Blossom End Rot: What It Is, What Causes It, and How to Prevent It

What Is Blossom End Rot?

Blossom end rot is a physical disorder, not a disease. It appears as a dark, sunken spot on the bottom of tomatoes (and sometimes peppers or squash). It's caused by a lack of calcium in the fruit, often due to irregular watering or poor calcium uptake—not necessarily low calcium in your soil.

Common Causes of Blossom End Rot:

Starting seeds in cold soil

Soil pH imbalance

Root damage from overcrowding

Excessive nitrogen fertilizer

Inconsistent watering (the #1 culprit)

Each of these interferes with how your plant takes up and uses calcium.

How to Prevent Blossom End Rot

1. Start Tomatoes Right:

Begin seeds indoors 4 weeks before transplanting

Keep temps between 75–80°F

Transplant outdoors after the last frost (around May 1 for most)

2. Plant Deep and Feed Smart:

Bury the stem to encourage strong roots

Add compost and a balanced fertilizer like 5-5-5

For root support, try a 3-6-4 fertilizer

Optional: Add bone meal for long-term calcium support

3. Feed for Flowers, Not Leaves:

Switch to a lower-nitrogen fertilizer when flowering begins.

Use 3-4-6, 4-6-8, or 5-10-10 blends

Focus on phosphorus and potassium to support fruit

4. Water Consistently:

Use drip irrigation and mulch to keep soil moisture steady

Avoid overwatering or letting the soil dry out too much

5. Optional: Pinch Those Suckers

Removing suckers can increase airflow and reduce stress

Personal choice—I do, but you don’t have to

Takeaway: Stop Blossom End Rot Before It Starts

Consistent care, proper feeding, and deep watering are your best defenses. Give your plants what they need—and you’ll be rewarded with gorgeous, rot-free tomatoes

Next week:

“Weeds with a Message: What Your Garden’s Wild Invaders Are Telling You”

Think weeds are just freeloaders? Think again. That dandelion, chickweed, or crabgrass might be spilling the secrets of your soil. In next week’s Native Note, we’ll decode the hidden messages your weeds are sending—so you can garden smarter, not harder..

A Final Note

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