Kitchen Garden Forum

In the polytunnel I am growing some tomatoes in raised beds and some in Growbags. They seem to be doing well and fruit is setting on all of them. I have been watering them every morning, but is this too much? There does not seem to be clear advice anywhere about how much water to give each plant, and how often.
Advice gratefully received.

Well, I had a quick google expecting to find some clear guidance, but you are right, it is hard to find. Geoff Hamilton does give some ideas of quantity in his Organic Gardening book, but I can't remember them...

Of course it depends on your containers, and how hot it is, and how big the plant is. I would say that you need water once a day at least, or twice in the sort of weather we have today. Some sources say 3-5 gallons per plant per week, but that sounds excessive to me - bear in mind that that might be for plants in a commercial glasshouse, several metres tall ! My rule of thumb is starting to wilt = too little, sitting in a puddle = too much. I tend to be mean with my plants, too much water really compromises flavour. And flavour is the reason I grow them myself !

I can't give advice on the tomatoes in raised beds, but in growbags I always make two small slits about an inch up from the bottom of the bags, facing me, and when I am watering and the water starts running out of those slits, I know that is enough with some to spare and to be soaked up. Seems to work.

Thanks to Tony & Monika for your useful input. I guess I will carry on as I have been doing and try to keep the happy medium between too much and too little!

Useful growbag tip Monika, thank you.

So, Geoff Hamilton said:

"Water the plants in initially then leave them to search for water, thereby encouraging extensive root growth. Water again after about a week, and from then on give each plant an average of 1 litre (2 pints) per day. The smaller cherry tomatoes Gardeners Delight and Sweet 100, however need only about 1.5 litres (3 pints) per week if they are to retain their sweetness."

Tony.

This kind of advice is completely new to me. I wonder if it applies to toms in polytunnels as it does get really hot in there at times (up to 40C in June when we had that spell of good weather here in Wales) and the amount of water recommended seems very low. Anyway, it is too late for this year, but I will certainly try it next year with a few plants and see how they get on.
Many thanks.

Hi Columbine,
One thing I would suggest that you change in your watering regime for Tomatoes is to water after the sun has gone to bed and when you water the plants are not competing with evaporation and it means that what water you give them has all night to be drawn up by the plant.
This regime is especially good for those in a polytunnel. You will find that your plants will be able to sustain themselves with the onslaught of the sun and heat in the tunnel during the day.
JB.

Hi JB
That's a really useful tip about watering in the evenings. I shall do this from now on.
Many thanks.
Columbine