Q. Peter, we live at Harvest Gate in Puyallup in the Summit area where the underlying soil is clay and very rocky. I believe you recommended as an excellent soil builder a compost mixture that will sit over the winter months. My question: when, how much and is there a product that you could recommend? Phyllis Salisbury – Puyallup, WA
A. What can happen in developments where major topographic changes are made (with large machinery) subsoil is brought much closer to the surface. This can sometimes even expose glacially compacted subsoil, which is like an impenetrable “hardpan” that goes down for feet and is a nightmare for gardeners. Normally this subsoil has at least 18 inches of soil above it but in developments there can be as little as a few inches. If the soil is hard and unworkable then setting up raised beds is the best solution. If however your soil is clay and rocky but still tillable then adding a organic matter like compost will suffice. How much and when to apply compost depends on what you are growing. If you are putting in plants this fall then apply the compost before planting. But if you don’t intend to plant until the spring then I would wait. If you just leave compost out during the winter without plant roots growing into it many of the nutrients can be leached below the root zone during our rainy winter season. Initially I would start with three-inch layer of compost and then adjust the amount added each year from one to three inches depending on the quality of the soil. I mentioned last week that Pierce County Recycled Earth Products is a good source of compost, especially if you need a large quantity. I gave out the website last week so I’ll give you the phone number (253) 798-2179 and email address pcsolidwaste@co.pierce.wa.us this week.