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More on raised beds (are they even a good idea in Oklahoma?)

Shelley Smith
10 years ago

After my 'Waist High Raised Beds' post, I've been doing some thinking and reading about raised beds in hot, dry climates and I have turned up some conflicting information. I'd love to hear what you all think of this. I love gardening in raised beds but I am still learning how to garden in Oklahoma and I have to say, while my yields do increase each year, they are far from impressive compared to what many others post here. So, after four years of gardening in raised beds, I find myself doing a bit of reassessment. Before I put money and effort into expanding my garden area and rebuilding some of my raised beds that are coming apart, I would like to be sure that what I am doing makes sense.

Do you think raised beds are a good idea in Oklahoma? If no, why? If yes, have you done anything to modify your raised beds to make them better suited to our climate?

I would especially love to hear from those who have gardened in raised beds and at ground level - which worked better for you?

And now for some of the confusing stuff I found online:

http://the-grackle.blogspot.com/2011/07/raised-veggie-beds-good-bad-and-ugly.html

This really caught my eye: "Raised-bed gardening can increase soil temperatures by eight to thirteen degrees over ground level soil temperatures." That seems like it would be counter-productive in our long, hot summers. On the other hand, if you mulch and use shadecloth, could you offset these negatives?

http://www.humeseeds.com/raised.htm

I also came across some info on sunken bed gardens, which is interesting. But since we can also get several inches of rain in a matter of days here in Oklahoma, maybe that wouldn't be such a good idea?

http://homeguides.sfgate.com/sunken-bed-gardens-vs-raised-bed-gardens-39865.html

I'm also realizing that we really have multiple shorter growing seasons here, rather than one long one. My garden seems to come to life in the fall when it cools off, and I have great success growing various greens even through the winter. Those same greens really take off in early spring and I get incredible harvests into May from the overwintered greens as well as the ones I plant in February. As long as I get an early enough start, March through early June seems to be the ideal time to grow tomatoes as well. From late June through August, I have a tough time growing much of anything successfully. It probably doesn't help that I leave for Canada in late June and return two weeks later in early/mid July. Okra, sweet potatoes, basil and peppers seem to survive and produce through the summer, but even tomatoes stop producing once the heat sets in. I have seriously thought about just taking a break during that period and saving the water, but usually there is just enough producing to keep me watering and hoping. Then its always a challenge trying to get fall greens and root vegetables started early enough in August, when its still hot, that they have time to mature before the days get too short. I think if I started tomatoes in the summer and transplanted them in late July/early August I could even get a second crop of tomatoes if I got the timing right (which I haven't succeeded in doing so far). I have decided that a proper seed starting system is a must have for gardening in this climate and I am determined to have one set up by the end of December so I am prepared for next year.

Having said all that, I wonder if its more about when than it is about how (raised bed vs. in the ground). When I think about gardening in the fall/spring, then raised beds make a lot of sense.

Would love to hear everyone's thoughts on all this.

Comments (6)

  • chickencoupe
    10 years ago
    last modified: 9 years ago

    It would be awesome if you did it the way soonergrandmom suggested in the other post.

    Initially, it's a heavy load job, but well worth it as reflected in my smaller h-kulture planter. No watering needed (even in drought).

  • Shelley Smith
    Original Author
    10 years ago
    last modified: 9 years ago

    I read up on the h-culture beds and I'm very intrigued! Its fascinating how well it holds water. I don't get how it works but I guess it does.

    I was also thinking about making one large horse-shoe shaped bed instead of several separate ones. In addition to the wood under the soil, maybe the larger mass of one big bed would be less susceptible to heating up and drying out? I came up with a plan for one that is 12' by 11' with a 3' by 8' keyhole opening that would give me just over 100 square feet of bed surface. Thoughts?

  • sammy zone 7 Tulsa
    10 years ago
    last modified: 9 years ago

    I only read part of the other post, and thought aobut waist high beds.

    My first consideration would be weeding, and replacing soil that comes out with the weeds. Also adding compost and mulch. I need to lift bags a short distance, and should not be working where it is high because I might forget where I am if I am turned around, and fall.

    I happen to be old, but I tended to lose my sense of where I was when I was young. In trying to remove a weed, and avoiding a rose branch, I could simply fall off a structure.

    We did raise the level of our huge bed in the front, and spent a fortune to have the dirt trucked in. However, we cannot get trucks to the back easily, so that would be quite expensive.

    I haven't posted for ages here, and perhaps do not understand what you are asking. When we purchase soil, it is in bags. Usually 30-40 at a time. I don't know where it goes, but it goes, and always must be replaced.

    I'll read more and post later.

    Sammy

  • jerrydeacon
    10 years ago
    last modified: 9 years ago

    Here in cold damp Nottingham, UK, we don't share the same gardening issues as yourselves, however we love using raised beds, especially for growing vegetables. Have a look at some of these examples for ideas or inspiration:
    http://www.railwaysleepers.com/projects/raised-beds-with-railway-sleepers.
    Hope it helps!
    Jerry

    Here is a link that might be useful: Raised bed ideas

  • Okiedawn OK Zone 7
    10 years ago
    last modified: 9 years ago

    Shelley, I think a lot of the raised bed/sunken bed issue in our climate comes down to what sort of soil you have.

    If you have very sandy soil that drains very quickly, you have to add huge amounts of compost and other organic matter that will improve the soil's ability to hold on to the moisture if you build raised beds. Since raised beds do drain more quickly and also heat up more quickly, there is a balancing act involved where you have to try to ensure that they drain well during the rainier parts of the year and yet also retain moisture well enough during the hottest parts of the year. If you have dense, clay soil (like most of the soil in which I garden), while you still have to add a lot of organic matter in order to make it drain well, you also won't have quite as much of an issue with raised beds draining ridiculously fast since clay can hold on to moisture significantly longer than the sandy soil does. Having said that, once the daytime highs are routinely going over 100 degrees, and often even over 110 degrees, none of the soil retains moisture as well as it should, and that is why heavy mulching is a must with raised beds. Otherwise, you cannot even keep the soil moist enough for the plants to grow well and produce well. Some years, even with very heavy mulch and an irrigation system, I cannot keep the plants in raised beds happy enough for them to be productive in the hottest part of the summer. I might be able to keep them happy enough that they look green, but if they are too hot they still will stall during the high heat and not produce much until cooler temperatures and heavier rainfall return in the fall. So, in that situation, you have to decide for yourself if it makes sense financially to keep irrigating a garden that cannot produce in the extreme heat.

    Most of my raised beds are only 4 to 6 inches above grade level, and that is because of the issues involved with taller beds heating up more. I mulch not only the raised beds quite heavily, but also the pathways that surround them. If someone who doesn't understand my mulching system were to look at my garden in the middle of the summer, they wouldn't even know that we have raised beds at all because the mulch on the pathways is so high that it makes the garden look level, and that makes it look like there aren't any raised beds at all, obviously. The difference, of course, is that the raised beds are filled with enriched clay loam soil under heavy mulch and the pathways are just really heavy mulch, so on the rare occasions that we have heavy rainfall in the summer (which likely last occurred in 2007), the excess water still drains out of the raised beds into the mulched pathways. The pathways can be like little rivers carrying excess moisture downhill and away from the beds in wet periods, but even though the paths can be too wet to walk in during that time, at least the plants in the raised beds survive the heavy rainfall and don't waterlog and die. Keeping the pathways heavily mulched is the key to keeping the soil in the raised beds from heating up too much.

    If I have raised beds that sit 6" above grade level, that means the boards that hold the soil in the beds are exposed to sunlight and will heat up excessively, leading the soil within those beds to heat up excessively. Unmulched soil often is 20-30 degrees hotter in my garden in the summer months that heavily mulched soil. By putting six inches of mulch in the pathways, though, the boards that surround the beds are practically buried under the mulch themselves, or only the tops of the boards are exposed to direct sunlight but the sides are not, and that helps keep the raised beds from heating up as much as they would if unmulched. If you keep heavy mulch on your raised beds and pathways, you can keep the soil easily 20 degrees cooler than adjacent unmulched soil. I check my soil temperature often (with a thermometer) to ensure I have enough mulch on the soil to keep the soil cool. That's how I learned over the years just how thick to apply the mulch to get the results I need. With crops like potatoes that are sensitive to the high heat, sometimes I pile up grass clippings and hay mulch so high in the pathways In June and early July that you cannot even see the boards that make up the raised beds. That helps keep the potato plants setting and sizing up tubers even in fairly hot temperatures and gives me a couple more weeks of growing time before the air and soil temps get so hot that the plants cease to grow and begin dying back, and that can increase the size of the potato harvest a bit. The downside to using such heavy mulch is that many pests (scorpions, snakes, sow bugs, pill bugs, pine voles, etc.) love that heavy mulch, and since my area is very rural, there are obvious risks inherent in using the heavy mulch. I always have to be very aware of snakes, for example, and this year have had several close calls with timber rattlers which come out of the heavy woods and hang out in and around the yard and garden in the hottest weather. I had so much trouble and so many close calls with timber rattlers this year (it is a miracle that I wasn't bitten on at least two occasions) that there was about a 6 week period late July through early September where I barely stepped foot in the garden at all. In an unmulched garden you can see the snakes a lot more easily than in a heavily mulched one, but with our summertime heat, it is not an option for me to leave the beds or paths unmulched.

    I consider raised beds a necessity for some crops, but I don't grow everything in raised beds because the exceedingly heavy rainfall that is more common in central, northeastern, eastern and southeastern OK during the growing season is much less common in my part of southcentral OK. I always try to put onions, potatoes, tomatoes and peppers in raised beds, but everything else generally does just fine in grade-level beds. About the only time that excess rainfall is an issue here in our garden is in April through June in the rainy years. My raised beds drain well enough that even in April 2009, when we had slightly under 13" of rainfall in one day, I didn't lose plants due to waterlogged roots, even though subsequent heavy rainfall for about 6 weeks meant that the garden looked more like a pond that a garden. However, they also retain moisture well enough except in the worst of the drought years so that the garden somehow hangs in there and survives July and August of most years. However, I do have to water it. Even after I stopped watering in 2011, and we were having days with the highs around 113-116 with no rain at all for 2 months, a lot of the garden plants survived after I stopped watering and clung to life just enough that when rainfall returned in late August, they were able to regrow and produce a harvest. Even the Piricicaba broccoli survived (at the shady end of the garden) and produced a harvest from October through early or mid-December of that year.

    Sunken beds potentially could work for some people in some areas of the state, but in order for them to work, the soil would have to drain very well. In a perfect world we'd grow everything in raised beds in spring when rainfall is heavier and in sunken beds in summer when the rainfall is scarce and the heat is so intense, but I don't know how to make a raised bed in May turn into a sunken bed in June. : ) So, I've just learned to put the plants that need good drainage in raised beds, and the rest of the plants in grade-level beds. I wouldn't attempt to garden at all here in the summer without heavy mulch and an irrigation system.

    I do know people here in my area who don't make any attempt at all to keep the garden green and productive in July and August. At least one of them has a policy of not watering after July 1st at all. He has a great garden from late March or early April through the beginning of July. After July 1st, he doesn't water and just continues to harvest until the combination of heat and lack of rainfall bring an end to his harvest season. That is what works for him. Because I like to have a longer harvest period, I try to keep the garden watered at least through the end of July. If no rain is falling and the heat is brutal, there generally comes a time where I stop watering the garden and just let it survive (or not) on its own. Sometimes I reach that point in mid-June if the spring rains failed to materialize in the amounts needed, but sometimes I water until at least the end of July or even early August. When I do that, the plants may shrivel and wilt and look pathetic, but often they will just barely survive and then will green up, resume growth and produce a harvest in the fall. I just play it by ear every year and adapt my garden practices to whatever weather we are having, because we never know around here if we're going to have 25" of rain (one year we only had 18.75" and it wasn't a good garden year obviously) or 45" or 50" of rain. In a lot of ways, since we have dense clay that drains slowly, the really wet years are more challenging in my garden than the average to really dry years.

    Bon, I'd have nothing but hugelkultur beds if it wasn't for the venomous snakes that lurk around their edges. But ,(hopefully) most of the people on this forum do not live in very rural land in the bend of the Red River with lots of Wildlife Management Land near them and, therefore, have plentiful wildlife like I have here and maybe in that case the hugelkulture beds wouldn't be so scary. I cannot even turn my compost in the snake season, which runs roughly from April through November, because of the large population of snakes, both venomous and non-venomous, that seem to love hanging out in and around the compost piles. However, I still do add lots of wood directly from the garden, often adding big chunks of half-decayed wood gathered in very cold weather (so the snakes aren't out) from our woodland. I dig the chunks of wood into the ground though, and don't leave it above ground where it would attract snakes. Another issue with any part of our garden that has wood on the surface is that the scorpions love it....so I have to be very careful to never pick up a board or log or anything in the warm season because the scorpions will be on that wood or underneath it and will sting me every time. (This makes my garden sound like it is a combat zone....and sometimes it feels that way! lol) For me, March through June is when the scorpions are the worst in the garden. By the end of June, they retreat more into the adjacent shady woodland which stays more cool and moist than the fenced-in garden areas in full-sun.

    One more thing, Shelley......when you read online about gardeing, you always have to consider the climate in which the writer gardens. A lot of what is written about gardening is written by people who live in areas where 90 degrees is considered an intense heat wave. Thus, some of what is written just doesn't apply to us and those recommended practices that work for them do not necessarily work as well in our climate where we sometimes have high temperatures over 100 degrees virtually every day for anywhere from 2 or 3 weeks to 2 or 3 months.

    Before we moved here, if someone would have told me that I'd be trying to garden in high temperatures in the 110-115 degree range some years, I probably would have stayed in Texas, where about the highest temperatures my garden ever had to endure was a rare day when the high might hit 105 or 106. When we had high temperatures in the 111-113 degree range during our very first summer here, my main reaction was 'uh oh'. I was hoping that was a rare occurrence and we wouldn't see temperatures like that very often. Unfortunately, those hot temperatures are a lot more common than I expected them to be. We just have to learn what works best in whatever kind of soil and weather we have here in any given year because the weather can swing wildly from mild to brutal some years, and we have to be able to adapt to quickly changing conditions.

    In April 2009, we were at the tail end of about a 16-18 month drought and had tremendous wildfires in early through mid-April, followed by incredibly heavy rainfall in late April through June, so the poor garden plants that were baking in hot, dry soil in early April that was almost totally devoid of moisture, suddenly had to endure a couple of months of completely waterlogged soil, high humidity and lots of clouds/very little sunlight.

    When you plant your garden here in late winter through late spring, you never know what weather challenges you'll be dealing with, so to me it is always a guessing game where I'm trying to figure out in March just what kind of summer weather to prepare for....and some years I guess it right and other years I get surprised. Gardening in Oklahoma is not for sissies (and don't we know it!!!). It can be really challenging to garden in an area where you might have 2" of rain one May and then 16" of rain the next May. You might have 60 to 90 consecutive days with high temperatures over 100 degrees one year, and no days over 100 degrees the next year. Your last killing freeze will be in February some years and in May other years. Your garden may be 20 degrees one day and 80 or 90 degrees the next day. It is the unpredictable nature of the climate here that keeps us on our toes. You never can expect the weather to do the same thing two years in a row because we rarely have that kind of consistency here, and that's part of the challenge of gardening here. I do things really differently in a year when we have 20 or 30" of rainfall than I do them in a year when we have 40 or 50" of rainfall. The problem is that a planting time, you never know what surprises the weather has up its sleeve, so you try to plant for the conditions you think are most likely to occur, and then you hope you 'guessed' right.

    I have some relatives who garden in an area where 85 degrees is considered a really hot day, and while they face other kinds of challenges in their gardens, they never have the issues we deal with because of our intense summer sunlight and heat. On the other hand, though, they can have trouble getting good yields from crops that demand a long, hot growing season. So, when they tell me it is very hot where they live, I kinda grin to myself because their idea of very hot weather is really different from our idea of really hot weather and, all things being equal, I'd still rather garden here than in a significantly colder climate with a significantly cooler and shorter growing season. Of course, I do think it would be lovely to have a summer where an 85 degree was about as hot as it gets, but we almost never have a summer like that here. Dorothy and I both have mentioned here several times that we remember one summer in fairly recent times where both TX and OK had a cool, wet summer and it was around 1996 or 1997....but we haven't had a nice cool summer like that since then.

    Dawn

  • soonergrandmom
    10 years ago
    last modified: 9 years ago

    Even within the State we have very different growing conditions. I live in the NE corner and most years we have ample rainfall and we are nearing 47 inches and will likely add another inch or more before the end of the calendar year. I didn't water the in-ground things at all and only watered the raised beds twice. In 2012 I had to water a lot more during the summer months.

    I have 3 raised beds and one is an asparagus bed which is permanently planted. I use one bed for early leaf crops so I can plant early and they are less likely to be covered with mud splash during our normally heavy Spring rains. This year I followed it with peppers and it worked great because they like the heat of summer, so the raised bed is no problem. I grew onions in the other one. I didn't plant after the onions this year, but last year I grew squash there so I could keep row cover over them until they started to bloom.

    In Fall I cover my entire garden with leaves and they stay all winter. One of my neighbors has a large leaf cage behind his lawn mower that is about 4 feet square and he brought me 3 loads yesterday. They are waiting on the north side of my house until I get my garden cleaned up. There will be many more loads delivered. It is easier for them to drive their lawn mower a block and dump them here than it is for them to burn them, so it is a win-win for each of us. He and his neighbor share the same equipment and they both live on the waterfront with stronger wind and each have lots of trees, so they start picking up their leaves early. I love it.

    I live in a crowded little lake area and my garden is almost surrounded with buildings. Many times when I am working in the garden, I can see the trees moving and hear the wind, but it is 20 feet above my head. I don't get a lot of wind to dry out the soil, but I do get the summer heat.

    I have had some years when my small tomato plants were almost covered in water. I decided it was better to plant transplants when they were a little larger and able to keep their heads above water. Too much water is harder on the plants than too little when they are small.

    So I agree with Dawn that not only do conditions differ from year to year but they differ from season to season within the same year......and don't expect it to be the same 2 years in a row. LOL We kind of chuckle when catalogs say a plant needs at least 8 hours of direct sun to grow because in some cases that would be from rare to well done for our plants. We can grow great crops in Oklahoma, and sometimes we wonder how we do it.