Soil preparation is critical to success with annuals. Proper site and soil preparation will ensure a healthy environment for annual flowers. First, make sure the site has good quality topsoil. This may require addition of topsoil, particularly in new home sites. Amend the soil by adding 3-5 inches of well-aged compost or manure. This is especially important in the arid, calcareous soils of southern Idaho. Add the equivalent of 5 lb/1000 sq. ft. of nitrogen in the form of a complete fertilizer, such as 5-10-5. The fertilizer choice should be high in phosphorus and should preferably include sulfur. After amendments are added, the soil should be tilled to a depth of at least 8 inches, leveled, and smoothed (but not packed). Just prior too or after planting, it is a good idea to add two or three inches of mulch (wood chips, bark, etc.) to the soil surface.
August 16, 2012