If you have plants in "large containers" and they droop after being late with water only part of a day, you may have a watering problem. Are the BER fruit all on one plant or are they on random plants? What are the roots growing in?

Tomato plants are more prone to BER in containers than in ground for the following reasons:
== Irregular moisture level .... wet <> dry ...wet <> dry cycle. Smaller the pot/container the bigger and more probability of having BER.
== Lack of Calcium: This depends on the kind of potting mixed used. Does it come with Ca ? If not then does your fertilizer has Ca ?
=== Some variety of tomatoes are more prone to BER than others. This is an inherent genetic characteristic of the variety not being able to deliver Ca to the fruit, even though there is plenty of Ca in soil and even in the plant tissues itself.. I can name one such variety : ROMA (my personal experience)
JMO

Sey

I use gypsum on my BER plants and it fixed it right up, even saved a fruit that already have it.

Perhaps if you defined "large containers"? Too small a container for the plant is a major contributing factor as it is nearly impossible to maintain the consistency of the soil moisture level. And using too small a container would explain your comment on wilting after such a brief period without watering.

Also you mention "soil" in these containers. Hopefully you are actually using a soil-less potting mix. If not then that is another major contributing factor.

Dave

If I get BER it's always the first ones. It seems to get better with time.

Thank you for taking the time to respond to my post. I am using 5 gallon containers. One plant per pot. My soil is a mixture of potting soil, compost and peat moss. The plants are on my deck and get sun from 10 oclock on and that is why I assumed the pots seem to dry out fast. We just purchased a sun shade to help with the afternoon blistering sun we can have here. I am at a loss. Patsy

An addendum to my post. We decided to try containers at least for some tomatoes b/c we live in a wooded area and for the last 3 years have lost everything we planted to deer and squirrels

Hi Patsy and welcome to the tomato growing place on Garden Web!
"I am using 5 gallon containers. One plant per pot. My soil is a mixture of potting soil, compost and peat moss."
This is a marginal size for growing tomatoes as mentioned by digdirt and usually results in difficulties. Just because it looks large to you vs. some other pot, doesn't automatically mean the tomato is suited to be grown in it. Many in this forum use 20 gallon containers, one per plant, A tomato is truly happy in a barrel if you containerize it. People have learned many tricks and can do it in a container, but:
"potting soil, compost and peat moss" is a lethal combination in a small 5-gallon container. You may be watering to much and the roots may sit in water until they dry it out. Tomatoes drink a great deal of water, so although the shade cloth may help, remedy the part that is from the Sun, the tomato plant still wants to drink a lot.. A picture would be helpful. BER can have its root cause in many things, though it may be as simple as too weak fertilizer and waterlogged roots for part of the day. As mentioned by Sey it can worsened by a lack of calcium in sufficient quantities. That is easy to do if you depend on Miracle gro. The plant's demand spikes for fertilizer as soon as it has fruit to support, in addition to the growth it dopes anyways.

Good luck with the deer and I hope this helped a little about the reality of the situation.
PC

Hi Patsy, I grow in containers also, but much larger ones. 5 gallon containers are really too small for tomatoes unless they are dwarfs. Some people can do it, but it will be a lot more work. In hot weather you will probably have to water twice a day, maybe more. Every time you water you are washing out nutrients, so you will need to fertilize with a good liquid fertilizer with all the macro and micronutrients. For your size containers, I would say every three days when you are watering twice or more a day. When you get your moisture level more constant, the BER will end. Good luck and next year consider 15 gallon pots for each tomato.

Jennie

PC and I posted at the exact same time, with the same info! How funny. Good luck Patsy.

Jennie

Unfortunately that is what I feared and why I asked. 5 gallon containers are definitely not large containers when it comes to tomato plants. So until you can somehow stabilize your soil moisture issues - like with some sort of auto water system if you can't be home to check them at least 3-4 times a day - BER will be a on and off problem for you depending on the weather, plant variety and size, fruit load, etc. Next year consider at least doubling the size of your containers. 15 gallons is ever better.

I have the same problems - woods, deer, squirrels so we greatly expanded our container garden on the deck this year (34 plants) and all are in a minimum of 10 gallons Dwarfs), some determinates in 15 gallons and all indeterminates in 20 gallon containers.

Dave

Thank you all so much for the info. I hope I can salvage something. Such a shame b/c the plants are so full and healthy. Guess I will just have to suck it up and make changes next year. Thank you all again. Patsy

Pat, do not despair !
Often, BER goes away after a while.
In the meantime just try to control the moisture level by watering regularly, before the soil gets too dry.

Sure, big container offers an advantage in more than one way, as it mimics the in ground planting.
BTW: I am growing several dwarfs in 4 gallon pots. But in my location it does not get very hot. Many people grow tomatoes in 5 gallon buckets with relative success. The thing is that they need more attendance.

Sey

Just curious... was it hydrated lime or maybe dolomitic?