These tomatoes are in raised beds with drip tape w/a 5 gpm regulator. We use a moisture tester and watered as needed, usually 2-4 hrs a day, 2 -3 days a weeks. You can see the results. The drip tape is under the mulch
If you will go to the thread Coconut fiber blocks you will see tomatoes being watered daily with a single emitter per plant with good success.

My water needs vary depending on the weather. I only use a PVC system and it is all manual.

Nate,

No one can tell you how to water or when to water, but what you should know is that you cannot water on a schedule because you have no idea, day to day or week to week, what sort of rainfall Mother Nature will, or won't, send your way. If you set yourself up to water for an hour a day every other day, maybe that will work....but maybe it won't. The plants' watering needs vary too much to be put on a strict schedule.

Everyone's watering routine will vary, based on many things: how much rain is or isn't falling, how hot it is and how much the heat is evaporating the moisture out of the soil or how fast the plants are transpiring moisture, etc. Different kinds of soil absorb and hold water differently. Clay soils, once wet, can hold water a long time, making it unnecessary to water them for a while, while sandy/silty soils may absorb the water better but then they also dry out more quickly. So, you have to tailor your watering scheme to the specific kind of soil you have as well as to how much water your plants are getting from rainfall. You cannot water by a schedule or by some sort of plan.

It would be nice if somebody could say "water at 5 gpm for 90 minutes a day every third day in June, but increase it to 90 minutes every second day in July..." but real life doesn't work that way. No one, not you and not us, knows if you'll be getting 6" of rainfall in June or 1", and only you can watch your soil and see how quickly it dries out after receiving rain or after a set irrigation period. I don't even water my sandy soil areas at the same rate that I water my heavily-amended clay loam areas.

You have to do what Ponderpaul and Larry both said....water according to whenever the plants need to be watered. You know, small tomato plants that are a foot tall in April have certain watering needs, but plants that are 6' tall and loaded with ripening tomatoes in June have entirely different needs. There is no cut-and-dried formula. You merely have to check your soil and water when it is dry.

You can use a moisture meter (I saw some of them on the seed racks at Lowe's last week) or you can stick your finger down into the soil to see how dry or wet it is.

With tomatoes, it is important that the soil be kept evenly moist. If you let the soil fluctuate back and forth from dry to wet you likely will have issues with blossom end rot. And, to be clear, moist soil is good and is desirable. Soggy, wet soil is not as it can lead to root problems and diseases. Also, tomatoes that are overwatered as the fruit ripens often have poor flavor, so you don't want to overwater your plants and have nothing but poorly flavored fruit as a result.

If you have tomatoes growing in containers, once you have them set up in the containers and have set up a drip line system, you can put it on a timer. In fact, you likely will need to because containers may need to be watered during the day on a hot summer day while you are at work. Even when you put a drip system on a timer for your containers, you shouldn't just set it up and walk away and forget it. You need to check your container soil every day and make sure it is getting wet enough but also not getting too wet. I try to put containers on a dripline that are all the same size and are filled with a similar mix so that they have the same basic watering needs, but I have to watch the soil because some tomato plants suck up a lot more water than others. That is to be expected because some tomato plants still will get 6 to 8' tall in containers and will drink a lot of water, what smaller determinate or ISI types stay smaller and don't need as much water.

I run emitters every few inches through most my beds and try to water the whole bed evenly. Here's why. If I had tomato plants 4' apart and only put emitters 1' away from each plant on either side or all 4 sides or whatever, then the soil that is farther away from the emitters would get dry and could, can and will wick away moisture from the wetter soil adjacent to it. So, you need to evenly water the whole bed to avoid the wicking effect. I also water the beds evenly because I companion plant smaller plants in the same beds.

With practice and experience you'll figure out how your soil holds and releases moisture, and you'll be able to customize your watering accordingly. However, you cannot expect it to remain constant throughout the growing season. Take into account plant size, heat, evaporation and transpiration rates, the needs of plants loaded heavily with fruit, etc. Your plants needs will vary from year to year. In 2010 we had great rainfall in my county---almost 50" at our house and I barely had to water at all. In 2003, we had 19" of rain and I had to water a lot more. What worked in one year will not work in another year with different conditions, so you have to be flexible and constantly experiment to learn what works for your garden in your soil with your weather and with whatever stage your plants are at during that period.

It sounds harder than it is. Check your soil (I suggest using a moisture meter). When the soil is drying out, water it. When it is moist, don't water until it dries out some. What matters is not so much what system you use or how many emitters you use (as long as you use enough of them at a rate that moistens all the soil evenly). What matters is that you give the plants adequate moisture when they need it and otherwise leave them alone. I have found more people overwater than underwater. It is part of a phenomenon commonly referred to as "loving your plants to death".

I can tell that you are giving a great deal of thought and putting a lot of effort into doing everything right this year. That is admirable. However, you cannot garden "by a formula or a schedule". You have to garden intuitively, from your heart as well as from your brain. Trust yourself to check the soil, decide if it feels too wet, too dry or "just right", and be willing to make adjustments week to week or even day to day.

Taking care of a garden is a lot like taking care of a newborn child. Everyone tells you what to expect, what to do, how to do it, etc. But, every child is different and every garden is different. My son was a light eater who never wanted to finish the amount of formula that "they" (the pediatrician, the books, the magazines, etc.) said a newborn child should drink. Nor did he particularly want to eat on a regular schedule. He wanted to eat when he was ready to eat, not when my clock said he ought to eat. My nephew was the opposite. He wanted to have the amount that the experts said he should, plus a whole lot more. He was hungry all the time. If you tried to feed him on a strict schedule, he threw a fit because he was hungry now! He needed more food and he needed it when he was hungry. What worked with my son did not work with my sister's son. Yet, both grew just fine and were happy and healthy. So, remember that with your garden---its needs are unique to it and may not be the same as what my garden, or Larry's or Ponderpaul's or anyone else's garden's needs are. Just focus on giving it what it needs when it needs it, and only you can observe it and figure out what those needs are and how to meet them. That is part of the mystery of gardening. This month we start our 15th year here in Oklahoma, and I have not done things the exact same way in any 2 years because each year throws different variables into the mix. It keeps life, and gardening, interesting, and is part of the challenge of being a gardener.

Dawn

I appreciate Nate asking this question. I am installing a drip system for the first time and also wondering which emitter I should use for watering needs in my tomatoes and peppers. Thanks for the answers, especially Dawn. I live in Idaho.

I use the same rate of emitter tape on all of my garden areas but do vary when I water. I water only when needed. I was skeptical when I purchased the first tape and it said to pre water for 24 hrs of longer before planting. Has worked well especially in my raised bed and also my garden ares which have a sandy texture. Understand all of my garden areas have a sandy texture and some are basically 100% although I have built them up through the years. Even in the heat I only water the raised bed once every 2-3 weeks once the plants are established. I was gone a lot last summer and nothing ever hurt for water even when I was gone 5-6 days. I deep water for a min of six hours and then wait until the plants show they need water before watering again. I think most of my tape has 1 gph emitters. I like the tape as it waters between the plants and encourages the roots to spread out and develop a good root system.

I'm already regretting not using the 'tape' rather than individual emitters. Mainly for the rationale elkwc gave! We'll see how it goes for a while but my next purchase will likely be 1/2" emitter tubing... It's quite frustrating not to have knowledgable clerks around.