Drip Irrigation Spacing Question, Raised Bed

11 years ago

I am putting in a new raised bed garden at our new house. This time I would like to add drip irrigation because our summers here in the North Carolina piedmont are hot hot hot and I hate to get out in the garden and water at the times that are usually available to me (I have three young children and timing is very sporadic as to what I can do when).....

I'm going with poly drip and here is the general plan:
tomatoes - individual drip emitters installed directly on 1/2 tube - one 1/2 g/h emitter per plant at the base under mulch. Tomatoes will be planted approximately 18 inches apart.
cucumbers - same as tomatoes except these are closer together
squash - same as tomatoes except these are further apart
peppers - 1/4 inch "soaker hose" drip tubing with emitters on the inside, 12 inches apart to match the peppers planted 12 inches apart
beans - 1/4 inch "soaker hose" drip tubing 6" apart spacing

Does this sound reasonable? I have 10 different beds, some 4x8s and some 2x22-27s.

I have done lots of research, still having trouble figuring out which plants need which spacing. My plan is to run 1/2 inch tubing at one end of each short bed and both ends of the long beds and run lines off of this - either 1/2 inch tubing for the individually spaced emitters or 1/4 inch "soaker hose." I am planning to put a control valve to control each bed so that they can be turned on and off. I am also planning to use the "direct-loc" control valves so that I can change out configurations between the beds when I change crops.

Of course I will start the setup with a pressure regulator and filter at the beginning. I do have one question about that - my garden faucet is about 50 feet from the garden, slightly downhill and across the driveway. I thought I would install a splitter at the faucet and then run a hose to the garden, across the driveway (eventually hope to run pvc pipe under the driveway) and install the pressure regulator and filter where the hose enters the garden through the fence. Should I do that or install it at the faucet?

Any thoughts or comments would be much appreciated!

Thanks for listening! Nicole

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Comments (4)

lehua49
11 years ago
ng,

Spacing is not as important as time. You can run ay system long enough to get the proper water needs to the plant. The difficulty starts when you have different plants with different water need amounts on the same zone. You have the right idea about being able to shut off sections to cultivate the plot while growing other plots. Different vegetables have different life cycles. Soaker hoses are difficult because you can't control the amount of water coming from the hose (they also clog over time) as with drip tape or emitters. On the same zone you can have plants with larger drip rates and those with slower drip rates but it is trial and error to set up. It is better to have separate plant zones with similar watering needs together and just work out the time by trial and error method. You do have to initially check the water in the soil to see if plants are getting what they need. Your idea about getting water to the beds is a good one and the way I would do it. Make sure you pour some concrete at all the bends so they can't move (thrust blocks). JMHO Aloha
ngraysmith
Original Author
11 years ago
Thanks for your response. I do want to be able to set the system on a timer and leave for a few days. It sounds like I really need to look at the water needs of the different crops.

I know cucumbers need lots of water, so perhaps I should put two emitters with them, although I'm hoping that having the emitters closer than tomatoes would compensate for this. And, I might switch the beans over to every 12 inches and see what happens.

Any other thoughts?
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I think 1" to 2" per week sounds good. lets take 2". So you gave to figure it out how much time with a given flow rate you will get that. Lets say that a bed is 4ft by 8ft. That is 32 sqr ft. ONE inch water will add up to 5.3 cu.ft. That is roughly 40 gallons of water. Now we have to know the flow rate (GPM = gal per min). Roughly, a fully open garden hose will have over 3 gpm. But lets say that your drip line(just the part coming to that bed) has a ONE gpm flow rate . Then you will need 40 minutes. But right now I will cut it in half and if rains, just shut it off completely. ......................................... HOW to measure flow rate: Jut put the hose in a 5 gall bucket and time how long it takes to fill it: flow rat = 5/time (in minutes)
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Hello everyone i recently put in six raised beds. I would like to do drip irrigation in the beds but I don't know if it is possible. I know that i can get hoses but they are too long for my raised beds. If i run them between the beds then the ground between the beds will also be getting watered. Does anyone have any ideas on how I can solve this problem? I would really appreciate any ideas. thank you all
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How far apart are the hoses? Also, you have to dig your hand into the mix to see if the water is fanning out as it goes down, or if it is mostly dropping straight down. It is entirely normal for the surface to remain dry except for an inch or so on either side of the hose. What your mix is comprised of makes a difference as well. If you are using Mel's mix you may need to up the percentage of compost to get the moisture to wick into the drier areas well. The peat, once dry, won't wick the moisture to itself. It has to be at least damp before it will do any wicking. Using a light mulch also helps as the water will kind of circulate a bit from evaporation under the mulch and provide a more even moisture level. In any case I don't think you will get away with anything over 12" spacing with those soaker hoses (I have the same soakers). Anything over 6" spacing between the hoses and unless you use a moisture trapping mulch you won't get the entire surface moist, but the water should fan out enough as it drops that 3" down everything is watered. If this isn't the case either move the soakers closer together or increase the amount of compost in the mix.
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You can also add in extra water emitters for higher-water needs plants. I have a limited number of zones I can break my beds into, so simply changing out one type of emitter for another works fairly well. For example, instead of using the drip lines for your squash and tomatoes, run a regular (non-emitter) line directly to the base of the higher water use plants with a larger emitter on the end (1-, 2-, 4-gallon per hour, depending on how often/long you have your system set to run). All of my beds have one large half inch hose running the length of the bed, which I then adjust by adding groups of in-line emitters (for things like spinach or lettuce, carrots, etc), or separate 1/4" tubes with drips or sprayers at the end (for the larger plants, usually one line to each plant), depending on what I'm planting each season. I also have shutoffs on each bed, so my plants that don't like as much water, I can just shut irrigation off for awhile separate from the whole system. I'm not aware of a lot of resources on "how to" this irrigation stuff, outside of learning the general water/space requirements for plants and planting them as "like" groups as much as possible. Unfortunately a lot of "how much and for how long" relies on your personal climate and soil type, so there's going to be a lot of experimentation and learning how best to work things for your situation. It's definitely a little steeper learning curve than just letting the rain take care of it most of the time!
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lehua49
11 years ago
ng,

It is all trial and error at some point. Try your system. Check how it is doing and then make adjustment. It can always be changed. You can't make progress without making mistakes and doing better next time. With your lesson learned, pass on the info to others. Aloha
Kippy
11 years ago
I have a similar question.

Does anyone know of a drip system friendly guide to water needs for individual veggies? Something like: a zucchini plant needs 1" per day, a green bean .5" etc?

Smith, I have my large terraced veggie garden getting a new drip system this season. I rigged up a station with half a dozen 1/2" pvc ball valves coming off a main run that has the drip filters/regulators etc on the in coming end and the hose connections on the out put end of the ball valves. I can then pick what veggies get watered and for how long.

Hoping to save enough water that it pays for the system.

Drip Irrigation Spacing Question, Raised Bed

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lehua49

ngraysmith
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Kippy

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Drip Irrigation Spacing Question, Raised Bed

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lehua49

ngraysmithOriginal Author

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ngraysmith
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