Question: I grow in an area where the soil is a bit too acidic—about 5.7 to 5.8. What’s the best way to raise my soil’s pH without overdoing it? I want to grow in open soil without containers—unless you think it would be better if I used containers and imported soil.
Answer: Hello Keri,
Thankfully, this is a simple fix. There is nothing wrong with growing in open soil as long as you make sure you first amend the soil as needed and ensure that you’ve thought of all the potential pest and irrigation issues that could pop up. To safely adjust the pH I would suggest picking up some fine dolomite lime. Fine dolomite lime is a compound of magnesium and calcium and is very safe to use because it has a stable pH of 7.0 and won’t raise the soil’s pH above that. The only potential downside would be if you don’t mix it into the soil as thoroughly as possible because large concentrations can cake up and burn the roots. Be sure to purchase the finest grade variety, called flour. It will begin working a lot faster than the courser stuff that could take up to a year to start working. As an added benefit, fine dolomite lime will act as a buffer against slightly acidic fertilizers.
For more immediate results, mix a quarter cup of hydrated lime in warm water for every cubic foot of soil, and saturate the soil with this mixture. It’s important to not overdo it as using more than half a cup of hydrated lime per cubic foot can toxify the soil. If this happens it’s pretty easy to flush out the excess with a lot of plain water. The hydrated lime will probably wash out of the soil on its own in a couple of weeks anyway. Plenty of growers use this method to jump-start their soil’s pH and follow up with a longer running treatment of fine dolomite lime.
One more thing: NEVER use quicklime. It will kill your plants!