This year I decided to grow one of the most challenging vegetables to start from seed, especially in a northern climate, like where I live in zone three: the luffa sponge. From what I can tell in my research, it’s pretty challenging to grow in any zone from 6 and lower. But I had dreams of growing luffa sponges for both the bragging rights and as a non-plastic dish sponge and exfoliator, so the challenge was on.
But before I go on about the strategies to grow a successful luffa plant in a cold climate, let’s get one thing out of the way. . .
What is a Luffa and what do you do with it?
A luffa sponge, also spelled loofa, loufa, and probably another billion variations is a vining plant that initially looks like a zucchini (and can be eaten like one when its young) and hardens into a fibrous sponge. It can be used as a gentle and natural scrubber for cleaning your dishes or marks on your walls, or as an exfoliating sponge for your skin as-is or in a soap.
Contrary to popular thought, luffas actually have nothing to do with the sea or sea creatures.
Growing loofa sponges is extremely attractive for those living a zero waste lifestyle, or even if you’re just looking to cut down your plastic consumption.
With that out of the way, let’s talk about the challenges. . .
The Challenges of Growing Loofa Somewhere Cold and How You Can Succeed
The first challenge, is that the louffa plant needs 200 days to get to maturity. 200 days!! When your whole growing season is 90-110 days, this presents a giant problem.
Second, the loofa is a giant baby that doesn’t like the cold. Sure, you can baby it indoors, but if it goes outdoors in anything colder than 10 degrees Celsius, it stops growing for up to a month!! What kind of jerk plant does that!?!?
To make matters worse, once the temperatures start dipping again, the sponge will be ruined if it gets just a touch of frost. There are no taking chances, no covering your loofa and hoping for the best. One tiny bit of frost and it’s toast.
To sum things up: Long growing season + Unreasonable cold intolerance = ridiculously challenging plant.
But I’m a sucker for punishment and gardening glory, so here’s what I did. . .
Step 1: Start the Seeds in January
This is going to vary depending on your first frost date, but you must count back 200 days from whatever that is. For me in Saskatoon, SK, Canada, that puts my optimal seed starting time at the last week of January or first week in February.
My seed packet said to start 6 weeks before my last frost date, but I ended up starting more like 12 and I’m very glad I did. If you live in zone 2, 3, or 4, do not listen to the seed packet or other articles that say to start your seeds 6-8 weeks before the last frost. Our temperatures just don’t get warm enough at night soon enough and long enough for the loofah vine to flourish like it does other places.
The loofah plant can take awhile to germinate, and has notoriously low germination rates. Out of 25 seeds, only 16 germinated for me.
I didn’t use a heating pad to speed things up, but I think it would be a good idea. When the loofah plant opens, it resembles a squash plant and looks like this.
Loofah’s don’t like to be moved or transplanted, so either plant them in a soil block, newsprint pot, or a very large pot 18-24 inches across (probably not practical for our growing situation).
Step 2: Find Somewhere for the luffa to climb
Now that our loofah plant has germinated, it’s going to grow quickly and fast outgrow the space under our growlight. I am very lucky in my home to have a tall south-facing window, so once my seedlings outgrow my growlight, I transfer them over to the windowsill.
The loofah sponges were very happy there and attached themselves to my window screen. Eventually, they grew so tall that they got taller than the window and fell back on themselves. Next year, I’ll attach a string to the pot for the vine to climb up. It will also be much easier to transfer outdoors that way.
To my great surprise, the loofah plants started flowering indoors! I wasn’t sure if I had to pollinate them or not, but since I was very pregnant and tired, I kept forgetting to pollinate them. Fortunately, I found out by accident that they are indeed self-pollinating, and I started to get baby loofah!!
*insert happy dance*
At this point I started to doubt the wisdom of when I started my plants, but as you’ll see by the time you read the rest of the article, it was still the right choice.
Step 3: Wait Until the Nightly Temperature is Warm enough
If you remember earlier, I told you that loofa sponges can’t survive in temperatures colder than 10 degrees Celsius. Hugely problematic when you live somewhere cold. Even though freezing temperatures stop at the end of May, it did not get consistently warm enough at night until the middle of July. (This is written about the summer of 2020, and our June was a lot colder than normal.)
I tried to experiment with wrapping up my vines and providing protection for them, but they were too big and it just didn’t work. Well, it worked for awhile, until we had a surprise night of -5 degrees Celsius temperatures. They were toast. But it was okay, because I was sacrificing these plants in the name of science!! Anyway.
The most effective way to harden off my louffa plants was to open the window that they were growing on, and leave that window open during the day, then close it at night. When it was finally time to transfer them outdoors, they didn’t go into shock for too long.
Step 4: Transfer the Vine Outdoors
When the night time temperatures are consistently above 10 degrees Celsius, you can finally transfer the louffa outdoors. Save the warmest spot in your yard, and make sure the vine has a lot of space to climb. While it won’t get insane like it does in warmer zones, mine still grew to around 10 feet during a colder than normal summer.
If at any point there is a risk of frost, pick your louffa sponges. They will be ruined and/or discoloured if they get frost, and all your hard work will be for nothing. Don’t worry if they are green, you can dry them indoors.
As a side note, I also found that any flowers that were on the vine immediately fell off when I set it outdoors. Once the plant had established itself again, flowers continued to bloom.
Mature Loofah Sponges
Once my little sponges were tan coloured, totally dry, and rattled inside, I knew they were ready. Mine were much smaller than I expected them to be, and I have a feeling that if I had left them indoors and not tried to transfer them outside, they would have gotten larger.
Ideally you pick them at this stage, but if frost came when they were still green, I’d still pick them and dry them indoors.
What I’d Do Differently
So in a perfect world, I would actually grow louffa plants in a greenhouse or high tunnel and keep them there the whole summer. I think they would be a lot happier and I’d get much larger fruit from them. As you’ll see in my pictures, my best louffa sponge was only the size of my hand. Not like those huge ones that literally everyone else on the internet who grows them gets.
Now that I know that I’ll be growing my luffas indoors for a good chunk of their lives, I’ll start them in newsprint pots and transfer them to a larger pot indoors. In fact, I’m going to experiment with growing one vine entirely indoors and never transferring it outdoors. I’ll update this article in 2021 and let you know what happens!
Even though the vine gets crazy indoors, I’m going to stick to the same planting schedule as I did this year. Anyone I know in the same zone as me that started their sponge 6-8 weeks before the last frost date and put their plant out at the same time as all their other plants did not get any sponges.
Where Do You Get the Seeds?
This year I purchased my seeds from the Ontario Seed Company. If you have a locally owned garden centre, just ask them if they could bring them in for you. Most owners will be happy to bring in items that they know their customers want to buy.
Since I had two of my 3 sponges get completely to maturity, I actually have a few of my own seeds to grow next year! However, since the germination rate can be bad, I’ll probably order a seed packet, just in case.
So that’s my story of growing loofah plants in zone 3! I hope you found this post helpful. If you want to see me grow loofahs again in real time, follow my Instagram profile, @shifting_roots. It will be all over my stories, promise.
Kristen is a former farm kid turned urban gardener who owns the popular gardening website, Shifting Roots. She is obsessed with growing flowers and pushing the limits of what can be grown in her zone 3b garden. She also loves to grow tomatoes, but oddly enough, dislikes eating them raw.