Raised Bed Soil Testing #382616 - Ask Extension


Raised Bed Soil Testing #382616

Asked January 21, 2017, 9:34 AM EST

Hello, I have a 4x8' raised bed that we built 2 years ago, and have done a vegetable garden each year, but only with intermittent attention given :) I was looking at your January calendar of activities and it looks like soil testing is one of them. I would like to do a lot more veggies this summer but want to make sure they're healthy for my family - do you recommend soil testing for small raised beds like mine? Or is that a service that's typically only for much larger gardens or farms? Thank you! Barb

Multnomah County Oregon

Expert Response

Thanks for your question about raised bed gardening and soil testing.  Soil testing is helpful for 2 reasons: you can determine your soil's pH, and you can determine whether there are adequate amounts of the three main nutrients (nitrogen, phosphorus and potassium) in the soil.  Most vegetables need a Ph between 5.5 and 7.5 (so slightly acidic to neutral).  Here's a link to a table for vegetables you might want to plant.

You can purchase an inexpensive pH test kit at most garden stores; you can also bring a soil sample to the Garden Discovery Day event on March 4 from 9:00 to noon at the Milwaukie Center, and Clackamas County Master Gardeners will test it for you.  Here's a link to information about the event; note they need your soil sample(s) before 11:30.  (And you might want to sit in on one or more of the free talks!)  They will also give you an idea about what to add to your soil for nutrients.

The soil sampling for the 3 nutrients I mentioned can also be accomplished by one of the inexpensive test kits, but know that the levels of these can vary widely throughout the year.  If you've had vegetable gardens in this soil in the past, and haven't added compost regularly, your soil may be deficient in one or more.  (Especially nitrogen, which is the one most needed by plants with foliage.)  You can help the texture of your soil, as well as replenish the nutrients, by adding composted matter.  It ranges from the compost you can create from your own rotting plants, to purchased compost, mushroom compost, worm casting compost, aged steer manure, and well aged chicken manure.  Here's another link to an article about adding compost.  Note that tilling or otherwise disturbing the soil while it is wet will not help the texture of the soil; wait until the ground has dried out.

Hope this is helpful.  Good luck!
Kristena LaMar Replied January 21, 2017, 3:15 PM EST

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