If you see a dark, rotting spot on the bottom of your tomatoes, it’s blossom-end rot. This problem, caused by a calcium deficiency, can be solved a few ways.
When tomatoes, peppers, melons, and eggplant develop a sunken, rotten spot on the end of the fruit, the cause came long before you found the problem. It’s called blossom end rot, and here is why it happens.
Vegetables need calcium for healthy development. When tomatoes, peppers, melons, and eggplant can’t get enough from the soil, the tissues on the blossom end of the fruit break down. The calcium shortage may be because the soil lacks calcium, or calcium is present but is tied up in the soil chemistry because the pH is too low. Also, drought stress or moisture fluctuations can reduce its uptake into the plant. Another reason is that too much fertilizer causes the plant to grow so fast that the calcium can’t move into the plant quickly enough.
The best way to get around all this:
Unripe tomatoes can develop blossom-end rot, too.
Start now by testing the soil. Although most vegetables do well with a soil pH of 6.2 to 6.8, for those with blossom-end the pH should be 6.5 to 6.8 to free more calcium in the soil chemistry. Test results will indicate the amount of lime to add. Even better, lime also contains calcium. Work the lime into the top 12 inches of soil. Use a lime labeled “fast-acting,” which is better than ground limestone unless you have weeks to wait for the lime to react in the soil. If the pH is already correct, the soil test will recommend a different calcium source, such as gypsum. Also, add crumbled egg shells to your compost or bury them in your garden over time to help maintain the calcium levels.
Don’t over-fertilize. Too much nitrogen during early fruiting, especially with nitrogen made from ammonia, ties up calcium in the soil chemistry.
Avoid moisture stress. Use mulch to keep the soil evenly moist. Vegetables need about 1 to 1 1/2 inches of water a week while fruiting. The best way to water tomatoes planted in the ground is with a soaker hose. In hot climates it is especially tricky to keep big tomato plants in pots watered well during the summer. Make sure to water them daily or set them up on a drip system with a timer.
As a stop-gap measure, spray tomato plants with a calcium solution made for blossom-end rot. Follow label directions. Apply two to three times a week, beginning when the first blooms appear. This is not a long-term fix, but it may salvage your crop until you can take the steps mentioned above. The spray seems to work better on tomatoes than other vegetables.
First time tomato grower and the plant is growing and has 2 tomatoes. Planted on 1/21/12. The flowers bloom but then dry up but otherwise the plant continues to grow. What to do about the flowers drying up? Thanks. ps – I live in East Central Florida.
Hi Suzanne,
Congratulations! I am so jealous of your year-round growing season in Central Florida. Typically, if a tomato plant is not setting fruit, it’s because of hight temperatures. Read our article “Tomato Plants Not Setting Fruit? Here’s Why” to learn more.
Good luck in your first year growing tomatoes! Be sure to consult our How to Grow Tomatoes page if you have questions.
Kelly, Bonnie Plants
When I battled blossom end rot, an elderly gardener pointed out that a simple spray bottle with any kind of milk in it spritzed on the plants’ leaves until soaked would absorb calcium faster than any other method. I’ve done this each time it’s reared up in containers or ground planted tomatoes and it has worked perfectly! Long term, the lime addition is the way to go, but when your tomatoes need rescuing NOW, milk does a veggie good.
What type of milk do you recomend to put in a spray bottle: whole, skim 2% or powdered milk? I have blossom rot on my tomato plants.
Hi Sarah,
If you grow tomatoes, you’re bound to run into blossom-end rot at some point. You can read more about and get a better understanding of blossom-end rot in our article “Conquer Blossom-End Rot”. This physiological problem is caused by the plant’s inability to uptake calcium from the soil, due to a variety of potential factors. So to your question about milk… As a home remedy, some gardeners add powdered milk to the soil, which certainly can’t hurt but may not help either (and may cause a stink). Other gardeners spray a milk solution on the plant in an attempt to increase calcium (it doesn’t matter whether whole or skim, just whatever you have around), but it’s not a good idea to wet tomato leaves (which encourages disease) and, again, this may not help either. You can try the milk remedy, but I suggest you read about the solutions we recommend in “Conquer Blossom-End Rot” and try these as well.
Sorry for such a long answer, but blossom-end rot is quite the complicated problem. I hope this helps! If you continue to have problems, use our Ask an Expert service to get additional help.
Happy growing!
Kelly, Bonnie Plants
What is the best insecticide to use for my plants? They are in containers, but something is eating the leaves on my pepper plants.
Hi Rose,
Sounds like you need our Ask an Expert service. Be sure to include a photo of what’s happening so you can get the best advice.
Kelly, Bonnie Plants
I have a raised garden 4×8 with soaker hose,garden mix, mulch etc. Live in southern calif, San Bernardino area.How far should the water be soaking down. now I water every othe day for 10 min. thank you
Hi Bill,
Check out our article How Much Water Do Vegetables Need? I think it’ll give you the info you need.
Best,
Kelly, Bonnie Plants
I had blossom end rot my first year and then was informed by a seasoned gardener that egg shells mixed in the soil at planting prevents it. I am going into my fourth year of growing and the last two years have been blossom end rot free because of my egg shells! This is even during a very rainy and humid season last year when we had tomato shortages all over OH. Mind kept going strong!
Hi Shannon,
That is fantastic news! Calcium in any form available for the plant’s intake is a necessity to prevent blossom end rot. They also require consistent watering, which it appears you had in the “very rainy season.” I’m glad to hear from your personal experience it does the trick. In my own garden, I’m trying it this year, too. In fact, I wrote an “egg” themed post at Easter on the very topic! Hoping I have the same successful experience you have. ~Mary Beth @ Bonnie Plants
I usually have -and/or try to keep outdated eggs (cheap ones from Aldi’s and just put an egg in bottom of hole when planting in addition to adding crushed egg shells to garden/compost all year. Haven’t had much of problem with end-rot. Jan
Hi Jan,
Thanks for the tip! Yes, the egg can add calcium to the soil. This method isn’t scientifically proven, but if it works for you, it works! Read my colleague Mary Beth’s blog post “Incredible Eggs in the Garden.” She’s testing the egg method this season, too, and should report back later in the season.
Happy growing!
Kelly, Bonnie Plants