Kitchen Garden Forum

I feel a bit of a hypocrite. A couple of weeks ago I was happily advising someone else on the forum about how much water to give tomatoes, and now I'm getting blossom end rot problems with one of my greenhouse varieties, Olivade.
So - a bit of information, and a question.
First, I've been reading Terry Marshall's new book, Tomatoes. He quotes some old research from the Fairfield Experimental Station, which suggests that the daily watering needs of a tomato plant range from a quarter to half a pint on very dull, cloudy days, to one and a quarter, one and a half pints on fairly sunny day with some bright periods, and up to three and a quarter on very sunny days. Terry says these trials were done on free-draining soil, and moisture retentive soil would require much less.
So that all goes to show how complicated it can be.
Now my question. My greenhouse tomatoes are in big pots, standing in appropriate saucers. I've been watering them once, sometimes twice a day, depending on the weather. But I suppose I haven't been very scientific about it, just given them a big slosh from a 2-gallon watering can. I believe tomatoes have 'feeding roots' at the top, and the 'drinking roots' are at the bottom, so I suspect I haven't been giving the plants enough water to sink down to the bottom of the pot.
Would it make sense to water them to the point where water just seeps out of the bottom of the pot, into the saucer?
Sometimes that means they will get more, sometimes less. Obviously it is a bad thing to have them standing in water, because that rots the roots.
Olivade is on the hotter side of the greenhouse, so probably needs more water than Gardeners Delight, whihc to some extent is growing in its shade. I've had no blossom end rot on Gardeners Delight.

Hi Ken,

I don't know the answer to your problem but...

Three summer ago I grew tomatoes in clear storage boxes (£2 or £3 depending on size) as these were about 30 litres and I had rather a lot of them I 'adapted' a techinique described in Gardening under plastic-Bernard Salt. Basically straw bales are used with the tomato plant and some compost being either buried in the bale or placed on top in a pot with the bottom cut out. He also explains that the top roots take water and feed, but the bottom roots only take water. You water and feed the top (pot) and generously water the straw bale. However I half filled the storage boxes (NO HOLES) with straw and topped up with multipurpose compost. The tomatoes were planted in the compost and liberally watered until I could see water pooling at the bottom. I could then safely leave watering until the compost was drying out at the top and all water gone from the straw sump! The clear side allowed easy viewing. Result, no bottom end rot, but other toms in pots (with holes) did succomb. At the end of the season the straw had rotted beautifully.

Hope this helps

Hi Ken

Following your research I decided that it was the regularity and volume of the watering that was key so I have two practices now:

1 Each plant in the greenhouse get a measured litre of water per day(empty pop bottle full.

2 Each plant elsewhere gets a count of 6 seconds from the hosepipe per day. ( Thats how long it takes to fill the bottle.)

The plants at the allotment get watered if I go up and have the time and it hasnt rained. I dont fuss wiht watewring them becuase i didnt last year and had a bumper crop.

Hope this helps

David

As well as the water, aren't there some minerals that make a difference to blossom end rot?

I had a feeling that Calcium might be one - certainly a compound called dolomite is both cheapish and has good range of minerals that Tomatoes find beneficial for things like B.E.R.

That's in addition to your water volume calculations

You are probably right but it occurs to me that the tomato feed should have the right mix of minerals etc to prevent this occuring........... any chemists out there?

D

Thanks, everyone. Yes, I agree that blossom end rot is related to calcium deficiency, but the experts seem to think that it is not so much that there isn't enough calcium in the soil/compost, as the fact that at some point when the young tomatoes were developing, there wasn't enough water to deliver the calcium they needed. And Vivianne - are you still using your experimental method, or was it a one off three years ago?

Hi Ken,

Sorry, but it was just a one off experiment...I had put up a plastic greenhouse on a concrete slab and was using the plastic containers with straw as I had the containers availble after using them to move my partners books, record collection etc into my house. The next year I had moved the plastic green house onto soil and grew the tomatoes in the ground (did not get as good a yield, but May was horrible weatherwise last year too hot in the day and freezing at night, so my first lot of toms died and I had to buy plants in late May to replace my earlier grown ones.

I'm thinking of a hydroponic experiment, with a plastic container and those clay beads (I have about 30 litres of them sitting in the shed doing nothing) and one stray plant I had on my kitchen window (next to rubber plant) decided to root it's self into these bead in the drip tray...unfortunetely it's too late to set up this year...or is it? Any body use hydroponics for tomotoes? You can get kits, but they are horrendously expensive.....I also suspect this will be the equivalent of battery hens, but for Toms, you may get the yields but what does the product taste like?