Reasons behind a hollow heart cucumber.

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Why Do My Cucumbers Have Holes In The Middle? 

Cucumbers are a popular crop for home gardeners. They are a delicious addition to salads and are ideal for home canners who enjoy pickles and relishes.

Even the cucumbers that look amazing on the outside when you harvest them, might have internal problems you don’t see until you cut into them.

If you have ever cut into a fresh picked cucumber and noticed it has holes in the middle you probably have a lot of questions. 

The first question you’re going to ask is why do my cucumbers have holes in the middle?

These holes, more commonly referred to as a hollow heart, is a common problem in cucumbers resulting from a growth defect.

There are a few reasons researchers have identified as the culprit behind hollow centered cucumbers. These include inadequate pollination, reduced seed set, boron or calcium deficiencies, excessive nitrogen, irregular watering, and rapid growth rates.  

These issues shouldn’t stop you from trying cucumbers when you are planning your garden. Read on to learn even more about these holes in the middle of your cucumbers.  

What Causes Holes In The Middle Of My Cucumber? 

I have sliced into a fresh pick cucumber but notice a hole in the middle.

This issue, commonly called hollow heart, happens to even experienced gardeners. 

Hollow hearts even happen in controlled environments, like greenhouses, when all conditions are easily maintained. Cucumbers aren’t the only commonly grown garden plant to develop hollow hearts either.

You might find this happening in melons and also summer and fall squash.  

Here are reasons of hallow heart fruits

  1. Inadequate or poor pollination
  2. Rapid growth
  3. Nutrient Deficiency
  4. Irregular Watering

  • Poor Pollination– Research has identified a few reasons for the hollow centers in your cucumbers and other plants in your garden.

    The hollow heart has sometimes been found to start from the very beginning of the development of the fruit, with inadequate pollination and a reduced seed set.   
  • The rapid growth of the cucumber fruit is a major reason for the hollow heart. A rapid growth, where the fruit grows too quickly and the development of the seeds cannot keep up, is caused by several things.

    Some of these factors you will have control over, while others might be difficult to prevent.

    From the weather and temperature to water levels, and light quality and amount, rapid growth happens to all growers.  
  • Poor Nutrition can also cause a hollow cucumber, Nutrients are so important for the healthy development of any plant, and cucumbers that are deficient or have excessive amounts of what they need may have rapid growth and develop a hollow heart.

    Studies have identified deficiencies in calcium and boron as a likely reason for the hollow centers of the cucumbers. While boron is not needed in high amounts, the plant does need it as they form cells and seeds in the fruit.  

    Excessive nitrogen is another reason for improper growth rates. With too much nitrogen, the interior growth of the fruit won’t be able to keep up with the growth of the plant.

    This means it won’t be able to fully develop the interior seeds you find in cucumbers. With this poor development, those holes will develop.  
  • Irregular watering has also been identified as an issue leading to those holes in the middle of cucumbers. These plants need regular and adequate amounts of water to survive and produce fruit.

    This is especially important just after pollination during the fruit set and into the development of the cucumber.

    While they do need water, too much is just as disastrous for the plant. While the cucumber fruit is developing, excessive water may cause excessive growth leading to hollow heart.  

How To Prevent Holes In The Middle Of Your Cucumbers 

While you definitely won’t be able to completely eliminate this problem form your gardens and cucumber plants, there are some things you can do to reduce the likelihood of it happening and increase the quality of your harvest.  

Try to maintain a watering schedule and make sure you are flexible with it.

Excessive watering will likely wash away nutrients the plants need and it also causes that excessive growth we talked about before. Monitor the ground around your plants to ensure they have some water, but not too much.

They need at minimum about one inch per week for proper growth. If you have a large rainfall, you might not need to water, but during a drought, break out that hose, because too little water will hurt the whole plant.  

Check your soil for nutrients, making sure it is the right pH and contains the very important nutrients they need like calcium, boron and nitrogen.  

When you have your plants outside, maintaining an ideal temperature is going to be a challenge. When it comes to improper pollination, there is little you can do to prevent hollow heart.

Try to focus on the elements you can control, like water levels and nutrients, and don’t focus on those you can’t. Doing so will help reduce the occurrence of those holes in the middle of your cucumbers. 

Cucumber Hollow In Middle. Hollow Heart Cucumbers

Are Hollow Cucumbers Edible? 

There is nothing more frustrating than putting in all the work to grow and nurture a plant, watch the fruit develop and find, upon harvest, it is inedible. Luckily with hollow cucumbers, this is not the case and you won’t have to toss them in the trash or on your compost pile.  

Cucumbers with hollow heart are edible, and not dangerous to people in any way. However, you might find cucumbers with this issue may taste a little bitter.

You can also still use them in your pickling and relish making. Whether you are canning or doing refrigerator pickles, they are still safe to use.

We do not recommend using them when making crock or fermented pickles, instead, save these hollow cucumbers for relishes or chunk style pickles. Hollow cucumbers often lead to improper fermentation if you attempt to use them. 

Identifying Hollow Cucumbers Prior To Slicing 

Hollow cucumbers do not have to be tossed out completely, but it is startling to cut into one and find those holes.

If you are making whole pickles you won’t want to cut into your cucumbers before pickling. Luckily, you don’t have to cut into every cucumber in order to identify those with a hollow heart. 

There is an easy trick to identify those hollow cucumbers. Cucumbers with holes in the middle will float when placed in water. Cucumbers that have properly developed will sink.

When you are washing your cucumbers, fill up the sink with water and any you see floating to the top will be hollow. Pull these for use in relishes or chunk type pickles rather than in making fermented or crock spears, slices or whole pickles.  


Opening up a-cucumber to find it hollow might be a little jarring, but it is a common problem for gardeners. Even those with a lifetime of experience and all the best tools.

Hollow heart is found in cucumbers, and also melons and squashes, and while you can’t always prevent it, there are things you can to to minimize the problem.  

Between reduced pollination and seed set, to nutrient deficiencies, irregular watering and rapid growth, there are many ways for these holes to develop in the middle of your cucumbers. While you can work to reduce the chances, this issue is difficult to prevent completely.

Luckily, the cucumbers do not have to be tossed into the trash and can still be used in recipes and as a snack. With the tips in this article, you should be able to minimize the development of hollow heart and increase the quality of your yearly yield.