QUICK ANSWER
Blossom end rot is a dark, leathery, sunken spot on the bottom of the fruit, caused by a calcium shortage inside the fruit itself, but the actual cause is almost always inconsistent watering, not a lack of calcium in your soil. It’s most familiar on tomatoes, but peppers, squash, cucumbers, eggplant, and watermelon can all get it too. Fix the watering and new fruit typically stops showing spots within one to two weeks.
Why Blossom End Rot Happens
Calcium doesn’t move through a plant on its own — it travels with water, pulled up from the roots as the plant transpires. When soil moisture swings between soaked and dry, that calcium delivery gets interrupted right when the fruit needs it most, during early development. The soil almost always has enough calcium already; the problem is that inconsistent watering stops it from reaching the fruit in time.
Watering is the most common trigger, but it’s not the only one. Root damage from careless cultivation, cold soil that slows uptake, drought stress, crowded plants competing for the same water supply, and excess nitrogen or salts in the soil can all interfere with calcium reaching the fruit even when your watering routine is solid. This is why blossom end rot tends to show up in bursts — a dry week followed by heavy watering or rain is the classic trigger, especially on the first flush of fruit each season, before a plant’s root system and your watering rhythm have both settled in.
One quick way to tell it apart from other problems: true blossom end rot is a physiological disorder, not a disease — it starts at the bottom of the fruit and feels firm, dry, or sunken, not wet, moldy, or spreading from a wound on the side. If it looks or feels different from that, you may be looking at a different problem entirely. Peppers are a genuine exception to the “bottom of the fruit” rule worth knowing about specifically: rather than the classic blossom-end spot, a pepper is more likely to develop the damage along its side, which is exactly the spot sunscald shows up too, meaning the two get mixed up more often than you’d expect.
How to Fix It This Week
• Water on a consistent schedule — deep watering once or twice a week beats a little bit every day. Water thoroughly enough to soak the root zone. Inconsistency is the actual problem, not total volume.
• Mulch around the base of each plant to buffer soil moisture against hot, dry stretches.
• Skip the calcium spray, and hold off on fungicide too, unless a real soil test shows a genuine deficiency. Testing helps confirm whether your soil pH is in the 6.3–6.8 range where calcium is most available — if it’s low, gypsum adds calcium without altering pH. In most gardens, adding more calcium does nothing because the soil already has plenty, and since this isn’t a fungal or bacterial problem to begin with, a fungicide has nothing to actually treat.
• Give plants real room when you’re setting them out — crowding increases competition for water between neighboring roots and makes consistent watering harder to achieve across the whole bed.
• Avoid high-nitrogen fertilizers like urea — too much nitrogen can reduce calcium delivery to fruit and push excess leaf growth instead.
• Remove affected fruit so the plant isn’t wasting energy on it, and check new fruit as it forms — it should come in clean once watering evens out.
When One Plant Is Affected and Its Neighbor Isn’t
A bed doesn’t always water evenly from end to end, and local site factors are usually why. Something as simple as where a gutter drains, a slight grade in the yard, a big root system quietly pulling moisture from underneath, plants in containers, or just being tucked up against a wall can leave one corner of a raised bed noticeably drier than the rest — producing healthy fruit on one plant and blossom end rot on another just a few feet away. If you’re only seeing the problem on certain plants and not others nearby, it’s worth walking the whole bed after a rain and again during a dry stretch to see where water actually pools and where the soil dries out first, rather than assuming something is wrong with that specific plant.
Related Questions
Does adding crushed eggshells fix blossom end rot?
Usually not. Most garden soil already has more than enough calcium; the issue is getting it to the fruit consistently, which eggshells don’t solve.
Can I still eat a tomato with blossom end rot?
Yes — just cut away the affected spot. The rest of the fruit is unaffected and safe to eat.
Will it come back on the same plant?
Not necessarily. Once watering evens out, most plants stop producing affected fruit within a couple of weeks, even on the same vine.
