The first season of a raised bed garden is the honeymoon. The second year plants may be less productive. By year three youre throwing your hands up in disgust and ready for the divorce. 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 that come and go within a single years time. Annuals require a great deal of nutrition because they work hard and must sprout from seed, mature, flower and set fruit within the span of 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 theres little out there to explain this nutritional decline. Poor diet weakens the plants immune systems, making them vulnerable to all sorts of pests and diseases that would not afflict a well fed plant. They also may be less tolerant of heat and drought and 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 dont have many options.
For this reason its vital to provide nutritional supplements to your organic garden soil every year. Organic gardeners cant use fast acting synthetic fertilizers. Instead you must select high quality organic fertilizers.
Dont confuse fertilizers with bagged organic soil amendments such as compost. Fertilizers are far more potent, and depending on their formulation they 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 years 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 wont benefit until early summer, and thats 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.
Dont wait for your third year failure to occur before you enrich the soil. Plan for it in advance by fertilizing that worn out potting soil in the warm fall months, or be ready to get out in the cold muddy yard to feed early enough to prevent it.