What Is the Optimal Soil pH for Daffodils?
The optimal soil pH for daffodils is 6-7.
What is pH?
The pH scale ranges from 0-14, with 7 being neutral.
According to the USDA Natural Resources Conservation Service, the most common classes of soil pH are:
Extremely acidic: 3.5 – 4.4
Very strongly acidic: 4.5 – 5.0
Strongly acidic: 5.1 – 5.5
Moderately acidic: 5.6 – 6.0
Slightly acidic: 6.1 – 6.5
Neutral: 6.6 – 7.3
Slightly alkaline: 7.4 – 7.8
Moderately alkaline: 7.9 – 8.4
Strongly alkaline: 8.5 – 9.0
The soil’s pH level affects the solubility of the soil’s nutrients, and some plants cannot thrive in soil that is too acidic or alkaline. In these cases, the soil needs to be amended to meet the particular plant’s needs.
How to Raise Soil pH
You can raise the pH of your soil, or make it more alkaline, by adding materials such as wood ash, hydrated lime, or limestone. In order to raise the pH to 6-7 for daffodils, you will need to amend the soil based on a soil test and the current pH level and add a proportionate amount of limestone. For example, if the soil pH is 5, you will need to add 8 lbs of limestone per 100 square feet.
How to Lower Soil pH
You can lower the pH of your soil, or make it more acidic, by adding materials such as organic mulch, sphagnum peat, sulfur, aluminum sulfate, iron sulfate, or acidifying nitrogen. For smaller beds, the most efficient soil amendment is sphagnum peat. Work in a 2″ layer to the top 12″ of soil.
For larger areas, sulfur is more cost-efficient but slower-acting. In order to lower your pH to 6-7 for daffodils, you will need to test the soil to know your exact pH and then add a proportionate amount of sulfur. For example, if your soil has a pH of 8, in order to lower it to 6-7, you need to add .3 lbs. of sulfur per 10 square feet.
Resources
“Soil Quality Indicators PH.” USDA Natural Resources Conservation Service, Jan. 1998, https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052208.pdf.
“Bulbs & More: Planting and Care.” University of Illinois Extension. University of Illinois, n.d. Web. 29 Mar. 2011. <urbanext.illinois.edu/bulbs/planting.cfm>.
“SUNY-ESF E-Center: Soil pH: What it Means.” SUNY-ESF, SUNY College of Environmental Science and Forestry. N.p., n.d. Web. 22 Mar. 2011. http://www.esf.edu/pubprog/brochure/soilph/soilph.htm.
“How To Change Your Soil’s pH | Horticulture and Home Pest News .” Integrated Pest Management at Iowa State University. N.p., n.d. Web. 22 Mar. 2011. http://www.ipm.iastate.edu/ipm/hortnews/1994/4-6-1994/ph.html.
