Blossom end rot on tomatoes

I have read different stuff about this problem and I am wondering if there is anything that can be done about this or is it just something that you have to live with? Are there any effective ways to combat this problem on tomatoes? Thank you!


I think it’s typically calcium deficiency that causes this. No, you shouldn’t have to live with it.

Best solution is to get a soil test and follow the recs, but in the short term find an all purpose fertilizer that’s not too high in N and has good calcium.

Drew, I save egg shells and till them into the row along with gypsum, calcium sulfate. Takes care of the problem even on real sensitive varieties.

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Also be aware, you may have adequate Ca in your soil but extremes of watering (too wet, too dry or both) can cause the roots to be unable to absorb and transport Ca to the tomatoes. As can root diseases and critter nibbling on the roots.

I’d agree with marknmt and Chikn, get the soil tested for Ca and follow the recommendations. But also keep an eye on soil moisture levels, not too wet and not too dry, and lookout for root eating critters too.

And there are foliar sprays (Ca salts of some type) which you can apply if in spite of your other actions you still get BER on some tomatoes. And some varieties of tomatoes are more prone to BER, many of the Roma-type varieties suffer more from this.


Yup, Calcium deficiency. You can do a soil test which will help you know how much available Ca++ you have in your soil (which is elemental Ca++ plus a pH not too high, which will lock up the Ca++ and not make it available for absorption). Then, apply the appropriate soil conditioners and fertilizer, which needs to have additional Ca++ (there are several tomato fertilizers out there that have additional Ca++). You’ll want to do that right away, so you can get your soil properly prepared prior to planting your tomatoes. And, C++ and Mg+ work together in union, so you’ll want to make sure your Mg+ levels are also in good ratio with Ca++. Amending your soil correctly is important. Depending on where you are in the country, you’ll want to amend with lime or calcium carbonate in the east (more acidic soils), and if you live in the west, you’ll want to use gypsum or calcium sulfate (more alkaline soils). Lime tends to raise the pH, gypsum tends to lower it. You don’t want to elevate your soil pH to the point where it will lock up Ca++.

The other key issue in controlling blossom end rot, is water. Or, I should say, controlling the amount of water. This is really critical. If your watering widely varies, it can significantly alter the amount of Ca++ available to your tomato plants. So, putting your tomatoes on a drip system that has a rain sensor will help. You can also apply Ca++ in the form of calcium chloride or calcium nitrate right into your drip system, which is the ultimate for effective Ca++ absorption. For me, when I lived in Indiana, there just was no controlling when the skies would open up, and drop like 6 inches of rain! So, the third thing in my arsenal was to apply calcium carbonate right to the roots, as well as apply a foliar blossom rot spray (again, more Ca++). I just stuck a Tums tablet (or 2, 3 or 4, depending on the size of my plant) pushed into the root area of the plant, immediately after a huge rainstorm. And then I sprayed as well. I know experts say the Ca++ in foliar sprays is not well absorbed, especially in the more mature leaves, but I felt that this double punch did the trick for me after my big storms… I was so frustrated with the rot I would get, after growing perfect tomatoes in California. It just was the combination of not enough Ca++ in my soil, and these huge, drenching thunderstorms. This gave me gorgeous, beautiful, unblemished tomatoes.


Everyone says Calcium, but it sure looks like the plant can’t transport enough water and the fruit gets necrotic.

We used to get it a lot in Phoenix and the soil was pretty much nothing but Calcium. Or it seemed like that.

Kokopelli, we may have lots of calcium in our soils, but it’s not very available due to our ore alkaline soils. It’s “all about the calcium”. That means elemental calcium that isn’t locked out due to pH levels :slight_smile: We have the same issue with citrus here as well. Some the micros - Ca++, Z, and Mg+ get locked out due to our higher soil pH. And, our winter rains make it worse. Our citrus can look just terrible after our heavy winter rains - very chlorotic looking.

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Perhaps so----I’m going to be experimenting with calcium Nitrate this year.

Color me skeptical that this can be cured with a few eggshells, though.

Well the first question I have is where are your tomatoes? In ground, raised beds or containers? The second important question is the pH? I myself have pretty much eliminated BER. How bad is it too?
BER is caused by the inability to uptake calcium, this is what has to be fixed. Low calcium is one of many possible causes.
If you eliminate all the possible causes, you won’t get it.The causes I know of are high pH, low pH, root rot, over watering, and under watering. The most common in my experience is over watering, pH issues seem to be common too. ,Lack of calcium is very rare. Almost all tap water is loaded with it. I take that back all tap water is loaded with it. In almost all cases calcium deficiency is a symptom, not the cause.
I do agree adding calcium can be beneficial because when the plant is loaded with it, it does better when it loses it’s ability to uptake more. it has a good reserve of calcium. This really helps in places with high rainfall. As you can’t really do anything about the over watering. Well you could use well draining soil if possible.
In my experience tomatoes like to be dry before you water, they are very sensitive to over watering, much more tolerant of under watering. I don’t suggest to do this all the time, but it’s a good idea to figure out when they are too dry. How long does it take? I grow in containers, raised beds, and in ground. I experimented with how long before they droop from lack of water in containers, raised beds and in ground… Once I figure that out I water the day before they start drooping. The only way to figure out this time frame is not to water till they droop, and figure it out. Make sure hot conditions are not causing them to droop. So drooping in early morning or late evening is from lack of water, at high noon where it’s hot, they will droop because they can’t absorb enough to prevent it.That even happens here in Michigan. They lose more than they possibly can absorb, thus they droop. This is quite normal.
If you have a lot of rain, it may be better to grow in raised beds, or containers, Where you can control moisture levels better.
I get BER in about 1-10 tomatoes out of a few hundred each year due to too much rain. Mostly in ground. I increased drainage by adding pine bark into the ground soil.
Sold as soil conditioner.
The good news by mid-summer in most situations it goes away as ground becomes warmer, and stays drier.

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Part of the issue is that it isn’t just our soils, our water in Phoenix is also pretty alkaline. The elevated pH prevents the tomatoes from utilizing the calcium. I’ve gotten good results using acidifying fertilizers.

Two years ago I used it and found it helped a touch. 20% less BER. I was disappointed with that and no longer use it. the plants seem to really like it though. I would rather use organic fertilizer with some slow release too. I have a big bag of Tomato-Tone for this year. Why it didn’t help much was lack of calcium was not my problem, too much water was. Growing them in raised beds and containers helped a lot with controlling moisture. That decreased BER a lot more. I add gypsum to my soil mixes to make sure the mix has calcium. Lime or calcium carbonate make the soil too basic to be useful for me. Anyway even some known varieties that are susceptible didn’t get any BER.

Yes, excellent method. I found that mixing pine bark in the soil helped too.Peat moss would work also. I saw dramatic results with onions, which promptly doubled in size where I used peat or pine, compared to beds without it. . I now add pine every year to my raised beds. Peat is light and can blow away, if not well mixed. Although I use it for new beds. mixed in throughout. I guess the constant watering with tap really turns the soil basic.

This product might have already been listed but I didn’t see it. They sell a product similar to Blossom End Rot that is in a spray form. I’m sure this is designed for a short term solution. I have not recently used it but I assume it is still available.

Egg shells very good source of calcium, but they have to be ground and burned. This is the form the calcium is much easy to extract. I use household mixer to grind them and then burn them in the oven on broil setting. It smells though :grinning:.

Galina, I also collect eggshells for tomatoes and peppers. I put them in microwave for 2-5 min and they get very hot and brittle. After they cool down I grind them in the old blender. They do smell. It is surprising how much Ca we can collect in the eggshells during the year, otherwise we just waste it (I like to be frugal when it is possible). I had blossom end rot on my peppers only the first year when I started gardening. The following years I added eggshells and I also used drip irrigation. The combination of the both completely eliminated the rot problem. My neighbor who is not doing any of this still has blossom end rot on her peppers and tomatoes.

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There is a lot of good advice here, but what you have to remember is that blossom end rot or BER is caused by a lack of calcium. That lack of calcium is caused by either a lack of calcium in the soil or an issue with uptake/availability. A soil test will let you know if you have an issue with calcium or with the uptake/availability. It’s important to determine what’s going on, as adding more calcium to the soil can actually exacerbate BER if you have an issue with uptake/availability as well as cause other issues with your tomatoes. Also, paste tomatoes (roma, san marzano, et al.) are much more susceptible to BER than other tomatoes. To the point that I will have zero BER except for the romas (almost without fail) until later in the season. They really benefit from a calcium spray.

Warning, anecdotal evidence follows this disclaimer: It has been my experience that if I have BER in my container plants it’s almost always a watering issue. Sometimes work is too busy and my wife doesn’t have the chance to water my tomatoes in the middle of July/August and yo-yo watering (going from bone dry to fully hydrated) is not appreciated by my container tomatoes.

I love that Tums tip!

Just my 2c. Already lots of good advice on here. Last year we grew over 30 varieties of tomatoes. Some were Roma type fruit, long and narrow. Just about all of these varieties had bad BER, the more roundish fruit didn’t.

I had read that calcium and uneven watering were the main culprits. This spring I had a soil test done, and the Ca levels were really low, about 700lb/acre. It should be at least 2000/acre. Plus my soil was super acidic, around 5.0. In addition the P and K levels were low. Just about all of our garden plots and other areas are this acidic, and low in Ca. Add to that, we had sporadic rain, some weeks, not a lot, other weeks very heavy rain.

From what I’ve read, if the soil is too acidic, whatever nutrients are in the soil already are locked up and can’t be utilized by the plants. To remedy this, I applied lime to help get the pH up, even though it may take a year before it gets fully broken down and absorbed into the soil. After I plow it under, I’ll add the rest of the lime and fertilizer.

Please note, I’m in NE Kentucky, and most of the soils here are very acidic and low in calcium. Creek valleys here are a bit more alkaline and fertile, which is prob true for most places.

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Supposedly soaking tomato seeds in an aspirin solution before planting prevents diseases, putting crushed aspirin in with the plants and spraying the plants with an aspirin solution. Using Epsom salt works at preventing it, some people say that Epsom salt helps with nutrient uptake in to the roots.

Thanks for the heads up on Roma. I have seven in small containers that I will soon plant. I will keep an eye out for BER.

I have heard of aspirin being used that way, but I am not entirely convinced of its efficacy.

Epsom salt will add magnesium to the soil. That’s great if you have a magnesium deficiency, but you can have too much of a good thing. Adding too much will also lower your PH.