I always feel that creating a new garden area is a lot like painting a room – 90% of success is in the preparation. For the better part of the past year, I have been doing the preparation work for my new Serenity Garden. First, I laid out the boundaries of this new garden area and did a sun study (see Planning the Serenity Garden). Then I created a design plan of suitable (I hope) plants (see The Plan). When I was home in Maine in late April, I took a sample of soil from the new garden area and sent it off to the Maine Soil Testing Service at the University of Maine. The information from this test will tell me just what I need to do to turn my glacial sand into perfect garden soil.
Many gardeners purchase do-it-yourself soil testing kits, but I prefer to send my soil samples off for professional testing. In the United States, soil testing services are usually provided at reasonable cost by the land grant state universities (do a browser search for “soil test” plus your state’s name to find information), and the results come with a set of specific instructions for amending the soil to correct any problems.
In Maine, the University of Maine Cooperative Extension Service provides both instructions on taking a soil sample and handy little boxes for mailing the soil sample off to the lab. The instructions recommend mixing samples from at least 15 different parts of the field to be tested, but that seemed a bit excessive for my 120 square foot flower bed. Nevertheless, I dug several holes dotted around the planned garden area by pushing away the pine needles that cover this area and using a trowel to dig out a plug of soil about 8” deep. I mixed the soil from all my holes together in a bucket and then filled the box from that mixture.
The box was sent off with a form providing information about how the garden area would be used and a check for $15 to cover the cost of testing.
The low pH of the soil is typical for my property and hardly a surprise in this area at the edge of the woods where decades worth of pine needles have dropped and decomposed. Although the proportion of organic matter is also low, it is actually higher than is typical for my property, which means that I won’t need to add as much manure and compost as I usually do. A separate sheet of information on managing micronutrients that came with my soil test report tells me not to worry about these; if I get the pH right, they will take care of themselves. There are also additional pamphlets and information sheets about how to interpret my results that are easily available from the soil lab website.
The recommendations for soil amendments are designed for farmers planting fields of crops, so they need some adjustment and interpretation for my flower beds. Since the amounts are per 1000 sq. ft. of field, and the Serenity Garden will be a little over 100 sq. ft., I can simply divide the recommended quantities by 10 and round up a little. The first thing I notice when I read these recommendations is that I can get the both the potassium and the pH in my soil up to optimum levels by adding about 10 lbs. of wood ash. Since I heat my house with wood, this is a soil amendment that I always have readily at hand! I’m less sure how to interpret the results about adding manure; these seem to assume that I have access to raw manure from a local farmer (or my own farm animals), but I’m planning to use bags of composted manure from the garden center. Happily, my report came with the email address of a soil analyst who can answer any questions I have, so I will ask how to convert bushels of raw manure into bags of composted manure. While I’m at it, I’ll ask how much the addition of composted manure and compost should reduce the amendments for nitrogen and phosphorus.
I usually dig new flower beds in 6 square foot sections (see Garden Alchemy), and there will be 20 such sections in this flower bed. So once I have determined the appropriate amounts of each soil amendment, I’ll divide that amount by 20 and that is how much I’ll add to each section.
Many gardeners have success with a more intuitive, seat-of-the-pants approach to soil preparation, but I’m most comfortable with data-driven decisions. I love having numbers based on scientific testing that I can put into a formula to create the perfect home for my new plants. Soon, I’ll be able to put that information to use as I actually start digging this new flower bed.