The Modern Victory Garden

In order to thrive, plants need to be in soil that is within a certain range of PH levels.   If it is too high (alkaline) or too low (acidic) for that plant then it will not be able to avail itself of required nutrients from the soil.   Most vegetables and fruits prefer a range from 6.0 to 7.0 with some of the more notable exceptions being potatoes (which prefer a slightly more acidic soil of 5.5 to 6.0) and blueberries / cranberries (which prefer a much more acidic condition of 4.0 to 5.0).                   

Each year in the fall, I do a check of the garden PH levels to determine if adjustments are needed.   Last year when I did this, most of the regular garden beds indicated a need to have some dolomitic lime added to raise the PH level and the blueberry / cranberry areas indicated a strong need for sulfur to be added to lower the PH level.   The adjustment indicated for the blueberries and cranberries was pretty significant so a complete correction was not attempted but rather a step down in the PH level with a plan to continue adjustments in the future.   Adjusting more than 1 point in a given time period can cause undue stress on plants and it is generally advisable to try and improve the PH level over a period of time rather than to attempt extreme adjustments all at once.       

There are two small (relatively inexpensive) tools that I would recommend every gardener have on hand.   One is a good soil thermometer.   The other is a soil PH meter.                                 

They are both readily available at most garden centers.   There are also chemical PH test kits available as well.   Not all meters are of the same quality and reliability.   I have had a few “duds” in my time that read the same no matter which bed it was placed in!   The one in the picture above is the meter I currently use and have found it to be reasonably accurate.   However, if I get readings that indicate an adjustment is needed, I always go back and do a second check to verify the results before proceeding to do an amendment process adjusting PH levels.   In addition to the meters and test kits, you can also take soil samples and submit them to your local cooperative extension service office.  For a small processing fee they will test your soil for PH and nutrient levels etc.,   If you contact them they will provide instructions on how to do this and where to submit the soil for testing.   Here is a link that will help you find a local office near you if you are interested in this.

http://www.csrees.usda.gov/Extension/                                       

To test soil PH using a meter with probe:

• Always thoroughly clean the probe before and after each insertion in soil.   My meter comes with a scrubber pad to initially clean and prep it - I then use a dry paper towel between tests and afterwards to dry it off before putting it away.
• If the soil is soaked from rain then insert the probe several inches (more than 4 inches) into the soil and wait one minute to take the  reading.   If you get a very strange reading, the probe is likely touching a bit of debris.  Pull it out, clean it, and try again somewhere close to the original insertion point. 
• If the soil is somewhat dry, dig a small hole and remove any debris such as rocks or twigs, pour distilled water (preferable) or rain water (second best) into the hole until the soil is thoroughly wet.   Then insert probe and allow one minute before reading.
• For garden beds, take several readings at various places in the bed area and determine the range of readings indicated.   Soil will be different throughout a bed due to a variety of factors and can vary significantly from one part of a bed to another.

This afternoon I took the time to test all of my garden beds and more permanent container plantings.    Including the potted blueberries…                

…. and every one of the other garden beds too.                        

The readings were placed in a spreadsheet that compared those results to the desired PH range for the bed and it’s current or expected future use.     

It appears that all of my adjustments to increase  PH last year worked very well and there are no indications that I should add lime to any of the garden beds at all this year.   However, the beds that will hold the potato patches next year and the cranberry and blueberry planting areas all need additions of garden sulfur to reduce the PH level.   The blueberry and cranberry areas in particular need rather significant reductions still.   I will wait to do the potato beds next spring, as they currently have crops in those beds that prefer the current PH range.   I went ahead and applied garden sulfur to the blueberry and cranberries today though.        

Follow the instructions carefully on the bag regarding how much to apply for a given plant or garden area to adjust the PH level.   If I am adjusting PH upwards, I like to use dolomitic lime  - as it adds calcium and magnesium while also increasing PH.   Again whatever product you need to use, follow the directions carefully on how much to apply.

Have you tested the PH levels in your garden?