What is Greensand?
Since ancient Rome, the pigment known as “green earth” or “Verona green” was a prized mineral on a painter’s palette. Today, this same mineral is better known in gardening as greensand fertilizer, valued not for its color, but for its ability to improve soil health organically.
What is greensand? Greensand, sometimes called green sand, is a naturally occurring, mined rock product that formed millions of years ago in low-oxygen marine environments. The sediment found at the bottom of stagnant seas was rich in minerals like iron, potassium, silicates, and trace elements, which gradually transformed into the rock we now call greensand.
Greensand gets its name from its distinct green color and its crumbly, sandy texture. Unlike typical sand, greensand soil amendment acts as a powerful soil conditioner. It helps retain both water and nutrients — holding up to one-third of its weight in moisture — and slowly releases valuable minerals into the soil over time. While its performance can vary depending on soil conditions, using greensand fertilizer can significantly boost your garden’s water retention, soil structure, and long-term fertility.
Benefit of Adding Greensand to Your Garden
- Helps the soil's moisture and nutrient holding capacity, so you can water and fertilize less often.
- It improves the soil’s structure as well, such as by increasing the Cation Exchange Capacity or CEC.
- Greensand contains the minerals it accumulated when it was formed as marine sediment, and is especially good for a slow-release source of potassium.
Applying Greensand to your Garden and Orchard
- For DTE Greensand, apply to your garden in spring, use 5 to 10 pounds per 100 square feet, or 1 to 2 pounds per plant. Mix it into the top 6 inches of soil.
- After the first year’s application, you can use smaller amounts every one to two years. For most gardens, 1 to 2 pounds per 100 square feet is a good maintenance application.
- To use greensand for your trees, apply 1 to 2 pounds per inch of trunk diameter, spread over the root zone.
If you’re not sure how much to add, applying the larger amount is a safe bet because greensand cannot burn your plants or over-fertilize. However, applying more than the recommended amount will not give your plants an extra boost, as it releases too slowly to do this. Because of the slow-release nature of greensand, it is not the best choice for potted plants. It will provide very little potassium during the life of your potting soil, so a quicker acting fertilizer such as Peaceful Valley’s Liquid Fish will benefit your potted plants more.
If you’re looking to improve soil structure or drainage in your potting soil, greensand can help, or you might consider instead adding perlite, vermiculite, or coco peat. Use greensand to create garden worthy of an oil painting, and grow organic for life!
