For tastier flavour, Zucchini Tromboncino fruit are best harvested when small.
Zucchini Tromboncino is a heirloom vegetable common throughout Italy. Valued for its abundant, tasty harvests. It was developed in Liguria, in northern Italy. The fruit has a very pale green skin and can have varied faint white stripes like some zucchini varieties as well. The really nice thing about this variety is that all the seeds form in the bulbous part at the end. That means you’ve got a whole long length of stem with no seeds.
Tromboncino is a highly vigorous variety of zucchini, growing easily to a height and width of 1.5 and possibly more depending on where it is situated in the garden. The good news is that it’s a vining plant, which means it can be trained up a trellis to make great use of vertical spaces.
How to Grow Zucchini Tromboncino
Zucchini tromboncino can be grown vertically to save space
In temperate climates, such as Melbourne, tromboncino seeds can be sown from late September, right through to late January. When sowing the seeds, make a small mound with a depression in the top. Sow two or three seeds in the depression about 4 cm deep. Water in well and keep the soil moist, until they germinate in a week or so.
Use large stakes, reo-mesh, or other trellis to train the vines vertically. Be warned, these vines grow really quickly, especially when the full moon provides enough night time light to support 24 hour growth.
Pollination is usually done by bees, but if you don’t see much bee activity in your garden, try helping them out, by picking a male flower, removing the petals and rubbing the remaining stamen inside the female flowers. The female flowers are identified by the baby tromboncino at its base.
For a better-tasting fruit, start harvesting them once they get about 20 to 30 cm long (They can grow over 120 cms in length.). One plant can put out two dozen fruit.
Zucchini tromboncino appears resistant to powdery mildew.
Hey,
THey aren’t resistant to powdery mildew. I had them on my tomatoes and they finally spread. Took a month or so after the tomatoes but it did happen!
Madeleine
Hi Madeline,
Thanks for your comment. I agree they are not fully resistant to powdery mildew, but much better than most of the other cucurbits. Our zucchinis and some of our pumpkins have been overwhelmed in the last month, and only just recently the tromboncino plants are starting to show signs of the fungus.
Good luck and happy gardening!
Duncan
Just love the idea of growing a zucchini variety that produces plentiful. One of the best source of vitamins and fibre I will growing them from now on. Thanks for the information.
Max Manjimup WA
Hi Max,
Thanks for the great feedback.
Good Luck & Happy Gardening
Duncan
Hi Max I will be prepare to pay for same tromboncini seeds I live in Perth it will be no problem to posted to me , just let me know how much and I will organise payment to you>
thank you
Germano
Where can one get s pack of seeds?
Hi Helen, Diggers, 4 seasons seeds, Greenharvest and many other online seed suppliers stock Tromboncino seeds. Good luck and Happy Gardening!
Duncan
If you keep them on the vine until they grow big and turn orange, you will have a more pumpkin like tromboncino. They are deliciously sweet and juicy and taste similar to a butternut pumpkin. Great for soups and roasting!
Great tip. Thanks for sharing Kimberley.
Good Luck and Happy Gardening!
Duncan
I am having a wonderful first crop of Tromboncino zucchini! We’re having a long hot summer season. I’ve kept the water up and we have many bees. We’re enjoying them in many different ways.
Glad to hear it Sandra. They certainly are very productive when watered well.
Good Luck & Happy Gardening!
I AM NOT VERY GOOD ON THE COMPUTER SO PLEASE BEAR WITH ME
LAST YEAR FOR THE VERY FIRST TIME I GREW A ZUCCHINI TROMBOCINI
I GREW IT ON A TRELLIS APPROX.6MTRS BY 3 MTRS
BUT I ONLY GOT 2 ZUCCHINIES
I DID NOT SEE ANY BEES FLYING AROUND AND 95 % OF THE FLOWERS WHERE ALL MALES
WHAT CAN I DO TO GET MORE FRUIT MY TRELLIS GETS THE FULL SUN NEARLY ALL DAY
WHEN DOES THE VINE STOP PRODUCING FRUIT
PLEASE HELP ME I ENVY OTHER PEOPLE WHO CAN GROW THEM WITH NO PROBLEMS
CAN I CALL SOMEONE????
Hi Charles,
It sounds like you are doing most things correct. The aspect that makes the biggest impact on the success of tromboncinos is watering. If you want your plants to produce prolifically then you need to water them – lots!
If you’re having trouble with the plant setting fruit, then hand pollination may also help.
Good Luck & Happy Gardening!
Duncan
THANKS DUNCAN FOR REPLYING TO MY LETTER
I HOPE NEXT YEAR I WILL SEND YOU A PHOTO
OF A VINE FULL OF TROMBOCINOS
THANKS
Good morning and Happy New Year ,
I already receive your wonderful monthly newsletter. Thanks. I have a query about tromboncini. I have about 12 vines growing well but only three have the fruit. This leads me to wonder if they have male and female plants rather than flowers.
Last year was the first time I’d grown them. They are so exciting because of the speed they grow. I had a 37″ fruit which we left to harden like butternut pumpkin. The soup we made was beautiful.
I sent seeds to my 9 year old grandson in Brisbane and he’s growing them on his balcony along side snake beans. Get them into gardening young with unusual fast growing produce!!
I look forward to your newsletters though they sometimes make me feel like a absolute amateur. I am reassured when you tell of your mistakes!
Many thanks,
Megan.
Hi Megan,
I’m so glad that you find our newsletters inspiring and supportive. I’m also happy that my mistakes help to reassure you – mistakes are the best way to learn!
Thanks for sharing your story with us. Please keep us all updated.
Duncan
Should some of the male flowers be cut off?
I wouldn’t as these are needed for pollination. We tend to just let our vines grow without pruning or much interference. They are prolific and grow well without much help!
Good Luck & Happy Gardening!
I have planted some tromboncino this year for the first time and have ended up with very healthy looking vines I am however seeing a very high failure rate with the fruit. Of the hundreds of tromboncino that have developed on the only two have ended up growing to a size worth harvesting, the majority end up yellowing and shriveling up by the time they are around 3cm long.
The vines are receiving plenty of water. Does anyone have any ideas or tips on what I might be doing wrong?
Hi Jason,
It’s likely to be a pollination issue. To overcome this, you’ll need to hand pollinate some of the fruit. Hand pollination is best done in the morning as the flowers are opening up. Pick a male flower, remove the petals and rub the stamen inside the female flowers.
Hope that helps!
Duncan
Thanks for the reply Duncan, the fruit that are failing are doing so before the female flowers are developed enough to even open.
Then without seeing the plant for myself it is difficult to diagnose. Could be a nutrient deficiency or other stress on the plant. Has the problem rectified itself yet?
This variety of zucchini makes amazing creamy soup withjust onion,garlic braised in butter and olive oil, chicken stock and vitamize in a blender. Delicious
Great tip – thanks for sharing Neil!
Hi there, I’m growing these zucchini’s for the first time. I unfortunately didn’t position a trellis, however they have plenty of room to spread my question is some of the flowers are falling off, does this matter? I have approximately 5 zucchini’s so far
Hi Vicky, the flowers that are falling off are likely to be suffering from a lack of pollination. As long as you are getting some fruit then there shouldn’t be any issues. If you find this continues then try some hand pollination to see if that helps improve things.
My tromboncino plants are about 3 months old. The problem is that they produce lots of flowers but then fell off. There are some fruit (not alot) but they become yellow and dry out. I water them every day (they are in pots). What have I done wrong?
Hi Susie,
It is likely that your flowers are not being pollinated. Try hand-pollinating and see if that helps.
Good Luck & Happy Gardening!
Duncan
I was very interested in the dehydration process. It’s such an an abundance of zucchini, it’s a space saving way to store for winter
Glad you found it useful Donna
Last week I started using a little paint brush every morning to pollinate and this week I’m thrilled to have about 6 new little squash growing. I put the paintbrush into the male flower and scrape as much pollen as I can without disturbing the bees. Then I brush the tips of anything that looks like the tiny start of a squash. Seems to be working in NorthEast Tennessee.
Great tip Julia, thanks for sharing.
These are very tasty and I would like to grow them in the veggie garden (central Victoria): where can I get seeds out this way?
Cheers,
Stephen.
Hi Stephen,
Perhaps trial one of the online seed stores? I know that many of the more popular website stock them. I’m not sure who in central Victoria might stock them.
We had a very successful year growing them this summer. I think the timing of seed sowing must be critical to success. The previous two summers we have had poor crops because I think the seed was sown either too early or too late.
Good Luck & Happy Gardening
Duncan
Hi. I’m growing a tromboncino up a small dracaena palm. Will it kill the plant?
Doesn’t seem strong enough really.
Not much fruit on it & the flowers are falling off.
Would it hurt if I cut the end of the tromboncino plant off.
Thank you, in advance
Lyn
Hi Lyn,
I doubt it will kill the dracaena palm. Cutting the end off the vine will encourage it to branch and send out laterals. It shouldn’t hurt it so much, but will make it more bushy.
Happy Gardening
Duncan
Hello!
Are you doing another Tromboncino competition for 2023/24?
Hi Ellie,
It’s been a few years since we’ve done this. Running the competition takes a lot of time and effort – buying, packaging and sending out seeds etc. Most folks ask for the free seeds and then I never hear from them again. So I decided to not bother with it any more. I’m always happy to have updates from folks who have grown monster trombos. Let me know how you get on this summer.
Duncan
Thank you- I was unsure when to harvest- black Jack zucchini I like to let grow large to stuff with other vegetables, mince and cheese. Now I know I need to harvest earlier as the Italian zucchini’s I have harvested have been over a meter in length.
oh wow, that’s some long zucchinis!
Happy gardening
Duncan
Hi Duncan, I’m in SE Qld and growing Tromboncino for the first time. I picked up a small single plant from Bunnings. It’s been growing great, I’d say it’s about 3m plus growing up and over my trellis and almost touching the ground again. I’ve just harvested my first 4 zucchini, they are about 30cm+ and the flowers were just about to open (but I didn’t want them to get too big just yet). I plan on pollinating a few fruit and letting them grow out to full size, I’m eager to see how big they will grow, and tasting the mature fruit. I’m also planning on saving some seed for next year.
Hi Sharleen,
That’s great. They are really fun to grow and can be incredibly prolific. Thanks for sharing your experience with growing tromboncino.
Happy gardening
Duncan