Good Gardens Start with the Dirt

Tips on How to Improve Your Garden’s Soil

Garden health starts with the ground, and the best way to understand where to begin is to test the soil for its pH level and basic nutrients.

Written by and photographed by Amy Grisak

With gardening season just around the corner, it’s time to start planning ways to ensure that plants have the best growing conditions possible. 

Garden health starts with the ground, and the best way to understand where to begin is to test the soil for its pH level and basic nutrients. A simple test kit purchased at a garden store can give a better understanding of how to enrich the soil.

One of the most common issues with Montana soil is a high pH, indicating alkalinity. Most fruits and vegetables prefer a soil pH of 6-7. If it is higher than that, nutrients such as zinc, iron and copper are less available to the plants, resulting in obvious deficiencies. Luckily, there are amendments that can be added to modify this level. 

Gypsum, also known as calcium sulfate, is a common addition to the home garden. This is particularly helpful in clay soils, but not as effective in sandy soils.  

Adding elemental sulphur is another option. It should be applied as early as possible as it requires several months before it mitigates the pH level effectively and is most effective when added in the fall. For acidic soil below a pH of 6, which is not nearly as common in Montana, the go-to additive is lime, which is sprinkled before planting to help “sweeten” the soil.

The key nutrients to watch for are nitrogen, phosphorus, and potassium. To improve all of these, add organic matter to the garden. This includes well-aged manure, compost, coffee grounds and crushed eggshells. While compost, coffee grounds and eggshells are easy to find and apply, it’s important to the know source of the manure.

One of the primary risks of using manure is burning the plants because of the potentially high nitrogen levels. Chicken manure is the most notorious for this issue, which is why it’s important to compost it before applying it to the garden. A better choice is rabbit manure, which is rich in phosphorus as well as nitrogen, and is often mixed directly into the soil because it breaks down quickly and is at low risk for burning plants. 

Always make sure there are 120 days between adding fresh manure and harvesting from the garden to prevent possible food contamination. 

Use well-aged manure to reduce the risk of burning plants and to also eliminate the potential of passing weed seeds into the garden. Horse manure is particularly notorious for introducing new weeds. 

Be aware of and do not use manure from horses that were fed certified weed-seed free hay. The residue from herbicides used on the hay crop can remain in the manure for years with results of curled leaves and dying plants. Be safe and avoid manure from animals fed weed-seed free hay. 

Phosphorus is critical for root growth and overall development. To correct for low phosphorus, add bone meal or rock phosphate around the plants. Usually, the problem is a higher phosphorus number. Add zinc and iron to the soil to help the plants utilize the micronutrients. 

Often, improving one macronutrient, such as potassium, also benefits others, as in the case of using greensand, which also improves magnesium and iron levels in the soil. Greensand, also called glauconite, is a natural mineral amendment derived from the soils of ancient ocean beds. It also helps in clay soil to improve the tilth and is an easy way to give plants a potassium boost, critical for plants’ overall health. 

The use of raised beds is another way to deal with marginal soil, reduce weeds and allows for control of the quality of the soil.

The use of raised beds is another way to deal with marginal soil, reduce weeds and allows for control of the quality of the soil. To create the walls, one of the cheapest materials is untreated new or used lumber, an affordable material that will last at least five years in Montana’s dry climate. 

For something more permanent, consider using cedar, hardwood or a raised bed kit. Raised beds can be creative, incorporating galvanized metal, bricks, or natural stone to form the sides, offering beauty, function, and interest to your garden.  

A good rule of thumb for a solid garden soil “recipe” is to use 50 percent topsoil, 30 percent compost, and the remaining 20 percent a combination of manure, potting soil, coco coir or peat moss, as well as “goodies” such as worm casting, coffee grounds, and even mycorrhizal fungi to help kickstart the life in the soil. 

Now is the perfect time to whip the garden soil into shape or create a few raised bed gardens to prepare for planting in the next several months. Whatever you choose, you can never go wrong adding organic matter, including aged manure and compost, into the beds now to reap the benefits come summer.