From time to time, we receive questions about the soil in the gardening beds of the Growing Dome. The question of soil, like many things in gardening, can be a life-long pursuit or can be a spontaneous leap of faith. Examining the interactions between micro-organisms, fungi, minerals, biomass and more keeps laboratories at the most prestigious universities busy in perpetuity. Their studies reveal much useful information, but humans have been farming for millennia, during most of which advanced measuring instruments have not been available. Successful farmers are mostly impromptu field scientists that test and experiment on the go. The good news is that depending on your style you have a multitude of resources available to optimize your soil’s health. You can submit a soil sample directly to a university laboratory (try your local university extension office) or you can test different amendments to see how they affect your plants. Most people likely appreciate a blend of the two extremes and many may even prefer to try the different soil investigation techniques. Because of this, we’ve put together a short list of various soil testing resources. Some of these testing services give you recommendations for your soil and others leave it up to you to figure out what’s best. Again, it depends on how much time you would like to invest in learning.
As far as the question of where to purchase your soil when building your greenhouse, we recommend you do what fits your budget and your wishes. To avoid spending money at all, you can utilize the soil from your property. Things to keep in mind before jumping ahead are: Is this soil especially rocky or sandy (clay soil is also difficult to work with, but is easier to amend)? What plants are growing in the soil right now? Do they look healthy? Does this soil receive runoff from roads that may have contaminated it? Just remember that most weeds or grass in the soil can be weeded out once in the greenhouse. If you stay on top of weeding then for the next couple of years you’ll find that you have virtually no weeds at all. The one main weed to avoid at all costs is bindweed. It’s incredibly hard to remove from anywhere. Another thing to keep in mind is that if there is other organic matter such as downed wood or leaves on your property, it’s a good idea to mix those in with the soil you bring in. If you don’t have soil at your site that you’d like to use, the most economical route is to purchase top soil in bulk from a local landscaping company. If you are worried about the quality of the soil, you can get a sample in advance to have tested and/or you can ask the distributor about the location from which the soil came from. If they’re really on the ball they may even have some information about the content of the soil to share with you. Things to keep in mind are if the source of the soil is near a manufacturing facility or waste dump, if it’s previously been used for farming, and other such questions about the history of the land it came from. We do know of some people who have cut straight to the chase and bought all of their soil bagged from their local nursery. Although this method is the best way to ensure you start with quality soil we don’t necessarily recommend it for two reasons: it’s not eco-friendly or economical. Yes, the soil is high quality, nutrient rich, and possibly free of pesticides and herbicides, but there was a substantial amount of energy and fuel put into gathering, packaging and shipping all that weight. Part of gardening is getting in touch with the land and how better to get started than at home or close to it?
Now, on to the links, but beforehand we’d like to add the disclaimer that we haven’t used any of these tests ourselves, yet. The first comes recommended by friends in the gardening world, the second is a good resource for gardeners here in Colorado, and the third is one we’re trying out this season. We’ll let you know what we find out and if you have any to recommend for or against please do share in the comments below.
University of Massachusetts Soil and Plant Testing Laboratory (many testing options and no recommendations): http://www.umass.edu/soiltest/list_of_services.htm
Colorado State University Soil, Water and Plant Testing Laboratory (many testing options and no recommendations, often your local extension office will offer the service of sending your samples to this laboratory): http://www.soiltestinglab.colostate.edu/
GrowOrganic.com (a couple of do-it-yourself options with information booklets): http://www.groworganic.com/fertilizers/soil-test.html