I have been trying to grow luffa (or loofah) for the past three years (2022-2024). The key word here is ‘trying’ as I have yet to be fully successful. However, I thought it might be useful for others to check out the problems I’ve had growing luffa in a temperate climate, as most of the content I’ve found online or in books makes it sound so easy. Surely I’m not the only one!
Suffice to say, my luffa growing attempts have improved year on year, so maybe I will finally succeed in 2025. Watch this space!
There’s plenty of general information online about growing luffa so I’ll focus on my own experience and learning. It’s worth noting that in year 1 of my luffa adventure, my seedlings only grew one pair of true leaves before biting the dust. They looked sickly and pale and barely grew. In year 2, the plants got a little further on but went the same way after a month or so of life. In year 3, I got at least something right with three plants grown to maturity. As a result, the experience discussed below is based on only one growing season as well as from other reading and research.
Timing Challenges
Time to maturity
Luffa have a long growing season and this is cited as the main issue when growing them to harvest as sponges (rather than using the younger edible fruits) in cooler climates. Some sources say 200 days are needed for fully mature fruit which is 6-7 months! Here in the western UK our last frost date is usually early-mid May with the first frosts possible in October/November, so it is just about possible when growing them indoors or in a warm, sheltered position.
Each year I’ve started off my seeds with warmth indoors, and in 2024 I started them on the 31st March along with my tomatoes. I did get fully grown luffa which started the process of ripening and dying back however, the cooling autumn temperatures create a lot of moisture in my (ventilated) greenhouse and the fully-formed fruit started to mould before they were ready to harvest. This may be an issue specific to the cooler, wet year of 2024, or my specific conditions.
[Tip? – I subsequently saw a video on Sage and Stone Homestead’s YouTube channel where they harvested sponges from the still-green fruit. Whilst I’m not sure mine were developed enough to have a good internal structure for use a sponge I wished I’d seen this option before abandoning all hope].
So, in 2025 I’m going to start the seed a couple weeks earlier and see how we go, and I may still have the option of extracting sponge from fruits which aren’t fully ripe.
Speeding the process and avoiding setbacks
I’ve since also read that luffa hate root disturbance. In other plants which are sensitive to this, indelicate handling can cause a pause in growth whilst the plant gets re-established. It would make sense that taking all efforts to reduce this risk could have a big impact on overall growing period and the chance of obtaining a successful harvest.
It may or may not be significant, but in 2022 and 2023 I started my plants in small pots and potted them up a couple of times before they seemed to stop growing altogether. In 2024, I planted them out fairly promptly into large pots with good soil and lots of worm castings after which they were undisturbed. There will be many factors at play so this hypothesis is untested, however it’s an intriguing thought…
Another way to save precious days within the growing window is to speed up germination. Warmth is a must, but I’ve also since learned that the seeds benefit from scarification (scratching away/removing some of the outer hard seed coating to allow better absorption of moisture and quicker germination). I have previously soaked the seeds in warm water for at least a few hours which is often recommended for all plants in this cucumber (curcubit) family but in 2025 I will also try scarification.
Pollination
Inadequate pollination can be a reason for poor fruit set on plants grown indoors. My little 6′ x 8′ greenhouse was left open for most days (and nights in the summer) allowing access to pollinators, and I also grew basil within the pots as a potential companion plant and pollinator attractant. As it was a relatively cool and damp summer at times I did hand pollinate the flowers using a paintbrush to boost my chances.
However, my main challenge seemed to be getting male flowers to appear, and then to have both male and female flowers open and ready for pollination at the same time.
I was so excited when the first flowers opened with little luffa fruits behind, however I seemed to have weeks (maybe months!) where these just shrivelled and fell off. It was then I realised that these were the unpollinated female flowers and there were actually no male flowers in attendance!
Eventually the male flowers did appear and I set to with my paintbrush. Apparently it is unusual for the female flowers to appear before the male flowers, and that their appearance is temperature-related. My only thought is perhaps that a hot spell in the spring caused the development of only female flowers, whereas once (ironically) it cooled down later in summer, the male flowers could start to be produced. Who knows?! It was also interesting that one of my plants started producing male flowers much sooner than the other one. Towards the end of the season it became a gamble as to whether a male flower would open in time before the female flower wilted and dropped off. I’d be interested in any other information on this topic.
The pictures below show a female flower on the left. These are borne singly have a mini luffa-shaped bulge behind the petals/bud which would develop into a fruit once pollinated.
The male flowers (right) are borne in little groups of rounder/wedge-shaped buds and lack any sort of swelling behind the petals. Both male and female flowers are lemon yellow in colour and of a similar size (female flowers might be slightly larger).
I think the main factor helping ensure I got at least some pollination, was having multiple plants growing simultaneously. In my experience it was rare for a single plant to have both male and female flowers open at the same time.
Pests and diseases
I’m not sure whether disease was a factor in the failure of my 2022 and 2023 plants, perhaps damping off? If I had better notes I’d be able to tell whether these seeds may have been started too early or perhaps if the weather conditions had been significantly different to 2024.
In 2024, my luffa plants were affected by red spider mite and, to a lesser degree, mildew. As a grower of other squash and cucumber, I was aware of these risks and tried to take some organic preventative actions. Red spider mite hit first and quickly spread, affecting many of the leaves and turning them mottled and dry. The plants did continue to produce new healthy leaves so I tried to improve humidity by spraying the plants with water, keeping them hydrated and also watering the concrete floor of the greenhouse on hot days. I was conscious that this may improve the chance of mildews and that did eventually take hold later in the year. I have in the past tried to prevent/control mildew by spraying plants with a mixture of whole milk and water (with or without added garlic), though I find it hard to remember to prepare this and it is rather unpleasant. As 2024 was my first year renting a horsetail-infested allotment plot, I soaked (non-fruiting) horsetail stems in water and used the solution to thoroughly spray the plants. I’d read that the high silica content of the horsetail solution provides an inhospitable environment for the mildew spores, so I thought that this might be a good dual-action defence, increasing humidity to deter red spider mite whilst not encouraging mildews. Whilst I was affected by both issues, I’m not sure that it severely impacted the growth of the plants (or my neighbouring cucumbers) . I like to think that the spritzing helped (possibly wishful thinking) and I will try it again this coming season, not least because I don’t want to compost the weeded horsetail plants and this is a good use for them!
The only other ‘pest’ I noted were aphids. These were well tended by ants which also apparently visit the luffa to make use of nectar exuded by non-floral parts of the plant. In other plants at least, these ‘nectaries’ are used to attract ants which then protect the plant from predators. I didn’t do anything specific to prevent the ants or the aphids and I did notice natural predators in the form of 22-spot and harlequin ladybird larvae which was fantastic! As with the above, I don’t think they had a significant impact on the health of the plant but this could be different in other years, and perhaps the aphids contributed to the spread of mildew? The ants were a slight management nuisance however as it was difficult not to brush past/under them when working in the greenhouse and they reacted vigorously to my attempts to pollinate the flowers or remove dead leaves.
Conclusions (so far...)
Albeit challenging, I will continue to persevere with growing this useful plant. I’ve learnt alot already and hopefully taking extra steps to scarify seed, start early and be prepared to harvest green fruit, will mean I get some success on 2025. If not I will keep trying as every year is different. I’ll continue to update this post with any useful new discoveries. I’d be interested to hear any other tips for growing luffa in a temperate climate.
