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newbie with raised beds! help!

Posted by kawaiineko_gardener 5a ( on
Wed, Dec 26, 12 at 19:52

The only method of gardening I've done is container gardening; I use lg. plastic storage containers with holes drilled in the bottom.

I have some 4' x 4' and 4' x 8' raised beds.

The first question I have is how many gallons (I am assuming this would be by volume) would I need per 4' x 4' and 4' x 8' raised bed to fill them?

My 2nd question is what type of soil to use in the raised beds. For container gardening I use a soilless mix that drains well, which is what is recommended for container gardening.

I was told my 'soil' mix I used for container gardening (which uses coarse vermiculite, spaghnum peat moss, pine bark mulch, lime, and some pelleted fertilizer) would drain too fast for raised beds.

Can anybody recommend a good soil mix for raised beds?
I've done searches on threads, but haven't really found anything specific.

Please don't say 'just use a decent soil mix and it's up to you what you want to use'. I know nothing about gardening in raised beds, so I don't know which type of soil mix to use. As such, I'd prefer to use a mix that people have used in raised beds before, that they've had success with.

THis is a guideline I've found for what to use with a soil mix, an outline rather.

Al Tapla (who posts frequently on soil mixes to use for container gardening on this site apparently) recommended it.

THis is a condensed version of what he posted

he recommends 70%-80% mineral components as the structural base - topsoil, sand, fine Turface ... and 20-30% other organic ingredients to make up the rest

I would need the percentages converted to gallons based on how many gallons I would need to fill per 4' x 4' and 4' x 8' raised bed.

Can somebody give examples as to what 'mineral components' and examples of what 'organic ingredients' are.

I always use Osmocote (a pelleted fertilizer) for my container mix. Could I include that in the 20%-30% organic ingredients, as it seems that is mostly for providing the plants nutritional needs? For a 4' x 4' and 4'x 8' bed, if I can add osmocote, how much (in cups gallons etc.) could I add for a 4' x 4' bed and how much for a 4' x 8' bed?

I am leary to add compost when I tried using compost to my soilless mix unfortunately the mix absorbed too much moisture. I don't mind adding compost to a raised bed mix, but I don't want to have the same problem.

Follow-Up Postings:

RE: newbie with raised beds! help!

Do I understand correctly that these raised beds are in the ground, and not in the storage containers? If so, a lot might depend on what kind of soil the beds are built on top of, and its condition, and whether you intend to incorporate it or just plunk stuff on top of it. Also, volume would depend on a third dimension, height. Are they six inches high? Two feet? This would give a very different answer to your volume question.

As far as your Osmocote question, that would depend on the nutrition available to plants in the present soil of the beds. What does the label say about using it outside in garden beds?

RE: newbie with raised beds! help!

This was the info on the labels of the raised beds....

Here are the dimensions....

For a 4' x 4' it says.... 4' x 4' x 7" (I'm going to assume the 7" refers to the height/depth of the box)

The 4' x 4' has 16 square feet of growing space. It requires 8 cubic feet of soil (per 4' x 4' box)

Here is the info for the 4' x 8'..

For the 4' x 8' it says....4' x 8' x 10".5-7" (again I'm going to assume this is referring to the height/depth of the box)

The 4' x 8' has 32 square feet of growing space and requires 22 cubic feet of soil (per 4 'x 8' box)

Unfortunately cubic feet of soil tells me nothing of how many gallons I'd need to fill a 4' x 4' box and a 4' x 8' box, and I am horrible with math/conversions. I could really use help and clarification with this.

RE: newbie with raised beds! help!

The conversion tables show 6 gallons per cubic foot for a dry mix, and 7 gallons per cubic foot for a liquid. For the 22 cubic foot amount above, this equals about 141 gallons. For the 8 cubic feet example, you have 48 gallons.

Also, 1 cubic yard = 27 cubic feet if you ever need to buy materials by the cubic yard, as is commonly done with variousb soil amendments.

Here is a link that might be useful: Cubic feet to gallons conversion

RE: newbie with raised beds! help!

For as much soil as you will need, and I would suggest a good top soil, you should be looking for a bulk supply such as a landscape supply. I see no reason to pay the premium prices of having your soil bagged. The empty bags will just add to you waste disposal. Al

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