I'm using dripline  1/4" tubing with laser cut incisions about every six inches  I picked up at Ace Hardware. The stuff comes tightly coiled, so it would be impossible to keep it straight unless you pin it down somehow, even if it's been in the sun for a while. As an aside, when we had our backyard landscaped last summer I had them go ahead and run 3/4" line on it's own valve out to where the garden would be. They installed seven ten foot lengths of dripline directly from the buried main line. I turned it on for the first time a week and a half ago when I completed my first square foot box; I noticed this last weekend that the area where the dripline emerged from the ground had become a sodden mess. A plug or three and replacing dripline with normal drip hose and the problem is solved. And I'm actually reusing the landscaper's dripline in my first box, but it still won't stay straight, even after a summer of Southern Arizona heat. Anyway, I've got two short lengths of 1/4" tubing coming off of the 3/4" line going to my box. Each one has a small micro-valve, and then goes to a tee. Out of the two tee's come four ten foot lengths of dripline, that I have coiled throughout the box. I'm still trying to figure out how long to water and, as the summer attacks, I'm sure I'll be adjusting the water duration weekly. It's quite possible I have too much hose in such a small area, but I think it'll work out well, especially once my seeds germinate and I can lay down a layer of straw mulch. One downside that I do see is that I don't have a fine a level of control as I may need later in the season. For example, I've got tomatoes and onions (among others) in the same box, and my understanding is that you're supposed to stop watering onions when the stalks turn brown, something that would be bad for the tomatoes and other veggies. Oh, well, I'm sure I'll figure out something by then ...

Typical well designed spray irrigation will at best be ~ 60% efficient WRT water utilization. Atomization in air, overspray, runoff, and surface water evaporation create the water loss and decrease efficiency. Most systems are so poorly maintained and not adjusted for seasons that this numbers is significantly lower. Typical well adjusted drip systems are more than 90% efficient with water use. Even when they are not adjusted for season, they conserve more water than even a fine tuned spray system. The challenge with drip is two-fold: 1. It is usually more labor intensive to deploy and maintain. 2. To meet the high efficiency number you must do a lot of figuring and arithmetic to design the system correctly. To the second point; A proper design requires: a) Calculating the daily amount of water each type of plant needs during the hottest, driest month. b) Determining the water holding capacity of the soil. c) Deriving from above data the best schedule for achieving the least frequent deep watering of the plant root zones while providing their daily need of water. If you spend a few rainy cold winter days figuring these things out, it can pay great dividend come growing season with healthy happy stress free plants.

With emitters I always look at how well the water disperses. In sand the water does not spread well side to side and tends to go down in the shape of an inverted funnel with steep sides. In clay soils it will spread out much better, then there is everything in between. The water retention capacity of your soil also makes a difference, as does the requirements of the plants being irrigated. So with all of these variables and not knowing more I would start with 40 minutes a day and adjust from that point. I have come to rely on what I call my finger tip test. Just push a finger tip into the soil, here in Florida the cooler to the touch the more moisture in the soil. I hope that this gives you something to start with that will be useful to you.

There is no simple answer. It is something you have to determine specifically for your garden, the size of the feeder line, the size of the drip emitters, the type of plants being watered, the soil composition, how well it drains, the size of the bed, the climate, etc. Plus any attempt to determine a set schedule still has to be flexible because the frequency changes as the season progresses and the plants grow. And even then you still have to stick your hand deep into the soil first. So like any method of watering, the schedule isn't something that can be written on a calendar but is done as the plants indicate they need it. So assuming we are talking about tomatoes and only tomatoes and assuming they are in ground and assuming the standard 1/2" line and 1/2 GPH emitters then 60 minutes once a week is a fairly good place to start. But in Florida you may need 30 mins 3 x a week in the heat. That is a lot of assumptions without much info to go on. :-) Dave