Ripen Your Pumpkins: How to Top Off Your Winter Squash Vines Before First Frost in Denver
Let’s talk pumpkins. And butternuts. And delicatas. And all the cozy fall squash that makes your garden and your kitchen feel like magic in September.
If you’ve got winter squash growing in your Denver backyard garden right now, I’ve got a quick tip that could make a big difference in your harvest:
👉 Top off those vines!
It’s a simple step that tells your squash plants, “Hey, stop growing and start ripening what you’ve already made.” And trust me, with our unpredictable Colorado frost schedule, you’ll want to give those pumpkins every chance to finish strong.
Let’s dig into what it means and how to do it 👇
Watch my behind-the-scenes video of this process! 👇
Why You Should Top Off Winter Squash Vines in late summer and early fall in Denver
Here’s the situation: your winter squash plant is doing what it loves to do: stretching out vines, putting out new flowers, and trying to make baby pumpkins like it’s still July.
But here in Denver, we know better. We’ve got frost lurking just a few weeks away, and those new baby pumpkins? They’re not going to make it in time.
That’s why topping the vines in late summer and early fall is so helpful:
It redirects the plant’s energy into ripening the fruit that already exists
It stops new growth that won’t mature before frost
It helps you get bigger, more mature, better-storing squash in your final harvest
How to Top Your Squash Vines
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This is exactly what I did in one of my clients' gardens this week.
Here’s the step-by-step:
Follow the vine all the way to the end
Look for the last developing pumpkin or squash on that vine
Use clean garden shears to cut the vine just a few inches past that last fruit
Repeat for all the long vines with fruit that still needs to ripen
That’s it! Simple, quick, and surprisingly effective.
Hot Tip:
If the vine is still putting out new flowers or baby squash, you can leave it only if you have time before frost and the variety matures quickly (like decorative minis). But for full-size pumpkins and winter squash, cut it off and let the plant focus.
When to Do This in Denver
I recommend topping your vines around early-to-mid September, usually a few weeks before our average first frost (which tends to fall between October 5–15 in the Denver area).
Waiting too long means your plant may keep wasting energy on fruit that won’t stand a chance. Doing it now helps consolidate energy and gives your mature squash a better shot at ripening in time.
What About the Tiny Pumpkins Still Forming?
Here’s the honest truth: If you’ve got little baby pumpkins that just started forming in September, or flowers that haven’t even opened yet… those probably aren’t going to ripen in time.
In this garden, I found a couple tiny decorative pumpkins forming on a side vine. Since those tend to mature more quickly, I decided to leave that one alone, but I topped most of the others.
You’ve got to use a little gardener’s judgment:
Full-size squash = Top the vine now
Quick-growing mini pumpkins = Might still make it, so leave them if you have a warm spell ahead
What to Expect After Topping
Once you snip the ends:
Your plant will start channeling energy back toward the fruit already on the vine
You may see a bit of yellowing on the ends, that’s okay!
You’ll likely notice your pumpkins starting to deepen in color and fill out more fully
Bonus Tip:
If frost does hit early, you can harvest pumpkins slightly underripe and let them cure indoors. But topping the vines now helps them ripen as much as possible on the vine before that happens.
Final Thoughts: Set Your Pumpkins Up for Success
Winter squash and pumpkins are long-season crops, which means every day counts this time of year.
If you’ve got trailing vines and baby fruit still trying to grow in mid-September, it’s time to top those vines and help your plant finish what it started.
It only takes a few minutes per vine, and it could mean the difference between soft, underripe squash… and sturdy, flavorful pumpkins ready for roasting, soups, and spooky porch decor 🎃
Got questions? Reach out! I’m always happy to help you get your hands dirty (in the best way).
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Meet the Gardener
I’m Elisa Mack - a mom and Denverite who went from being a green-ish thumb to a kitchen garden fanatic simply by dedicating myself to the study of all things Colorado gardening.
Landscapers don’t design. And nurseries don’t make house calls.
We take a more full-service approach, from designing your dream garden to keeping it beautiful year-round.
And as your coach, I’ll help eliminate the guesswork through every season, no matter your level of knowledge.
