How to Ripen Green Pumpkins
Gardeners plan for big, round pumpkins that are uniform in color, but sometimes you have to harvest them early when they’re still green. Whether you had an early frost or had to protect your precious gourds from disease, you may now be wondering how to ripen green pumpkins. Thankfully, it’s a simple process that only takes a few weeks. Plant biologist Emily Estep will tell you everything you need to know about how to ripen green pumpkins.
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There’s nothing more autumnal you could grow in the garden than pumpkins. Like most squash, they’re fairly easy to cultivate. You may even discover that seeds from last year’s jack-o-lantern germinated all on their own, producing a volunteer pumpkin plant in your yard.
Despite how vigorously these plants grow, there are reasons why you may find yourself harvesting green, unripe fruits early. Perhaps your vines have come down with a bad case of a fungal disease.
Perhaps the dreaded “first frost” has come early. Or perhaps you got a bit too enthusiastic with the pruners, accidentally severing an unripe fruit from the host plant. Whatever the cause, worry not. You can still ripen late-season green pumpkins in time for carving, harvesting seeds, or home-grown fall decorations.
We’ll walk you through the basics steps, from how to determine if your pumpkin is salvageable to how to achieve the rich, orange pumpkin of your dreams off the vine.
Decide to Harvest Early
Before we get into the process of how to ripen, let’s consider a couple of scenarios in which you should harvest early. The most likely situation is that they haven’t ripened in time for the first frost.
While a light frost or two won’t be a death sentence, colder temperatures can cause damage. The number you’re looking for on the radar is 28°F (-2°C). A 28-degree night can seriously damage fruit, so if the forecast is looking risky, you should harvest. Ripe or not.
Gardeners can ideally avoid this scenario by planting seeds at the appropriate time. Seed packets and catalogs will list the number of days to maturity from germination. Research the predicted first frost date in your region, and plan accordingly.
That said, predicted first frost dates are just that: predictions. Sometimes winter comes a little bit early, even if you planned appropriately. Snap freezes are hard to avoid.
Another potential reason to harvest early is that a disease is killing or has killed the host plant or the vine that a fruit is attached to. Downy mildew can be the culprit, a fungal disease among other possible diseases. While a little mildew isn’t the end of the world, and fully dead vines are a reason to harvest early.
Determine Your Probability of Success
Whatever the reason, even if that reason is that you accidentally removed the unripe pumpkins, now you have green gourds and are wondering, “will this ripen?”
Though you can successfully ripen many green pumpkins, they aren’t savable at every single stage of growth. If yours was nearly ripe already, encouraging it to reach the finish line of jack-o-lantern orange will be a breeze.
On the other hand, if a blossom had only recently developed into a fruit before a tragic pruning accident, the small, unripe gourd in your hand is never going to fully ripen. Nature has its limits. The key here is to determine to the best of your ability where exactly the line is.
There is not always an exact answer. However, you have a pretty good shot at guessing whether or not ripening will be successful or if it’s simply too early.
- If the fruits hadn’t even yet reached their full size, then it’s too early. They’re not going to ripen. Toss them in the compost pile.
- If the fruits reached their full size and began to change color, then you should be in the clear. They will likely ripen for you.
- If the fruits reached their full size but hadn’t really begun to change color, it’s a toss up. This could go either way. It’s worth a shot to see if they’ll ripen, but it’s far from guaranteed.
At this point, you should have a decent idea about your pumpkin’s ripening viability. Now let’s discuss the next steps.
Clean Up the Pumpkin
We often retrieve pumpkins from the garden to find them covered in soil and maybe even a few slugs. It’s important to clean the fruits before finding a spot for them to ripen. Use a clean cloth and lukewarm water to wipe any debris away.
Make sure your fruits are clean and dry. Otherwise, you can be promoting the spread of fungal disease, which is the last thing you want to do, especially if you decide to ripen and store the pumpkins in your greenhouse or in your home.
If the reason you’re trying to ripen fruits that were picked too early is that their host plants were struggling with disease, then cleaning is more important than ever. If the plants had powdery mildew, try spritzing the pumpkins with a drop of hydrogen peroxide diluted in water.
Find a Warm Spot
Despite the fact that healthy, still-growing gourds are usually in outdoor, autumnal temperatures—harvested, unripe gourds actually prefer heat. The ideal temperature range is between 80 and 85°F (27-29°C), and they’ll do best in high humidity, too, about 80 percent.
This makes a greenhouse the ideal spot for ripening. A greenhouse is probably warmer than your house, and it probably has higher humidity. Note that fungal disease spread can be a problem in greenhouses, so if you store your pumpkins there, provide good air circulation. Don’t pile them up in a corner.
If you don’t have a greenhouse, the next warmest spot may indeed be your home in a window. While temperatures in the 80s are ideal, room temperature (around 70°F or 21°C) can get the job done as well. What’s key here is to keep the pumpkins warm. A sunny room with a humidifier would be the best location possible.
Depending on the time of year and your climate, you may even want to keep them outside. If it’s still pretty hot outside and you harvested early for disease reasons, then the great outdoors may be your best bet. Consider whether your home or your backyard will be warmer, and place your unripe pumpkins in the warmest location.
Wherever you choose, note that night temperatures should not drop below 60°F (16°C), which will make it difficult for the fruits to ripen fully.
Aim For the Sun
So now you have your spot, whether it’s in a greenhouse, a sunny window, or on the side of your house. Pumpkins will ripen fastest on the side that gets the most sun, so it’s important to rotate them.
If your fruits are in a window or on the side of your house, rotation will be key. Place them in such a way that the greenest part faces the sun initially. Then, every couple of days, rotate them so that a different side faces the sun.
Over time, you should see uniform ripening if you’re rotating regularly. After a week or two, if yours aren’t getting any more orange, then they may have been too young. These gourds will make a great addition to your compost pile, and their seeds may even germinate unexpectedly next year.
The process can take several weeks, but once you start seeing the change, it will inspire you to remain patient. Even though you had to harvest early, you got your pumpkins to ripen anyway. Success!
Cure For a Longer Shelf Life
Curing is crucial, especially if you’re hoping to store your pumpkins for a while. Whether you intend to keep them in the basement for winter nourishment, keep them on your front porch until Thanksgiving, or at least keep them in good shape until Halloween night, you need to give them time to cure.
The curing process itself takes about one to two weeks. You should now move pumpkins to a much cooler, dryer place. The high temperatures and high humidity that helped them ripen are now too much for curing. Avoid these locations. Instead, a cool basement or similar location between 50 and 60°F is ideal (10-16°C). Anything lower than 50°F might be too chilly.
During this time, the skin will harden. Small wounds and nicks in the skin will heal. Any final ripening will take place. Now your pumpkin is ready. It may survive for two to three months without decay, assuming it’s cured properly.
(Carved jack-o-lanterns have a much shorter shelf life of about five days to two weeks. They will last longer if you cured them properly before carving.)
Prepare for Next Year
With this year’s growing season getting smaller in the rearview mirror, now is a great time to make note of lessons learned for next year.
If you started seeds too late and your harvests weren’t ready before the first frost, make note of that. It will be easy to forget again next spring if you haven’t recorded any of these mishaps in a journal or in a note-taking app.
You could start a wish list of cultivars that have a shorter growing window for next year, such as ‘Black Kat,’ which can produce mature fruit in as little as 75 days, or ‘Jack Be Little,’ which should take about 80 days.
If you hope to grow something classic, like the ‘Jack O’Lantern’ cultivar, you’ll need a season that lasts at least 105 days, so start as early as necessary next year. And if you aim to grow huge pumpkins, like ‘Big Max’ or ‘Atlantic Giant,’ you will need four months and the foresight to prepare for it, starting now.
Similarly, if your plants came down with a dreadful case of downy mildew, take notes. Research the malady that forced you to harvest early so that you know how to prevent it from happening again.
For example, you can prevent downy mildew from spreading aggressively by providing more air circulation between plants and always watering at the soil line instead of spraying the leaves. You can do the math now to see how much space your plants will need, and you can look into setting up drip tape irrigation.
Next spring, you’ll be empowered to start seeds and grow pumpkins once again, and hopefully, they’ll get to ripen on the vine.
