How much daily water required for tomatoes?

[philpill]

Hi I'm a newbie to this website, and an unaccomplished tomato grower. I have on several occasions attempted to grow tomatoes in the past in New Mexico with varying
results ( mostly bad). I moved to Phoenix , Az a last year and decided to try again. i planted for varieties of plants to see which might work here for me. Well being a newbie,
i planted small plants in early april , not understanding the effects of excessive heat in Phoenix ( over 100 consecutive days temps well above 103 degrees last summer), so after reading multiple blogs on how to grow tomatoes , decided to try. I now have beautiful large dark green plants with some small green tomatoes which are growing very slowly. We've already had 10 days of temps above 100, so I think the heat is now
my worst enemy. I had 3 tomatoes ripen , one which I ate and enjoyed and 2 which
the birds ate for me. I didn't know birds liked ripe tomatoes. I've also found out Phoenix has two tomatoe growing seasons.. Feb thru May .. and mid-sept thru mid-december.
so, unfortunately my plants over the last few days are wilty and slooooow fruit growth
and I think the heat won this round. After much reading on fertilizing needs i'm ready to try again this fall. so.... that's me................ A long post, but the admin says do this intro. Thanks , Phil

[Milan HP]

Well, it's actually a philosophical question. It all depends on what we are like and what the plants need at any given moment. It's rational as well as emotional.
There are a few guidelines we may or may not follow, but absolutely no "if you follow this, you'll be (or rather your plants) always safe". And that's the beauty of growing anything.

Speaking only for myself, I'd never delegate all the responsibility to an automatic watering system, even though it was controlled by a "clever" computer or even AI. I still believe that human brain is superior to any Artificial Intelligence. We see, we react. Promptly. No AI can have the same level of input info (self- driving cars are a good example). And there's also the problem of my feelings: I would probably feel "excluded", but definitely without control.

I fully agree with KarenO: there isn't an "instruction manual" for watering plants. Managing that is always up to the gardener, no matter if commercial or amateur. It's quite intuitive. It's part of how well we master the job or hobby.
Does it make sense?
Milan HP

[Volvo]

For our neck of the Woods and cropof late i have been trying to only water once or twice a week at best as there is consistant moisture in the soil and when i add Food to the plants i try water it in..

[Milan HP]

Hello Volvo,
that's exactly the point. I believe that most mistakes we make (myself too) result from too much water we give our toms rather than too little. No, it doesn't usually harm the plants, but it spoils the fruit quality, mainly taste.

Milan HP

[D.J. Wolf]

Milan, you may have a point about too much water affecting taste. That said, here last year you couldn't have overwatered the tomatoes if you had tried to lol. This year isn't as bad, but I'm still shooting for somewhere around an inch every 3 days. I do have a rain gauge though, and track all our rainfall so I can adjust the amount of water I put on everything.

I probably should have rethought my irrigation setup for the year to be honest. As it is, I'm watering bell peppers, all 15 tomatoes, broccoli, cauliflower, and pumpkins all on the same soaker hose hookup. It causes me a little bit of extra work hand watering stuff that I think needs "a little' more water than everything else, but it works. Next year, I think I'll have all the tomatoes on one line so I can evenly water them.

[Milan HP]

Hello D.J.
that's exactly my point: we've got to do our best to get enough info about the real conditions and to understand the principles (or better still the other way round). And, of course, act accordingly. Automatic systems can't really do that, especially if they attend to more sorts of vegetables.

Milan HP

[D.J. Wolf]

Well, I wont have to water for awhile Milan...if there's anything left out there after the rain we just got. Thunderstorm came in and just dumped. My potato plants are flat on the ground, and there are puddles standing in the freshly replanted corn patch. I have not yet checked the gauge, but I would guess we got an inch or more in about 30 minutes, then it slowed down to just a downpour!

[Milan HP]

Hello D.J.,
my poor toms got 2 storms with hail very soon after I planted them out. I am happy to say they survived and as we've had a spell of warm weather for app 10 days they are recovering just fine. OK - zero killed.
Milan HP

[D.J. Wolf]

Milan,
Just an update on the rain. Had 1.75" (44.45 mm), most of which came in the first 20 minutes or so of the storm. No hail luckily. Everything seems to have survived, even though the potatoes are no longer standing straight up.

A bit more on topic, this thunderstorm illustrates the difficulties of keeping your tomatoes, and other crops, evenly watered. As I stated before, I shoot for about 1" of water every 3 days. In super hot dry conditions I'll do .5" every other day, or even around .33" every day. But mother nature can and will mess up the best made irrigation plan in a heartbeat and there isn't much we can do about it. What works for one person in one area might not work for the next person in a different area. I do think it is good to set a target amount of water/day or week or whatever, but you have to be ready to adjust based on what the plant seems to need, and what mother nature decides to give you. Obviously, my soaker hoses will remain off for quite some time lol.

[rockman]

Years ago an old timer said the plant is ok if it looks stressed during the day, but if it is still wilted the next morning that is watering time. He said the tomatoes are sweeter in a drought and they find their own water, like strawberries do.

[D.J. Wolf]

I don't know about sweeter rockman. But I believe all plants will try to find the water they need to survive. Pull a big kosha plant out of a wheat field during a drought, you wont believe the root system they develop trying to find water. Dandelions are the same way. The problem is, in my opinion, that forcing a plant to do this can, and will, cut production. I do agree that a plant is fine if they look a bit droopy or wilted during the heat of the day, but I feel that if they get to the point that they are still wilted or droopy the next morning, they needed water the day before.

There is actually a scientific formula used to show the estimated total water usage per day of plants in various stages. What the actual formula is, I have no idea. But you can look up evapotranspiration rates online to get a guess or idea of generally what plants in your area need. The state of Montana used to maintain sites at different locations, and the noon ag broadcast would report the previous days rate. The nice thing about that, for those who were irrigating, was it was total water usage for the day, both what the plant used and how much was evaporating directly from the ground and "lost"

[Milan HP]

Yes, D.J.
It's always been my philosophy: one man's meat is another man's poison. Flexibility and paying attention to the conditions are the key to success.
In my experience over-watering - but I admit that there are some spots in the world where that is virtually impossible - is probably worse than keeping toms on a water diet. Of course, commercial growers need as high production as possible, unlike us, small gardeners, who only grow the plants for the family and friends. This year I'm going to strive for the best taste, not maximum yield. There's a snag though: I suffer when I see my plants stressed. So I am not quite sure what I'll actually get.
Milan HP

[Gardeneer]

There are soil and weather factors...Where does the water go ? DOWN THE GROUND OR UP IN THE AIR ?
But I give it a ball park weekly number.. 2 inches. That is about 1/3 gallon per plant per week..Assuming a plant takes up 6 sqr ft.

[Milan HP]

Words of gold, Gardeneer.
What about a list of factors at play? I'll give it a try, feel free to correct or expand it.
a) the climate as it is displayed in the weather. In fact, what weather we can or should expect. Our crutch: the weather forecast (in my experience reliable up to 70% for tomorrow, 60% for the day after tomorrow and then it's a toss of coin)
b) the size of the plant
c) the size of the container or the ability of your garden soil or mixture to retain water
d) where the water actually goes: to the roots or just in the general area (I use plant containers with holes in the bottom set in the ground an inch or two above the root system at the moment of planting out. Disadvantage: on cold days it lowers the soil temperature)
e) your expectations: that is if you want big toms or rather tasty ones (but the big ones are far from tasteless)
f) how well/often the ground around your toms is hoed
g) how many weeds there are under your plants and of what size
h) human nature, in other words our beliefs and mainly our laziness. Which includes the difference between an automatic system and manual watering.
Have I missed anything?
Milan HP


P.S. And there's a big difference between a professional grower and an amateur/hobby one.

[Gardeneer]

Milan, your list nails it.

So there is no one answer to all conditions. The fundamental thing is to keep the soil/media consistently moist but not soggy.