Have you ever prepared a little garden plot, chosen just the right plants for your area, fed and watered them diligently, then had them turn yellow and pathetic?

Frustrating, I know. But don’t give up. It may be a pH thing.

Gardening is chemistry. You don’t need to be a chemist to get it right, but you do need to understand pH. In fact, I have a suspicion that soil pH issues are the reason many folks think they “don’t have a green thumb.”

What is pH?

pH stands for potential Hydrogen. There is a lot of science-y stuff behind it, but the bottom line is that pH affects your plants’ ability to absorb nutrients. So, if the pH is off, your plants cannot take in the nutrients you give them, no matter how much you fertilize. It’s like drinking through a tiny straw; try as you might, you can’t get enough.

Hence the puny yellow streaks between the veins on the leaves of your plants. There may be food all around but they can’t get to it.

Raspberry leaf with iron deficiency due to incorrect pH.

What pH do plants like?

The soil in your garden sits somewhere on a pH scale from 0 to 14. Seven is neutral. Anything less than 7 is called acid; above 7 is alkaline. Most garden plants do well between 5.5 and 7, or slightly acidic (There are exceptions. For instance, blueberries like a super acidic 4.)

There are a couple common enemies to optimal pH, especially in suburban settings. First is municipal, or “city,” water. Unless you are on a well (and even then sometimes), you can assume your water tends alkaline, which can move your garden up the pH scale. The other issue is that before many homes are built, the builders bring in fill dirt to level the lot. Depending on where that fill came from, it may be alkaline. Plant your garden in it and you could have pH problems.

How do I know the pH of my soil?

You can have your soil tested for nominal cost. Nearly every area in the country is served by a Land-Grant University Extension Office that exists to help you with this sort of thing. Find yours and make friends with them.

What if my pH is not where it should be?

The simplest answer is to use plants that like the pH level of your soil. However, if you want to grow tomatoes, for instance (acid lovers), in your alkaline soil, there is a remedy.

Remember limestone and sulfur. Limestone makes things more alkaline, sulfur more acid. There are powder and granule versions of each (granule is better) that can be added to your soil to adjust the pH up or down. Beware, though. These are temporary fixes and not 100% reliable. You will have to reapply regularly to keep the pH where you want it. And if your soil is way off from where you need it to grow a certain plant, it’s probably best to let it go or grow in a raised bed where you can control the conditions better. Nature will win in the end.

Right plant, right place.

You’ll hear me (and every experienced gardener) say this a million times. Have your soil tested, and then try to plant things that already like your conditions. It will save a lot of headaches. However, is you choose plants that thrive in your pH range, you’re already half way to gardening success.

Kevin