IDENTIFYING the Best pH For Tomatoes

What is the Secret of Tomato pH?

The best pH for tomatoes is a must-have requirement for a great harvest. Tomato plants will suffer if the soil pH is not adjusted. You will see healthier tomato plants and better crops if the soil pH is correct. 

The proper soil pH is essential for growing a healthy garden, but gardeners often overlook it in favor of nutrient levels and soil consistency. 

While these are essential factors to consider, the pH of the soil has a significant impact on how well your plants absorb the nutrients you provide them, so it’s critical to get it right.

Tomatoes growing in the garden

Do Tomatoes Like Acidic Soil?

Do tomatoes like acidic soil? Tomato plants prefer slightly acidic soil with a pH of 6.0 to 6.5. Nutrients become less available if your soil is too acidic or alkaline. For tomato plants, you can use sulfur to acidify the soil (lower the pH) or lime to “sweeten” the soil (raise the pH).

According to Rutgers University, tomatoes prefer slightly acidic soil, with a pH of 6.0 to 6.5. They thrive in soil with a pH range of 6.0 to 6.5. Make no mistake: tomatoes can grow in soil with a lower pH than this ideal range. The University of New Hampshire Extension, for example, suggests that tomato plants grow best in soil with a pH between 6.2 and 6.8.

On the other hand, tomato plants will thrive in soil pH close to the ideal range. The further your soil deviates from this range, and the poorer your tomato-growing results will be.

What is the pH of Tomatoes as a Fruit?

What is the pH of tomatoes? Fresh tomatoes have a pH of 4.3 to 4.9, indicating acidic. Because of the additives used and the cooking process, the pH of various tomato products will vary. The pH of canned tomatoes is in the range of 3.5 to 4.7, lower than the pH of fresh tomatoes due to the preservation agent added to increase shelf life.

The pH of tomato puree and tomato juice ranges from 4.1 to 4.6.

How Do You Acidify Soil for Tomatoes? (6 Ways)

Too acidic (low pH) soil will slow tomato plant growth and reduce your harvest. Too acidic (or too basic) soil will also cause nutrient deficiencies, resulting in problems such as blossom end rot on tomato fruit.

A pH of 4.2 in the soil is far too low (too acidic) for tomato plants to thrive. Because pH works exponentially, soil with a pH of 4.2 is approximately 100 times as acidic as soil with a pH of 6.2! A soil pH that is too high, on the other hand, will reduce the growth and yield of tomato plants. For example, as soil pH rises above 6.5, iron availability in the soil begins to decline.

Even in the higher pH range of 5.0 to 6.0, some nutrients, particularly phosphorus, become less available to plants. Calcium becomes less available, which can cause blossom end rot in tomato plants.

Below are ways to acidify tomato soil:

Use Additives

The best way to adjust the soil pH for your tomato plants is to use dual-purpose additives. Add amendments that raise the pH while also providing nutrients that your soil requires. Just keep in mind that before you add anything to your soil, you should get a soil test. A soil test will reveal your soil’s pH and nutrient levels.

Sending a soil sample to a local agricultural extension office and telling them what you’re growing will get you recommendations. The soil test results will tell you whether you need to amend your soil. It will also help you decide what to use. 

Remember that a soil pH of 6.0 to 6.5 is ideal for growing tomato plants. Outside of this range, some soil additives should get considered.

Begin with Compost

Adding compost to your garden every year is one of the best ways to maintain good soil for gardening. Compost feeds your plants while also adding organic material to your soil.

This organic material promotes the growth of earthworms and beneficial bacteria in your garden. Furthermore, it improves soil structure, allowing the soil to drain better (if heavy clay) or retain more water (if sandy). You can make compost from yard waste and kitchen scraps, such as:

  • Grass cuttings
  • Leaves that have fallen
  • Fruit and vegetable peelings
  • Grounds for coffee

Common pH-Lowering Soil Amendments

  • Sulfur: Elemental sulfur reduces the pH of soil. It does, however, work slowly and can take several months to take effect fully. Nevertheless, sulfur is a nutrient that plants require, so adding this amendment will help to avoid a sulfur deficiency.
  • Sulfates: Either iron or aluminum sulfate – reduce soil pH. They are also more efficient than pure elemental sulfur. However, if you use too many of them, you may end up with too much iron or aluminum in your soil. This will cause additional issues for your plants, so be cautious with the dosage you use!
  • Ammonia-based fertilizers: Ammonia-based fertilizers such as ammonium nitrate and ammonium sulfate will both rapidly lower soil pH. But be cautious – they can be dangerous.

Add Peat Moss

Adding peat moss (decayed sphagnum moss) to your garden is one natural way to acidify the soil.

Hands holding soil peat moss

How to Measure Soil pH

As a gardener, you need to know the ideal soil pH for tomatoes. First, it’s critical to test the pH of your soil. Certain plants can only use the nutrients in the soil if the pH is within a specific range. If your soil is outside of a plant’s preferred range, no amount of plant food or fertilizer will help.

A soil pH (potential hydrogen) test determines how many hydrogen ions are present in the soil. A pH less than 7 is acidic, seven is neutral, and a pH greater than seven is alkaline. Of course, it doesn’t matter whether your soil is acidic or alkaline; it all depends on what you’re growing. Most plants can tolerate soil pH levels ranging from 6 to 7.5, but some have specific preferences.

Let us look at two ways to measure soil for the best pH level for tomatoes:

Using Kitchen Supplies to Test pH

When an acidic solution gets mixed with something basic, it usually reacts. As a result, you can use vinegar (acidic) and baking soda (essential) to determine the pH of your soil quickly. This test will reveal the general soil composition and get recommended for gardeners with relatively healthy gardens but could benefit from more targeted care. Follow these steps:

Obtain a Soil Sample

To obtain a soil sample, dig 4 to 6 inches (10.16 to 15.24 centimeters) below the surface of your garden with a hand shovel.

Soil Purification

Take out any stones, sticks, or other debris from the soil. Make a point of breaking up any large clumps.

Combine the Soil and Water

Pour 1 cup of soil into a clean glass container and cover enough water to make mud.

Pour in the Vinegar

Stir in 1/2 cup vinegar to the mixture. Your soil is alkaline if it fizzes, foams, or bubbles.

If There is No Bubbling, Repeat the Process

Take a soil sample, clean it, place it in a clean container, and mash it up.

Mix in the Baking Soda

Stir in 1/2 cup of baking soda. Your soil is acidic if it fizzes, foams, or bubbles.

Using Soil Strips to Test pH

Testing your soil with vinegar and baking soda can tell you which end of the pH scale. A soil pH testing kit, on the other hand, is the way to go for an exact measurement. Follow these steps:

Look for a Sample

To obtain a soil sample, dig 4 to 6 inches (10.16 to 15.24 centimeters) below the surface of your garden with a hand shovel.

Gather the Soil

In a clean glass, place 1 to 3 teaspoons of soil. Take out any sticks, stones, or other debris.

Fill the Container with Distilled Water

Fill the glass to the same level as the soil sample with distilled water.

Soil Agitation

Stir or swirl the mixture vigorously. Allow the solution to stand for 30 minutes.

Remove the Sample

Pour the soil sample through a coffee filter into a separate clean glass. Check that the solids get captured while the liquid is allowed to pass through.

Make Use of the pH Test Strip

Immerse the test strip in the liquid. Pay close attention to the instructions regarding how long the strip should remain in the liquid. To determine the pH, compare the color it turns to the chart on the manufacturer’s packaging.

Repeat the Procedure

To determine an average pH, repeat the process several times with samples from different parts of your garden.

If you test your soil with vinegar and baking soda and neither test produces a significant effect, your soil is most likely in the neutral range. Therefore, there is no need for additional testing.

Does Soil pH Affect Tomato Plant Growth?

Too acidic (low pH) soil will slow tomato plant growth and reduce your harvest. Too acidic (or too basic) soil will also cause nutrient deficiencies, resulting in problems such as blossom end rot on tomato fruit.

A pH of 4.2 in the soil is far too low (too acidic) for tomato plants to thrive. Because pH works on an exponential scale, soil with a pH of 4.2 is approximately 100 times as acidic as soil with a pH of 6.2.

How to Lower Soil pH

Making your soil more acidic can be difficult because water is frequently alkaline, and limestone in the soil constantly breaks down increasing alkalinity. Fortunately, some organic methods for lowering soil pH in gardens have proven very effective. Here they are: 

Test Your Soil

You must analyze your soil to understand the pH level better. A simple test kit is available at your local garden center. This information will help you decide what steps to take next to amend your soil.

The pH scale runs from 0 to 14, with 7.0 representing neutral. pH levels ranging from 0 to 6.9 are acidic, while those between 7.1 and 14.0 are more alkaline. The general goal for vegetable gardens is to have around 6.5, though some plants require a different pH growing environment.

Use Well-Decomposed Compost to Improve Your Soil

Every time you plant in your garden, make sure to add plenty of organic matter. Over time, well-decomposed compost helps to lower the pH of garden soil. Amending your soil rich in organic matter compost each season is by far the best way to make your soil more acidic because it is done gradually and provides the most benefits for plant growth.

It also improves soil structure and introduces beneficial microorganisms.

Compost Tea

Watering your plants with compost tea can also help to acidify the soil naturally. It’s also a great way to give your plants quick-acting nutrients. Place a 5-gallon (19-liter) bucket of water outside in the sun for 24 hours to allow any chlorine to evaporate. 

Dump some well-decomposed compost into the bucket, usually 1-2 cups per gallon (per 4 liters) of water, and stir it every 48 hours to ensure a good steep. 

Separate the soil from the liquid using a filter. Pour the liquid into a sprayer and use it as a foliar feed, or pour it into a watering can and use it to water your garden. Work the solids into the soil around the dripline.

Garden Sulfur Elemental

Organic, elemental garden sulfur is a safe and effective way to increase soil acidity. Sulfur is an essential nutrient that can help plants resist disease. However, when it comes to this nutrient, it is critical to follow the directions on the package. Although it is beneficial to plants and can significantly lower the pH of your soil, it can also be harmful to your plants if used excessively.


In your garden beds, use organic mulch. The material will degrade over time, contributing to the acidification of the soil. Mulching with pine needles or oak leaves can help to increase acidity. Organic mulches are also beneficial for reducing soil erosion, retaining moisture, regulating temperature, and releasing beneficial nutrients into the soil.

Ground Coffee

Don’t underestimate the power of a good cup of coffee in the morning! Save those coffee grounds and scatter them around your garden or compost pile. As coffee grounds degrade, they contribute to the acidification of your soil.

Sphagnum Peat Moss 

Adding peat moss to your garden soil can also help gradually lower the pH of your soil. Peat moss is an excellent soil amendment for acid-loving plants that is simple to incorporate. Add two to three inches (5.08 to 7.62 centimeters) to the top of the soil and work it into the topsoil layers beneath.

Soil analyzing

What to Avoid When Adjusting the Soil pH Level

When amending your soil, avoid adding anything with a high salt concentration. For example, adding unprocessed manure can expose your plants to high salt levels, which will burn them. 

Also, avoid adding too much of anything that contains a lot of one nutrient.

For example, if you apply too much high-nitrogen fertilizer at once, it will burn your plants. Furthermore, avoid adding anything too acidic or killing beneficial bacteria, such as lemon juice.

Finally, keep in mind that adding amendments can result in more than a specific nutrient when you don’t need them. For example, assume adding too much Epsom salt (magnesium sulfate) to your garden soil. Any calcium in the soil will become less available to your plants if there is too much magnesium in the soil.

This is because calcium and magnesium “compete” for uptake by plant roots. This is because calcium and magnesium are in the same periodic table column (both have a +2 charge as ions), which means they behave similarly. Your plants will then show signs of calcium deficiency, such as blossoming.


You now know that the best pH level for tomatoes is 6.0 to 6.5. You can also use some methods to adjust soil pH and nutrient levels as needed. The level of soil acidity will always affect tomato pH. So, with this information, you plant your tomatoes. 

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