Thwarting Tomato Blossom End Rot

“For years I have bought Viva Italia seed to raise. The last two summers have been hit with blossom rot in all plants late in season.  What information do you offer that can prevent this plants or otherwise??

Thank you,


Zone 5

In The Russet Potato Capital Of Idaho”


Hi Clarus,

Thank you for your question regarding Blossom End Rot on Tomatoes.

Blossom End Rot on Paste Tomato

Blossom End Rot is caused by a calcium deficiency in the soil in relation to uneven moisture levels or excessive fertilizing.  Calcium is required in relatively large concentrations for normal cell growth and development.  It is moved from the soil through the roots to the meristem (tips of the plant where active growth occurs) via differentiation in water potential and pressure in the xylem of the plant.  When there is not a steady flow of water to the plant, the areas of the plant that growing will have a deficiency.  If the active growth point is a fruit, it will show up at the tip (end) of it.  What is actually happening to the tomato is that the cell walls are weakened by not having enough calcium.  The cell ruptures and discolors as it dries out.

Overfertilizing with nitrogen can also cause problems.  Extra nitrogen increases the speed at which the fruit grows and its size.  Calcium uptake by the plant remains steady in relationship to what would be the normal rate of growth.  Essentially, this means that the calcium uptake is almost ‘lagging’ because everything else is accelerated.  As a result, the fruit lacks calcium. Once the problem develops, quick fixes are difficult. Stabilize the moisture level as much as possible.  Remove the fruits that have been damaged. Feeding with manure or compost tea is recommended by many if this occurs in a garden plot.  You can also do foliar applications of calcium, but I’ve read that the results are not always the best because Calcium is a rather bulky element (larger than Nitrogen and others that are normally used in foliar feeding) and not easily absorbed through the leaf tissue.

In my own garden, I have found the best success with using an application of Epsom salts.  These can be found at your local pharmacy — usually in either the laxative/digestive health area or with things like bath salts/bubble bath. You want to get the plain, unscented type and make sure that it is not mixed with other additives like sea salt.  I use an old scoop from Lipton’s Ice Tea  (about a 1/4 cup measure) and give each plant a heaped scoop – sprinkling it in a circle around the base of the plant and with about an inch or two between the stem and the ring..  Repeat again in about two weeks for sandy soils, four for clay soils.

I hope this information helps you out.  If you have any other questions, please feel free to ask.


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10 thoughts on “Thwarting Tomato Blossom End Rot

  1. My daughter says I shouldn’t tell you this, but I don’t see the harm in doing so.

    Last winter I called, e-mailed and sent a letter to 31 different seed companies trying to get an answer about blossom rot. To date, my results have been:

    Never Responded After Contacting 6 Times (sent letter, called, emailed, called, emailed, called) Over 3 Months Time (October-December 2013):
    –Park Seed
    –Tomatobob’s Heirloom Tomatoes
    –Totally Tomatoes
    –Vermont Bean
    I guess these companies are too wonderful to care about the questions from their simpleton customers. Do to their lack of concern (especially on the part of Totally Tomatoes, because they sold me the seed), I will NEVER do business with any of them again!

    Tried To Sell Me Fertilizer Or Spray:
    –Botanical Interests
    –Bountiful Gardens
    –Gardens Alive
    –Henry Fields
    –High Mowing
    –Penny’s Tomatoes
    –Select Seeds
    –Southern Exposure
    –Thompson & Morgan
    –Tomato Growers Supply
    –Urban Farmer
    The items that they tried to sell me may work. I just didn’t want to buy something without further research. I already use fish emulsion (one of the things that they tried to sell me) and would never spray.

    Gave Me A Answer That Didn’t Make Sense:
    –Baker Creek (nothing can do, weather related)
    –Harris Seed (put egg shells around base of plant throughout summer)
    –Kitazawa (said no night watering)
    –Seed Savers (nothing can do, weather related)
    –Seeds of Change (nothing can do, weather related)
    –Sow True (person rambled on about leaf cover and told me to add lime)
    I already used egg shells to deter slugs and don’t water at night because I don’t want blight. I’ve done it before and after having the blossom rot, so I guess that doesn’t help. I’ve had weather similar to the last two years in the past and never had a problem with blossom rot before.

    My daughter likes to read your blog and told me that not only do you sell tomato seeds and seem know a bit about that, but you also answer peoples questions. As a last resort, I asked you to see if you would tell me anything different that what I’d already been told. Good thing I asked. You will now have another reader.

    Over fertilizing is likely to be what is happening in my raised beds. I water by drip lines and a timer so no shortage there may be overwatering but steady and no shortage. The Epsom salt idea I have never heard of, adding lime yes but not Epsom. I will add both this year and not much fertilizer and then only tomato type at that. Thank you for your time and effort.

    • Thank you for the kind comment. Unfortunately, your experiences with the various companies seems to be about par for the course. The October-December window in a seed company is somewhat busy, but definitely not to the point where people have an excuse to be outright rude. When a company doesn’t call you back after 6 efforts to contact them, that shows a flagrant lack of regard for the customer base. In other words, I want your money, but forget you thereafter.

      The companies that tried to sell you something doesn’t surprise me either — it’s a seed company’s way of “putting candy and 20 oz sodas in the checkout line” way of upsale-ing. As for the information you were given by those that responded, it seems like you were given a cookie cutter answer.

      All seed companies have a database that their customer service reps can refer to that will answer basic questions. This allows the particular seed company to hire anyone that passes the mirror test to come in and work seasonally for them in their CS department. If asked a question about tomatoes, regurgitate information from database as appropriate to their question. When you get a decent answer, it means that the person has worked there a long time or has some real gardening experience. If you get a off the wall answer that doesn’t make sense, you know it is a person that simply passed the mirror test.

      … and there is my soapbox piece of information for the day that was gleaned from my time spent in some big name seed companies, working as a little minion. 🙂

      • That explains a lot of my calls and letters over the years. Do seed companies have people that know anything about seeds?

      • Yes and no. I cannot speak for all companies.

        There is one key factor that you have to keep in mind. Most seed companies are simply resale places, for the most part. For example, the companies I worked for in the past bought in 99% of their products from someplace else. Let’s say we were going to look at tomato seeds. If you have an offering of 20 varieties, they might have come from 20 different vendors — Seminis, Rupp, Bejo, Seeds by Design, Seed Savers, etc. And sometimes, depending on the year and prices, a single variety may have had the seed sold during the first part of the year come from Seed Savers, while the second part of the year it came from Seeds by Design because there were different lots used.

        Given that, it really isn’t necessary for a company to have many people ‘in the know’. Those that are ‘in the know’ are usually worth a lot more. All a company needs is a couple people that know something about seeds and gardening to write up the information, and then hire a bunch of people with no knowledge to disperse the information.

        I know that sounds harsh, but it is the reality of this world — not only in a seed company, but most businesses across the board.

      • Forgot to mention — when it comes to that 1% not bought from a vendor: that is usually something that they can produce for less than what they can buy it in. For example, I know of a company that grows their own common lilacs and lily of the valleys to sell, but buys other stuff in. Why? Because the lilacs and lily of the valley grow like weeds and they can dig and dig and never do anything in terms of management with the plants. They make 100% profit (if wages of person digging/packing/etc. not included) versus buying it from a vendor and having to pay for it.

  2. So how do you know if a company has their own products? Does anyone? Or are some better than others? Now knowing all of this, it makes other things I’ve heard make sense like how a lot of garden seed comes from China.

    • The only way to know is to really do your research and to really know your company. Unfortunately, a seed company came make a claim… and not be completely honest with the customer.

      Let’s use a hypothetical with how most companies work. For example, we’ll say that Jim’s Fantastic Seeds (a mailorder seed company) buys a Really Buttery Squash seed from Squash Breeders Wonderful Seeds (squash seed vendor). Squash Breeders Wonderful Seeds is based in the U.S.

      Jim’s Fantastic Seeds has a customer call in and ask where the seed comes from. The customer service person says it comes from the U.S. The customer is happy.

      However, Squash Breeders Wonderful Seeds did not grow it in the U.S. They grew it in China and imported the seed. Due to how the seed laws are written, Jim’s Fantastic Seed can say the seed is from the U.S. because they bought it from Squash Breeders Wonderful Seeds in the U.S. However, it is from China.

      How would you, as the customer, know of the deception? You don’t, unless you ask for the source seed documentation, which would list the seed as being grown in China.

      Now don’t get me wrong. Not all seed companies are shady and some will tell you up front that they grow their seed elsewhere. For example, Seed Savers Exchange and Baker Creek seed source a lot of their seed lots in from Southeast Asia and South America. Seminis/Monsanto gets seed from Southeast Asia (about 80% of their vegetable seeds). European companies like Hem Zaden have a lot of their stuff grown in India and southern Africa.

      The only way to completely escape the system is to know your grower (like me or those in Seed Savers Exchange and similar) or to save your own.

  3. Thank you for all the wonderful information. It gives me a lot of food for thought. I’m glad my daughter recommended your website. You seem to be a very smart woman and it is good to hear that people like that still exist if this is how the seed catalog world is acting. Thank you again for all your help. I’m honored that you would spend so much time helping out a simple man like me.

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