Blossom End Rot (Toms)


I have been reading about cures for 'blossom end rot' and I find that the methods for

curing are not very clear and contrasting. Some say water deeply and less often

and others say little and often and to apply a mulch around the base of the plant.

I have 27 plants in a polytunnel and on one plant two tomatos on the same truss

have blackened undersides.


I have used 2 feeds of nettle liquid fertiliser but have stopped this as too much

nitrogen isn't good.

I now feed once a week with a tomato feed and water twice a week.

The tomatos are in plastic pots and I leave the 6 window vent flaps open

permenant. The temp during the day is between 25/30 degrees.

Even though I water twice a week the soil seems to dry out very quickly between


Any help appreciated as to remedy this.





  • DovefromaboveDovefromabove Central Norfolk UKPosts: 43,789

    I don't think you need to feed as often as once a week.

     Mine get fed when  the first truss has set, and then 2-3 weeks later, then another 2 weeks later.  That's usually enough.    

    Over-use of fertiliser can restrict the plant's uptake of calcium from the compost, and it is lack of calcium that causes BER.

    Hope that's helpful. image

    No-one knows if you've done your housework, but everyone knows if you've done your gardening !
  • Andrew KennethAndrew Kenneth Posts: 153

    Very helpful indeed.

    Are yours in pots or in the ground, outdooors or in and how often do you water?

    This is my set up.

    Thanks again..



  • The cause of blossom end rot is a lack of calcium, that however is most often caused by poor water transport through the plant, stopping shy of the end of the fruit and is fairly common.

    Most nutrients are salts, especially nitrogenous ones, if these are applied too often and especially to dry soil then it draws the moisture out of the roots and therefore stops the plant moving it around. the best thing you can do is water if the plant is dry and water thoroughly.

    Just remember, to make things harder if you over water you cause splitting and tastelessness in the fruits so don’t water if it isn’t needed.

  • The more your plants grow the greater uptake of water will occur due to the natural transpiration of the plant: more foliage = faster rate of transpiration. If you let the plant dry out and the foliage flops you can restore the foliage if you water in time but the plant's ability to take up some of the nutrients will be impared.

    Many gardeners (me included) will reduce some of the foliage to reduce transpiration rates and help send the plant's energy into the production of fruit but for my part I don't like to take too much foliage off because the plant still needs to be able to breathe and photosynthesize.

  • ItalophileItalophile Posts: 1,647

    Andrew, BER is the result of plant stress impacting on the plant's ability to distribute calcium to the fruit. It's not necessarily related to watering but it can be. Excessive, prolonged warmth can cause it. Anything that stresses the plant.

    I've had BER turn up on a couple of my toms. The temps here are constantly in the high-30sC with not much overnight relief. My BER is heat stress related.

  • DovefromaboveDovefromabove Central Norfolk UKPosts: 43,789

    Andrew - my toms are outside in large pots on a south facing terrace.   I water in the evening when they're just beginning to lose turgidity - probably about twice a week at the moment - when I pot them I leave quite a big gap at the top of the pot (about 4 or 5 inches) and when watering I just fill that up with the watering can. 

    This year I'm growng only Heirloom varieties - I've had BER on two fruits on which were on the same truss of a plant which I understand is prone to a little BER - otherwise nothing else - so far!!!  

    Last year I was battling with Late Blight - by nipping out every affected leaflet twice a day and quarantining affected plants I managed somehow to contain it and we still got a crop off all plants (Marmandes) in what was a really horrible year.  

    Good luck with yours image

    No-one knows if you've done your housework, but everyone knows if you've done your gardening !
  • Andrew KennethAndrew Kenneth Posts: 153

    I didn't realize it could be so stressful growing tomatos.

    Maybe one of my problems is that I have to water around midday because my plot is on a farm not to close to home and I cannot get there in the evenings which has to be the best time to water when the temps have gone down.

    Beggers can't be choosers in my case.

    Thanks for all your imput.



  • ItalophileItalophile Posts: 1,647

    When you water isn't really a factor, Andrew, it's the watering pattern that's important. And too much can be as frustrating for the plant as too little.

    Early morning is probably best because the soil is still cool, the water will penetrate, and any water you get on the leaves will dry out as the day warms up.

    Growing toms shouldn't be stressful. In fact, I think people worry about their toms too much. They're very tough, resilient plants and arguably do their best when left to their own devices. Within reason, obviously.

  • Andrew KennethAndrew Kenneth Posts: 153

    Thanks Italophile,

    I feel better now.

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