Why Your Small Squash Fruits Are Rotting on the Vine (and How to Fix It)
Rotting squash fruits are not what you want to see on your garden walks. Maybe they’re falling off before the flowers open, or they’re growing a little then dying off. No matter the problem, we’ll figure out what’s going on and learn how to fix it.
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Rotting squash is hard to deal with. You expect a lush harvest, only to find small squash fruits with yellowing ends! Squash vines can be finicky when they don’t have the conditions they need to thrive.
This condition isn’t contagious, as it’s a physical response the plant is having towards the environment. The vine struggles to move the nutrients it needs towards its fruits. Don’t worry, as there are a few ways to fix this.
Whether you’re growing zucchini, summer squash, or winter squash, this condition can affect your vines. Learn first what’s going on when squash is rotting, then discover ways to correct the problem.
Hint: It’s One of Two Things!
Squashes falling off before they’re ripe is likely due to one of two reasons: blossom end rot or poor pollination. Both can affect squash vines in gardens across the U.S. Poor pollination is common in cold and stormy gardens, while blossom end rot has a range of causes.
Poor Pollination
A lack of pollen entering the female squash blossoms occurs when pollinators are lacking in the garden. Cold weather, rainy storms, and winds can prevent pollinators from entering gardens. The squash flowers fade before they receive the pollen they need.
If the issue is poor pollination, the fruits will quickly rot and fall off. They won’t grow and then rot; they’ll turn yellow and fall off.
If pollinators aren’t frequenting the site, you can use a paintbrush to hand-pollinate the blossoms. Dip the brush in a male flower’s pollen, then transfer the pollen to the female flowers. The female squash blossoms have mini squashes behind them, while the males do not.
Blossom End Rot
Blossom end rot is the likely culprit when squash is rotting. This affliction is common in areas without consistent moisture, though a range of things can cause it. It’s due to the squash vine being unable to move calcium into its fruits.
In a healthy plant, the stems use moisture to transport nutrients from the leaves and roots to the rest of the plant. When there’s not enough moisture or calcium, then the squash plants are unable to move nutrients into their fruits.
The fruits may swell and enlarge at first. Then, you’ll notice a brown, ugly spot on their rear. The spots will spread and enlarge. It’s best to cut them off and let the others ripen.
It Could Also Be…
More often than not, calcium struggles to move because of other factors. Droughts, frosts, excessive moisture, and root disturbance can cause it. Give your small squashes what they need when they’re young to avoid squash rotting.
Extreme Heat
Summer droughts are harsh on plants. Most squashes rely on irrigation to thrive, and occasionally the irrigation doesn’t penetrate deep enough. Sprinklers may not hit the roots sufficiently, and hand watering may not be enough to satisfy thirsty squash plants.
The heat grows unbearable over a certain temperature, and it can affect the fruit quality. Heat is more often an issue when it’s coupled with low or insufficient irrigation. Water your squashes well to protect them from extreme droughts.
Early and Late Frosts
Opposite extreme heat waves are extreme frosts, and they too aren’t good for squash fruits. They cause ripening fruits to turn mushy, and they’ll exacerbate end rot issues. Calcium will struggle to move into ripening squashes and zucchinis.
Frosts are best avoided by planting squash seeds at the right time. Sow them in spring when the sun warms the soil, a week or two after your last average frost date.
Overfertilizing
Too many and not enough nutrients can harm ripening fruits, causing squash to start rotting. Too much nitrogen early in the growing season causes excessive leafy growth at the expense of flowers and fruits. The stems cannot sustain the fruits while they’re growing the extra leaves.
Not enough fertilizer may also be the issue, though this is rare. It’s most likely due to an extraneous factor that’s preventing the squash roots from taking in calcium.
Disturbances
Root disturbance is another likely cause. If the stems are damaged or severed, the squash plants will struggle to transport nutrients. They’ll likely suffer from leaf loss and blossom drop before the fruits can ripen.
Disturbance is common for container plants and those growing in cramped conditions. Other roots can grow into the squashes’ root zones and affect their ability to transport nutrients and water.
Animal disturbance is another way the roots struggle. Moles, voles, or other rodents may tunnel below the squash and affect the root zone.
How to Fix It
Solve poor pollination with hand pollination. For end rot, the problem is a tad trickier. First, find out what’s causing your squash rotting issue, then correct the problem.
Regular Moisture
The most common cause of end rot is a lack of adequate moisture. Roots struggle to transport water, and nutrients fail to move as a result. The solution is regular irrigation that reaches the roots.
To see if you’re watering enough, stick a stick deep into the ground. If it comes up dry a few inches down, you’re likely not watering for enough time.
Whether you use hand watering or automatic irrigation, ensure your squashes receive enough moisture during the growing season. Potted plants are especially prone to drying out, and they’ll need more water than in-ground specimens.
The pH
Some soils have an insufficient pH for growing squash. Too low or too high a pH prevents nutrients from moving from the soil into the roots. Even though tons of calcium may be present, the roots will be unable to pull it up.
An acidic pH below 5.5 is not ideal for the roots. The plants will struggle as they’re unable to take in calcium, among other nutrients.
Use a soil test to verify the pH of your garden’s soil. Then, use amendments this fall or spring to make the soil more alkaline. Shifting the pH takes many weeks, and it’s difficult to fix for squash plants already growing. Add lime to raise the pH, and sulfur to lower it.
Protection
Protect your squashes! Whether you’re dealing with pests or the weather, there are ways to ensure your plants stay secure through challenging times.
For frost and pest protection, use row cover. It’s a lightweight fabric that covers plants and traps heat. It also protects them against flying insects that land on the leaves, like vine borers and beetles.
Guard against root disturbance by growing squashes in raised beds or planters. The wooden base will prevent burrowing critters from entering.
Key Takeaways
- Regular watering is key to preventing rotting squash.
- Though calcium deficiencies often cause rotting squash, the lack of calcium can be due to a range of different factors.
- Poor pollination occasionally causes rotting squash. Solve it by hand-pollinating the flowers.
- Use a soil test to determine how poor or rich your garden’s soil is. Then, use amendments to get it where it needs to be.
