What soil to use for a raised bed.

by Christy
(Ohio)

I want to make a fairly large raised bed (berm?) with some mountain laurel shrubs in our yard. From what I understand, these plants like well drained, acidic soil.

Our soil is clay, and not particularly acidic.

We have neighbors who raise a variety of livestock, so we have easy access to manure - though I'm not sure of what age. We also have a large pile of dead brush we could chip, but we don't have enough compost up and running yet to contribute significantly. We will probably not be planting until fall, if that would be enough time for things to compost sufficiently.

What should I use for the raised bed? Would any of the materials we have available be useful, or will I need to buy fresh? Will I want to add sulfur or something else to help the acidity, or should I start with naturally acidic materials?



Doug says - the easiest way to do this is to use peat moss as both the acidifying agent and organic matter to help break up that clay.

If this were my garden bed, I'd start double digging the raised bed area and add a shovel of peat for every shovel of soil I turned over back into the trenches. The soil would be much more acidic and you'd have an organic soil rather than a clay soil. (organic as in structure - not as in not using chemicals) :-)

In subsequent years, add compost to the mix simply by laying in on the top of the bed; the worms will quickly drag it down.

The only fly in this kind of bed is that it will settle down in a year or two and you're going to have to top it up with soil/peat mix. But you'll have to do this in any case if you go to an organic soil for laurels/rhododendrons etc.

The alternative is to mix small amounts of sand into the bed every year for the next few years until you get your drainage and soil composition right (too much sand all at once creates a really bad mess of chunks of soil separated in a sea of sand)

Once the drainage and composition is right, you an acidify with sulfur and/or peat.

So depending on large the bed is going to be, it will either be a snap to get growing or a ton of work.

But you're right in that you'll have to adjust the pH if you want to grow this lovely plant. And depending on much clay you have, you're likely going to get better results if you modify the soil structure.

Or you could pick another shrub - one that fits your area and soil.