Gardening with Laurie: Rock powders valuable ingredients to gardeners

By Laurie Garretson
April 11, 2013 at midnight
Updated April 10, 2013 at 11:11 p.m.

Most gardeners would not like the idea of covering their gardens with rocks. Right? Well there actually is a great advantage in covering any soil with rock powders.

Rock powders are high in minerals and contain micro-nutrients. These are valuable ingredients to organic gardeners and should be to all humans. Rock powders equal healthy soils. Healthy soils equal healthy foods.

In recent weeks, I mentioned one of these important rock powders, glauconite. More commonly known as greensand.

Greensand is mined from mineral deposits that were once part of the ocean floor. Greensand contains iron, magnesium, silica, potash and many other trace minerals. Used on heavy clay soils greensand will help to loosen it.

Lava sand is another one of the important rock powders to have in your soil. Many gardeners believe it to be the most important rock powder to have. Lava sand, as the name suggests, does come from volcanic rocks.

Lava sand is the leftover material from lava gravel manufacturing. Lava sand is known by many gardeners as the soil energizer. It will make nutrients in the soil more readily available to plant roots. It provides aeration and porosity to soils when needed and helps to retain moisture in loose sandy soils.

One other rock powder I'd like to mention is crushed granite. It is another one of the wonderful rock powders that adds minerals to soils. I believe this rock to be one of the most versatile of them all. Crushed granite packs well and is a great product to use as natural walkways.

I am amazed at the difference it can make to already healthy plants. When we started using it as a top dressing to our beds, it helped to make already nice looking trees and perennials much darker green and more able to withstand drought and heat.

Crushed granite makes a good mulch or can be mixed in soils. I think its mauve color goes well with southwestern-style landscapes.

Most rock powders are used at the rate of 40-50 pounds per 1,000 square feet. They can all be used in beds, on lawns, around trees or mixed in with container soils. Being rocks, rock powders last a long time before breaking down, which is a good thing.

On the other hand, it can sometimes take longer to notice all the benefits rock powders provide to your plants. All this means rock powders will release all their wonderful goodness over a very long time to come.

Until next time, let's try to garden with nature, not against it, and maybe all our weeds will become wildflowers.

Laurie Garretson is a Victoria gardener and nursery owner. Send your gardening questions to or in care of the Advocate, P.O. Box 1518, Victoria, TX 77902.



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