"I know that Blossom End Rot can be caused by uneven watering, but I water every day until water comes out the bottom of the containers."

It sounds like you may be creating the problem by too much watering; watering everyday is just about guaranteed to be way too much water. On the BER FAQ page, the causes are listed as "... low calcium levels in the soil, drought stress, excessive soil moisture, and/or fluctuations due to rain or overwatering." I think it's fair to say that watering everyday is too much and falls into the "excessive soil moisture" category.

I've added a link to the BER FAQ page in case you hadn't found it yet.

Here is a link that might be useful: BER FAQ

Agree. But it isn't so much uneven watering or too much or too little. It is maintaining always consistent soil moisture levels and that is very difficult in such a small container.

Plus a Stupice is an indeterminate, a big plant for a 5 gallon container so it may already be rootbound. If so, it won't matter how often you water it. Is it at all possible to transplant it to a much larger container?

And you have only fed it once? Container plants, especially ones in such small containers that require frequent watering often require weekly feeding minimum. Sometimes even more often as all the nutrients leach out the bottom every time you water. Many folks use a diluted strength of a low nitrogen fertilizer every time they water. So likely there are no nutrients left in it given the daily watering.

Using small containers can work but they almost always require an auto drip irrigation system and a regular feeding system to replace the lost nutrients for success.

If you can, transplant it. If you can't then I would prune it back substantially, feed it well and plan to do the diluted feeding at least every other watering to see if it will adjust. I'd also find a deep pan filled with water to set the container in - something not normally recommended - in the hopes it can help stabilize the soil moisture level by the plant reabsorbing at least some of what runs out between waterings.

Dave

I've successfully grown indeterminants in containers before, so I don't think its necessarily container size. I know lots of people here grow in only 5 gallon containers. The plant did shoot up and get huge, so the "too much nitrogen" might have been a cause as well. The sungold next to it is massive, and is covered with fruit, but no end rot - but that's a cherry, so it'd be hard to get.

Also, the containers haven't been drying out - we've been humid and rainy, if anything. Typically, though, I found that I still need to water, even with rain, because the foliage keeps most of the rain out of the containers, once they get big enough. I can try to back off on the watering, but its not as if they are sopping wet.

I've been worried about too much nitrogen in the potting soil because both my Great White and Hawaiian Pineapple are massive plants (I've upended another 54 inch cage on top, they are are both at the second rung of the second cage already), but with no fruit and few blossoms - that's why I've been conservative on the fertilizing.

Last year, I actually used top soil in the containers with hybrids (although they were larger than the 5 gallons - but no bigger than 10), and fertilized 3 times, and had great yield.

I don't think its root bound - its not developing root bumps on the stem, and I don't have roots on the stem reaching into the dirt. It does need some top dressing from normal settling though.

Here's a pic from a few days ago:

My amish paste, which is also in a 5 gallon pot and is a smidge smaller, is doing great - but it has about 3 fruit instead of 15.

Your picture didn't load. It just says "unavailable".

Yes I know many here grow in 5 gallon containers - myself included at times - but you will also find that most all use auto drip irrigation systems for watering and fertigation systems for feeding. Makes all the difference in the world. Currently my 15 container plants are on 1/2 gal./hr. drippers for 1 hour 2x a day and low-dose auto feeding every 3rd day. All are thriving and no BER.

As the BER FAQ linked above indicates, there are other contributing factors to BER so perhaps you need to explore them as possiblities.

Dave

I only grow a few tomato plants in containers -- some 5 gallon and some 15 gallon. They're usually the "leftovers" -- the emergency reserve backup plants that cannot fit into existing garden space, but you can't bring yourself to destroy them.

Anyhow, I tried container growing for the first time last year, just a couple of plum types, which are prone to BER. I used to say "oh, they come with BER built in". The problem was, imho, that I wasn't feeding them regularly enough. Actually, I downright neglected them.

Unlike soil in the garden/ground, potting mix doesn't contain nutrients and micro-nutrients, so you have to give the plants an assist with those things.

Unfortunately, before I could feed them regularly and hopefully turn things around, every single one of my plants ended up with late blight and the experiment came to an abrupt stop.

I have to think that potting mix probably does not hold nutrients like regular garden soil, and it's a fairly sterile medium to begin with, so they need to be fed maybe every week or so with a fertilizer that contains immediately-available nutrients, such as a water soluble, all purpose fertilizer.

I started regularly fertilizing the container plants this year, have some fruit set, and no BER so far. So, another question would be: are you feeding your container plants regularly?

All the best!

I too, think you may be overwatering. If they are not wilting, they do not need water. But FWIW, you can head down to a WM, HD or Lowes and pick up a cheap soil moisture meter and check it.

Having grown lots of toms in containers as an experiment, I have come to the conclusion that lack of Calcium and Magnesium is a major flaw in my grow trials. For reasons I have not identified, plants in pots seems to have trouble intaking Calcium.

If you can find some liquid Cal-Mag supplement and add a bit of it, you may get some success.

BTW, from what I understand, you can let the toms ripen, pick them, cut the bottom off and the rest will still be great to eat.

YMMV,

Mike

Oops, here's the pic that should have worked:

I gave the matter some thought, and I think its a couple of things, all of which everyone has mentioned. I'm sorry, I didn't mean to come across as hardheaded.

One, last year I did hybrids in pots that were a bit larger, in top soil. That probably explains why I didn't have to fertilize as much. I just got done fertilizing half of this years with MG tomato.

Second, I think I started out overwatering, then in the midst of my move, they got underwatered, then I think I wasn't quite giving them enough water - I was looking at my massive Great White plant, and most of the buds never got beyond tiny bud stage - they look dried up.

Third, to make matters worse, I believe that Stupice plant got LAST years potting soil - it was unused, but had sat in an open bag in my garage all winter. I'm guessing that's not good for artificial fertilizers.

The good news is that all of the tomatoes that set on the lower half of the plant seem fine, so not all hope is lost. None of my other plants are showing any sign at all. Last year I put a Stupice in a 5 gallon container in July as a test, and got blossom end rot on one of them, but they stabilized quickly. Then late blight got me, so I never got a ripe one.

My second stupice, which was transplanted about 3 weeks after the first, in fresh potting soil, after my move, isn't showing any BER at all, although it only has a few fruit set - one of them is pretty large though.

Here's a fused fruit where only half of the fruit got BER - the pointy end.

I have a few left over plants in 5 gallon pots and they have to be watered daily, sometimes twice. 100 degrees daily plus full sun means the smaller containers will dry out pretty fast, especially if they drain well as mine do. I see you are on concrete, mine are as well. That concrete gets hot and stays hot if it is in sun. Consider getting them up off the ground if that is an issue...just sitting up on some 2x4s would get them off the heat and allow air to move underneath. (Of course in zone 5 you may may call that warmth and find it good...in Dallas, concrete gets to where it burns your feet it is so hot and plants don't like that heat either). I've been giving mine waterings with liquid calcium and fertilizers a couple of times a week (daily waterings) and the earlier BER issue has decreased dramatically with very few fruit affected. Good luck.

I'll have to see how hot that part gets - it doesn't get full sun the entire day, especially on days with no cloud cover - the house and garage casts shadows on part of it.

We can get up to 100s in IL, but I think high 80s/low 90s is more typical. :) Right now, its 79 degrees, with a high of 90.

I had to go to Menards for more potting mix and cages, and picked up a moisture meter. It turns out that I'm overwatering. I tested at 9pm after a 90 degree day. The big pots were wet - a few of them pegged the meter. The 5 gallon buckets were all in the upper part of the moist area.

I top dressed most of them with potting mix, but didn't water. I'll test again tomorrow.