Raised bed amenments

Asked August 19, 2020, 2:08 PM EDT

Is using perlite or vermiculite to keep soil from compacting in a raised bed and/or a flower garden a good practice?

Multnomah County Oregon

1 Response

You didn't state what you will be amending, but let's assume that it's existing garden soil.

Perlite and vermiculite are typically used in potting mixes where there is minimal disturbance. in a garden bed, they will be subjected to repeated soil cultivation and planting procedures which will ultimately destroy their desirable properties -- perlite helps aerate root media whereas vermiculite holds plant-available water.

Organic matter is widely used for both its ability to aerate all soils, whether clay-based or sandy, even as it helps soils hold water. But with time, organic matter decomposes such that more must be added every year.

Pumice is a useful substitute for perlite in garden beds as it is resistant to cultivation and to a limit extent, foot traffic.

For further info, see the following:
- "Growing Your Own" - an over view about growing vegetables but is also applicable to growing flowers. - Go to https://catalog.extension.oregonstate.edu/em9027 ND click pdf.
- Improving Garden Soils with Organic Matter" - Go to https://catalog.extension.oregonstate.edu/ec1561 and click pdf.