The Q&A Archives: alternative to lime

Question: Hi. I'm from Pennsylvania. My hydrangea used to be pink but now it has turned to blue. I like it pink. What are the alternatives (non chemical if possible)to lime treatment of soil to make it less acidic?
Also, how do I propagate my hydrangea and Preston Lilac?
Thank you and more power...

Answer: Areas with high rainfall tend to have acidic soils; areas with low rainfall tend to have alkaline soils. Acidic soils produce blue hydrangea blossoms; alkaline soils produce pink hydrangea blooms. If your soil is too acid, you need to add alkaline material. The most common "liming" material is ground limestone. Ground limestone breaks down slowly, but it does not burn plants like "quick lime" does. Apply it to the garden and lawn in the fall to allow time for it to act on soil pH before the next growing season. A rule of thumb for slightly acid soils: apply 5 pounds of lime per 100 square feet (say a 5 x 20-foot raised bed) to raise the pH by one point.

Applying wood ashes also will raise soil pH. Wood ashes contain up to 70 percent calcium carbonate, as well as potassium, phosphorus, and many trace elements. Because it is powdery, wood ash is a fast-acting liming material. Be careful, a little goes a long way. Limit your application to 2 pounds per 100 square feet and only apply it every other year in a particular area.

If you would rather not add lime, you can add organic matter to your soil (compost, for instance) as it tends to neutralize both acidic and alkaline soils. It may take a period of 3-4 years, though, for you to see a difference in your hydrangea. A final option would be to grow your hydrangea in a large container filled with commercial potting soil which is typically in the neutral range.

To propagate a hydrangea simply bend a branch down to the ground, anchor it with a couple of rocks and it should root where the stem touches the earth. Or you can take tip cuttings, dip the cut end in rooting hormone and set it in a container of moistened potting soil.

Lilacs generally send up suckers from the roots. All you need to do is cut straight down between the main shrub and one of the suckers and dig it out, roots and all. Transplant it into another area of the garden and you'll have a new plant.

Best wishes with your landscape!

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