Question: I am having a problem with some tomato plants in my back yard. The plants are growing good and strong and small green tomatoes are begging to grow. I looked at the bottom of one tomato and it is turning black. Can you please tell me what is causing this. There are several tomatoes on the vines of this plant, but only one tomato has this black section on it.
- George K.
Answer: Hi George,
Your black bottomed tomato sounds a lot like blossom end rot. I don’t have a picture of it to post but a quick search will bring up countless photographic evidence for identification. The reason I am ruling out other problems is because you describe your plants as healthy. Blossom end rot appears as a blackened, sunken spot on the bottom of green or ripening fruit. The plant itself rarely shows any signs of a problem. In fact some stricken fruit is found growing on plants that are exceptionally leafy and health. This particular brand of the condition is a symptom of excessively fertilizing with a high nitrogen fertilizer. In that case, much of the plant’s energy goes into producing big, healthy leaves, leaving little else for fruit production.
Blossom end rot is a very common condition said to be caused by a calcium deficiency, however in general the problem is not caused by a lack of calcium in the soil but inconsistent watering, drought, and uneven soil moisture making it difficult for the plant to draw nutrients up through the roots.
From your description it sounds like your tomatoes are growing in-ground however this problem is especially common for container grown plants since containers dry out quickly and can be difficult to keep consistently watered.
The good news is that the problem is easily fixed — future tomatoes grown on the same plant aren’t doomed to be diseased if you follow the advice below.
General Tips to Avoid Blossom End Rot
- Amend poor soil by adding lots of organic matter like compost. This will provide better nutrition for the plants and make for soil that holds moisture well.
- Water tomatoes deeply, but less frequently. This means give them A LOT of water when you do water rather than watering regularly but in small quantities.
- Water more often once your plants start to produce fruit, continuing to water deeply each time. Tomatoes are a watery fruit, your plant will need lots to grow healthy fruit.
When Excessive Nitrogen is the Problem
- Cut back on high nitrogen fertilizers like fish emulsion.
- Add kelp meal or liquid seaweed to ergular waterings. You can even spray the blossoms with this mix when they first open.
Tips for Container Gardeners
- When growing in a container, grow only one tomato plant per pot.
- Choose a container that is appropriately-sized for the plant. Small busing and dwarf tomato plants will do in a hanging basket but most tomatoes have very deep and ample roots requiring lots of space. Garbage bins are the way to go.
- Grow tomatoes in plastic pots when possible. Plastic retains water much better than terracotta, a difference that will become much more noticeable at the peak of summer drought.
“What that kind of attitude and approach is saying over and over again is that gardening is not for you; you don’t belong here.”
I met up with Teresa Cheng a few weeks ago for lunch at my favourite long-time local eatery, Cafe Bernate for an in-person interview to talk about urban gardening, growing food, and sustainability. We popped back to my place after the interview to take some quick snaps and of course I sent her off with some extra tomato and anise-hyssop seedlings I had kicking around. I have a tendency to unload plants or herbs onto visitors. I may be a terrible sales person but I know how to “sell” a plant.
The result of that conversation can be found on the Taste T.O site, Talking the Green Revolution with Gayla Trail.
I will be traveling to Columbus, Ohio next week to be on a panel at the Ohio Floraculture Association’s “Short Course” conference. As a result I have set some time aside to see the city and take in gardening in that area. I am told there is an active community of urban gardeners in Columbus.
I know it is very last minute to ask but I am hoping to find some gardeners who would allow me to come into their space and take some pictures of them for my Green Minds photo project. If you would be willing or know someone who is please go to the site and fill out the form. I’m trying to find a diverse range of people so no gardener is too beginner.
And since I have never been to Ohio I would deeply appreciate any suggestions of things to see and do in Columbus, gardening-related or otherwise. And just in case I don’t bring enough film: Does anyone know of a store in the city that still sells medium format film? I am also looking for a health food store and a cafe that serves good espresso-based coffee beverages.
Click the image to see full-size.
This is a panoramic of the roof garden taken just this week. There are a lot more plants out there then I was able to get into a composite. Unfortunately with the gazebo top on I could not shoot the photos from above, perched high up on a ladder like I did for the before image. As far as Project The Best and Most Ass Kicking the Roof Garden Has Ever Been, EVER 2008 is concerned I think things are well underway. One of my challenges for this year was to Eliminate All Messes. I’m not quite there yet but I have managed to reign it in by strategically placed furniture that acts as holding pens for the junk. I only just managed to get most of the transplant chaos alleviated so more attention to aesthetics will be coming up shortly.
I recently did an interview with REV Magazine that is now up on their site. I love what they wrote in the introduction about how I complain about the weather. Because I do, don’t I? Quite a lot actually. But I want you to know that I withheld this week and didn’t tell you about THE HAIL. In an act of progress that shows that I am rolling with the punches and conceding to less need for control I did not bring up the tiny balls of ice that plummeted to the ground threatening my basil in the last days of the month of June! And then the next day was hot and sweaty — a proper summer.
Okay, to confess I did complain about it in the forums.
Today is the solstice and tomorrow is supposedly the longest day of the year, two days I have been looking forward to for months and will likely be looking forward to come next December. Low and behold the weather has cooperated. Skies are currently clear and sunny. You could even call the current temperature “warmish” something I have not been able to do for over a week now. We’ve had torrents of rain nearly everyday recently and the temperatures have dipped so low that I’ve been forced to pull out sweaters I thought I had seen the last of until September. This turn in the weather has left me very worried and anxious about the kind of summer ahead, so the return of the sun has lifted my mood substantially this morning, even if the forecast is calling for 40% chance of showers.
I shake my fists in your general direction Environment Canada!
While I am known to complain, “This flower is wilting” once or twice or thousands of times when the temperature and humidity rises above a comfortable level, I really depend on the intensity of summer to make me feel even marginally positive about the future coming of winter. I want to sweat like a pig and really suffer from the heat so that when I look into my future through the haze of high smog days and the salty, stinging sweat burning my eyes, a future engulfed in snow and ice almost looks good. What I do not want to experience is a repeat of that grey, cold, and rainy summer a few years back. All of the sun-loving plants like tomatoes and peppers under-produced and the basil rotted on the spot.
Now, THAT would quite possibly be the worst thing to happen in America.
But so far only I am complaining. The plants have been loving the constant stream of showers. Everything is lush and beautiful — you can practically sit and watch the mint and tomatoes grow an inch. I already have a first hot pepper developing on the ‘Chinese Five Color’ plant, a personal record I am sure. And when I think about all the time and water I have saved over the last week I realize I should just shut up and enjoy it before the inevitable drought and crippling heat arrives and I find myself whining about the endless buckets of sloshing water and my horrible humidity hair.