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Your squash blossoms are rotting because of a combination of moisture, poor pollination, and environmental stress that causes the blossoms to break down before they can set fruit.
If you’ve been asking yourself “why are my squash blossoms rotting,” you’re definitely not alone, because this is one of the most common frustrations for gardeners growing zucchini, pumpkins, and other squash varieties.
The good news is that squash blossoms rotting is usually fixable once you understand what’s causing it.
In this post, we’ll take a closer look at why your squash blossoms are rotting, what you can do to stop it, and how to keep your plants healthy so you actually get a harvest.
Let’s dig in.
Why Your Squash Blossoms Are Rotting
Squash blossoms rot for several reasons, and identifying the culprit is the first step to saving your crop.
Here are the main causes behind why your squash blossoms are rotting:
1. Blossom End Rot From Calcium Deficiency
One of the biggest reasons squash blossoms rot is blossom end rot, which happens when the plant can’t take up enough calcium.
This isn’t always because your soil lacks calcium, though.
More often, it’s because inconsistent watering prevents the plant from absorbing calcium properly.
When squash blossoms rot from this issue, you’ll notice a dark, sunken, leathery spot at the blossom end of the fruit, and the flower itself may shrivel and decay.
The fix is to water deeply and consistently, and consider adding a calcium-rich amendment like gypsum or crushed eggshells to your soil.
2. Poor Pollination Leads to Rotting Blossoms
If your squash blossoms are rotting and dropping off without producing fruit, poor pollination is likely the problem.
Squash plants produce separate male and female flowers, and if pollen doesn’t make it from the male to the female blossom, the flower will wither and rot instead of developing into a fruit.
This happens a lot early in the season when bee activity is low, or during rainy stretches when pollinators stay away.
You can hand-pollinate by picking a male blossom, removing its petals, and gently brushing its pollen onto the stigma of a female flower.
3. Too Much Moisture and Humidity
Excess moisture is another major reason why squash blossoms rot.
Squash blossoms are delicate, and when they stay wet for long periods, they become a breeding ground for fungal diseases and bacteria.
Overhead watering, heavy rain, and poor air circulation all contribute to squash blossoms rotting before they can open fully.
To prevent this, water at the base of the plant instead of over the leaves and flowers, and give your plants enough space so air can move freely between them.
4. Fungal and Bacterial Infections
Sometimes squash blossoms rot because of pathogens like fusarium, verticillium, or bacterial wilt.
These infections often start in the soil and work their way up the plant, causing blossoms to turn mushy, brown, or black.
If you notice other symptoms like wilting leaves or discolored stems, your squash blossoms rotting could be a sign of a bigger disease problem.
Remove and destroy affected blossoms and plant debris, and rotate your crops each season to keep pathogens from building up in the soil.
How to Stop Squash Blossoms From Rotting
Now that you know why squash blossoms rot, here’s how to stop it.
1. Water Consistently at the Base
Keep the soil evenly moist but not soggy, and always water at the base of the plant.
This keeps blossoms dry and reduces the chance of them rotting.
2. Improve Airflow and Spacing
Give your squash plants room to breathe.
Proper spacing improves airflow, which helps prevent the humid conditions that cause squash blossoms to rot.
3. Hand-Pollinate for Better Fruit Set
If pollinators are scarce, hand-pollinating ensures your female blossoms get the pollen they need so they don’t rot and drop.
4. Remove Rotting Blossoms Promptly
Pick off any blossoms that are already rotting so they don’t spread disease to healthy flowers and fruit.
5. Feed Your Plants Balanced Nutrients
Avoid over-fertilizing with nitrogen, which promotes leafy growth at the expense of flowers.
A balanced fertilizer with adequate calcium supports healthy blossoms and fruit development.
So, Why Are My Squash Blossoms Rotting?
Your squash blossoms are rotting because of moisture, poor pollination, calcium issues, or disease, and often it’s a mix of these factors working together.
The good news is that squash blossoms rotting is usually preventable with consistent watering, better airflow, hand-pollination, and prompt removal of affected flowers.
Once you address these issues, your squash plants should start producing healthy blossoms and plenty of fruit.
Happy gardening.