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  • Writer's pictureJefferson Landscape

Soil Conditioning

What is Organic Soil?

Organic soil refers to the organic matter component of soil, consisting of plant and animal detritus at various stages of decomposition, cells and tissues of soil microbes, and substances that soil microbes synthesize. One way that may be easier to think about it is to substitute the word “organic” for the word “living.” Organic soil is a soil that is created by the decomposition of plant and animal materials to create a nutrient and mineral rich mini-ecosystem with microorganisms that feed and breathe life back into the soil. Or, to put it another way, organic soil is how soil exists in nature. Organic soils can help improve the native soil found in your garden or landscape!  By adding organic matter back into your native soil, you can turn nutrient deficient, difficult-to-grow-in dirt into thriving, living soil.  Knowing the different soil types can help you determine how best to treat your soil and how to enrich it.  Soil types from sandy to clay to silt can each be improved with organic matter.


What is the Difference Between Soil Amendment and Fertilizer?

Soil amendments are anything mixed into topsoil to promote healthy plant growth. They function in a number of ways. For example, they may change the pH of soil or supply nutrients. Jefferson Landscape and Design uses a 4-4-2 soil amendment with our soil. That is to say 4% Nitrogen, 4% Phosphorus, 2% Potash (Potassium). Nitrogen (N) is a building block for growing new stems and leaves, plus it is a necessary part of chlorophyll, which makes the leaves green and helps plants photosynthesize. Phosphorus (P) is needed for developing flowers, fruits, and root systems. Potassium (K) keeps roots healthy and also aids flowers and fruits. It helps plants tolerate stress, such as drought.


Fertilizers are primarily valued for their ability to supply additional nutrients, but they are often overused, and because of that reason alone we should stick with the organic varieties. Even manure, when too much is applied, can lead to nutrient leaching and excessive growth that inhibits proper crop development. When using your own urine as a fertilizer (yes, you can!), one gallon should cover a 10 x 10 area and is good for a couple of weeks. The addition of urine might even benefit soil pH slightly, since many soils tend toward acidity.


The pH of your Soil

The vast majority of flowers, perennials, vegetables, and fruits grow well in a neutral soil pH between 6.2-7.0. But some plant species require an acidic soil for optimum growth and health. pH is the measure of how acidic or alkaline your soil is: 7 is neutral; lower numbers are more acidic, and higher numbers are more alkaline.


The pH scale is logarithmic, meaning that a change in 1 pH unit is a 10X change in acidity or alkalinity. A soil pH of 6 is 10 times more acidic than a soil pH of 7; a pH of 5 is 100 times more acidic than a pH of 7. So, it’s important to know the natural pH of your garden soil (the pH you can expect across your property) and if a particular plant requires an acidic soil or neutral soil. The only way to know your pH definitively is to buy a testing kit at a garden center or online.


Most plants do just fine in neutral soil. But some plant species perform middling to poorly in neutral soil. Lowering the pH of your soil slightly below neutral can lead to increased yields and help crops fight off pests and disease better. For gardeners growing an acid loving plant like blue hydrangea or azalea, learning how to make soil acidic is important.


Hydrangeas will grow perfectly well in a soil pH of 7.0 where their flowers will be pink. But if the soil pH is below 5.0, the flowers will be blue (some soil acidifiers are sold specifically for this purpose). Do your research before planting and don’t assume that fertilization is the problem if a plant is struggling – it could very likely be the soil pH.


How Do I Make My Soil More Acidic?

If your plants aren't growing in your soil conditions because of too much alkalinity, then it may be necessary to raise the acid level in your soil’s pH. One of the easiest ways to make soil more acidic is to add sphagnum peat. This works especially well in small garden areas. Simply add an inch or two (2.5-5 cm.) of peat to the topsoil in and around plants, or during planting. For another quick fix, water plants several times with a solution of 2 tablespoons vinegar to a gallon of water. This is not really practical for ongoing watering and probably better for adjusting the pH in container plants, but we all get in a pinch sometimes. Acidifying fertilizers can also be used to help raise acidity levels. But again, these are easy to over use and therefore we suggest always erring on the side of caution if they must be used at all.


Types of Plants Grow in Acidic Soil Include:


American Bittersweet                        Apple                   Azalea 

Balsam Fir                                         Bayberry              Beech 

Begonia                                            Blackberry                 Black-Eyed Susan     

Black Raspberry                                 Blueberry                   Calla Lilies

Camellias                                           Carrot                       Cauliflower    

Celery                                                Chestnut                    Clematis        

Cosmos                                              Crabapple                  Crape Myrtle

Cucumber                                           Dicentra                   Dogwood       

Eggplant                                             Fraser Fir                  Fringe Tree    

Garlic                                                 Gardenias                Gladiolus       

Grapes                                               Hemlock                  Holly  

Hydrangea (for blue flowers)             Iris                          Juniper          

Lily-Of-The-Valley                             Lima Beans              Lupine 

Maple Leaved Viburnum                   Marigold                  Mountain Laurel       

Narcissus                                            Nasturtium             Norway Spruce          

Pansy                                                 Parsnips                   Pine    

Pin Oak                                             Potato                       Pumpkin        

Purple Coneflower                             Red Oak                   Red Pine        

Red Raspberry                                   River Birch               Rhododendron          

Rhubarb                                             Rose                          Rutabaga       

Saucer Magnolia                                Scotch Heather         Serviceberry  

Snap Beans                                        Snapdragon                Spruce 

Squash                                               Strawberry                 Sumac 

Sweet Corn                                        Sweet Pepper           Sweet Potatoes

Tomato                                              Watermelon               Wayfaring Tree

White Oak                                         White Pine                 White Spruce 

Willow                                              Winged Euonymus       Zinnia


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