How Much Dolomite Lime per Gallon of Soil?

The GardenSpring |

Dolomitic limestone is a type of limestone composed mainly of dolomite. Limestone generally consists of calcite and aragonite, crystalline forms of calcium carbonate.

As a mineral compound rich in calcium and magnesium, dolomitic lime can be used as a fertilizer for cannabis grown in nutrient-poor soils by controlling pH.

So in this article, you’ll discover how much dolomite lime per gallon of soil. Let’s start.

Why is dolomitic lime used in native cannabis cultivation?

Whether in hydroponics or soil cultivation, pH is an important factor in the quality of the plant harvest.

Autoflowering cannabis plants can grow in most soils without problems. However, they grow very well when the soil pH is between 6.2 and 6.5.

Native cannabis plants that cannot absorb enough nutrients from the soil suffer from nutrient deficiencies, begin to wilt, and eventually lose their yield.

When should dolomitic lime be used?

If your cannabis plants show signs of calcium or magnesium deficiency, this can be a clear indication that your soil is nutrient deficient.

Soil nutrient testing can help you get a clear picture of your soil’s nutrient content. This report will help you determine if you need to add dolomitic lime to your soil.

Dolomitic lime is one of the most effective agents for stabilizing acidic soils. Dolomitic lime has a neutral pH of 7. It cannot raise the soil pH above 7, so there is no need to worry about the soil becoming too alkaline.

Calcium and magnesium, on the other hand, are cations and are not likely to lower the soil pH.

Controlling soil pH in cannabis requires close attention to several factors. The best time to add dolomite lime to the soil of homegrown cannabis plants is in the spring or fall when there is no frost in the area.

Also, if you are growing your flowers outdoors, you should choose a day when there is no rain or wind predicted. This is because the soil should be able to absorb the dolomite lime sufficiently without being washed away by strong winds or rainwater.

You can also add dolomite lime to the soil before you start growing cannabis for added benefits.

How much dolomite lime per gallon of soil?

how much dolomite lime per gallon of soil? When applying dolomite lime to the soil of cannabis plants, the most important factor is the amount of dolomite lime to be used in the soil.

Ideally, 6 to 7 teaspoons of fine dolomitic lime should be added per liter of water.

Using fine dolomitic lime is very important because it takes a year for the coarse dolomite to be absorbed by the plant roots. For example, if you mix enough soil for five liters of water, you need to add 30-35 teaspoons.

This calculates the amount of dolomite lime that needs to be added to a gallon of water to have an immediate effect.

However, if the pH of the soil is not very acidic, you can first add 2-3 teaspoons of dolomitic lime to 5 gallons of water and see how the cannabis plants react before adding more.

What is the effect of lime in the soil?

There are two types of lime that gardeners should know: agricultural lime and dolomitic lime. Both types of lime contain calcium, while dolomitic lime also contains magnesium. Lime adds these two essential elements to the soil but is generally used to correct the pH of the soil.

Most plants prefer a pH of 5.5 to 6.5; if the pH is too high (alkaline) or too low (acidic), plants cannot absorb nutrients from the soil. Nutrient deficiency symptoms occur, such as poor leaf color and poor growth. Using lime in acidic soils raises the pH and allows plant roots to absorb the nutrients they need.

How much lime does the soil need?

The amount of lime needed in the soil depends on the initial pH and the nature of the soil. Without a good soil test, determining the amount of lime is a process of trial and error. A home pH test can give an indication of soil acidity but does not take into account soil type.

The results of a soil test performed by a professional soil testing laboratory will provide specific recommendations tailored to the needs of the soil.

Turf can tolerate a pH between 5.5 and 7.5. To correct a weakly acidic lawn, grind 20 to 50 lbs (9 to 23 kg) of stones. (20 to 50 lb) of limestone per 1,000 sq. ft. (93 m²). In very acidic or very clayey soils, up to 46 k. (100 lb).

For small beds, the following figures can be used to calculate the amount of lime needed. These figures indicate the amount of finely ground limestone needed to raise the pH of a 9 sq. ft. soil by one point (e.g., from 5.0 to 6.0).

  • Sandy loam soil – 5 lb (2 k.)
  • Medium loamy soil – 7 lb (3 k.)
  • Heavy loamy soils – 4 kg (8 lb.).

Method and timing of lime addition

A marked difference in soil pH is evident as early as four weeks after the addition of lime, but it may take six to twelve months for the lime to completely dissolve.

The full effect of adding lime is not apparent until the lime has completely dissolved and mixed with the soil.

For most gardeners, fall is a good time to use lime. Adding lime in the fall allows it to dissolve for several months before planting in the spring.

To add lime, first, prepare the soil bed by digging or plowing it 20-30 inches deep. Spread the lime evenly over the soil and stir it into a depth of 5 cm.

Photo by Lisa Fotios from Pexels

How much dolomitic lime is needed per gallon of peat moss?

Peat moss, a dry, partially decomposed form of moss that grows in very acidic bogs, has a pH of 3.5 to 4.0, which is about the same as the acidity of orange or tomato juice.

Dolomitic lime has an alkaline reaction and is often used to raise the pH of the soil and floral mixes. The amount you need to add to peat moss depends on the type of plant you want to grow and the pH of your usual soil.

About peat moss

Most peat moss sold in North America is sustainably harvested from Canadian wetlands. Peat bogs are well-drained, and the accumulated peat layers are removed and then regenerated as active, peat-storing peat bogs. This peat is dried, pressed into bales, and shipped to retailers.

Peat has a high water storage capacity. Peat itself is not rich in nutrients, but it stores nutrients supplied as fertilizer and prevents leaching from the soil. Peat is resistant to decomposition and its fibrous structure improves soil aeration.

Use peat for acidic plants

Some plants, such as heathers, rhododendrons, azaleas, and blueberries, prefer a pH below 6.0. Blueberries, for example, grow best at a pH of 4.0 to 5.0.

If the pH of your garden soil is 6.5, you’ll get the best results by adding the peat directly, without lime; for acidic soils with a pH of 5.0, a pinch of lime is recommended when using peat.

Dolomitic lime is a combination of calcium carbonate and magnesium carbonate; calcium and magnesium are beneficial for plant growth.

Use of peat in vegetables

Most vegetables prefer soil with a near-neutral pH, but a pH of 6.0 may also be acceptable. Potatoes are an exception and do best in soil with a pH of 4.8-6.5.

If peat is added to increase organic matter, dolomitic lime can be added to adjust the pH. Mix the lime with the peat before working it into the soil, as lime works slowly and can take 3-6 months to take full effect.

The exact amount of lime depends on the acidity of the soil, but 1/2 to 1.5 ounces of dolomite per gallon of peat is recommended.

Using peat in soil mixes

Peat moss is often used as an ingredient in soil mixes because it is sterile, lightweight, and well aerated. Cornell University has developed several formulations for soilless potting soils for commercial gardeners and has applied them for home use as well.

One is for foliage plants and consists of a half bunch (4.5 gallons) of peat moss, 1/4 bunch vermiculite, 1/4 bunch perlite, 8 tablespoons dolomitic lime, 2 tablespoons superphosphate, 3 tablespoons 10-10-10 compost, 1 tablespoon ferrous sulfate, and 1 tablespoon potassium nitrate.


City, A., Gardens, M. V. B., Hoang, L. D., Pickering, M., McCarthy, B., Lipanovich, M., Falon Land Studio LLC, McCarthy, B., Falon Land Studio LLC, & Gaskill, L. (2021, October 22). How Much Lime to Adjust Container Soil pH to Any Arbitrary Target. Houzz.

M. (2020, July 8). How Much Dolomite Lime Should I Use for My Autoflowering Cannabis Plants. Autoflowering Cannabis Blog.

Leave a Comment