Wednesday, April 28, 2010

Tomato Blossom Rot and Epsom Salt

First things first.  Should anybody have the mistaken belief that I am any kind of gardening expert, may I please first refer you to my Gardening Expertise Disclaimer. Back? Good. Now that we've got that out of the way...

So, you've carefully planted your tomatoes into a perfect soil blend you mixed up yourself and into environment friendly raised beds, or nice, roomy planters, and tenderly fawned over them, watching them every day as they grow, sprout blooms and then shortly after, little buds of tomatoes. You beam with pride and joy.  Until, one morning you wake up, grab your cup of coffee and wander into the garden to admire your handywork, only to find this.

Akkkk! What the heck?

Blossom rot.  When a tomato grows, first you have a blossom, from which behind the fruit comes. Blossom rot is what occurs when the area where the blossom was, begins to turn black and rots, destroying the entire fruit.

What is blossom rot?

Well, first of all, and thankfully... it is not a plant disease. It is a physiological response by the plant that is primarily thought to be caused by a calcium deficiency. Usually this is induced by variations in the water supply to the plant due to root damage, acidic soil, high humidity, or over watering - either by human sources or by mother nature.

One of the best ways to control Blossom Rot is to monitor your soil pH levels by testing, and applying dolomitic lime {if the soil calls for the adjustment} several months before planting your tomatoes. You can also help to retain moisture by using a mulch source around your plants - shredded newspaper, straw, and pine straw are good sources.

Yeah. I'm probably not gonna do all that, soooooo, in my own personal, albeit limited, experience of growing tomatoes, I have found that using Epsom salts has pretty much eliminated problems with blossom rot. Some experts will tell you not to use Epsom salts unless you have tested your soil and found a deficiency. So, while it's certainly advisable to do soil testing if you have both access and the time, I disagree. I feel that line of thinking applies when you are talking about major deficiencies in a large crop garden - not a simple, tiny, backyard garden like I have. But again, that's just my opinion.

Despite the name, Epsom salt is not salt! Not in the sense that we think of salt being that is. Regular salt, like table salt is deadly to a plant! In fact, if you want to get rid of some grass or plants somewhere, treat it with a heavy dose of regular salt and see how fast it dies.

Epsom salts are actually a chemical compound containing magnesium and sulfate, both very beneficial to plants, and which may help to increase chlorophyll production, helping plants to transform the sunlight into food for the plants. The blend also may improve both the phosphorus and nitrogen uptake, making your fertilizer work better, and make your plants grow bushier. It also has been shown to help seeds to germinate.

As a sidenote, years ago, I started using Epsom salts on my roses and ever since, it seems that the plants are just so much more bushy and beautiful and loaded with flowers than they were without it. {if only Epsom could eliminate black spot, but that's another post}

But, I also sprinkle Epsom salt around my tomato and pepper plants. Epsom salt is not persistent, so you just really can't overuse it and honestly, in my personal experience and opinion, using it results in bigger and stronger pepper plants and since I started using it on my tomatoes, while I can't prove it is because of the Epsom, I've not had a problem with blossom rot at all {crossing fingers.}

Generally I sprinkle a little bit of the Epsom salts down into the hole where I am planting, along with a little granular fertilizer and scratch that into the soil. I also top dress the tomatoes with Epsom, about every other week.

The best way to keep up with your planting and fertilizing schedules is to pick up a garden journal or a calendar to use for your garden! You'll never remember when you planted what, or when you fertilized what. Just get a calender dedicated solely to your garden and make it easy!

To use Epsom salts, use 1 tablespoon for every foot of height on the plant, and simply sprinkle it all around the outer ring of the plant, just as you do with the granular fertilizer. Be sure to thoroughly water them in. I only use Epsom salts on my tomatoes and peppers in the veggie garden. Nothing else.

A WARNING: Definitely do not use Epsom anywhere near where you have sage planted! For some reason sage and Epsom do not get along and Epsom salt will kill your plant.

By the way, once a plant contracts blossom rot, it will not repair the area that is infected. Pluck it and chuck it. I know... it hurts to see an otherwise perfectly good tomato go like that, but if you leave it there hoping to eat it when it ripens, you are making your other vegetables vulnerable since the damaged area on the tomato can act as an entry point for other tomato diseases that can take over your entire crop!

If you find your garden is affected by multiple cases of Blossom End Rot, you can treat the plants by spraying them with a calcium solution (4 tablespoons of calcium chloride or calcium nitrate per gallon of water) 2 to 3 times a week when the second round of blossoms begin to appear. If you live in a hot climate like I do with daytime temperatures exceeding 85/90 degrees, be advised that calcium chloride can burn plants. Use calcium nitrate instead.

As always, with any gardening advice on this site, take it all with a grain of well, epsom salt! :)  I am certainly no expert, and I'm simply sharing my experiences. Please see my disclaimer


Recap - How to Build a Raised Bed Vegetable Garden

Step 1: Build a Box
Step 2: Dirt Mix
Step 3: Add a Grid (for Square Foot Gardening)
Step 4: Planning the Plants

Click HERE for all the Year One 2009 Square Foot Vegetable Garden Updates


  1. I have never heard of doing this before. I am going to try it. I always get blossome rot at some time or the other during the summer. Thanks. I will let you know how it goes.

  2. Oh gosh, I love your saying: "Pluck it and chuck it"!!!

  3. Hi Mary, I love to soak in Epsom Salt the Lavender kind anyway...I will pick up some sans Lavender..and give this a try. I started all from seed..I think way to soon. and my plants are lanky and need to be transplanted into the soil soon..I will have to check the frost date here. The rule of thumb after Memorial day we are safe...I don't think I can wait that long...But I will definately get some epsom...thanks
    for the info.

  4. Nana, let me know how it goes!

    LOL Holly!

    Faith I love a good soak in some Epsom too though I tend to "flavor" my own with my trusty chest of essential oils! Isn't Lavender amazing?! Love it. Gosh, I cannot imagine having to wait so long to plant. Course I'll be complaining about bugs bugging my plants about the time that you are enjoying your beautiful plants!

  5. What a great idea. I would have never thought of this one.

  6. I always learn so much every time I stop by and visit you! I love home grown tomatoes!! YUMMMM!

  7. One of many reasons blossom end rot can be caused by too much nitrogen. E.g. if the 1st number in your fertilizer's N-P-K is too high.

    Epsom salt is magnesium sulfate. And magnesium can help eliminate excess nitrogen.

    Also, the balance of calcium and magnesium should be maintained. Too much magnesium will cause problems. In a hydroponic system, I read that 3:1 ratio produced the greatest yields. So make sure calcium is at least 3:1 with magnesium.

    This year, I'm trying to prevent blossom end rot by crushing Calcium Citrate/Magnesium tablets and adding it to the dolomite. For humans, they are 2:1 ratio so it'll gently raise the magnesium.

    If you're not using dolomite lime (not hydrated lime), then that should be step #1 before messing with magnesium levels.

  8. Hi I have a roma plant growing and it was doing great my first tomato was growing iw as excited and then one day i see brown leather on the bottom of the tomato and was stunned but now after reading this site I see where the problem lies. I'm first going to try pushing some crushed egg shells down into the soil but i've never heard of the epsom salt idea i will keep that on had now for some other things i have growing. Thanks for the info

    1. You're welcome!! Isn't that aggravating to have a beautiful tomato after all that TLC and wait only to find blossom rot?! Best of luck - hope the info helped. You reminded me that mine are due for a dose too. Just make sure that you're using Epsom salt like that pictured of course and not any kind of a regular salt.

  9. Thanks a ton for the info! I haven't had blossom end rot in YEARS since I always use extra lime.. But...this year I decided to move the whole thing to a new spot Two rows about 60 feet long where corn has always grown fine.

    My problem is that I compost leaves in the garden...Been doing that for 30 years. This time around I didn't use extra lime in the new place...and poofs.... rot!

    I dug out my ancient bottle of Rot Stop, which works gangbusters....but I wanted to see why... Which brought me here. Tomorrow the plants get a swoosh of Rot Stop, and a slosh of Epsom salts. My peppers too.

    So, SUPER thanks! I had NO idea.


  10. Blossom end rot is usually caused by a calcium deficiency. Lime helps solve it too.


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