Rotten blackberries

In this brief guide, we will shed light on “what is the cause of rotten blackberries?”. We will further talk about how to store blackberries, how long do blackberries last and how to tell if blackberries have gone bad.

What is the cause of rotten blackberries?

Botrytis cinerea is the cause of rotten blackberries. It is a fungus that produces gray mold and can destroy almost every portion of the plant. 

However, Botrytis cinerea is not the only cause of rotten blackberries. Penicillium also causes blackberries to rot. It produces green mold with white undertones. Penicillium starts by affecting the surface of the blackberries. 

At first, small spots will develop which ultimately grow into bigger spots of rot. The white fuzzy growth occurs at the end of the rot, causing the texture of the whole blackberry to get very mushy. 

Penicillium thrives in warm, moist conditions in temperatures between 65-85℉. It grows more commonly in ripened blackberries. 

It can enter the berry from any sort of damage. Quite often, it happens because of harvesting and packaging, which turns perfect blackberries into rotting blackberries in their containers. 

How to safely store blackberries?

Just as you reach home with the blackberries, look out all of them and toss the blackberries that have mold or are damaged. Fungi can rapidly spread in blackberries, any one or two rotten blackberries can eventually destroy half of the pack the next morning you see them.

Avoid washing the blackberries until you intend to eat them. Move them in a shallow sieve and wash them under tap water with care. This is the safest thing to do. But if you like to keep blackberries prepared, you can rinse them, but ensure to properly dry them before storing them.

To store blackberries in the refrigerator, consider the following things:

  • Ensure the container is well ventilated so that the moistness can escape.
  • Avoid crushing the blackberries as they are delicate and can easily get damaged. For their protection, they must be kept in a container.
  • To store blackberries for a longer period, you can either keep them in a freezer or use them for making jam. 

How to dry-freeze blackberries?

After emptying the water, leave the blackberries on paper towels for a minimum of 15-30 mins. Afterwards, pat them dry. 

Set the blackberries in one layer over a baking sheet, so that they do not touch each other. Place them in the freezer, and wait until frozen.

Put the frozen blackberries in packets. If you use a freezer packet, make sure to draw as much air as practicable before packing it. 

Place the packaged frozen blackberries again in the freezer.

Frozen blackberries are best used in almost 6-8 months, but they should remain safe considering their quality for a more prolonged period.

To thaw the blackberries, it can be done overnight in the refrigerator, or lukewarm water in case you have less time. As an alternative, if you are adding the blackberries to a smoothie, or cooking them in an oven, you can neglect to defrost, no matter what.

How long do blackberries last?

Blackberries last almost 1-2 days at room temperature. If the weather is hot and you leave them out for a night, some of them will likely be rotten.

If you keep them in a refrigerator and observe all the safety guidelines mentioned, they can last up to 7 days. That, obviously, relies on their quality, when they were picked, and their storage duration before you brought them home. 

In general, it is safer to consume them within 3-5 days to have the best quality and barely rotten blackberries.

Blackberries1 – 2 days4 – 7 days

How to tell if blackberries have gone bad?

Fresh blackberries are bluish to blackish, relatively even in color, and juicy-looking. They are soft and not mushy.

Slowly, their color fades and a few of their bulbs are not juicy-looking anymore. They also get very mushy. Such blackberries, though not having the best quality, are still fine for eating. Or adding in a smoothie, a fruit salad, or making jam with.

Regarding the blackberries that certainly need to be tossed out, examine these signs:

Mold. Any indications of mold mean the blackberries are not safe to eat.

Slimy, lacking juicy, or damaged. If it feels like the bulbs have no juice in them, or the blackberries got damaged along the way, toss them out.

Off smell. Sniff the blackberries, if they give a bad odor, toss them out.

Other FAQs about Black berries that you may be interested in.

Can you eat blackberries whole? (+3 health risks)

How to tell if blackberries are bad? (3 Ways to tell)

How long does it take for blackberries to grow?


In this brief guide, we have shed light on “what is the cause of rotten blackberries?”. We have further talked about how to store blackberries, how long do blackberries last and how to tell if blackberries have gone bad.


Hi, I am Charlotte, I love cooking and in my previous life, I was a chef. I bring some of my experience to the recipes on this hub and answer your food questions.