Horticultural charcoal is charcoal that is added to garden soil to raise the soil's pH level, improve air circulation and raise the soil's capacity for water and nutrient retention. However, it is different from the charcoal typically sold for use in a grill, as it doesn't contain any additives to increase flammability.
The benefits of horticultural soil can last for many years and help a home's garden stand out from its neighboring yards, according to SFGate. Horticultural charcoal can be obtained from most garden centers and should be added at a ratio of 1 pound per 2 square feet of garden.
Before adding the charcoal, the garden should till the plot to a depth of 8 inches. Rocks, roots and miscellaneous debris should be cleaned out, and the charcoal shouldn't be added if the soil is wet or sticky. Once the garden is prepared, the charcoal should be spread out evenly and tilled completed into the soil. For optimal results, the charcoal should extend down at least 6 to 8 inches into the soil. After adding the charcoal to the garden, the tender should water and fertilize the soil for the best results, as the charcoal helps to increase water and fertilizer retention.