soil testing/yellow leaves

Asked July 1, 2013, 2:50 PM EDT

We recently put in raised beds and filled them with a 4-way mix of top soil, compost, sand, and manure. Nothing in them is growing well from seed, and the starts have all turned yellow. Should we buy a soil testing kit from somewhere?

Multnomah County Oregon horticulture soil and fertility issues

2 Responses

Good day, and thank you for using Ask an Expert.

Just today, I was discussing raised beds with several colleagues. Both reported variable results with a 4-way mix even though they previously had excellent results with the same product from the same supplier.

There’s no easy answer to this problem. Here’s what we discussed:

- Obtain a test from a professional laboratory to determine what fertilizer elements to add. (My thought: Probably all of them!)
- Before you plant again, mix in a large quantity of compost and/or composted manure.
- Realize that, essentially speaking, your plants are in a large container filled with potting mix and will need regular applications of an all-purpose fertilizer.

You can obtain a professional soil test from A & L Western Agricultural Laboratories; 503-968-9225. Phone them to learn how to collect, and submit, the sample. Explain that you are a home gardener planting in a raised bed filled with a 4-way mix. Request a general soil test with recommendations.

For your current plants, I suggest you add a soluble fertilizer. If the fertilizer doesn’t help the seedlings and new transplants, then start over by following the above suggestions and planting again.

Two cautions with fertilizer:
1. Add dissolved fertilizer only when the 4-way mix is already moist.
2. With our current heat wave, it’s probably wise to use half-strength twice as often as the label directs.

Resources for you:
- Growing your own; A chart with planting dates is on page 7; we’re in Region 2:
- Raised Bed Gardening (See especially the section about Maintaining the Beds):

- Fertilizing Your Garden: Vegetables, Fruits, and Ornamentals

Enjoy your garden,

Hello again,

I need to add some information to my response. First, when it comes to which fertilizer elements you may need to add, ignore my comment of "probably all." It’s far better to base decisions on the recommendations of a professional soil test rather than guesses.

After I posted my response, I also realized that you hadn’t described how you prepared the beds. Far too often, gardeners lay down layers of paper or cardboard, then add 6 inches or less of planting mix, which, in your case, is a 4-way blend. Such beds have problems because of the shallow depth, also because neither water nor roots are able to penetrate into the underlying soil.

Please let me know if you have further questions,