Dolomite for Container Gardening

Dolomite for Container Gardening

If you’ve ever had some sad-looking potted plants that hang limply over the rim of your pots, you have probably heard of soil pH. When your soil pH is too acidic, it can lead to plant disease, lack of airflow, and root death. Dolomite, also known as lime, helps rebalance the soil pH profile by neutralizing the acidic components of peat moss. 

What Is Dolomite? 

Dolomite also goes by the names dolomitic limestone or dolomitic lime. Dolomite is a limestone compound in powder form that comprises magnesium and calcium. 

The best dolomite mixture will have 8-12% magnesium and 18-22% calcium. Magnesium and calcium help balance the pH of the potting soil you use for your container gardening projects.  

Some dolomite mixture also has sodium; however, this should only be 0.2% maximum. If there is too much sodium in the dolomite mix, it changes the soil’s salinity, which can kill plants.  

Why Do You Need Dolomite for Container Gardening?  

The potting soil you use for container gardening is usually a mixture of topsoil and compost. The mixture may not be the right pH for the plants you choose. So you may need to add dolomite to increase the soil’s pH to make it more plant-friendly so your plants can thrive. 

Don’t add dolomite to the soil or potting mix if you don’t know what the pH is. You also need to know what pH is best for the plant you are planting. 

Start with a soil pH test. You can buy this at your local garden center. Most plants grow well in soil that has a pH of 6.0-7.4, while other plants prefer an acidic potting mix.  

If the soil’s pH measures 5.9 or below, you can add dolomite to increase the pH of the soil. The magnesium in the dolomitic limestone helps neutralize the acidity of the soil, especially if the soil needs to be more neutral for plants to grow. 

You can also add dolomite to the soil of containers if the plant has a lot of seeds inside the fruit or vegetable. Tomatoes are an example of such a plant. Generally, tomato plants need more calcium to thrive. So by adding dolomite to the tomato plant’s soil, you give the plant the extra nutrients it needs. 

If your plant needs more magnesium to grow well, for example, you can also add dolomite to the potting mix.  

Dolomite for Container Gardening
Anything can be the container for your container garden!

When Do You Use Dolomite in Container Gardening 

Dolomite can be used when you have performed an acidity test and found the potting soil you have been using to be too acidic. A calcium deficiency can lead to soil acidity increasing. To remedy this situation, you can add dolomite (which is calcium-rich) as a topping to the soil around your yard and in your potted plants. 

Since dolomite comes in a talc-like powder, it is advisable to choose a dry and sunny day when dousing your plants with dolomite. Rainwater or watering your indoor plants can lead to the dolomite powder washing away. 

When your plants begin wilting, you can perform a simple soil acidity test. Simply collect a tablespoon of soil from the pot or yard area. Add clear still water, swirl, and use a pH meter to read the soil acidity.  

Potting Soil Mixed with Dolomite for Container Gardening
Mixing Potting soil. Dolomite for Container Gardening

How to Add Dolomite to Your Gardening Containers 

When you want to add dolomite to the potting mix for your gardening containers, ask why you are adding the dolomite. The reason you add the dolomitic limestone to the soil will dictate how and why you should add it. 

Adding Dolomite to Increase the Soil’s Calcium and Magnesium 

If you are adding a dolomite mix to boost calcium and magnesium in the soil, add it two to three weeks before planting. This time frame will ensure the dolomite has a chance to break down in the soil so your plants can use the extra calcium and magnesium when they take root in the soil. 

You can also add more dolomitic limestone once you’ve planted the plants in the containers. Simply mix the dolomite into the top six inches of the soil.  

Mixing Your Own Potting Soil With Dolomite 

You can mix your own potting soil for your container gardening projects with dolomite. 

  1. In a ratio of 1-1-1, mix all-purpose potting soil with moist peat moss and perlite. 
  2. Add ½ cup of bone meal for one gallon of potting mix to the large container. The bone meal helps your plants grow healthy roots by providing phosphorus. 
  3. Add ¼ cup of dolomite for one gallon of the potting mix. Wear gloves and protective clothing. Also, ensure there is no wind when you add the dolomite. 

Lime can burn your skin and irritate your mucus membranes. 

  1. Moisten the potting mix with a fine spray attachment on your garden hose. 
  2. Fill your gardening containers with the potting mix and plant your chosen flowers, trees, veggies, and fruit plants.  

Adding Dolomite to Adjust the Soil’s pH 

If you are adding dolomite to increase the pH of the potting mix, some math is needed. 

For example, let’s say you’ve measured the soil’s pH level and found it to be at 5.5. If you would like the soil’s pH to be 6.5, so one point more, add five pounds of dolomite for every 100 square feet of space. Alternatively, add a quarter cup of dolomite for every gallon of potting mix. 

Which Plants Prefer Dolomite-Balanced Soil?

When dolomite is added to your plant’s soil, the plant-soil begins to take on a more neutral pH, and it is easier for the plant to grow and produce fruit. Beets, asparagus, lilacs, and beans are plants that prefer to grow in dolomite-rich soil. 

The fruits of certain plants also grow bigger and better when planted in limestone-rich soil.  


Is dolomite good for soil?

Dolomite reduces soil acidity. When soil produces a high acidity reading, it will burn plants, and it is poor in nutrients too. Luckily, adding dolomite to the soil will improve the soil’s fertility by lowering the acidity.  

What time of the year should I add dolomite to my garden?

Spring or fall is the best time to add dolomite as these are usually seasons when rainfall is less, meaning your addition of limestone can help balance the soil without being wasted when the rainwater washes away the top layer. 

How fast will dolomitic lime begin to work?

Dolomitic lime usually takes a full year to improve the soil’s fertility. If you have a soil type that is really poor in nutrients, it may be necessary to seek alternative planting areas as your soil may need to be rested while the dolomite gets to work. Adding dolomite to your initial planting mix is a great way to reap the benefits from the start.

Final Thoughts 

Before you grab your tub of dolomite limestone, you should consider the impact of having too much of it in your potting soil. Add a few spoonfuls of dolomite to your plants, watch and observe, and keep track of your plant’s pH levels.