Most homeowners put lime on their lawns, and many gardeners put lime in their gardens. But how much lime is too much – and how do you figure out how much to use?
So, can you put too much lime in your garden? It is possible to put too much lime in your garden. Excessive lime will make your soil pH too high, leading to nutrient deficiencies in plants. Too much lime will also cause excessive calcium in your soil, which will prevent plants from absorbing magnesium (an essential part of chlorophyll).
Of course, you can still use lime in your garden. You just need to be careful about how much you use and when you apply it.
In this article, we’ll take a closer look at garden lime and how much to use. We’ll also get into how you can fix excessive lime in soil if you have already added too much.
Can You Put Too Much Lime In Your Garden?
It is certainly possible to put too much lime (calcium carbonate) in your garden. In the right amounts, lime provides calcium to plants and raises the pH of acidic soil.
However, too much lime can cause several problems with your soil, including:
- High soil pH
- Excessive calcium in soil
- Rapid spike in pH
Let’s take a closer look at each one of these problems and why they matter for your plants.
Too Much Lime Makes Soil pH Too High
If you add too much lime to your garden, the soil pH will be too high (basic or alkaline). Most plants prefer a soil pH of 6.0 to 7.0, which is slightly acidic (7.0 is a neutral pH.)
Remember that pH works on an exponential scale. For example, let’s say your plants prefer a soil pH of 7.0, but your garden soil pH is 8.0. In that case, your plants want the soil to be 10 times more acidic than it actually is!
If that is too theoretical for you, then think about the difference between:
- a glass of pure orange juice (100% orange juice)
- a glass of 10% orange juice and 90% water
The pure orange juice is ten times more concentrated than the water & juice mixture. You can easily tell the difference in terms of taste and color.
As you might guess, a small change in pH can cause big problems for plants. When soil pH gets too high, plants have a harder time absorbing nutrients through their roots.
For instance, boron availability drops off as soil pH approaches 8.0. Phosphorus availability decreases as soil pH approaches 8.5.
For more information, check out this chart from Research Gate on the effect of soil pH on nutrient availability.
Unfortunately, high soil pH can cause nutrient deficiency even if there is plenty of that nutrient in the soil! So, adding fertilizer to your garden won’t necessarily fix a nutrient deficiency caused by high soil pH.
Too Much Lime Causes Excessive Calcium In Soil
There is another problem with adding too much lime to your garden: you can end up with excessive calcium in your soil.
Calcium is an important nutrient for the health of plants. According to the University of Georgia, calcium helps plants with:
- Building cell walls
- Extending primary roots
- Transporting nutrients
Although calcium is vital for plants, too much of it will cause problems. For example, high levels of calcium in the soil will prevent plants from absorbing magnesium (both elements are in the same column of the periodic table, so they behave similarly).
Magnesium is the central atom in a molecule of chlorophyll (the compound that makes plants green). You can imagine the problems that will occur if a plant is unable to absorb enough magnesium to make chlorophyll!
For more information, check out my article on magnesium deficiency in plants.
Adding Lime Too Quickly Will Spike Soil pH
Finally, there is a potential problem if you add too much fast-acting lime to your soil all at once. If there are plants growing in your garden, the rapid change in pH can shock the plants and cause damage.
Even if you calculate the correct amount of lime to adjust your pH, it can still be problematic if you add too much at once when plants are growing.
One solution is to add lime in the fall, after the harvest is over and there is no danger to plants. Another solution is to split the application of lime: use half of what you need in the fall, and then use the other half in the spring before planting.
How Long Does It Take For Garden Lime To Work?
Garden lime can start working to raise pH within a few months. However, it can take 2 to 3 years for lime to completely react with the soil.
“Lime will react completely with the soil in two to three years after it has been applied; although, benefits from lime may occur within the first few months after application. How long the effects of lime last will depend on the kind of lime used, total soil acidity, amount of organic matter, kind and amount of clay, and cropping and management systems used. A soil test three to four years after lime application will help provide the answer.”https://www.canr.msu.edu/uploads/resources/pdfs/facts_about_soil_e1566.pdf
This means that the current soil pH and composition (clay, sand, or loam) will have an effect on how quickly lime works, and how much you need to use (more on this later).
For more information, check out this article on soil acidity from the Michigan State University Extension.
Can You Use Too Much Dolomite Lime?
It is also possible to use too much dolomite lime. It will cause the same problems as too much ordinary lime.
The soil pH will get too high, the pH may rise too rapidly, and you may end up with excessive amounts of calcium or magnesium in the soil.
Dolomite lime is simply calcium carbonate and magnesium carbonate together (so it provides both calcium and magnesium for plants). However, it acts to raise pH, just like ordinary lime.
Dolomite lime should be used to raise soil pH if magnesium levels in the soil are low or marginal.
For more information, check out this article on lime from the Michigan State University Extension.
How Much Lime Should I Put In My Garden?
There are three things you need to know to find out how much lime to put into your garden: current soil pH, desired soil pH, and soil type.
- First, get a soil test to determine the current pH of your soil. You can get a kit to test the soil yourself, or you can send it away to a local agricultural extension lab for testing. For more information, check out my article on soil testing.
- Second, you need to decide on the desired soil pH, based on the plants you want to grow – more on this later.
- Third, you must find out what type of soil is in your garden: clay, sand, or loam (or some combination). To find out, you can do one of several tests.
One way to determine the type of soil is to feel it with your hands:
- If the soil is gritty with large particles, then it contains more sand.
- If the soil is smooth with small particles, then it contains more clay.
Another option is to mix soil and water together. Then, swirl the mixture in a glass jar and see how it settles:
- Sand will settle first (since these particles are the largest and heaviest).
- Silt will settle next.
- Clay will settle last (since these particles are the smallest and lightest).
For more information, check out this article on soil from the Penn State Extension.
Once you determine these three things, you can to use this table, based on your soil type, current pH, and desired pH.
Lime per 100
(raise pH from
4.5 to 5.5)
Lime per 100
(raise pH from
5.5 to 6.5)
|Sand or |
need to raise soil pH, based on the type of soil.
Note that the table does not cover all possible starting and desired pH values. You may need to use some rough estimates.
For example, to raise the pH of sand or loamy sand (first row in table) from 5.0 to 6.0, you would need to add somewhere between 2.30 and 2.75 pounds of lime per 100 square feet.
For more information, check out this article from UC Davis on changing pH in soil.
Let’s look at an example to see how this would work in practice.
Example: How Much Lime To Put In A Garden
Let’s say that your current soil pH is 5.5, and you want to raise it to 6.5. This means we will be using the far-right column in the table above.
You also find that the soil is sandy, meaning that we will use the first row of the table.
You have a 20 foot by 20 foot garden, so the area is 20 feet x 20 feet = 400 square feet. This means that there are 4 areas that are 100 square feet.
The table above tells us to use 2.75 pounds of lime per 100 square feet to raise the pH of sandy soil from 5.5 to 6.5.
So, we need to use 4*2.75 = 11 pounds of lime, spread evenly throughout the garden.
When To Apply Lime To A Garden
You can apply lime to a garden at any time. However, applying too much lime when plants are growing can raise pH too quickly, which will hurt your plants.
According to the University of Maryland, the best time to apply lime to a garden is in the fall, after harvest is over. The freeze-thaw cycle over the winter and spring will help to spread the lime into the soil.
Use a spreader (such as this one from Home Depot) to distribute the lime evenly over the soil.
How Do You Fix Too Much Lime In Soil?
If you add too much lime to your soil and make the pH too high, there is a way to fix it. You can add sulfur to your soil to lower the pH, making it more acidic.
This can be done with elemental sulfur or ammonium sulfate, but be careful! If you add too much sulfur, you may end up on the opposite end of the spectrum, with soil that is too acidic.
Finally, remember that sulfur also takes time to work completely, just like lime does. So, there will be a delay between when you add sulfur to the soil and when you see a noticeable drop in pH.
For this reason, it is best to apply sulfur to your soil in the fall, to give it plenty of time to work over the winter and spring. That way, the pH should be closer to normal when you go to plant the next year’s garden.
Of course, the best way to avoid pH problems is to get a soil test from an extension office & get advice from them, depending on what plants you want to grow.
Which Plants Do Not Like Lime?
Most plants prefer a pH in the range from 6.0 to 7.0, but there are some exceptions.
For example, blueberry bushes, rhododendrons, and azaleas both like the soil pH to be in the range of 4.5 to 5.5, which is more acidic than most other plants. As such, these plants usually do not require any lime, and they may suffer if the soil pH is in the 6.0 to 7.0 range.
Potatoes are another popular garden crop that can tolerate more acidic soil. According to the University of Minnesota Extension, potato plants can tolerate a soil pH as low as 5.0.
Now you know that it is possible to use too much lime in your garden – along with how to fix the problem. You also know the steps to take before adding any lime (do a soil test, find out the soil type, and figure out the desired pH).
I hope you found this article helpful – if so, please share it with someone who can use the information.
You might also want to read my article on how to raise soil pH here.
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