Choosing the Right Soil
By Shelly Montgomery, Master Gardener In Carpenter, Wyoming
Home gardeners spend a significant amount of time fighting weeds. Here in the Rocky Mountain West we also face prolonged dry weather, hot sun, and often dense soils.
Are you ready to take gardening to the next level?
Do you want to understand more about your soil?
Dig-in to soil science and discover the recipe for getting more from your cultivating efforts – indoors and out!
Knowing Your Garden Soil
Whether you have been gardening for years or you are just getting started, your efforts will be rewarded by understanding your soil. A soil test is a good place to start if you are starting a new garden plot or it has been a few years since your last test.
Soil testing information can be found at your state’s cooperative extension service website. In most cases there is a small fee and specific sampling instructions to follow.
There are also multiple DIY tests available that range from test kits to soil probes. These tests measure pH and nutrient levels. If you are interested in digging a little deeper investigate the Mason jar texture test.
Let’s explore some basic soil chemistry to help guide you in your soil choices.
Soil is made up of about 45% minerals. These include micronutrients like copper and iron and macronutrients like nitrogen and potassium. Water and air make up 25% each, while the remaining 5% is organic matter.
Organic matter is the decaying material that feeds the soil. Adding organic matter encourages water absorption and retention. This increases the nutrients available to growing plants. Soils in the Rocky Mountain West are typically sandy, clay, or a combination of both. Using compost, mulch, animal bedding, and other organic materials decreases soil compaction and allows for optimal root growth.
Another important component of soil chemistry is pH. Soil pH below 7 is considered acidic while soil pH above 7 is considered alkaline. Soils of the High Plains and Rocky Mountains tend to be alkaline although this can vary greatly even within the same region.
Why does this matter?
Different plants have different pH requirements. Most berries, potatoes, cucumbers, and pumpkins prefer slightly acidic soil. Beans, peas, spinach, and many herbs are happiest in a more alkaline soil.
Many vegetables and herbs are tolerant of less than optimal pH, but this limits the amount of nutrients available. Most gardens do well with a pH range of about 5.5 to 7.5. If you are struggling with a particular type of plant (raspberries for instance) pH may be the culprit. A quick online search will provide you with many resources regarding optimal pH for specific garden plants.
Simple soil amendments can help you increase organic matter, balance soil pH, and enhance soil nutrients available to your garden. After you have amended your soil to correct any problems, you should re-test your soil.
Soil amendments fall into two categories: organic and inorganic. Organic amendments are made from something that was once alive; compost, grass clippings, wood shavings, and straw are a few examples. Inorganic amendments, like perlite and limestone, are mined or man-made.
Some soil amendments and ready-to-use products contain the OMRI listing seal. This means that these products meet criteria for use in certified organic production by the Organic Materials Review Institute.
Compost can be made from many different organic materials including kitchen scraps and some animal manures. It takes time and the correct conditions to make healthy compost at home. If you are hoping to improve conditions this growing season, a number of healthy composts can be purchased and added to your garden beds.
A few examples of ready-to-use compost products available at your local Murdoch’s Ranch and Home Supply include:
- Coop Poop – Composted chicken manure. OMRI listed.
- Black Gold Garden Compost – Contains compost, bark, and peat moss. OMRI listed.
- Yard Care Composted Sheep Manure - Sheep manure mixed with ponderosa pine and Douglas red fir bark. Great for sandy and clay soils.
- Mountain Magic Natural Mountain Compost – Aids in moisture retention and adds valuable nutrients to the soil.
Bark is used as both a mulch and a soil amendment. It helps decrease weeds, increase moisture retention, and maintain soil temperatures.
Murdoch’s Ranch & Home Supply carries a variety of bark and mulch products:
- Yard Care Shredded Western Bark
- Montaho Cedar Bark Mulch
- Mountain Magic Gorilla Hair Mulch
Peat moss, often referred to as sphagnum peat moss, helps sandy soils retain moisture and clay soils loosen up, improving drainage. It can lower the pH of your garden soil and create acidity for acid loving plants.
- Black Gold Canadian Sphagnum Peat Moss – OMRI listed.
- Fox Farm Happy Frog Soil Conditioner – Contains soil microbes, bat guano, and earthworm castings.
Perlite is expanded volcanic rock. It creates air in the soil mix and improves drainage. Dampen perlite prior to mixing with soil as the dust from dry product can be harmful if inhaled.
Limestone or lime is used to neutralize soil acidity. Many soils in the Rocky Mountain West are alkaline and will not require the use of lime. Only use after you have tested your soil and the pH is below 5.5 or for creating acidic soils for specific plants.
Murdoch’s Ranch & Home Supply carries a few different limestone/lime products:
- Agricultural Limestone
- Landscapers Select Rapid Release Lime
General purpose soil mixes are ready-to-use. They can be mixed with soil in your existing garden beds, added to new garden beds to increase nutrient value, and used in potting mixes.
Some general-purpose garden soils available at Murdoch’s Ranch & Home Supply include:
- NuLife Topsoil – Increases the volume of your garden soil.
- Yard Care All Purpose Top Soil – Contains bark, peat moss, and native soils. Excellent foundation for making your own potting mix or garden soil.
- Sun Gro Black Gold Garden Soil – Formulated for the Rocky Mountain region. Contains slow-release fertilizer.
Containers are a great option for the short season in the Rocky Mountain West but they require more than just garden soil.
Vegetables, herbs, and flowers are all suitable for container gardening. Containers make it easy to protect your hard work during cold snaps and hail storms. One downside to growing in containers is that they often dry out quickly with the hot sun and high altitudes.
Ready-to-use potting soils can offer a convenient growing medium that contain amendments for water retention, drainage, and nutrients.
- Greensmith Nursery Mix – contains perlite, indoor/outdoor, veggies or flowers
- Sun Gro Black Gold All Purpose Potting Mix - peat moss, bark, compost, perlite or pumice or cinders, earthworm castings, and controlled release fertilizer
- Sun Gro Black Gold Natural and Organic Potting Mix plus fertilizer – peat moss, bark, compost, perlite or pumice or cinders, earthworm castings, and organic fertilizer. OMRI listed
- Fox Farm Bush Doctor Coco Loco Potting Mix – Potting soil with added coconut palm humus. Also great for seed starting
- Fox Farm Happy Frog Potting Soil – Contains earthworm castings, bat guano, and composted forest humus
Starting seeds at home can add to the variety in your gardening pursuits and give you greater control over lengthening an already short season. You will need more than garden soil to get the best results.
It is easy to make your own seed starting mix with a basic recipe:
- 1-part soil or compost
- 1-part sand
- 1-part peat moss
Mix together and heat in the oven at 250 degrees for about 30 minutes to kill any potential seed-inhibiting bacteria. Do not overheat or cook too long as this can damage the structure of the soil.
Alternatively, some potting mixes are suitable for seed-starting. Murdoch’s Ranch & Home Supply has a few products perfect for sprouting your spring seeds:
- Jiffy Natural & Organic Seed Starting Mix – Ready-to-use mix. OMRI listed.
- Glacier Gold Potting Soil – contains soil/compost, peat moss, and perlite. Made in Montana. Great for seed starting or container gardening.
Understanding the chemistry of your garden soil gives you a better understanding of what makes plants grow. This article only scratches the surface of soil science but provides a solid foundation on which to grow your garden and your knowledge.