Why Are Your Squash Plants Rotting at the Base?

It’s very sad to see your squash rotting on the bottom after pouring a lot of care and effort into growing them. This problem is prevalent among squash, eggplants, and tomatoes, and there are a few possible causes as to why it happens.

Squash rot at the base when they don’t receive enough calcium, the plant is stressed, or the soil conditions are too acidic. This reaction is known as blossom end rot, and it’s not a disease but rather a response to the plant not getting the nutrients it needs, so it can’t spread among your plants.

In this article, I’ll discuss what causes blossom end rot in more detail, so you can learn how to prevent it from happening with your plants.

What Is Blossom End Rot?

Blossom end rot is a disorder that can appear in some fruits and vegetables, including squash. It gets its name from the rot occurring at the blossom end of partially developed produce. The affected produce will spoil quickly, and the yield will significantly reduce if you don’t change the plant’s conditions.

Blossom end rot starts as bruises on the bottom of your squash. As time passes, the bruises darken and sink in, then spread across the base of the produce. It also slows the growth of the squash so that it won’t reach a decent size.

Rotting can also happen just inside of the squash. For instance, it looks fine outside, but you cut into it and see that the bottom interior is rotting. Bacteria, pests, and fungi can enter the rotted sections, so you shouldn’t eat them.

Overall, blossom end rot isn’t a disease that can spread to your other plants. It’s a reaction that stems from issues in the soil that cause stress. You’ll want to correct these problems as soon as possible, so your plant can return to producing healthy squash.

How To Identify Blossom End Rot

You should know how to identify this problem to remove the affected squash immediately. While it can’t spread to the rest of your squash, leaving produce with blossom end rot on the vine allows the rotting squash to keep taking nutrients from the plant.

Blossom end rot happens on the squash’s side opposite the stem. You’ll notice it appears on partially developed fruits as a wet, small bruise or water stain before it expands. Eventually, the spoiled area will cover most of the bottom of the squash. The site rots away, causing a black dent to form there.

Unfortunately, it’s challenging to spot blossom end rot before it starts just by looking at your growing squash. You’ll need to test the soil often so you can make adjustments if needed.

Leading Causes of Blossom End Rot in Squash

There are different causes of blossom end rot in squash. Most of the time, the plant doesn’t have access to calcium or is too stressed to absorb nutrients properly. Here’s a quick breakdown of these common issues:

  • The soil doesn’t have enough calcium. When there’s not enough of this nutrient in the ground, the squash starts to break down.
  • The plant is stressed. Stress to the plant from poor weather conditions, over or under-watering the soil, and temperature can cause it to react with blossom end rot. 
  • The soil is too acidic. Plants struggle to absorb nutrients, including calcium, in soil that’s too acidic. So, while the calcium may be there, the plant can’t take it in, leading to rot.

You can perform tests on the soil to see what’s causing this reaction in your squash. I recommend using the Garden Tutor Soil Test Kit from Amazon.com to check your soil’s pH. You receive 100 test strips and get accurate results in just one minute, making them easy to use when adjusting your soil’s pH levels.

Squash prefers to live in soil that has a pH between 6.0 and 6.8. You can lower the pH using lime and raise it using peat moss.

For testing calcium accurately, you’ll often need to go through professionals by sending a sample of your soil to a lab. You can also try using a calcium meter, such as the LAQUAtwin, which measures calcium ion levels.

Does Blossom End Rot Affect the Whole Plant? 

Blossom end rot can affect the whole plant since it happens when it doesn’t receive enough calcium. However, you might notice it only on some of your squash since the plant might have the nutrients to supply some of its growth with enough calcium, but not all of them.

So, if you see blossom end rot on your squash, you don’t need to remove the entire plant from your garden. It’s better to remove the affected produce and then start working on changing the garden’s soil. In doing so, you can stop blossom end rot from impacting the next round of growing squash.

While blossom end rot can affect a whole plant, making adjustments as soon as possible saves the next crop. 

How To Prevent Squash Blossom End Rot

The best way to prevent squash blossom end rot is by adding more calcium to the soil. If you make your own compost, you’ll want to include eggshells since they can deposit good amounts of calcium. You can also buy plenty of fertilizer products that offer this nutrient.

If you think overwatering might be the cause; you can move your squash to a fabric pot. The fabric provides more aeration to the soil, helping to dry the roots. Plus, you can move the squash inside if there are harsh weather conditions that could cause stress to the plant.

Lastly, you’ll need to test the pH of the soil and make changes if it’s too acidic. You can use lime to do this.

Can You Stop Blossom End Rot Once It Starts?

Unfortunately, you can’t stop blossom end rot once it starts. You’ll want to remove the affected fruits or vegetables, then correct the soil conditions so the plant will grow the next batch without issue.

To do this, you must ensure your garden soil has enough calcium, weather conditions aren’t stressing the plants, and the earth isn’t too acidic. While it sounds like a lot, your squash will thrive after you make these adjustments.

Removing the affected food is essential too. Leaving the squash on the vine lets it continue to take moisture and calcium from the plant, which can cause new growth to also have blossom end rot. Taking the affected produce away allows the plant to focus its nutrient distribution on incoming growth instead, which is helpful after you add more calcium to the soil.

So, when it comes to squash rotting at the bottom, prevention is key! You can’t stop it once it starts, and the produce will spoil quickly.

Does Miracle-Gro Help Blossom End Rot? 

Miracle-Gro can help prevent future blossom end rot in your squash, as long as you use a product that contains enough calcium. However, you shouldn’t use it unless you test your soil and the result shows a significant calcium deficiency. 

As mentioned above, once a squash starts to rot on the bottom, there’s no way to stop it. You shouldn’t expect a calcium-rich fertilizer to reverse blossom end rot. However, adding it to your soil can prevent it from happening again.

You also don’t want to over-fertilize your plants, but occasionally offering Miracle-Gro before a harvest could benefit your squash.

Lastly, Miracle-Gro is an efficient way to put more nutrients in acidic soil. It doesn’t lower the pH but makes essential nutrients more available, allowing your squash to absorb them better, even in acidic conditions.

Does a Fungus Cause Blossom End Rot?

When you see blossom end rot on your squash, it’s easy to confuse it for a fungal attack on your plants. However, blossom end rot isn’t caused by outside forces, including bacteria, pests, or fungi. Instead, it’s an internal reaction your squash plants have when their living conditions aren’t suitable for them.

Most of the time, that means the plant is very stressed from the weather or watering it receives, as well as not being able to access enough nutrients from the soil. In short, blossom end rot is not a fungus, despite it looking very similar to one.

That said, a squash rotting at the bottom is more susceptible to attacks from bacteria, pests, and fungi. So, while the damage starts with blossom end rot, it could also lead to damage from a fungus soon enough.

Powdery mildew is another common disease that affects squash plants. If you see the symptoms, you should deal with them very soon. But how? Read my guide to learn more about it: How to Deal With Powdery Mildew on Squash


To summarize, when squash rot at their base, this is known as blossom end rot. It happens when your plant can’t absorb enough calcium from the soil, whether there’s not enough calcium or the soil conditions prevent the roots from taking it in.

Once you understand the causes of blossom end rot, you can prevent it by adding more nutrients to the soil and changing the pH level. You should always test your garden soil with a pH kit before making any adjustments.

Alexander Picot

Alexander Picot is the principal creator of TheGrowingLeaf.com, a website dedicated to gardening tips. Inspired by his mother’s love of gardening, Alex has a passion for taking care of plants and turning backyards into feel-good places and loves to share his experience with the rest of the world.

Recent Posts