Plan the perfect garden with our interactive tool →

How to Make a Compost More Acidic

Compost is a rewarding process that can be done at home easily, benefiting your landscape, the environment and your wallet. The key to composting is to keep the four main elements balanced: water, air, carbon, nitrogen. When compost piles are younger, they tend to be more acidic; when they are older, they are more alkaline. Depending on the plants you are using the compost on, you might need more acidic or alkaline soil. There are some tips to raise the acidic level in your compost, making it more beneficial for acid-loving plants.

Use a pH testing kit to test the soil. Follow the directions exactly, but usually you moisten the pH strip in the compost, then compare it to the color chart on the kit. A pH level under 7.0 is acidic. If the pH is over 7.0, you can take steps to lower the pH, or rather raise the acidity.

Add some fruit waste to the compost to help raise the acidity. This includes fruit cores, peelings, scraps and rotting fruit.

Add some pine needles to the compost from local trees. Use a shovel to mix the fruit and pine needles into the compost pile so it is evenly distributed.

Try not to add a lot of deciduous leaf and cuttings because these are more alkaline. Also avoid adding lime or calcium carbonate.


Adding compost is one of the best ways to boost a garden's ability to thrive without the use harmful chemicals. Carbon-rich, or "brown" matter, includes items such as tree bark, leaves, twigs and paper. Microorganisms such as bacteria, already present in the decaying matter, work together to break the pile down. A well-balanced compost pile produces usable compost in several weeks to several months, depending upon the size of the heap. Straw, shredded paper and chunks of plain corrugated cardboard are also excellent brown-matter add-ins for your compost pile or bin. * While fallen, dead branches count as brown matter, fresh garden clippings, such as pieces from pruned shrubs, are green matter. The paper filter counts as brown matter, completely welcome in the pile. A compost pile that heats up as it should will kill any weed seeds present. Breads, pasta, dairy and meat products, bones, animal waste, and kitchen grease or oils should not be added to a compost bin. Also avoid putting any materials treated with potentially harmful chemicals into the compost pile, as these may either kill the microbes that help break matter down or they may introduce harmful chemicals to the compost and to the areas where compost is spread. Try these sparingly at first to ensure they break down in a reasonable amount of time. Get started by selecting a shaded area that's easily accessible, since you'll add materials and water to it from time time. Always cover the green matter with 5 inches or more of brown to help keep insects and vermin away. Sprinkle the pile with water if it feels too dry, or whenever you add dry brown matter. A tarp over the top of the pile isn't required, but it helps keep the moisture in. If you feel a compost pile or homemade bin is too messy or difficult to deal with, consider a pre-made composting bin such as the barrel-shaped style designed to either roll or turn on a spindle. Expect it to take several months before the compost in a pile three feet tall is ready. Compost is considered gold in the garden, and it has several uses: * Add fresh compost around garden plants in layers up to 3inches deep as a mulch.

Garden Guides