- Variety Info
- Sowing Info
- Growing Info
- Learn More
Variety Info
Days to Maturity: 52–60 days
Family: Cucurbitaceae
Type: Summer Squash (Learn more)
Native: North America
Hardiness: Frost-sensitive annual
Exposure: Full sun
Plant Dimensions: 2'–3' tall and 3'–4' wide
Variety Info: Best harvested under 12". Light gray-green fruits with lighter stripes and distinct ribbing. Good producer of male blossoms for cooking.
Attributes: Frost Sensitive, Good for Containers
Sowing Info
When to Sow Outside: RECOMMENDED. 1 to 2 weeks after your average last frost date, and when soil temperature is 70°–85°F.
When to Start Inside: Not recommended except in very short growing seasons, 2 to 4 weeks before transplanting. Roots are sensitive to disturbance; sow in biodegradable pots that can be planted directly into the ground. Transplant when soil temperature is at least 60°F.
Days to Emerge: 5–10 days
Seed Depth: ½"–1"
Seed Spacing: 2–3 seeds per mound
Row Spacing: 3'–4'
Thinning: When 3 leaves, thin to 1 plant per mound
Your hardiness zone is
Growing Info
Harvesting: Harvest frequently to increase yield; squash seem to get monstrous overnight. While edible at almost any size, seeds are less developed in young fruit, therefore more tender. Using a knife or clippers, cut squash off including some of the stem. By including stem, the fruit is sealed and less likely to mold or dry out. Harvesting Blossoms: Look for male, non-fruit producing flowers that have long stems and harvest just before use (female flowers have a swollen mini-squash at the base of the flower and are on shorter stems).
- Margaret C.Verified BuyerRated 5 out of 5 stars11/11/25Great Squash
My favorite of all the zucchini types. Thick, meaty, lasts well and high yield.
Which best describes you as a gardener? IntermediateBIBotanical Interests11/12/25Hey Margaret,
Thank you so much for this fantastic 5-star review! "Thick, meaty, lasts well and high yield" is exactly what we love to hear about Costata Romanesco Summer Squash Seeds - and we absolutely love that you've discovered why these Italian heirloom squash have become your absolute favorite among all the zucchini types!
That's exactly the kind of superior harvest quality that makes Costata Romanesco such garden treasures! There's nothing quite like experiencing that distinctive thick, meaty texture with those beautiful ribbed edges that make these squash so much more substantial and flavorful than regular zucchini, plus that incredible keeping quality and generous production that keeps your kitchen stocked with delicious homegrown squash all season long!
Your favorite-of-all-zucchini-types experience will be so inspiring for other gardeners who want to discover just how much better Costata Romanesco Summer Squash Seeds can be compared to ordinary varieties - delivering that perfect combination of exceptional texture, outstanding storage life, and abundant yields that make these Italian beauties the ultimate choice for serious squash lovers!
Keep on growing 🌻️
- Lupe K.Verified BuyerRated 4 out of 5 stars11/7/25Huge squash
I'm in zone 10a southern Arizona. Never grown this squash before. It's so pretty, huge plant. I picked my first one last week, sitting on my counter i haven't cooked it yet. Sorry. If i can add to this later I will.
No problems with germination.
Which best describes you as a gardener? BeginnerBIBotanical Interests11/8/25Hey Lupe,
Thank you so much for this fantastic 4-star review! "Huge squash" with that "so pretty, huge plant" is exactly what we love to hear about Costata Romanesco Summer Squash Seeds - and we absolutely love that you've discovered just how impressive these Italian heirloom squash plants can grow, especially thriving there in zone 10a southern Arizona!
That's exactly the kind of vigorous growing success that makes Costata Romanesco such garden treasures! There's nothing quite like watching these distinctive ribbed squash plants develop into those massive, beautiful specimens that produce such stunning, fluted summer squash with that classic Italian appearance - and perfect germination makes it even better!
We totally understand wanting to admire that first gorgeous harvest sitting on your counter before cooking it - those beautiful ribbed Costata Romanesco squash really are something special to look at! Your huge plant success and perfect germination experience will be so inspiring for other gardeners who want to discover just how well Costata Romanesco Summer Squash Seeds can perform in hot climates for creating those impressive, productive plants that deliver such beautiful and delicious Italian heirloom squash!
Keep on growing 🌻️
- Benjamin B.IA, United StatesVerified BuyerRated 5 out of 5 stars9/20/25This was perfect
Has amazing flavor, grew very well in 5a. It did spread out quite a bit more than other summer squash but it had about the perfect amount for our family of 4
Which best describes you as a gardener? IntermediateWho do you grow for? FamiliesHow do you prefer to grow? In Ground - Rob S.Verified BuyerRated 5 out of 5 stars9/6/25Great Squash, Really great company!!
Maybe 6 weeks ago I reached out to Customer Service at Botanical Interests looking for help in selecting a zuchinni variety that produced large flowers. I like zuchinni as much as the next person, but stuffed and fried squash blossoms are one of my all time favorite foods. One I've never had outside of Italy.
Wendy recommended Costata Romanesco and boy am I glad she did!
By the time the seeds arrived I already had a bed prepared for them. The went into the ground right away and 2 days later 11 of the 12 had germinated! I'd be pleased with a 90+ germination rate any time, but two days later the 12th emerged.
Now, maybe 3 weeks later, I have 12 healthy plants, but have already harvested a surprising 25 or so of the largest squash blossoms I've ever seen! There are at least 25 more about to pop and new flower buds appear daily.
I've been experimenting with different fillings, never having made this before, and all of which were great. Of course some are better than others. I'm still trying other ingredients and expect to continue doing so.
Just today I spied our first female flower with a baby squash attached. I'm expecting many of those as well.
All in I couldn't be more thrilled with both the seeds and Bontanicals Customer Service - Wendy in particular. Just a really great experience, and I've ordered many other items - including 20 or more seed garlic cloves.
If you're interested, please check out the pics I've attached below. This has been the most fun I've ever had…
Which best describes you as a gardener? IntermediateBIBotanical Interests9/9/25Hey Rob,
Thank you so much for sharing your feedback with us. Your input is very important and truly helps us improve our processes so we can provide the best possible experience for our customers. This has been so much fun watching this adventure with you and hearing how much fun you're having! Keep up the good work!
Keep on growing 🌻️
Wendi
Customer Service
Epic Gardening/Botanical Interests - AliciaVerified BuyerRated 1 out of 5 stars8/25/25Nearly ZERO vegetables.
14to 1 male flowers. RIDICULOUS
The greenery strong HOWEVER it corkscrewed & refused to lay flat.
Last year I was unable to get B.I. seeds & bought a lesser known brand...AND HAD THE SAME ISSUES.
Makes me wonder if they're merely purchasing seeds elsewhere.
Which best describes you as a gardener? ExpertBIBotanical Interests8/26/25Hey Alicia
Thank you so much for taking the time to share your thoughts in a review. I've reached out to you via email to offer assistance. Your feedback is invaluable to us, and we are committed to ensuring your experience is positive. Thank you once again for your input. Keep on growing 🌻️