What the Color of Your Garden Soil Means
Some soil colors are gardening gold, while others are a bust. Here's what your soil color means for gardening success, and how to fix it if it's off.
Imagine the dusty red dirt of the Utah desert, the dark spongy soils of the Cascades’ old-growth forests, or a gray sandy path through some lanky Florida pines. A glance at any of these soils can help you figure out what might grow there.
In your garden, the color of your soil can also be a clue to what you can grow successfully, or what you’ll need to add to make your soil more viable.
Black or Dark Brown Soil
The most coveted soil color. Called “black gold” by some gardeners, it has high levels of organic matter and probably sodium, which helps organic matter and humus disperse evenly. “The darker the color, the more decomposed the organic matter is into humus,” says Greg Niewold of Power Planter.
This is exceptionally fertile soil, in which most plants will thrive. “The only caveat is that black soil may contain more moisture, so plants that like it dry, such as lavender, may not respond well,” he says. To help develop your soil into black gold, add amendments like compost, peat, humus and worm casings.
Light Brown or Tan Soil
A lot of home gardens start with this. Depending on the saturation and intensity, browns can indicate an abundance or lack of organic matter. Consequently, this color often means moderate organic matter and soil structure, with low to moderate iron, phosphorous and available water.
“Pale soil needs organic matter, fertilizing and mulching, but the soil can sustain life,” says Niewold. It is also decent for low-water plants.
White or Pale Soil
These soils look bleached or washed out, or can be light brown when they’re dry. It might mean your soil contains a lot of sand, or that the iron, manganese and other key ingredients have leached out. “White soil is not suitable for plant life as it contains little nutrients or ability to hold water,” says Niewold.
It will take a lot of time and energy to improve by regularly adding organic matter, compost, humates and peat moss amendments. If this is your soil, consider gardening with raised beds and purchased soil from the local nursery.
“Reddish and red-brown soils come in a range of hues, but picture the red rocks of the Western U.S., a burnt, rusty red,” Niewold says. This soil may have a lot of the iron oxide hematite. It’s usually acidic, low in calcium and high in clay.
If it’s darker, that may mean more organic matter and less drainage. Bright red means excellent drainage. Pale red means nutrients have leached out. Niewold suggests growing lettuce, green beans, chard, and other vegetables with shallow roots in red soil because it retains water.
Broccoli, Brussels sprouts and cabbage also do well in red clay soil because their roots anchor better. Be sure to increase the levels of organic matter while adding any missing minerals. You can also add lime to raise the pH.
Yellow or Yellow-Brown Soil
Yellowish soil contains the iron oxide mineral goethite. As with red soils, the brighter the color, the better the drainage and nutrient availability, although these soils often have poor drainage and compaction. If the soil is pale yellow, it’s been leached of nutrients.
Regardless of your shade of yellow, you’ll need to add organic matter.
Gray or Green Soil
These colors are cause for concern, because it means the soil is waterlogging or drains poorly. Anaerobic bacteria have moved in so organic matter lacks oxygen to completely break down. “Gray-green soil is not suitable for plant life, as it contains little nutrients and roots will not have the oxygen needed to grow,” says Niewold.
Let it dry out, then amend it regularly with organic matter, compost and peat moss. If it’s in containers, make sure you have good drainage. If it’s in the ground, dig trenches and install pipes to divert water away from problem areas.
“Also, water your garden in the morning, not the evening,” he says. “When you water too late in the day, the soil stays wet overnight.”
Other Soil Health Considerations
While soil color is one indicator of its health and ability to grow healthy plants, there are other vital factors, including structure, composition and diversity of biology. Earthworms in your soil means you’re doing well. “Not only do we look at color, but we smell for an earthy, fresh odor,” says Kathy Glassey, director of renewable services for Monster Tree Service.
It’s also good to feel your soil to judge its consistency, composition and compaction.
“But the bottom line is, it’s time we view soil as an ecosystem,” Glassey says. “We need to begin talking about soils in a similar manner as our diets, because many variables matter and every type is different. Understanding the species you are planting and its specific needs is always a professional’s number one place to start. Still, the soil ecosystem is the foundation, and we all need a strong foundation in which to thrive!”