-shaped green volcanoes of sweet nectar that ranges from 15-75% sugar by weight (depending on how threatened the vine feels) on the nodes and under the leaves. The vine feeds this nectar to special varieties of ants, to 'pay' them to work as security guards. Generally, these ants aren't predatory; they aren't actually eating the herbivorous insects that come to attack the vine--they just harass the interlopers until they give up and leave.  This protection can extend to birds and mammals, as well, for the brave ants will attack anything that tries to harm the vine during the growing season.  Only when the luffa has produced enough mature gourds, in late summer or early fall, will it stop paying these protective ants, who then leave the plant in search of sugar elsewhere.

Ant drinking from EFN at a luffa vine node.

Luffas aren't the only plants to use EFNs to hire security ants, but they're noted for doing it really well and early in their growth (long before putting out flowers). Remarkably, the protective ants extend their services to other, adjacent plants in the garden as well.  For example, beans and elderberries growing near luffa vines will soon have the red 'bouncer' ants standing guard on them, driving away aphids and black farming ants, even though these plants are not paying them for this protection.

These useful ants ensure that luffa is rarely troubled by insects and insect-born diseases.  Children find the EFNs and alert guardian ants fascinating, so this is an excellent subject for young students learning about interconnectedness in the ecosystem (or for older students, studying permaculture and integrated pest management). Of course, it can be unnerving to face these ants when pruning and training the vines; gloves are helpful, although the ants found here in Virginia are not harmful and cannot cause serious bites or stings to humans.  If extensive handling of the vine is necessary during trellis-training, it can be a good idea to lightly shake the vine first to dislodge ants from that section.  Fortunately, the ants leave the vines in fall, long before harvest of mature gourds and cleanup of the vine remnants takes place.

Invasive?

One concern many gardeners have about vigorous vines is that they may be introducing a potential weed, or worse yet, an opportunistic plant that may escape cultivation and spread into the wild.  Luckily, the potential for such spread is very low with luffa.  The vines are frost-tender annuals and will not spread via rhizomes, so the chance of the cultivated vines escaping in temperate climates is minimal.  The seeds of the luffa are contained inside large, heavy gourds, and thus are not at risk for being carried off by birds or small mammals.  Seed dispersal is very unlikely by wind, as well, for the same reasons.  Furthermore, this tropical vine requires fertile, cultivated ground and warm temperatures for germination.  While it is possible that a gardener might find a few luffa volunteers within the garden, if the gourds were left on the vine until they rotted, these volunteer seedlings are easily culled with manual weeding.

Additionally, the luffa is a long-season grower that requires 25 days from soil temperatures triggering germination until it has its first true leaves, then another 30 days until flowers first open, and another 50 days from flowering to the first mature seed formation.  At minimum, then, luffa needs over 100 days of warm growing season after soil temperatures reach 70 degrees F.  In our climate, as well as in colder regions, the odds against luffa vines surviving in the wild are low.

Furthermore, luffa vines are quite tasty and attractive to ruminants, such as sheep, goats, cattle and wild deer.  The likelihood of a luffa vine seed making it into a wild setting, germinating, and escaping notice from the local deer population for long enough that it could mature its gourds is lower still.  Thus, luffa is a very safe choice for gardeners with concerns about invasive plants, and is a good candidate for less controlled areas such as chainlink fences along property boundaries, or at the edge of wood lines, since there is little chance of accidentally introducing a nuisance plant.

Want to know more?  Navigate to our other posts on luffa:

• Luffa overview
• Luffa as food
• Luffa sponges
• Luffa as medicine

Interested in growing luffa yourself?  Email us to purchase seed!