Raised Bed Trials

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30" Potato and Tomato Raised Bed

24" Potato and Tomato Raised Bed

We are testing a wide variety of raised beds in the Dirt to Dinner garden. Just this week I added two new No Dig beds with tall trellising for cantaloupe and spaghetti squash. They are made of “found” lumber (it was Clean-Up Week in our neighborhood, so the finding part was easy) that 50 years ago was a backyard fence. I figure anything potentially unhealthy has surely leached out of it in all this time. Right?

The first bed we added to the front garden we took up the turf and dug the soil underneath, so it’s somewhere between 18″ and 24″ of new ammended soil mixed with the existing clay and topped with an inch of turkey farm compost. This bed holds potatoes and tomatoes, so I’m sure we’ll learn a lot about the quality of both the drainage and the new soil from the way the plants develop. It’s also in a windy corner, which the bush beans we tucked in there while the potatoes and tomatoes are getting started don’t seem too happy about. This also means the bed dries out more quickly than I would like and needs a thick mulching as soon as the plants are better established.

5" No Dig Squash Bed

5" No Dig Squash Bed

The shallowest of the raised beds is a No Dig 5″ deep bed with as close to Mel’s Mix as I could make with the materials at hand. And I do mean, No Dig with this one. It’s made out of found redwood timbers tacked together and laid straight onto the lawn. I am very curious to see how this bed does through the summer. I planted my spaghetti squash in this one, so I really hope it does well.

The idea is that the grass will die underneath the soil, turn into a natural compost and eventually become one with the dirt in the planting box. I imagine adding a lot of compost to this one through the Summer to keep the moisture content up. But will the grass grow up through 5″ of soil?

2'x2' of 6" and 12" Square Foot Sections

2'x2' of 6" and 12" Square Foot Sections

We also have a variety of Square Foot style beds in the Dirt to Dinner garden. My favorite ones, surprisingly, are the bi-levels. I thought I would want everything as deep as possible to hold all the soil and plants I could imagine, but I like the way this one looks in the garden and so far the occupants seem happy with their digs.

By far the largest raised bed in the Dirt to Dinner garden is the kids’ growing area which is over 18″ deep. The kids removed the turf and turned the soil underneath before the bed was constructed. At 112 square feet framed in traditional English willow hurdles, it is unique and also seems to be holding up well. willow-planter-almost-done1I have no doubt that the bed will provide ideal growing conditions and can’t wait to see what the kids do with it.

The original raised beds in this growing space are large plank board planters that stand 3′ high and are 4′ wide. They are great for keeping the dogs out and not having to bend over very far, and they are sturdy enough that you can even stand on the edge to adjust your cages or add to the trellis systems. But they are so deep that the soil compacts in them by a foot down and they are very ungainly to try to turn the soil in them because of their size. It’s tough to get a shovel into them and you end up breaking your back digging them out by hand every year or two to lighten the soil.

7 thoughts on “Raised Bed Trials

  1. Always dig up the grass, it will toxify your roots and soil as it off gases and sometimes fertilizer is still present which will throw false numbers.

    • Thanks, Garden Freak. I haven’t heard the toxicity issue before. Now we take up the sod for our beds and it makes wonderful compost. We lay it grass-side down and cover it with a layer of coffee grounds and spent straw. The worms love it!

  2. Now that it’s July, I can report that 5″ is not deep enough for the grass we are planting on. The bed has grass coming up in it even through a think layer of mulch and growing squash vines. But 24″ is clearly not necessary to get good tomatoes or potatoes, though I’m sure it’s nice to have. Right now, for the soil, climate and turf we had in the Dirt to Dinner garden, 10″ is the minimum depth we are building new beds that go straight onto the grass. This Fall we will be digging up a few of this year’s raised beds to examine the soil layer underneath and see what else we can learn.

  3. I can’t wait to see how it turns out. I think I will try to kill the grass with cardboard or newspaper or something first, then add the soil and mulch and seeds.

    It does seem that if your raised beds are high enough that the moisture woudn’t be a problem because the roots wouldn’t go that deep the first season, right? I’m not sure if that’s how it works, but just thinking out loud here. :)

  4. Pingback: No tilling? « A Hippy Girl in the Country

  5. One of the local school garden experts told me that the danger is that a layer of moisture will form between the sod and the new soil that you add causing root problems. She encouraged us to at least disturb the existing sod before we put on the boxes. So we did some each way to test how it works for us. The whole world seems like a grand experiment sometimes!

  6. This is very interesting reading. I am planning on doing square foot gardening, too. We are waiting on some people to come till before we get started, but I am thinking that maybe just putting boxes out over the grass will work.

    I might just decide to skip the tilling. I’ll have to think about it more. Thanks for the information and ideas!

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