Blossom End Rot: Why Adding Calcium Often Doesn't Work
The Transport Issue That's Treated Like a Supply Issue
🌿 Garden Talk| by Guy Saldiveri | May 30, 2026
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| Tomato with Blossom End Rot |
You’ve got a great‑looking tomato or pepper plant — thick stems, lush green leaves, fruit everywhere — and then you spot it.
A few fruits have that ugly, sunken, brownish bottom that looks like they’re rotting from the inside out.
You search online, and every answer screams the same thing:
“It’s Blossom End Rot! Add calcium!”
Well… maybe — and here’s the down‑and‑dirty truth.
What Blossom End Rot Is and What It Isn't
Let’s clear the air: Blossom end rot (BER) is not a disease, not a fungus or bacteria, and it's not caused by pests.
It is a physiological issue — an environmental stress — and while it shows up as a calcium deficiency in the fruit, adding calcium usually doesn’t fix it.
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| Peppers with Blossom End Rot |
I know, that sounds backwards.
Calcium deficiency… but adding calcium doesn’t help?
Yep. And here’s why.
The Real Problem Isn’t Calcium — It’s Transport
BER is usually a transport issue, not a supply issue.
It can be caused by improper pH or a genuine calcium deficiency, but most of the time it's caused by erratic moisture levels. When soil constantly swings between too wet and too dry, fine root hairs get damaged. This disrupts the plant’s ability to move calcium (and other nutrients) up into the developing fruit. Unless you're using a complete soilless mix, most soils already contain a sufficient amount of calcium.
Adding more calcium when you have damaged roots is like trying to feed someone who can't swallow.
There's plenty of nutrients to go around, but there's no way to get it to the vital parts.
This problem rears its ugly head quite often, especially in the Deep South where early season weather patterns cause a lot of issues.
I just went through a month where I logged 25 inches of rainfall in my backyard. That's an enormous amount of water. After this pattern is complete, we might go into a six-week long drought.
It's happened time and again. Since I grow everything in containers, that drought period — especially in June or July — is definitely going to cause issues.
Hot temps in the low to mid‑90s, dry sunny afternoons — containers dry out fast. I water deep but still — these conditions create the perfect storm for BER.
What's my solution?
I add pelletized lime when I reset my containers at the beginning of the year. It's just part of my soil amendment protocol. All I need is about a half-cup for each wheelbarrow full and I'm good. That gets me through the year — plants need much less than the internet tries to make you believe.
After that, monitoring the moisture level in the soil, paying attention to my rain gauge, watering when needed, and backing off when I don't generally does the trick.
Quick Note: Crushing up Tums and tossing them into the soil won’t fix BER — they just don’t dissolve fast enough to matter. Better to hang on to those for all the indigestion you’ll get from reading some of the gardening myths floating around 😉
If you really want to make sure, you can use a slow-release fertilizer like Osmocote. It's balanced, releases fertilizer throughout the season, and contains all the micronutrients the plants need.
It’s also worth noting that the first batch of tomatoes often gets hit by BER simply because the plant is growing faster than its root system can keep up with. That's especially true here in the South because of the rainy spring pattern I mentioned earlier.
Frequently, as the root system matures later in the summer, the problem fixes itself — even if you do absolutely nothing!
Myth vs. Reality
Reality: Your plant can’t move the calcium it already has
Myth: Tums or eggshells fix BER
Reality: They don’t dissolve fast enough to matter
The Big Takeaway:
BER ultimately is a calcium deficiency — but in most established garden soils, the real problem isn't a lack of calcium in the soil — it's moisture fluctuations that prevent the plant from moving that calcium where it's needed.
Best Practices:
- Amend with pelletized lime (or similar) before planting
- Keep soil moisture as consistent as possible
- Use mulch to reduce moisture swings
- Avoid overwatering and underwatering
- Fertilize lightly throughout the season
- Check soil pH
Believe it or not, growing tomatoes in the Deep South is a full-time job. They're one of the fussiest plants you'll ever grow. When everything goes right, they're fantastic. When it doesn't, it's a disaster.
If you’d like more practical, porch‑talk garden advice, feel free to follow my blog — no pressure at all, I'll even buy the coffee. 😎
Happy Gardening 🌱
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