Raised bed height

[schill93]

I live in the Las Vegas desert where temperatures allow you to cook your vegetables while they grow, similar to Phoenix, Az.. I will be building raised beds for the 2017 season and wondered about height. Our soil here is clay and hard as rock with very poor drainage. It is also very alkaline.

Since moving here I have noted that planting anything in 15 gallon containers that are 16" tall did better than those in my 11" tall Earthbox"s with similar amount of mix. Which leads me to believe that the same would apply to raised beds.

I know many of you have rich soil and plant roots will benefit from extending down into it. In my case, not so much. Common wisdom seems to dictate that 12" should be adequate. However, I question that wisdom here.

I realize that anyone not living in such conditions may not be able to relate to my circumstances. But who knows. Thought I should ask in case anyone has had experience with it.

[Gardeneer]

if you install raised bed on native clay soil , then you would want the bed at least 18" high.
I had made mine 12" but the native soil was not as bad as clay. Then I also loosened it up and amended with pine bark fine before filling the bed.

[kchd..]

I built raised beds this past February. The site where I wanted the garden had lost a lot of the top soil due to construction, and I was down to that crappy white clay subsoil. The raised bed design I went with is 4x8 and 18" deep. I filled mine to 15" deep and the remaining 3" allowed me to apply a nice layer of mulch. Don't go cheap on what you buy to fill them with. I didn't, and I regret nothing.

[b54red]

The biggest problem with raised beds is keeping the soil moisture level high in times of intense heat and high wind. The raised beds also increase the soil temperature which is a bonus in the spring and fall but a definite minus during the late summer months. My beds are only 8" tall made with raw cut boards of cypress that are a full 2 inches thick so they act as some insulation from the heat but still the edges tend to dry out first and fastest. I have found that using a very heavy layer of cypress mulch makes all the difference in keeping my moisture levels adequate and keeping the soil cooler during the hottest months of the year.

My 8 inch tall beds are adequate because I had already amended the soil very aggressively for several years before I went to the raised beds. It sounds like you will need at least twice that depth with your underlying soil conditions. Made sure when you fill the beds that you use a very high amount of organic matter and enough organic matter that won't breakdown too fast so that the soil will not pack down too fast.

Bill

[kchd..]

I second what Bill says about organic matter. The mix I used to fill my beds was very high in OM and I have been very pleased with its moisture holding capacity.

[schill93]

Can you recommend what I should put in the beds, and in what order. I don't make compost here, so I will have to buy it. What formula would you use, and what other nutrients do you add (such as Kelp Meal, green sand etc.) .

I was using individual small adjustable sprayers for each container, but now, I guess I need a drip system. What say you? I know you have good success where you are which is quite hot too.

[MarianneW]

Mine are 20" masonry with basically only organic matter. Works great! I just dump in whatever I've got, whether compost, coconut coir, raised bed mix, shredded branches. Mine is on caliche. Embedding the first masonry course in the caliche was back breaking but worth it because the beds aren't going anywhere. I water mine by hand with a watering can because I like to.

[schill93]

Originally Posted by MarianneW

Mine are 20" masonry with basically only organic matter. Works great! I just dump in whatever I've got, whether compost, coconut coir, raised bed mix, shredded branches. Mine is on caliche. Embedding the first masonry course in the caliche was back breaking but worth it because the beds aren't going anywhere. I water mine by hand with a watering can because I like to.

Hi MarianneW. When you say 20", are you referring to the height that you built it?

[b54red]

I used to use a drip irrigation system but found myself spending almost as much time repairing it or hand watering where it clogged that I just scrapped it and went to using a hose with a good fireman's nozzle. Using the heavy cypress mulch means I don't have to water very often even in times of drought.

You might want to check with a large local nursery and see if they sell large quantities of planting medium. They usually mix their own with a lot of pine bark fines and other goodies. Sometimes they will sell it by the front end loader scoop at a fairly reasonable price and save you a lot of back breaking work.

Bill

[greenthumbomaha]

Eastern Nebraska soil is very alkaline too, as is the ground water. It doesn't seem to be a detriment to growing vegetables here. Clay may not be too bad of a deal when it comes to water and nutrient holding capabilities.

When I lived in New Jersey, the ground was so hard that you needed a pick axe to dig a hole. I had a yard of mushroom compost delivered and had a fantastic garden - not even tilled in. I can't imagine your needing a gigantic depth with the proper amendments.

Raised beds take a lot of material. Spading it up and adding a layer of cardboard under the amendments will go a long way. Find whatever you can to throw in around your place.

- Lisa

[kchd..]

I bought my mix to fill the raised beds from the local co-op. I combined the topsoil they had with a finished compost product they sold called Planters Mix. Buying in bulk (by the ton) was cheaper than buying a bagged product. I had both products tested. Other than the pH being a bit high, I've been happy with it. The plants have been happy with it, too.

[My Foot Smells]

Originally Posted by schill93

I live in the Las Vegas desert where temperatures allow you to cook your vegetables while they grow, similar to Phoenix, Az.. I will be building raised beds for the 2017 season and wondered about height. Our soil here is clay and hard as rock with very poor drainage. It is also very alkaline.

Since moving here I have noted that planting anything in 15 gallon containers that are 16" tall did better than those in my 11" tall Earthbox"s with similar amount of mix. Which leads me to believe that the same would apply to raised beds.

I know many of you have rich soil and plant roots will benefit from extending down into it. In my case, not so much. Common wisdom seems to dictate that 12" should be adequate. However, I question that wisdom here.

I realize that anyone not living in such conditions may not be able to relate to my circumstances. But who knows. Thought I should ask in case anyone has had experience with it.

it really depends on what you are growing, but for tomatoes I would suggest no less than 18", and 24" to be even better. My raised beds are 21"-22" and do fine for tomatoes, but have lower ones (14, 11.5, 16) that I usually plant other things.

I also think that placement plays an important, and maybe bigger, role. the beds I have that get full morning sun, but protected from afternoon sun, do the best. the ones that get "full sun" do good until the heat wrecks 'em.

I love KD's setup, and wise to test material before the big "dump." Wish I would have done that.

Remember also that raised beds give you the luxury of working at a reasonable height for weeding, etc.... so build it right and reduce the bending over bidness. Also, I used 4x6 or 4x7 posts, which makes for a nice width to set tools and drink on while playing in the beds, also can sit on edge.

lots of things to consider, have a good time.

[brownrexx]

This all sounds like really good advice for such a hot climate. I would recommend lots of mulch to keep the surface soil cooler and to retain moisture. Use whatever is available in your area. I use straw but you can use leaves, dead grasses, palm fronds, even dead weeds if they have no seeds.

[MarianneW]

Originally Posted by schill93

Hi MarianneW. When you say 20", are you referring to the height that you built it?

Yes. They're interlocking concrete blocks, instead of mortar I used locktite on the top courses. They're stacked 20" tall, more or less. It's a lot of work to put it in. I have one more to build in the next few weeks and my back already hurts when I think about it. But the beds are worth it, they look really nice and the plants do great.

As an aside, Katie--my Malih Helow chiles are in one of these beds and have just exploded! The chiles have a good, interesting flavor, good with meat.

[whoose]

12" minimum with good soil as a base. Use cedar or redwood 2X in 12" widths if you can find it. Do not scrimp on the boards or use treated wood. Pay now and it will last longer than you will. Then add a second board for the finished height.


See the container section "Going to the Dark side" for some pictures.

I plan to write an experiencial article on how to build a raise bed this Winter.