What's The Deal With The Black Seeds On The Inside Of Tomatoes?

Whether you prefer to puree your tomatoes into a warm tomato soup or slice them up for a cool caprese salad, the tomato is one of nature's sweet gifts — especially if you enjoy the vibrant nightshades at their freshest, in those warm spring and summer months when these tender, sun-loving plants thrive. 

Cut into a plump, ripe tomato and you'll notice tiny seeds dispersed throughout its uniquely textured flesh. Most of the time, those seeds will have a yellow or greenish hue; as their natural color, this generally means the tomato is healthy. But occasionally, you'll slice into a tomato and find dark brown or black seeds contrasted against the red pulp of the fruit. That's usually an indicator that something's up.

So what's the deal with those darkened seeds? There are two main causes of black tomato seeds: One has to do with the way the fruit matures, the other with the way the plant is cared for.

Most likely, the reason a tomato has black seeds is simply a case of over-ripening. The more a tomato ripens, the more its hormone levels and moisture content encourages the seeds to germinate inside the fruit. So the darkened shade of seeds is typically a sign that they are in prime condition to sprout and reproduce. Alternatively, if a tomato falls or is picked off too early, because it's detached from the plant, the fruit may not have what it needs to grow properly. This often results in an irregular, darkened color of its seeds.

The other reason for black seeds inside your tomato goes back to how healthy the actual plant is and how well it was cared for. Many tomatoes fall victim to a disease called blossom end rot, which causes a dark spot at the bottom of the fruit that can rot and affect the seeds inside. This is usually a result of improper watering or a lack of calcium. Other contributors to dark seeds can be an imbalance in pH levels, a lack of fertilization, or exposure to cold weather.

The good news is that whatever the cause may be, there's no reason to worry if you find black seeds in your tomato. While darkened seeds aren't natural, they're not necessarily harmful either. A good rule of thumb when it comes to black seeds is that as long as the tomato isn't moldy or emitting an odor and it seems otherwise normal aside from its seeds, it's generally safe to eat.

In the case of an overripe tomato, you'll notice the tomato is much softer and more difficult to cut through, and its texture might be mushier than usual. But it's still perfectly healthy to consume, and many people even prefer their tomatoes extra ripe. If it was cut off from its plant too early, again, the tomato may seem a little off, but eating it won't cause you any harm.

The same is true for the harvesting issues that can cause darkened tomato seeds, whether the plant was insufficiently watered or fertilized, or even if it developed blossom end rot (which sounds scary and seems unappetizing). You can always remove the black seeds or any darkened part of the flesh, but as long as there aren't any other concerning characteristics, don't let those black seeds stop you from enjoying a juicy tomato.