How Often Should You Fertilize Mint?

Before Planting

• Preparing the garden bed before you plant mint improves the soil by ensuring the proper nutrients are available to the young mint plants. Fertilize the bed within two weeks of sowing the new mint plants. Compost worked into the soil improves the soil quality while adding some trace nutrients. After composting the bed, add a general-purpose granular fertilizer, such as a 16-16-8 blend, at the rate of 1/2 tbsp. per every 50 square feet of mint bed. Use a slow release fertilizer, as these types release nutrients into the soil slowly over the course of the growing season.

Annual Fertilization

• Mint requires minimal fertilization once it's established in the garden. Too much fertilizer can decrease the amount of oils produced in the leaves, leading to a less flavorful plant. Fertilize established mint plants once a year in spring soon after the mint begins producing new growth and foliage. Use a balanced slow-release fertilizer for the annual application, such as a 16-16-16 or 20-20-20 blend. Apply approximately 1 tsp. of the fertilizer to each mint plant in the bed.

Application Methods

• Avoid applying the fertilizer directly to the mint plants. Fertilizer in direct contact with the leaves and stems can cause burning since the fertilizer isn't diluted. Instead, sprinkle the granules in a circle spaced about 6 inches out from the base of the plant. Water the soil immediately after the fertilizer application. Immediate irrigation rinses any fertilizer residue from the plant leaves before it can cause damage. Watering also dilutes the fertilizer so the nutrients can begin leeching down to the root zone of the mint.

Container Plants

• Container-grown mint, whether kept indoors or set out on a patio or balcony, requires more frequent fertilization than bedding plants. Watering flushes the nutrients out of the pot, so the soil requires replenishment via fertilization. Use a soluble balanced fertilizer, such as a 10-10-10 blend. These fertilizers are applied at a lower rate than slow-release varieties, allowing the plants to instantly access the nutrients. Apply the fertilizer at the rate recommended on the fertilizer package for the size of your mint plant and its container. Fertilizer every other month during the spring and summer. Mint doesn't require winter fertilization.