pH: The Most Important Thing You're Ignoring In Your Yard

Okay, I did make a bit of an assumption with that title, but I'd still be willing to bet that most of the people out there who garden, casually or otherwise, have never checked their soil pH.  I think most people who have been gardening for more than a season or two have read or heard that certain plants prefer a certain pH range, but even for those who know about those ideal ranges, it's often not the first thing that comes to mind when a problem pops up. 

You probably already know, on a basic level (hah!  See what I did there?) what pH is.  pH refers to the acidity or alkalinity of a substance.  That measurement is referred to in numbers from a scale ranging from 0 to 14.  Seven is considered pH neutral.  Any number below seven is acidic, and anything above seven is alkaline.  In gardening, we're usually talking about the soil when we refer to the pH of the garden or yard.  Different parts of the country tend to have different average pH ranges, depending on the composition of the soil in that region.  For example, the soil in my area tends to be pretty acidic by gardening standards, with averages hovering between 4.8-5.5.  The average soil pH in other regions can be more toward neutral, or even alkaline in certain chalky or limestone-rich soils.  It just depends on where you are, what's in the soil there, and what that soil has been exposed to in the past. 

So why does this matter?  Well, let's apply this to a tomato plant.  Let's say you're growing a tomato, and it did pretty well earlier in the season, but now the leaves are turning yellow with a network of green veins, and the plant just looks like hell.  For a lot of gardeners, the knee jerk response is to start spraying it with stuff.  Maybe it's a fungus, so you break out the Daconil, or maybe it's an insect, so you whip out a bottle of Sevin and go to town.  None of these things work, and the plant continues to decline.  You just wasted a lot of time, and sprayed a bunch of chemicals all over the place that didn't help, and the plant looks like it's on death's door now.  At this point, a lot of people would give up and let it die.  The more determined might google the symptoms or take a leaf to somebody in the know.  One way or another, you get an answer: iron deficiency!  You have a name for your problem, and probably a big assumption to go with it: your soil doesn't have enough iron in it.  So you buy a bottle of ironite, and it seems to help.  Problem solved, right?

Nope.

Here's the problem: chances are, the iron content of the soil was never an issue.  Most soils contain a decent amount of iron, and you may have just spent a lot of time and money adding something to the soil that was already there in spades.  Yeah, it fixed your problem for now, but it could have been faster, simpler, and cheaper, if your first reaction to a yellowing leaf had been one of these:

or one of these:

Now, before I get a flood of comments from people who really DO live in areas with low iron content in the soil, let me just say this:  your soil is weird.  Yes, truly iron deficient soils exist.  There are tests out there to check for this, and most local extension services can also check this for you, usually for a small fee.  But the majority of the time, iron deficiencies have nothing to do with the actual iron content of the soil.  The problem occurred because you're growing a tomato that likes a nice, acidic 6.5 soil, and you're trying to grow it in a garden that's sitting at 7.3.  Maybe you just live in an area with alkaline soil, or maybe you followed the advice of some old timer gardener who swore that adding lime to a tomato hole will make magical supertomatoes (which may have worked in HIS soil conditions, but your garden is not his, and your soil may be different).  But either way, you now have a problem. 

The issue with pH is that the acidity of the soil affects soil chemistry and root performance in strange ways, and those ways affect whether or not the plant is able to take up and use certain minerals and nutrients in the soil.  If the soil is more acidic than that plant prefers, the plant may have trouble taking up and using calcium, magnesium, and nitrogen.  If the soil is too alkaline for the plant, then iron, zinc, and phosphorus tend to get bound up in the soil, and the plant runs into trouble. 

This all might sound awfully complicated, but the practical solutions are pretty simple.  As with most things in life, an ounce of prevention really is worth a pound of cure.   Unlike most things in life, piling on some bullshit makes everything better.  Starting the season by tilling well-composted organic matter, such as manure, yard waste, and kitchen composts, into the soil does more than just add nutrients and improve drainage; it also buffers the soil against rapid changes in pH.  It helps stabilize things a bit, so that the pH will be less prone to wild fluctuations as the soil temperature rises and falls with the seasons.  Doing a soil test before planting is another preventative measure that can save you a headache and improve plant performance later; if you discover a problem before it causes a problem, it can be fixed.  You aren't stuck with your natural pH.  pH can be adjusted fairly easily with garden lime to increase alkalinity, or garden sulphur to lower it.  Both can be purchased from most garden centers, and both are pretty cheap. 

Now, all of that said, I'm a big believer in working with existing conditions instead of fighting them whenever possible.  Choosing plants that actually LIKE your natural pH will be less of a hassle and much cheaper in the long run than constantly having to measure and adjust your soil pH to suit the plants you chose.  You can maintain a certain pH for a long time through frequent testing and adjustment, but you'll never win that battle.  Of course, for things like vegetable gardens, you're going to grow the veggies you like regardless of soil conditions, and there's nothing wrong with that.  Just accept that you may have to do some extra work to keep them healthy and get a good crop.  But for ornamental plants, and even lawns, there are probably options perfectly suited to your yard that will perform better for you than others.  If you adore acid-loving azaleas but your natural pH sits at 7.0, you're going to be fighting with the natural chemistry of the soil every year.  You might have a nicer garden in the long run if you choose an alternative that does better in your area.  If you need suggestions, most areas have local extension offices that can give you lists of plants that are known to do well with whatever weather and soil conditions are normal in your area. 

So it all boils down to this:  buy a soil tester.  Own it.  Use it.  Love it.  Call it George if you must.  Or find an extension service that will test soil samples, and use that service.  It might solve some problems you've been battling for a long time, and will probably make life a little easier for you in the future.