Vegetable garden - crusty soil

Asked May 28, 2020, 3:57 PM EDT

I live S.E. of Portland and have had a decent size vegetable garden for several years. Always produced well. The soil is clay so I raised it and added multiple types of soils and compost, I wanted to loosen it up this year so I added Lime and sandy loam pre planting. All's planted now for 3 weeks, and finally getting to it after the rain I find not much has sprouted. Instead of loosening it up it now has a hard crust. I have searched online and it sounds like I screwed up with the sandy loam. I'm seeing gypsum might help break the crust. So the question is: Since i'm planted and some things have come up, what can I do to keep that crust manageable to get me through this season ? Then what would I need to do this fall to get a more healthy garden.

Clackamas County Oregon

1 Response

Thank you for choosing Ask an Expert for help with your garden. I would recommend a mulch (1/2” to 1” deep) over the surface of the bed. This will speed infiltration into the soil by irrigation water, protect the soil from the summer sun’s drying rays, help retain moisture, plus add valuable organic compounds to the soil as it breaks down over time.

I would also recommend a soil test to discover whether any nutrients are lacking and whether the pH is in the best range for your crops. Soil testing is available from a number of laboratories listed in this Extension Service publication—“Analytical Laboratories Serving Oregon”. See here:

The website of the laboratory you choose usually provides information on taking a sample and shipping it. Or give them a call. One to two cups of soil should be enough for the standard garden pH (acidity) and nutrient tests. Be sure to let them know that this is for vegetable or ornamental garden.

Testing should take just a few days, though rush services are available. The laboratory can provide recommendations for fertilizer and lime additions, as well. Results can be available on the web, by fax, by email, or by postal mail.

Be patient with your garden. Some seeds take longer than others to germinate, it’s not always a matter of warm soil and water. Radish seeds will generally sprout in four days, while lettuce can take up to 12 days. Many times this time-to-germination is listed on the package.

The use of gypsum on most Willamette Valley soils is not useful. We just don’t have the kind of clay gypsum helps with.

Be careful adding lime, which raises the soil pH (makes the soil more alkaline). It should be done in response to a soil test saying you need to decrease the acidity of the soil. Otherwise, you could be raising the pH above desirable levels. Plus, adding too much calcium and magnesium to the soil causes other nutrients to be unavailable. Your soil test will guide you.

The optimum organic matter for in-ground beds is 5% to 7%. If a raised bed has sides of 12 inches to 30 inches, it’s basically a container. Container soil or blended “raised bed mix” should be used. Adding native soil to container media, in a container, likely results in poor drainage.

For lots more information on vegetable gardening, soil and fertilizers, check out “Growing Your Own” here: also from the Oregon State Extension Service.

Have a good gardening year,