Cure for the raised-bed blues

The first season of a raised bed garden is the honeymoon. The second year plants may be less productive. By year three you’re throwing your hands up in disgust. If this sounds like your own raised bed gardening failure, read on to find solutions.

First of all, consider the fact that vegetables are annuals. Annuals require a great deal of nutrition because they must sprout from seed, mature, flower and set fruit within one growing season. All this activity requires more nutrition in the soil than less demanding plants. It may explain why your first year garden was luxuriant, productive and pest/disease free while each consecutive year the results decline.

All over America, folks with small raised bed gardens are having similar problems because there’s little out there to explain this nutritional decline. Poor diet weakens the plants’ immune systems, making them vulnerable to pests and diseases that would not affect a well fed plant. They also may be less tolerant of heat and drought so yields grow smaller and smaller.

The simplest fix is to rotate crops by rearranging the garden each year, but most raised bed gardens are too small to do much rearranging. You just don’t have many options.

For this reason it’s vital to provide nutritional supplements to your organic garden soil every year. Organic gardeners can’t use fast-acting synthetic fertilizers. Instead you must select high quality organic fertilizers.

Don’t confuse fertilizers with bagged organic soil amendments such as compost. Fertilizers are far more potent, and depending on their formulation may provide a much wider range of nutrients. Each organic product will show three numbers on the label that express the levels of nitrogen, phosphorus and potassium. Use them to compare potency and pricing.

In the past, organic gardeners had no choice but to use single material fertilizers such as blood meal, alfalfa meal or cottonseed meal. But single nutrients are not as ideal as a blend of all of them scientifically formulated for heavy feeding vegetable crops. Fortunately, you can now find such blended products at most home improvement stores or garden centers under the brands Black Gold, Espoma and Dr. Earth. Each formula contains materials such as fish bone meal, feather meal, kelp meal, alfalfa meal and rock phosphate.

All these organic plant foods pour on just as easily as synthetic fertilizers, making them easy to fork into last year’s ground. Do this as early in the season as the soil can be worked because it takes time for them to become available to plants. If you wait until just before planting time to apply organic fertilizers, your new plants won’t benefit until early summer, and that’s too late.

To apply organic fertilizer, spread it generously over the entire raised bed, then use the fork to turn that ground deeply. This puts it in place deeper down to benefit from the spring rains to begin the decomposition process.

Third-year failures can be counteracted in the fall too. Wait for the end of the growing season when plants are dead or nearly so, then strip them off and work in the plant food. Work it in and then mulch the surface with straw to keep soil microbes happier in their enriched earth over winter. You can use a lot more fertilizer in the fall because no living plant roots are present nor will they be added for many months. This provides a lot more time for the soil microbes to feed on the fertilizer and render your ground more fertile in the process.

McClatchy-Tribune News Service

Maureen Gilmer is an author, horticulturist and landscape designer. Contact her at mogilmeryahoo.com.

This story was originally published February 19, 2014 at 9:26 AM.