The Park Seed Trial Garden beds were established in 1961, and we’ve been improving them ever since. The key to their success is the annual addition of organic material. Many different kinds of organic material can be used to amend the soil. For instance, we have used composted bark, also called soil amendment, composted sawdust, cover crops, and also composted cow manure.
Avoid compacting the soil. The air space in the soil should represent 25 to 30% of the total soil volume. Compacting the soil decreases that air space. Try to avoid walking on your soil or using equipment that repeatedly travels in the same path across the area. Remember—bricks are made from compacted soil!
At Park Seed, we start our yearly bed preparation the previous season by removing old, spent plant material. This is especially important if the plants that were grown tend to reseed themselves. The beds are tilled and then lie fallow during the cold months. If winter weeds emerge, we till again. Soil samples are taken yearly and tested to determine the fertilizer formulation and the rate of application. These tests will also tell us if we need to add lime to raise the pH of the soil. Our fertilizer is custom-formulated to meet our needs (Home gardeners don’t usually have this luxury!). In the fertilizer, we want about 20% of the Nitrogen to be immediately available and the rest to be slow release.
In the spring, we apply the fertilizer and do one last tilling and shaping of the beds. A weed barrier, in the form of a brown paper (you can also use newspaper), is laid over the beds and then the soil amendment is put on top of the paper to a thickness of 3 to 4 inches. The young plants are planted through the mulch and the paper, making sure that the root system is in the soil. The edges of the beds must be weeded periodically. Water as needed. At the end of the season, till the soil amendment or mulch into the soil, thus adding more of the organic matter that is so important to your garden soil’s long-term health.
FYI: Using cow manure can introduce unwanted weeds. If you use bark or sawdust, make sure that it is composted and not ‘green’ or fresh. The bacteria that break down this ‘green’ material will use all the Nitrogen that is in the soil, and your plants will show Nitrogen deficiencies.
Hope this soil recipe will help grow better gardens.