Does the fruit of squash and pumpkins need light to complete its ripening process? Should you remove leaves so that sun can get to the fruit to speed up ripening? If pumpkins are picked green, should they be left in sunshine or not?
Key Takeaways
- Most answers in Google on this topic and many other gardening topics is wrong.
- Sunlight is not required to ripen fruit.
Gardeners vs Science
I did a Google search to answer the question, do squash and pumpkins need sun to ripen. What surprised me was the disparity between sources. It tells us a lot about using the internet.
I asked Google this question: “Do pumpkins need sunlight to ripen?”
Starting at the top recommendation I checked to see if the suggested source provided an answer to the question. If it did, I recorded the answer in the table below. I ignored any suggestion from an educational institution.
The top seven sources that met the above criteria all said pumpkins need sunlight to ripen.
| Source | What they said | do pumpkins need sun to ripen? |
|---|---|---|
| ask PHS | Pumpkins need sunlight and warmth to ripen | Yes |
| Rootsy | need air and sunlight to ripen | Yes |
| Haxnicks | Make sure that the sun gets to the whole pumpkin | Yes |
| Local food connect | ripen it by exposing it to the sun | Yes |
| Gardeners path | need to find a warm, sunny, dry spot | Yes |
| Garden Know How | Pumpkins need sunlight and warmth to ripen | Yes |
| Pumpkin nook | ripening process requires sunlight | Yes |
I then asked Google this question: “Do pumpkins need sunlight to ripen? site:.edu”
Note that it is the same question but I have added “site:.edu” at the end. This tells Google to only provide selections from websites that have an edu extension. These are mostly educational sites, with a strong bias towards American universities and their extension offices.
The top 5 links said no, pumpkins do not need sunlight to ripen. The sixth answer is not quite so clear and I marked it as a maybe. In most cases the answer does not actually state that they don’t need sun, but they imply it by their suggested method of ripening fruit.
| Source | What they said | do pumpkins need sun to ripen? |
|---|---|---|
| Cornell U. | if the vines die back, damage to the fruit from sun, disease and insects is more likely | No |
| U. of Vermont | After picking your pumpkins and winter squash, place them in a warm, dry and ventilated place, such as a covered or sun porch, garage or shed | No |
| U. of Main | I would not generally recommend trimming leaves | No |
| U. of Massachusetts | pumpkins can be ripened in a well-ventilated barn | No |
| Michigan State | Getting them out of the field and into a dry, somewhat shady area will allow for curing without as much risk for sunburn | No |
| U. of Minnesota | field-cure them in place for a week or two in dry, sunny weather | Maybe? |
Why is there such a discrepancy in answers?
I have been looking at garden myths for many years and one thing has become clear. Garden websites tend to copy their information from other garden sites and almost never check their facts. Their goal is to produce content and they don’t really care about providing correct information. If they did care, they could have easily done what I did above.
Learn to use Google correctly.
When is a Pumpkin or Squash Mature?
Botanically speaking, fruits are mature when seeds are viable. These fruits are mature when they start turning color and as the color develops seeds take on more oils as they move towards dormancy.
When the fruit is removed from the vine they are still physiologically alive and continue their internal chemical processes. As they develop their full color, their taste and their ability to store also improves. Along with a color change, the skin hardens, which is partially responsible for increasing storage life.
This post harvest process is called curing. It is best done by elevating storage temperatures to 75-86°F (24-30°C) with 75-80% relative humidity for about 5-10 days. After curing, the temperature and relative humidity should be reduced to 50-55°F (10-13°C) and 50-75%. Pumpkin and squash are sensitive to chilling and should not be stored below 50°F (10°C).
You will notice that there is no mention of the need for sunlight. In fact too much sunlight can damage the skin and should be avoided.
Pumpkins and Squash Do Need Sunlight
Let’s be clear about this. The plants need sunlight to grow and produce fruit. In fact they like all day sun.
That is not the same thing as needing sun to ripen fruit. Sun needs to reach leaves, but not the fruit. That is why they naturally hide the fruit under their leaves.
Should You Remove Leaves from Growing Plants
This is also common advice for growing plants. Remove some of the leaves so that “sun can get to the fruit to ripen it”. There is no basis for this advice.
You might have heard the same incorrect advice for cucumbers and tomatoes.
Removing leaves reduces photosynthesis, which reduces the plants ability to grow and develop fruit. It is never a good idea.
You can remove the growing tip of plants to keep them smaller, but don’t remove fully formed leaves. You can also remove small fruit or flowers if you want a smaller crop with larger fruits.
I don’t know whether to laugh or cry. I am not surprised at all by the results off your research. I AM dismayed by the results of your poll of “gardening websites.” Have those writers even kept a vegetable garden? I’ve watch my grandparents, parents and the commercial growers produce crops of squash and pumpkins. No one ever pruned the leaves of the plants…because that would be silly. Everyone knows the fruit needs nourishment and the leaves help with this! And I’ve been raising all kinds of squash and gourds and punkins’ all my life. Where do these ideas come from? And then they hit the internet and young gardeners believe the nonsense, share with other new gardeners and then ARGUE with us old-timers.
Keep up the good work! Continue with the crusade to inform and educate the gullible public. We who have learned from many sources, how to produce food from our gardens, thank you for your tireless efforts. Thank you so very much.
Many garden writers have not gardened or have very little experience in a garden.
I’ve seen youtube video’s of gardeners planting their squash and zucchini and then training the plants to grow vertically on a stake. As the plants grew, the gardeners would keep cutting the lower leaves off leaving the fruit open to the sun. Based on your research, is the aforementioned practice sensible to do, or are you describing something different?
What you describe makes no sense at all. Plants do not grow better with fewer leaves.
Pruning side branches may speed up the harvest of the first fruit, but it also decreases overall yield.
Robert,
As always, thanks for doing the groundwork for us! You are right about how gardening websites copy each other. Once I checked several websites for how to grow chayote squash, and about a third of them had the identical precaution, “Remember, you only need one,” inferring that they had experience to know that any chayote plant would be wildly successful. This did not prove true in my case.