Garden Lime: What It Is, How It's Used in Landscaping

Raise the pH Level of a Soil That Is Too Acidic

Image: 'Golden Oriole' azalea.
Azalea is an example of a plant that prefers acidic soil. You would not typically apply lime around such a plant. David Beaulieu

Garden lime is a rock powder used to raise the pH level of soils high in acidity. An application of lime "sweetens" a soil -- that is, it can make a "sour" soil more alkaline. Why might you wish to bring about such a change in the ground in which you are planting? Discover what soil pH has to do with plant performance here.

Note on usage: "lime" is both a noun and a verb. Above, the word is used as a noun. But you can also say, "I am going out to lime the garden now," in which case the term is being used as a verb.

The capacity of lime to sweeten ground to which it is applied also makes it useful for battling outdoor pet odors. But do not let all of this talk of sweetness lull you into a false sense of security. Garden lime is not a product to be used indiscriminately. It is a useful substance when used properly, but it is also possible to misuse it and cause harm to your plants.

Warnings About Using Garden Lime:

  • There are different kinds of lime, not all of which are preferred for landscaping purposes. As Charlotte Glen of the North Carolina State extension notes, agricultural or "garden" lime is made from calcium carbonate, and dolomitic lime from dolomite; both are suitable for landscaping use. But Glen warns that slaked lime and quick lime "are not recommended for lawns and gardens." The same source observes that both the type deriving from calcium carbonate and the kind that comes from dolomite furnish your garden with calcium, while the latter is a source of magnesium, as well. So while lime is not really a "fertilizer," it can, nevertheless, supply your garden with important minerals.
  • Have a soil test done before you even think about adding lime to your garden or lawn. To accomplish this, simply send in a soil sample to your local county extension office. Prior to taking any action, have them explain the test results and subsequent recommendations to you if you do not understand them fully. 
  • Remember, when adding such minerals to the soil, you are playing with chemistry. Unless you are a chemist and really know what you are doing, err on the side of caution -- do not add lime based on the erroneous notion that "it can't hurt anything because it is natural."
  • Some plant problems are caused by a soil's being too sweet. Chlorosis (appearing as a yellow discoloration on a plant's leaves) is an example. The Utah State University Extension remarks that chlorosis is "caused by iron deficiency, usually in high pH soils (pH above 7.0)." Iron can become unavailable to a plant growing in ground that is so high in pH (that is, the iron may be present in the soil, but the plant is unable to access it).
  • Lime often fails to provide a "quick fix." That is why liming is often treated as one of the tasks of lawn and garden care in the fall (as opposed to waiting till spring). If you rototill lime into your garden in autumn, you may actually start to see some results in terms of vegetable plant or landscape plant performance over the course of the following growing season.

    The majority of landscape plants grow best in soils that range in pH levels from 5.5 to 6.5. Some plants like to grow in earth that has a low pH level: here are some examples of plants that like acidic soils. Conversely, there are other plants that perform well in ground that has a higher pH.

    Note: Do not confuse "lime" with "Lyme." The latter is normally joined with the word, "disease" and signifies an illness borne by deer ticks. Learn all about deer-tick control in the landscape here.