Why Are My Cherry Tomatoes Black

If you’ve noticed dark or black areas on your cherry tomatoes, it’s a common and worrying sight for any gardener. Let’s figure out why are my cherry tomatoes black and what you can do about it. This discoloration is usually a sign of a specific problem, but the good news is that many causes are fixable with a few changes to your garden care.

The black color on your fruits can come from a few different sources. Some are related to environmental conditions and nutrition, while others are caused by diseases. Identifying the exact pattern and location of the blackening is the first key step to a solution.

1. Blossom End Rot: The Most Common Culprit

This is often the first thing gardeners think of, and for good reason. Blossom end rot (BER) starts as a small, water-soaked spot at the bottom (blossom end) of the tomato. It enlarges, turns dark brown or black, and becomes leathery. It’s not a disease but a physiological disorder.

Primary Cause: A calcium deficiency in the developing fruit. Importantly, this is usually not due to a lack of calcium in the soil. It’s caused by inconsistent watering, which disrupts the plant’s ability to take up calcium.

How to Fix Blossom End Rot:

Water Deeply and Consistently: Tomatoes need about 1-2 inches of water per week. Use a soaker hose or drip irrigation to keep soil moisture even. Avoid letting the soil dry out completely between waterings.
Mulch Heavily: Apply 2-3 inches of straw or wood chip mulch around plants. This regulates soil temperature and prevents rapid moisture loss.
Check Soil pH: Soil that is too acidic (low pH) can lock up calcium. A pH of 6.5-6.8 is ideal for tomato nutrient uptake. A simple soil test can tell you if you need to add garden lime.
Go Easy on Nitrogen Fertilizer: High nitrogen levels, especially from fast-acting synthetic fertilizers, can promote rapid leafy growth at the expense of fruit, worsening calcium uptake issues.

Remove affected fruits so the plant can redirect it’s energy to healthy ones. The damage cannot be reversed on that tomato, but future fruits can be perfect.

2. Fungal and Bacterial Diseases

If the black spots are not solely at the blossom end, you might be dealing with a pathogen. These often start as smaller spots that spread.

Early Blight and Septoria Leaf Spot

While these primarily cause black or brown spots on leaves, severe infections can sometimes affect stems and fruit, especially near the stem end (shoulder). You’ll usually see the tell-tale leaf spots first.

Identification: Early blight has “target-like” rings. Septoria spots are smaller with tiny dark specks in the center.
Solution: Improve air circulation by pruning lower leaves and staking plants. Water at the base, not overhead. Apply a copper-based fungicide or chlorothalonil as a preventative, following label instructions carefully.

Bacterial Spot and Speck

These are less common but cause distinct black lesions on fruit. They are spread by splashing water and thrive in warm, wet weather.

Identification: Tiny, raised black spots or scabs on green or ripe tomatoes. The spots are often surrounded by a yellow halo on leaves.
Solution: Unfortunately, there is no cure. Remove and destroy severely infected plants. Use disease-free seeds and transplants next season, and avoid working with plants when they are wet to prevent spread.

3. Sunscald Followed by Rot

This is a two-stage problem. First, pale yellow or white patches develop on fruit exposed to intense, direct sun—often after pruning too many leaves. This sunburned tissue is weak and dead.

Second, opportunistic fungi (like black mold) colonize the damaged area, creating a black, fuzzy appearance. The key is that the blackness sits on top of a bleached, sunken spot.

Prevention: Avoid over-pruning; leave enough foliage to shade the fruit. Use tomato cages or stakes that provide some natural cover.

4. Nutritional Deficiencies or Toxicities

Sometimes, an imbalance in soil nutrients can lead to poor fruit development and darkening. A severe potassium deficiency, for example, can cause fruit to ripen unevenly with dark, hard areas. Over-fertilizing with certain elements can also cause problems.

Always start with a soil test before adding amendments. It takes the guesswork out of gardening and saves you money in the long run.

5. The “Black” That’s Actually Ripe: Heirloom Varieties

Don’t panic if you planted certain heirloom varieties! Tomatoes like ‘Black Cherry,’ ‘Indigo Rose,’ or ‘Cherokee Purple’ are bred to have dark shoulders or fully dark skin. This is a beautiful, natural color.

How to tell the difference: The color will be uniform and glossy, not a spotty, sunken lesion. The fruit will feel firm and healthy, not rotten. Know what variety you planted—it makes all the difference.

Your Step-by-Step Troubleshooting Guide

Inspect the Pattern: Is the black at the blossom end (bottom)? Likely BER. Is it on the shoulders or sides? Could be disease or sunscald. Are the spots tiny and raised? Think bacterial.
Check the Leaves: Yellowing leaves with black spots point strongly to fungal disease. Healthy leaves with only fruit damage suggest BER or sunscald.
Feel the Fruit: Is the black area sunken and leathery (BER) or is it a surface mold (sunscald rot)? Is the fruit otherwise firm?
Review Your Care: Has your watering been irregular? Did you recently over-prune? What has the weather been like?
Take Action: Based on your diagnosis, implement the fixes listed above, starting with adjusting your watering habits, as this is the most common underlying issue.

Prevention is the Best Medicine

Most causes of black tomatoes can be prevented with good cultural practices. A little effort at the start of the season pays off with a healthy harvest.

Choose Resistant Varieties: Select tomato varieties labeled with disease resistance codes (like V, F, EB on the tag).
Rotate Your Crops: Don’t plant tomatoes in the same spot year after year. A 3-4 year rotation helps break disease cycles.
Water Smartly: We can’t stress this enough. Consistent, deep watering is the number one way to prevent blossom end rot.
Provide Good Support: Use sturdy cages or stakes to keep fruit and leaves off the ground and improve air flow.
Clean Up in Fall: Remove all tomato debris at the end of the season to reduce overwintering sites for disease.

FAQ: Your Questions Answered

Q: Can I eat tomatoes with black spots?
A: It depends. If it’s blossom end rot, you can cut off the black portion and the rest of the tomato is fine to eat. For tomatoes with fungal or bacterial spots, it’s safer to discard them, especially if the lesion is large or moldy.

Q: Is black on tomato plants always bad?
A: Not always! Remember those beautiful heirloom varieties. Also, some natural darkening of stems is normal. Focus on whether the black is on the fruit itself and if it’s causing decay.

Q: What is a home remedy for blossom end rot?
A. The best “remedy” is consistent watering and mulching. While some gardeners use calcium sprays (like antacid tablets in water), these are not very effective because the problem is uptake, not soil supply. Fix the watering first.

Q: Why are my green tomatoes turning black?
A: Blackening on green tomatoes is almost always blossom end rot or, less commonly, a disease like bacterial spot. Heirloom varieties will change color evenly, not just in one spot.

Q: Should I remove black tomatoes from the plant?
A: Yes, you should pick and discard any fruit that is severely affected by rot or disease. This helps the plant focus on healthy fruit and can reduce the spread of pathogens.

Seeing black on your cherry tomatoes can be disheartening, but now you have the knowledge to diagnose and adress the issue. Start with the simple fix—improve your watering consistency—as this solves the majority of problems. With a few adjustments, you’ll be back on track to harvesting baskets full of healthy, vibrant red (or beautifully dark) cherry tomatoes from your garden.