Tomatoes Rotting Before Ripe

There’s nothing more frustrating than watching your beautiful green tomatoes start to rot before they even turn red. Preventing early spoilage is the key to finally harvesting a full, healthy crop from your garden. This common problem has a few main causes, but the good news is that most are easily fixed with some simple changes to how you care for your plants.

Let’s look at why your tomatoes are spoiling early and what you can do about it right now.

When you see a dark, sunken spot at the blossom end of your tomato, you’re likely dealing with blossom end rot. It’s not a disease, but a physiological disorder. It happens when the plant can’t get enough calcium to the developing fruit. This calcium deficiency is usually caused by uneven watering.

Here’s how to tackle it:

Water Deeply and Consistently: Tomatoes need about 1-2 inches of water per week. Use a soaker hose or drip irrigation to water the soil directly, not the leaves. This encourages deep roots and prevents the wild swings in soil moisture that cause the problem.
Mulch Your Plants: Apply a 2-3 inch layer of straw, wood chips, or shredded leaves around the base of your plants. Mulch keeps soil moisture levels steady and prevents it from drying out to fast on hot days.
Test Your Soil: Before adding any amendments, do a soil test. If calcium is truly low, you can add gypsum (calcium sulfate) or crushed eggshells to the planting hole next season. Avoid high-nitrogen fertilizers, as they can make the issue worse.

Stopping Fungal Diseases in Their Tracks

Fungal diseases like anthracnose and early blight are major culprits for fruit rot. They often show up as circular, target-like spots that eventually turn mushy.

Prevention is your best defense:

Choose Resistant Varieties: Look for tomato varieties labeled with disease resistance codes like “F” (Fusarium wilt), “V” (Verticillium wilt), and “A” (Alternaria/early blight).
Water the Soil, Not the Leaves: Wet foliage is a paradise for fungal spores. Always aim your hose or watering can at the base of the plant, preferably in the morning so any splashes dry quickly.
Provide Excellent Airflow: Space your plants properly—usually 24-36 inches apart—and use sturdy cages or stakes to keep them off the ground. Prune off the lower 6-12 inches of leaves to improve air circulation.
Practice Clean Gardening: Remove any infected leaves or fruit immediately and throw them in the trash, not your compost. At the end of the season, clear all plant debris from the garden.

Preventing Damage from Pests and Sun

Sometimes, the rot starts with a small wound. An insect bite, a crack from too much water, or even sunscald can create an opening for decay.

Managing Insect Problems

Hornworms, stink bugs, and slugs can all damage fruit. Check your plants regularly. Hand-pick larger pests and use insecticidal soap for smaller ones. Encouraging beneficial insects like ladybugs can help keep aphids away.

Avoiding Sunscald and Cracking

Sunscald appears as a pale, whitish spot that becomes thin and papery. It happens when fruit that was shaded is suddenly exposed to intense sun, often after pruning.

Avoid over-pruning; leave enough foliage to protect the fruit.
Sudden heavy rain after a dry spell can cause fruit to swell to fast and crack. Consistent watering is, again, the solution.

Your Step-by-Step Prevention Plan

Follow this routine from planting to harvest for your best crop yet.

Start with the Soil: A month before planting, work plenty of compost into your garden bed. Compost improves drainage, moisture retention, and provides slow-release nutrients. Ensure your soil pH is between 6.2 and 6.8 for optimal calcium uptake.
Plant Smart: Choose a spot with full sun (6-8 hours minimum). Bury tomato stems deep, as they will grow roots all along the buried stem, creating a stronger plant.
Water Wisely: Set up a drip irrigation system or soaker hose on a timer. If hand-watering, do it in the early morning. Stick your finger in the soil; if it’s dry 2 inches down, it’s time to water.
Mulch and Support: After planting, apply a thick layer of organic mulch. Install cages or stakes right away to avoid damaging roots later.
Inspect Weekly: Make it a habit to gently check your plants. Look under leaves, examine new fruit, and remove any problems immediately.
Fertilize Correctly: Use a balanced, slow-release fertilizer or a tomato-specific formula at planting. Side-dress with compost when the first fruits are about the size of a golf ball, but avoid over-fertilizing.

What to Do With Affected Tomatoes

If you catch rot early, you can sometimes salvage part of the fruit. Cut away the rotted portion completely. The rest of the tomato is often fine to eat if it’s still firm and shows no other signs of decay.

For tomatoes with minor blossom end rot, you can cut off the bad part and use the rest for cooking. However, any fruit with obvious fungal infection should be discarded.

FAQ: Quick Answers to Common Questions

Q: Can I use Epsom salt for blossom end rot?
A: No. Epsom salt provides magnesium, not calcium. It won’t help and may worsen the problem by competing with calcium uptake. Focus on consistent watering and soil health instead.

Q: Why are my tomatoes rotting on the vine even though I water regularly?
A> “Regularly” might not mean “evenly.” Light, frequent watering leads to shallow roots. Ensure you’re watering deeply each time. Also, check if heavy rain is followed by dry spells, which disrupts calcium flow.

Q: Are coffee grounds good for preventing tomato rot?
A: Coffee grounds can acidify soil slightly and add organic matter, but they don’t provide a significant amount of calcium. They are best used in compost. Don’t rely on them to fix calcium issues.

Q: Should I remove tomatoes with blossom end rot?
A: Yes, pluck off the severely affected fruit. This allows the plant to direct its energy into producing new, healthy tomatoes. The plant can’t repair the damaged fruit anyway.

Q: Can you over mulch tomato plants?
A: Yes. Piling mulch directly against the stem can create a moist environment that encourages stem rot. Keep mulch a few inches away from the main stem, forming a donut shape around the plant.

By understanding the main causes—uneven watering, fungal disease, and physical damage—you can take targeted action. The solution isn’t usually one magic trick, but a combination of good practices: consistent deep watering, smart mulching, proper spacing, and regular observation. Start with your watering routine, as that’s the most common fix, and build your prevention plan from there. With these steps, you’ll significantly reduce the heartbreak of tomatoes spoiling on the vine and look forward to a plentiful harvest.