Flood Irrigation and "Lasagna Method" Raised Beds

GirlyGrr(9)October 20, 2013

We are on an acre, with flood irrigation, and trying to plan a vegetable garden.

First, I am trying to figure out whether the garden should be in-ground or planted in raised beds. We flood every other weekend, for about 1.5 hours. The water gets quite deep. My gut tells me not to plant in-ground.

Second, I have been reading Lasagna Gardening by Patricia Lanza. Arizona soil is quite clay-like and difficult to dig through. I really like this method, and many people have had success planting gardens this way.

I was thinking if I built wooden raised beds, then filled it per the lasagna method, it would get watered (soaked) with the flood irrigation but not get drowned.

Has anyone tried this, and if so, what has been your experience?

Or any thoughts or advice?


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seysonn(8a WA/HZ 1)

Probably in your climate (Arizona) In ground beds and flood irrigation is better. It will maintain moisture longer, roots will stay cooler and plants will grow deeper roots.

Raised beds, IMO, are more suitable where there is a lot of rain (Especially in the spring time). And most plants do not like their feet wet all the time. OR the native ground soil does not have good drainage(low land), or gets run off water.

Raised bed inherently get much warmer, dry up much faster and so need more frequent watering in hot climates like Arizona

ABOUT LASAGNA method. IMO, the garden soil should be as uniform as possible because the roots go and grow in all directions. What is the reason for having different kinds of layers? what purpose doe that serve ? Maybe it is easier when you are first building and filling a raised bed. But what would you do the third , fourth ..year to make lasagna ?
Maybe I don't know !!

    Bookmark   October 21, 2013 at 8:42AM
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In my experience, watering every other week even especially deeply isn't likely to cut it for most vegetables. It would help to know what you're looking to grow but it sounds like the water is too deep and too infrequent for either in ground or raised vegetable beds. Over two weeks in Arizona raised beds are going to dry out too much and in ground beds in poorly drained soil sound like they'd be inundated with each irrigation. It would be best if you could do a lesser irrigation more regularly.

I manage a demonstration lasagna garden at work. Annually we have several classes of elementary school kids come to learn about the processes in the soil and do the layering. I think this sounds like a great option for initially conditioning your difficult to dig soil. I'm on degraded sandstone so my soil issues are different than yours but the soil in the demonstration garden is black, moist, and full of tilth and worms. I can dig it with my bare hands and it takes a fraction of the water the surrounding areas need. Outside of the fence-line the soil is compacted sandstone that has terrible infiltration rates, low fertility, doesn't hold water, and minimal biological activity. I like to dig a handful of each (requires some serious elbow grease in the native soil) side by side and demonstrate to people the differences. I've had guests not believe me that the soil in the lasagna beds started out as the same stuff as outside. To give you a sense of the difference imparted by the lasagna technique, I'm watering salad greens in the lasagna beds less than agaves, euphorbias, and aloes outside of the demonstration garden. Maybe that says more about how bad our native soil is than anything. I didn't even get into the differences in salinity levels.

All of that said, I doubt you'll have to do the layering more than the first year. Beyond that a thick layer of organic mulch and returning all crop residues to the soil should be sufficient to keep the ball rolling. What I do here in San Diego for my own vegetable garden is to create hugelkultur beds but in ground, not raised. IMO raised beds are totally overrated for the southwest unless you have problems bending/stooping/crouching

    Bookmark   October 21, 2013 at 12:13PM
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donnabaskets(Zone 8a, Central MS)

Yes. The lasagna method is a one time operation for building good soil in the beginning of bed development. Then, you just need to do a good job of maintaining it as Guerno says. I agree with both above that you have two separate issues. One is building good soil for growing. The other issue is getting adequate, regular moisture to your plants once you are growing.

I grow in raised beds here in Mississippi. I love them because our heavy clay is so poorly drained, and the raised beds are easier on my back. In addition, my garden is on a hillside, so the raised beds keep my soil from washing away in winter rains.

I love my raised beds, but they do have their disadvantages, and the chief one, to me, is the fact that you lose several inches of soil in them every single year. So, you must be prepared to compost year round (and/or grow green manures) and probably will need to supplement compost with purchased bagged soils too to keep your beds full.

    Bookmark   October 21, 2013 at 5:28PM
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Thank you so much for all the input!

As for what I'll be planting: anything and everything I can.

I've been researching different types of plants, and their variants, that do well here in the low desert.

For example, it blew my mind that I could actually have apple trees here. I'm originally from Seattle. I just had to find the right type of apple tree. We planted 2 Annas and 1 Golden Dorsett.

So even though the soil may dry out quicker in raised beds, I am thinking that with the right type of plants, that won't be a problem.

I will, also, be planting some in-ground beds for those plants that really need more moisture.

I forgot to mention that the backyard is all grass, for the most part. So I thought with the raised beds, it would be easier to control the grass in the beds, as opposed to in-ground.

In the book, I read about doing the newspaper or cardboard layer, then layering with wood chips, and that should keep the grass and weeds from growing. If I circled the in-ground beds this way, would this keep the grass from encroaching?

We are planting new trees, as well, so the irrigation has to be the way it is, to water the trees that deep.

We will be composting year-round and have lots of material. We'll have even more once we get some chickens. We plan to raise quail, too. We have 2 wild quail families that visit us already on a daily basis. They love our compost pile!

    Bookmark   October 22, 2013 at 10:40PM
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Gurneogardens - I started looking up the hugelkultur method on here, and some of the threads have some amazing photos of the process.

I was wondering, for your beds using this method, did you dig a trench or just put down a layer of the wood?

    Bookmark   October 23, 2013 at 10:56AM
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I dug out the bed sorta like double digging. The garden is on a slight slope so I dug it out on contour and then built it back up based on the hugelkultur design. It's not always easy to find rotten wood around here and I'm lucky not to have bedrock just below the surface. My vegetable garden is a loamy sand with a lot of compost so it's pretty easy to dig. Cardboard and wood chips should take care of all but the really tenacious creeping grasses.

Anna and Golden Dorsett are the only apple trees that will fruit where I'm at too. Here if I treat them right I'll get two crops each year.

    Bookmark   October 24, 2013 at 11:57PM
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After considering everyone's advice, I was almost convinced of just doing in-ground beds for everything, but then I remembered we have rabbits and gophers.

I haven't seen any for several months for some reason, though.

The back of our property backs up against the desert, so we were getting quite a few rabbits and ground squirrels. We are also seeing a few gopher mounds. We've set traps and caught a few, but we still see a mound or two every once in awhile.

Would raised beds, with some type of mesh at the bottom, keep the critters from eating my plants?

Should I also put a short wire fence on the raised beds?

Or can I still do in-ground beds and keep the gophers away somehow?

    Bookmark   October 27, 2013 at 6:14PM
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gardensteph(9 Northern Calif.)

I imagine that if you dig out an in-ground bed, you could line bottom abd sides with hardware cloth, just like you could line the bottom of a raised bed. You will probably need fencing either way.

I am zone 9 in low hills outside of Sacramento, and even now it is quite warm for my plants in large containers. I do not even try them in summer. I plan to build deep beds of lasagne this fall, as it is still cooler than plastic pots! Good luck on your experiment

    Bookmark   October 27, 2013 at 6:30PM
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tishtoshnm Zone 6/NM

I think the best thing you can do is to talk to people in your area who also practice flood irrigation regarding the in-ground versus raised bed question. In the southwest, waffle beds were often used and you may be able to combine that with some hugelkultur to get good results.

My climate is not as warm as yours but it is dry. I am on 5 acres but do not use flood irrigation. I have sunken beds that are lined with wire. When the sunken bed fills up, the excess water flows off to another area where it is trapped by another sunken bed or berm and on and on. Some of my beds are not lined with wire and for those I am vigilant about keeping an eye out for gopher mounds and then we trap them. For rabbits, the best defense I have found is a fence around the perimeter with hardware cloth dug into the ground 8 inches. For the ground squirrels, we have used a trap and a pellet gun and some have been picked off by the local hawks. Raised beds will not deter rabbits unless they are very raised and even then, the squirrels could likely get into them. How much you invest into that will depend on how much damage they cause. Also, anything we plant that is perennial (berry vines, fruit trees, etc) are always planted inside a wire cage, just in case we do not notice the gopher activity in time.

    Bookmark   October 27, 2013 at 7:57PM
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Some considerations

1) if you have gophers, I would definitely go raised beds with hardware cloth at the bottom

2) it depends on what you grow. If you grow the usual popular veggies (tomatoes, squash, etc), all of them have roots going down to 4 ft. They will not care if the bed themselves get dry. Only lettuce and a few other small greens have only superficial roots.

3) I enjoyed flood irrigation at my previous site. I had the beds along a slight slope, and after a while I made a bed across the slope, at the end of the existing beds. That bed kept water in the paths for about 24 hours, and stuff grew well.

So I think if you make those beds, fill them with organic matter, and keep them mulched, you will be successful.

    Bookmark   October 27, 2013 at 8:53PM
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Just a note on hugel. Today I dug nine holes for new trees which I will plant this week. The previous trees were killed by deer (I fenced the spots individually now), but I had planted them with some care, with each hole lined by four 20-40 lbs logs. The first surprise was how much crumblier the soil was, as the original site has hard, very poor clay. Second, there were earthworms were none existed, and the logs (I had to take them all out) were quite covered in fungus with fungus visible in the surrounding soil too. But I also saw that the logs attract rodents, they just love to set up residence under a log. Nevertheless, surprised at how much improvement hugel can induce in poor soil in only six months.

    Bookmark   October 27, 2013 at 9:10PM
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Thank you very much to all who have contributed their experiences and advice. I apologize, but I do not get on here that often.

I've decided to do a combination of raised and in-ground to see what works best. I think I need to experience it myself, as everyone's input varied so much. :) But all of the advice will give me a great starting point and things to consider for both types of beds.

I'm experimenting with the lasagna method right now on the existing rose bed. The previous owner had rose bushes and many were dead, and the bed was overgrown with weeds.

So we will see how things go! :)

    Bookmark   November 19, 2013 at 3:48PM
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