Drip irrigation for 4x8 foot raised bed

How many 8 foot long lines of 1/4 inch drip tubing are adequate for a 4x8 foot raised bed for growing vegetables? Do I want to have 3, 4, 5 or 6 lengths?? I’m going to be growing mostly baby lettuces and a few tomatoes. I am planning on placing the plants close together. I live in a dry, hot climate. I don’t want my plants to die of thirst! Thanks.

I’m growing mostly baby lettuces and tomatoes.


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I wouldn’t use 8 ft lengths of 1/4 inch tubing. Make your 8 ft runs out of 1/2 inch tubing and plug the emitters directly into the 1/2 inch tubing. Or, use the 1/2 inch tubing that comes with the emitters pre-installed in it. It is called drip irrigation tape. One of the brands is T-Tape.

How close together you need to put them depends on the water carrying properties of your soil. In heavy soils, water tends to pool on the surface and spread horizontally. With light soils, it tends to sink into the ground vertically without much horizontal spread. Therefore, your emitters will need to be closer together in light soils than in heavy soils.


Ah - okay - that makes sense. Why do you like 1/2" drip tape better than 1/4 " drip tube (assuming both have emitters built in). Isn’t the drip tubing more durable?

The 1/2 has more volume for a more consistent flow throughout the bed. Personally I find using the 1/2 as a main line and short 1/4 stubs with emitters on the end to be cleaner looking. Don’t forget about soaker hoses too, I hide it under my mulch

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I run a 1/2 inch line 8ft down bed and then put 4ft pieces of 1/4 inch soaker hose tubing every 18 inches or so

As JimmyM said, for consistent flow. With the 1/4 inch tubing, you will find in a long run of it that the first couple feet release most of the water, and by the time you get to the end of the run the volume is considerably less. Also, 1/4 inch gets plugged up more easily, especially if you have sandy soil or hard water. I try to stay away from 1/4 tubing as much as possible.

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@CA_Poppy OK, sold. I wish they would advertise that fact at the drip irrigation store!

Unfortunately, there’s a lot about drip irrigation you only learn through the experience of using it in various situations. No one ever told me it’s of paramount importance to determine what happens to water dropped in the same spot on your type of soil before you design your system. Does it run right into the soil or pool on top of it? Does it spread vertically or horizontally? Or, as in my case (because my soil is the same kind of sand you find in sand dunes at the beach), does it just flow over the top of the soil in whatever direction is downhill without penetrating the soil at all? (And if you wondering, yes, I did make drip irrigation work, but I have to use sprayers, not drip emitters.) All of these things have a huge effect in determining your most optimal drip irrigation design.

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And do you set it up that way because you get more consistent flow from the 1/4 inch soaker? Or is there another reason you set it up this way? Thanks!

At my sister’s I setup a plain home depot soaker hose with a dedicated garden hose controlled by a timer. It’s all covered with landscape fabric because she hates weeding. It was much cheaper then the drip irrigation I setup but she still has great results for her tomato’s,kale and beans. The drip irrigation I have at my house is relatively expense because I used 1/2 main line and those barbed 1/4 connecters that fed individual emitters to each plant. I can’t see that working for spinach but they make small sprayers for that. You could get away with 3 or 4 inline emitters on one 1/4 tube but the first will surely water more then the last. Drip depot has a few starter kits and more information.

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I ran into this exactly issue with my first try for irrigation. The quarter inch tubing needs to be in very short runs because the pressure loss is enormous.

I did it because I find the single emitters sometimes clog mainly, but I think it does a better job of expanding plants roots because there is water in different areas for it to reach for

So – next question – if I have 1/2 drip tubing running down the length of my 8 foot long raised beds, how far apart should they be? The bed is 4’ wide. The soil is well draining. I’m planting a variety of vegetables.