Is Lime Good for Tomato Plants? (3 Benefits & 3 Cautions)


Are you wondering about whether lime is good for tomato plants?  If so, you may also be wondering if there are alternatives available, and how to use them.

So, is lime good for tomato plants?  Lime is good for tomato plants if the soil is lacking calcium or is too acidic (low pH).  Lime can also help to reduce nutrient deficiencies and improve water penetration in soil.  However, too much lime will raise pH too much and can block a tomato plant’s uptake of magnesium.

Of course, the amount of lime you will need depends on your soil’s pH and nutrient content, as well as the desired pH.

In this article, we’ll talk about the benefits of lime for tomato plants, along with some cautions.  We’ll also look at some garden lime alternatives and when to use each one.

Let’s begin.

Is Lime Good for Tomato Plants?

Lime (also called garden lime or agricultural lime) can be good for tomato plants when used in moderation.  In certain cases, adding lime to soil can help to solve soil problems.

calcium carbonate
Lime (calcium carbonate) is also called garden lime or agricultural lime. It is used to raise soil pH, and also adds calcium to soil.

For example, tomatoes grow best in soil with a pH of 6.0 to 6.5.  If the soil is too acidic (pH too low), adding lime will raise the pH.

In these cases, lime (calcium carbonate) is fine if applied correctly according to the instructions on the package.  Remember that the amount to use will vary depending on the current soil pH and the desired soil pH.

You can also use dolomitic lime on tomato plants.  Dolomitic lime (calcium magnesium carbonate) raises soil pH (just like lime), but it also adds magnesium to your soil.

Quick lime (calcium oxide, also called burnt lime) has a very high pH, due to the carbon dioxide being burned off in a kiln.  According to the North Caroline State University Extension, quick lime is not recommended for lawns & gardens.

No matter what supplements you decide to use in your garden, always do a soil test first.  This will tell you the soil pH and nutrient levels, which help to determine what is lacking in your soil.

A soil test provides information to help you make the right choices when it comes to soil amendments for your garden.  Without a soil test, you might be trying to solve a problem you don’t even have!

You can learn more about how to do a soil test in my article here.

Benefits of Lime for Tomato Plants

Lime has many benefits for tomato plants when applied correctly and in the proper dosage.  For example, lime can:

  • Raise soil pH
  • Provide calcium
  • Improve Soil Permeability

We’ll start with one of the biggest benefits: raising soil pH, since proper soil pH also helps to avoid nutrient deficiencies in plants.

Raises Soil pH

When you add lime to soil, it raises the pH.  This is helpful to counter the effects of nitrogen fertilizers, which often make soil more acidic (reduce pH) over time.

ammonium nitrate
Nitrogen fertilizers, such as ammonium nitrate, will lower soil pH over time, making it more acidic. Lime can help to counter this effect.

Having the proper soil pH is important to ensure that tomatoes can absorb enough nutrients for growth.  Tomatoes grow best in a soil pH between 6.0 and 6.5.

As soil pH drops below 6.0, magnesium and phosphorus start to become less available to plants, as you can see in this chart from Research Gate.

Even if there is plenty of a given nutrient in the soil, it will not be available to plants if the soil is too acidic (low pH).  This is because the plant will not be able to absorb the nutrients through its roots.

By adding lime to keep the soil pH within the range of 6.0 to 6.5, you can prevent nutrient deficiencies in your plants. 

So before you go adding extra nutrients to your soil, check the pH with a soil test, and adjust the pH as necessary!   This just might solve any problem you have.

Provides Calcium

Another benefit of lime (calcium carbonate) is that it adds calcium to your soil.  Calcium is a necessary nutrient for plant growth.

Tomatoes (and also other plants, such as peppers) will suffer from a condition called blossom end rot (BER) if they do not get enough calcium.  A lack of calcium in the soil is one possible reason that blossom end rot may occur.

These tomatoes are suffering from blossom end rot, due to a lack of calcium.

However, another cause of blossom end rot is uneven watering, which occurs due to dry soil or drought conditions.  Adding lime to your soil improves water penetration, which in turn helps to prevent this problem.

Remember that dolomitic limestone also adds calcium to soil, in addition to adding magnesium.  Magnesium is another essential nutrient for plant growth.

In fact, magnesium is the central atom in a chlorophyll molecule.  Chlorophyll is what makes plants green, and it is a vital part of photosynthesis, the process where plants turn sunlight, water, and carbon dioxide into sugar (energy) and oxygen.

If you want to add calcium to your soil without raising the pH, try using gypsum (calcium sulfate).  It will add both calcium and sulfur to your soil, while keeping pH stable.

Improves Soil Permeability

Adding lime to your soil will improve soil permeability.  According to Wikipedia, this means that water will be able to penetrate the soil more easily.

Instead of staying on top of the soil, water will work its way down deeper after rainfall or irrigation.  This means that the water is less likely to evaporate back into the air.

water
Adding lime to soil can help water to penetrate the soil more easily.

It also means that tomato plants will have to send their roots deeper to get this water.  A deeper, stronger root system means a healthier plant.

A healthy plant will be able to resist diseases and pests in the garden.  This will eventually lead to a more bountiful harvest at the end of the season.

Can You Put Too Much Lime on Your Garden?

Lime has many benefits, but it is possible to put too much lime on your garden.  This is more likely if you don’t follow the instructions on the package or fail to check your pH before adding lime.

Either way, you might end up with soil that has a pH that is too high for growing tomatoes or other plants.

You can certainly try to reverse the effect by adding elemental sulfur (which lowers pH), but it is best to avoid this problem in the first place.

Use the right amount of lime, based on:

  • current soil pH
  • desired soil pH
  • soil consistency
clay soil
Clay soil will have different lime requirements than sandy soil, due to the differences in structure.

You can learn more about how much lime to use in your garden in my article here.

Is Garden Lime Dangerous?

Garden lime can be dangerous if humans or pets consume it.  It can also harm your tomato plants (or other plants) if you apply too much all at once.

Quick lime (calcium oxide) is caustic, and can burn you if exposed to bare skin.  It is also much easier to burn plants with too much quick lime than with too much garden lime.

As mentioned before, quick lime is not recommended for use in the home garden.

How Long Does Garden Lime Take to Work?

According to the University of Michigan Extension:

“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.”

https://www.canr.msu.edu/resources/facts_about_soil_acidity_and_lime_e1566

The amount of time it takes for lime to work depends on the type of lime used, the size of the lime particles, the current soil pH, and the soil consistency (clay, sand, etc.)

Does Pelletized Lime Work Faster than Garden Lime?

Pelletized lime is more expensive than garden lime, but it does not work faster than garden lime.  According to the University of Kentucky Extension:

“Based on research from several states, it appears that the pelletized lime reacts no faster to raise the soil pH than good quality ag lime applied at recommended rates. In fact, incubation studies at Michigan State University found the pelletized lime to have a slower rate of reaction. Field research from other states indicate the rate of reaction is about equal to ag lime.”

http://www.uky.edu/Ag/Agronomy/Extension/ssnv/ssvl189.htm

Can You Use Wood Ash Instead of Lime?

You can use wood ash instead of lime to raise soil pH and add calcium to your soil.  In addition, wood ash adds potassium, phosphorus, and magnesium to your soil.

wood ash
Wood ash can provide nutrients to soil, and can be used to raise pH.

According to the University of New Hampshire Extension, wood ash contains:

  • 25% calcium by weight
  • 5% potassium by weight
  • 2% phosphorus by weight
  • 1% magnesium by weight

Remember that the exact nutrient content will vary by the type of wood burned to make the ash.

Wood ash is a good garden lime alternative.  However, you do need to be careful about the source of wood that is burned.

Some wood contains chemicals that are not destroyed by burning.  You might not want these chemicals to end up in your garden!

Also, wear a mask and gloves when moving ash around, since wind could blow it into your face.  You can learn more about putting wood ash in your garden in my article here.

Conclusion

Now you know that lime is good for tomato plants in moderation.  Remember that it is important to test your soil before applying lime or any other soil amendment.

I hope you found this article helpful.  If so, please share it with someone who can use the information.

If you want to read some of my most popular posts, check out the “Best of GreenUpSide” page here.  Enjoy!

~Jonathon

jonathon.david.madore

Hi, I'm Jonathon. I’m the gardening guy (not guru!) who is encouraging everyone to spend more time in the garden. I try to help solve common gardening problems so that you can get the best harvest every year!

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