Acidic soil is soil that has pH lower than seven. To better explain, pH, meaning potential hydrogen, is measured on a scale from zero to fourteen. A substance with a pH of seven is neutral, such as distilled water. Anything below seven is acidic, such as vinegar or stomach acid, and above seven is alkaline or base, such as sea water or bleach.
Soil commonly fluctuates in pH based on where it is located or came from, or what was done to it during processing in the case of purchased soil. Areas that naturally have more acidic soil are those that have a higher precipitation rate. Water washes away certain nutrients from soil. Higher distributions of acidic rock such as silica or that have been heavily fertilized often have a lower pH as well.
The majority of plants enjoy slightly acidic or neutral soil having a pH growing range of around 6 to 7.5. Those plants that prefer below a 6 are considered acid loving plants. Most plants, even those that enjoy acidic soil, will not tolerate a pH below 4.5, however.
This guide on how to increase soil acidity will explain some of the methods used to lower the pH, meaning increase the acidity, in any soil as well as cover some of the plants that prefer more acidic soil that you may need to adjust pH for.
The first step in raising the acidity in your soil is to find out where it stands pH wise to begin with. You need to be sure that number one, it needs to be altered at all, and number two, how much it needs to be altered so that you don’t create toxic soil for your plants. Knowing how to test the pH of your soil is also important during the process of decreasing pH so that you don’t lower it too much and know when to halt your efforts.
Testing soil pH is a fairly simple process. You will need to purchase a pH test kit. You can find these pretty much anywhere from department and garden stores to the internet. There are two major types, the first a pH meter is simple a tiny wand you stick into the soil as if taking its temperature. A few moments later the pH is given to you on a screen. These meters can be expensive, but if you are doing a lot of growing of plants that vary in pH preference, or hydroponic growing, you may want to invest in one.
The second type includes a vial or tube which you fill with your soil and then add a special solution and shake. The solution inside will turn a color which will correspond to a certain pH on a chart that comes with the kit. These kits are fairly inexpensive.
Once you know the pH of your soil you can begin to lower it hence raising the acidity of the soil. There are a few ways to do this, some of which will act faster and more dramatically than others.
Compost will not necessarily lower the pH of soil, but it does act as a buffer. Adding compost to soil will give it a range of pH, so to speak, making it acceptable for plants that prefer pH up to or less than one point from the actual pH of the soil. As an example, a soil with a pH of 8 would then have a range of 7 to 9. This is a good option for those that have soil that is almost proper for what they are planting or that want to plant a range of plants.
Artificial Frequent Precipitation:
If you are attempting to play Mother Nature and make a plant grow in soil that wouldn’t fit its natural habitat, play like Mother Nature. Heavy precipitation creates naturally acidic soil, so moistening soil frequently will do the same. This method is very slow, but plants that like acidic soil usually prefer to stay moist anyway.
The majority of fertilizers are high in ammonium nitrate, ammonium sulfate, and/or sulfur-coated urea, and because of this fertilizing soil will gradually change its pH. This is not a quick fix, but it is a good way to slowly make soil more acidic, which can make it far easier not to over shoot.
Sulfur can be purchased in various forms in gardening supply stores and nurseries. Though faster than the above mentioned methods, sulfur is also rather gradual and may take several growing seasons for large plots of land if you need a dramatic pH shift. As an example, adding 1.2 oz of dusting sulfur to sandy soil (sand requires less sulfur to alter pH) or 3.6 oz to regular soil per square yard will reduce soil pH one point. You generally should not attempt to change soil pH more than one point per season with this method. The sulfur you purchase should have precise directions for its particular use.
This is a quick fix and works especially well in container gardens or pots. Add two tablespoons of vinegar to a gallon of water for watering. Be sure to monitor the pH change closely as this method is easy to over shoot with.
One thing to avoid when attempting to increase soil acidity:
Lime is known to increase pH and not lower it. That is to be used to lower the acidity of soil. Naturally, when attempting to do the opposite the use of lime or products containing lime should be avoided.
Though this isn’t a step in increasing soil acidity, it does pay to know which plants prefer acidic soil to begin with. If you have some plants that just aren’t fairing so well despite proper care, soil pH very well could be the issue.
Below is a brief and, of course, not all inclusive list of plants that prefer acidic soil or a lower pH. It should also give you a rough idea of the type of plants that have this tendency. When in doubt, think of the native growing habitat of the plant and what pH those locations soil has. Understanding where a plant comes from can help drastically in providing the right growing conditions well beyond the soil pH. It is always a good idea to know your plant.
*-Hydrangea (Blue flowers, flowers will be pink in higher pH soil and may even be used to estimate soil pH. In the case of those with white flowers, this does not pertain.)
*-The majority of Evergreens
*-Various types of Oak
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