[cjskts]

I cant win with my tomatoes. I water them and ended up with blossom end rot, so i watered them more and now they are splitting. My tomatoes are in grow bags with pots and are in the greenhouse. One type is Moneymaker, not sure of the other variety as they were donated by another allotment holder. I have always watered them in the evening and made it up there every evening, but all of a sudden, they arent happy.

I am feeding with Tomorite as directed and watering all other times.

The tomatoes do still taste fab (way better than shop bought) and i'm still eating the split ones.

I watering every night too much now they are fruiting? (will add that this is my first year with an allotment)

[Ice]

Are you changing the amount of water according to how dry the compost is?  Regularity isn't the answer, maintaining a consistent level of moisture in the compost is best.  Also, water from the bottom if you can.

[Bernard]

I used to use growbags in my greenhouse for tomatoes but a few years ago started growing direct in the ground. The result is much better control.

[cjskts]

I generally fed/watered them 2 watering cans between 3 growbags. Just can't get a happy level now.

Growing in ground isn't an option, i dont think, i'll ask hubby.

[Livinhope]

I grow mine in black buckets (so have to water from top) and make sure that the compost never looks dry.  Doesn't blossom end rot occur when they have been allowed to dry out then watered copiously?

[Ice]

Yes, letting the soil dry out can cause this. 

[JayG]

I grow mine in black buckets (so have to water from top) and make sure that the compost never looks dry.  Doesn't blossom end rot occur when they have been allowed to dry out then watered copiously?

Splitting is definitely caused by inconsistent moisture levels in the soil, but can happen to some extent when there are wide variations in temperature as well.

Blossom end rot is also usually caused by irregular watering but it is a bit more complicated than that; some varieties are more prone to it than others, and also overfeeding can change the chemical balance of the soil which interferes with calcium uptake to the fruits.

Still really comes down to maintaining consistent soil moisture; you might have to water twice or three times as much in hot weather so there is no rule of thumb!

[kingdhesiii]

I will also add that if you aint really sure how moist the soil in buckets is then you could buy a cheap moisture probe which will let you no if the soil is moist enough right down into the soil.

[Bernard]

Just thought of a detail -
when I used growbags I always started by sticking the fork right  through then to put some small drain holes in the underside. Helps to counteract overwatering so you can always err on the heavy side to avoid under watering.

[Foghorn-Leghorn]

I know this is of no help for this year's tomatoes but for info for next year, this is how I grow my tomatoes.

I have built a bed in my greenhouse which I lined with thick polythene and then put pea shingle in.  I've then cut the bottoms off some large plant pots and planted the toms into the pots, using the contents of grow bags as growing medium. 

You then just keep the pea shingle topped up with water so the tomatoes can slurp up what they require and just feed in the top of the pots once a week. 

It works for me and I pinched borrowed this method from my dad and grandad and it works for them too.  Hope this helps. 

[CHICKENGIRL]

i think i might have to 'borrow' that method too Foghorn-Leghorn      thanks