Lime for the lawn, landscape and garden is an important tool. You may ask why… what does lime do for a garden?
The answer is: In sections where the soil is acidic, the proper use of lime may provide the key to better plant growth.
Therefore, it is important for homeowners and gardeners in such areas to understand how to use garden lime and how much they should apply to the garden soil.
Plants differ widely in their tolerance to acidity in the soil. A few, such as blueberries and evergreens, are acid-loving plants. The great majority of our cultivated plants, however, prefer a soil which is nearly alkaline.
If the soil in your gardens or lawns is acidic, it will be necessary to apply lime to the lawn or vegetable garden to partially neutralize the acidity and grow healthy, vigorous plants.
Applying lime to an acid soil will also unlock plant foods that otherwise may be unavailable to the plants; supply the essential plant foods, calcium and magnesium; create a condition favorable to the growth and activity of beneficial soil organisms; and, to a limited extent, improve the soil texture.
What Makes Soil Acidic?
The acidity of a soil is usually determined by the type of rocks from which the soil was originally derived. Quartz, granite, sandstone and shale produce acidic soils.
Limestone and marble are alkaline. In low areas, the presence of a high percentage of organic matter makes for acidity.
The amount of rainfall is another important factor in the acidity of a soil. The chemical substances capable of neutralizing acids are soluble in water.
These are dissolved in proportion to the quantity of water seeping through the soil and then carried off in the drainage water. These alkaline ions are then replaced by the acid hydrogen ions from the water, thereby increasing the soil acidity.
The removal of plant material from soil tends to make it more acid. The tomatoes you pick, the flower stalks hauled to the dump and the grass clippings raked from the lawn are all rich in alkalizing elements which must be replaced or the soil will gradually become more acid.
Two other factors which contribute to the increase of acidity in your garden and lawn soils are the continued use of acid fertilizers and the addition of organic matter, such as peat, unlimed compost and green manure.
There is no simple way to determine the acidity or alkalinity of a soil. The presence of green moss and sour-grass or sorrel in a garden or lawn are considered by many as an indication of acid soils.
This is definitely not true. And, peculiar as it may seem, the symptoms of trouble shown by a plant growing in a too-acid soil may be similar to those caused by an over-sweet soil.
The only certain answer is a soil test made by a reliable laboratory. This is an easy and simple operation. It consists of taking a cupful of the top six inches of soil from two or three places in the troublesome section, mixing them together and sending about a cupful of the mixture to your County Agent or State Agricultural Experiment Station.
The result will show the soil pH level and the kind of nutrients naturally present in the soil. This will help you determine the suitable type of lime application that should take place.
Soil testing kits like this can be purchased from garden supply stores or garden centers. Those testing for acidity or soil ph levels are inexpensive. These should be of great help in keeping tabs on the condition of the soils in your gardens and lawns.
However, I consider it very important to check the readings periodically by sending some tested soil samples to be professionally analyzed.
How Is Acidity Measured?
Terms, such as “very” or “slightly”, used in describing the acidity of a soil are indefinite. Even the term “acid” may mean one thing to one person and something else to another.
To provide a definite means of measuring the reaction of soils and other substances, a universal scale of 14 points and known as the “pH” scale was adopted many years ago.
In this scale the half-way point, or 7, is neutral. The numbers above 7 indicate the degree of alkalinity and those below 7 the acidity.
Modern soil-testing laboratories use an electric pH meter for testing the reaction of soils. This is a potentiometer calibrated to read the pH values directly. They are extremely sensitive instruments and must be frequently checked for accuracy.
In the test kits commonly- sold for testing soil at home, one general dye or several different and more sensitive dyes may be used for determining the reaction of the soil. Color charts are included with complete directions for using.
Unfortunately, there are several possible sources of trouble in the use of these kits.
The dyes are not too stable and may deteriorate over a period of several months; the color of the dye may be completely absorbed as it seeps through the soil sample; the chart colors may be poor to start with or fade within a few months; and the tester must have a good eye for colors or the reading will be wrong.
Hence my suggestion above for frequent checking of the tests you make.
What Do Plants Prefer?
You will find lists of plants with their preferred reactions given in many garden books and plant magazines. In most cases there will be a spread of 1-1/2 to 2 points given for each plant.
In some cases you will also find that authorities differ as much as a point or more in their recommendations. This may be due in part to the difference in other growing conditions experienced by these gardeners.
I would suggest that it only demonstrates how tolerant plants actually are to varying degrees of acidity.
The acid-loving or acid-tolerant plants should grow well in soils with a pH of from 4 to 5.5.
By far the greatest number of plants commonly grown in lawns and gardens prefer a slightly acid soil. Therefore, they should grow well in soils with a pH of from 5.8 to 6.8.
Under average growing conditions the so-called “lime-loving” plants, such as delphinium and others, will grow better in a soil with a pH of 6.8 than in a soil with a pH of 7.2. This is due to the fact that the desirable plant food elements are more soluble in a slightly acid soil than in a slightly alkaline soil.
What Is the Best Lime For The Garden?
There are three types of lime commonly sold under the general terms land or agricultural lime.
Hydrated lime is a very fine, fluffy powder similar to flour in appearance and feel. It is soluble in water and therefore gets to work immediately when spread on the soil and watered. It may contain from 60 to 80% active sweetening power.
Limestone is a grayish, gritty, cement-like material consisting of finely ground lime rock. It takes time to dissolve and, as a result, is slow to get to work.
It may contain from 20 to 50% sweetening power, the effectiveness of which is in proportion to the fineness of the grinding.
A mixture of the above two types of lime is commonly sold by farm and garden supply stores. The benefits of both are thus combined.
Over a period of years there is little difference in the effectiveness of the various types of lime when applied in equivalent quantities.
The total content of calcium and magnesium determines the “sweetening power”, so compare the percentages of these in the analysis which must be on the bag or tag.
For quick results use the slightly higher priced hydrated lime. For the “long pull” use the more easily applied, better keeping and less expensive ground stone.
Is Dolomitic Lime Better?
During the years soil experts have come to a better understanding of the value of the so-called “trace” elements.
These are plant foods, such as boron, zinc, magnesium and others, which are used by plants in minute quantities but are essential for normal plant growth.
Magnesium has been found to be important to plants in the synthesis of carbohydrates, fats and proteins, as well as an essential constituent of chlorophyll and of value in the production of good seeds. It is deficient in many soils, particularly those that are acid.
Dolomitic lime contains from 20 to 30% magnesium in addition to 30 to 50% calcium and has been gradually replacing the ordinary lime in many sections of the country.
It is available in both the hydrated and ground stone types and sells for about the same prices as the old kinds. I would recommend it if not too difficult to obtain.
You may have to go to a farm supply store to get it, but I have found it at Home Depot and Lowe’s.
When Is The Best Time To Apply Lime?
As lime is most effective when thoroughly mixed with the soil, it should be applied before the land is prepared for planting.
When plowing or turning over a soil which is highly acid, it is best to spread lime both before and after the operation, thus getting it well mixed with the soil.
If plants are already growing and the need for lime determined, it can be spread without injury to the plants and either watered or cultivated in. In such a case the hydrated lime should give the quickest results.
Limestone can be mixed with fertilizer and then spread, or applied before or after the fertilizer, as there is practically no chemical reaction.
If it is considered desirable to use hydrated lime and fertilizer at the same time, it will be best to apply one first and rake or harrow it in and then spread the other. In this way the two raw materials do not come into direct contact.
How Much Lime Do You Apply
The proper amount of lime to use on a certain lawn or garden area will depend upon the degree of acidity of the soil, the texture of the soil and the kind of plants to be grown.
If you give the proper information when sending your soil for a test, recommendations for the amount of lime to be used will accompany the results of the test.
The usual recommendations for average conditions is 4 to 5 pounds of limestone or 3 to 4 pounds of hydrated lime per 100 square feet of garden or lawn.
As previously suggested, when starting a new lawn or garden in a soil which is highly acid, or below a pH of 5.5, it is best to use two applications of these amounts, one before turning the soil and the other after.
Once the soil is up to par, or a pH of 6.3 for most plants, an application of the recommended quantity of lime once every 5 to 6 years should keep the soil in good condition.