First, a confession — I gardened for a few decades before I ever touched soil to test. And I only got one at all because I started growing food and my jaded urban farmer friends insisted that I do it before growing food. So, here’s what I learned about soil tests — for gardeners. (And here’s my blog post about this historic event.)
Who REALLY Needs Them
Anyone growing food, but especially in the city. Apparently there can be some nasty things in the soil — lead and other heavy metals.- Gardeners with unexplained plant troubles.
How they help ANY Gardener
- Tests can reveal problems before they kill your plants.
- A test will prevent the HUGELY common gardening mistake of fertilizing too much. The big companies don’t tell you this but most gardens don’t need potassium or phosphate at all (turns out mine didn’t), so all that phosphate runs into your local waterway and ultimately the Gulf of Mexico and creates dead zones and — well, it’s really bad, just as bad as pollution from farming. So targeting actual fertilizer needs is environmentally responsible AND saves the gardener money.
How NOT to Do It?
And the answer is: by buying one of those cheapie testers at the hardware store. They’re too imprecise and can’t possibly tell you what you need to know. Save your money.
Recommended Labs
There are surely dozens in the U.S. but I’ll start with the two I’ve heard vouched for and I welcome additions to the list.
A&L Eastern Lab is the most often recommended in the Mid-Atlantic area, and maybe farther afield for all I know. Their website and especially their price list is WAY CONFUSING for anyone except hort and ag geeks, but I’ve chatted with these folks and here’s what they tell me:
- Click on “Lawn and Garden”, then the Price List. Home gardeners should order either “MEL1″ for where they’re growing lawn (for $12) or “MEL2″ if they’re growing the imprecise “garden” (for $15). I asked what about edibles versus ornamentals? They say to tell them on your order form and the label on your sample what you’re growing in that soil — flowers, trees, vegetables — and they’ll advise you accordingly. Apparently the test is the same and will determine your soil’s pH level, nutrients or lack thereof, and ditto for organic content.
- Need testing for lead or other heavy metals? They say to call them for advice because that kind of testing can get expensive, and unlike so many university labs, A&L isn’t subsidized, and has to charge the actual cost. (Or see UMass below.)
- Their imprecise soil-sampling-and-packaging instructions say to use a “medium Ziploc bag” and ship it in a “sturdy box.” Since I’m short on sturdy boxes myself, I asked if a sturdy padded mailing envelope would work and was told yes. And how much soil do they actually need? 2 cups is best, they tell me. Don’t forget to slap a label on it with the required info.
University of Massachusetts Lab is one of those subsidized ones the private labs have to compete with and the one that I happened to use myself. I found the website and forms easier to use, but I’ll run through what I did just in case.
- Here’s their price list and look how simple and clear it is! The best choice for home gardeners is the”Standard Soil Test w/Organic Matter” for only $13 — a bargain. Notice that that test will even look for extractable heavy metals like lead, so if that’s a concern in your garden, this may be your best choice.
Best Time
Several months before planting in an area, so late fall and early spring are recommended.
