Blossom End Rot Puzzle

[Jungle Jane]

If the pots are left sitting in over an inch of water & the tray always has water in it,the compost would be too wet,if it’s waterlogged there’s less oxygen in the soil. Try not to leave them sitting in water?

[MarkPelican]

I'm going to agree with JJ. I remember seeing a comment from some "expert", "You're more likely to harm your tomatoes by overwatering than underwatering". Which I've always taken to heart. As has been said, as I understand its a calcium deficiency which can be caused by uneven watering but I think the point is that when you unevenly water the roots get dried out and then flooded. So I think you're overwatering them.

I've also seen it said that you should water from below and feed from above, that encourages deep roots for water. So the way I water my plants is little and often. I use MFBs stood in trays. A small amount of water into the tray most evenings but, if there's water in the tray skip it. Feed once/twice a week (when needed) into the top of the pot but don't water as well.

Another suggestion is cold soil but if you're in a greenhouse, that shouldn't be an issue (unless you're using very cold water I suppose). Again I tend to water my plants using a watering can which has been filled and left in the greenhouse during the day.

Having said all that I still get Blossom End Rot but mainly on Italian Plum tomatoes (Roma for example).

The other point about not overwatering is that it is said to concentrate the flavour so once the tomatoes are ripening you should minimise the amount of water you give them keeping them just "off wilting".

[It never rains..it pours]

Here always add lime in the soil mix preplanting and get few problems now

[Snadger]

I always grow Ails Craig tomatoes grown from my kept seed. They are one of the cultivars that are renowned for BER but I still grow them because of there size and taste.
I have always understood that it is erratic watering that is the cause, but with the recent cold spell any check to growth will have consequences I would imagine.

[rary]

I would suggest that you lift the buckets out of the water and rest them on bricks shove a bit of towering up through the bottom of the pot to act as a wick then keep a water level in the tray and the towel will draw it up into the pot and feed at the top of the pot

[rary]

Just to add, you should water the pot from the top to start the capillary action

[Bonjour]

As others have mentioned, Blossom End Rot is due to calcium deficiency, often caused by insufficient watering early in the development of the fruit.

I've read on some ag-scientific websites that adding gypsum to the soil improves the availability of calcium without changing the ph. I've had BER problems before, so I thought I'd try it. Being in the building trade, and a cheapskate, I've ground up some pieces of gypsum plasterboard and sprinkled a spoonful on top of each of the pots. It will be interesting, but inconclusive because I'm also being more vigilant with watering, to see how I do for BER this year.

[ameno]

As others have mentioned, Blossom End Rot is due to calcium deficiency, often caused by insufficient watering early in the development of the fruit.

I've read on some ag-scientific websites that adding gypsum to the soil improves the availability of calcium without changing the ph. I've had BER problems before, so I thought I'd try it. Being in the building trade, and a cheapskate, I've ground up some pieces of gypsum plasterboard and sprinkled a spoonful on top of each of the pots. It will be interesting, but inconclusive because I'm also being more vigilant with watering, to see how I do for BER this year.

Gypsum (calcium sulphate) is neutral so will indeed add calcium to the soil without altering pH (or to be more precise, it's actually what's called a pH buffer, which means it has a weak neutralising effect on both acids and alkalines, so will bring all soils slightly closer to neutral pH).
However, gypsum is not very water soluble, so you may not get much affect just by sprinkling it on the surface. You want to mix it evenly into the soil/compost before planting, and it will gradually break down into water soluble forms over time through the action of micro-organisms and chemicals in the soil.

[Bonjour]

However, gypsum is not very water soluble, so you may not get much affect just by sprinkling it on the surface. You want to mix it evenly into the soil/compost before planting, and it will gradually break down into water soluble forms over time through the action of micro-organisms and chemicals in the soil.

Had I known that earlier, it would indeed have been the better way to add the gypsum. Unfortunately, I didn't read the articles until after my toms had been in their final pots for a couple of weeks. Grinding it to a fine powder was the best I could do.

Next year, I may well powder some gypsum and add it to the potting mixture for my tomatoes, peppers and aubergines.

[Plot70]

My plot is red clay over limestone so a mixture of local soil and manure works quite well. The clay contains lime and iron.