Instructions on Planting Spearmint Seeds

Starting Seeds

• Seedlings may be started outdoors as long as they are in partial sun and moist soil. Sow the seedlings at least 1 foot apart. The preferable distance is about 3 feet apart. Remember, the plant is highly invasive and will take over the rest of your garden if not heavily controlled.

  The best way to start spearmint from seed is indoors as a houseplant. Give each one in its own pot to grow in with a circumference of 1 foot. Spearmint plants are very invasive, so more than one plant in a pot may crowd each other out and stunt growth. If you plan on transferring the plants outdoors once they have sprouted, you will need to start them 8 to 10 weeks before the last frost. To get the best growth results indoors, place your seedlings under compact fluorescent bulbs, high-output fluorescent bulbs or high-intensity-discharge growing lights, such as metal halide lights. However, standard fluorescent lighting produces acceptable results if the other lights are not available.

  Place standard fluorescent lights 2 to 4 inches away from the tips of the spearmint leaves once sprouted. If using a higher intensity light, such as compact or high-output fluorescent, keep the light at least a foot away from the leaves. Grow lights will need to be kept at least 2 to 4 feet above leaves.

  Keep the plants on a regular watering schedule and be careful not to overwater the seedlings. According to the Gardener's Network, spearmint can withstand high heat and drought, so keep in mind that a little water goes a long way. Use an oscillating fan to gently blow the seedlings and leaves for two hours a day to simulate an outdoors environment and help grow a heartier plant.

Transferring Outdoors

• If you transfer the plants outdoors, be sure to place them well away from other plants in your garden or use a border edging to control their root spread. According to Doug Green, maintainer of Simple Gifts Farm, the best way to restrain mint growth is to keep your mint in the container and bury the entire container in the ground. Cut back any stems that travel to other plants and keep the area well watered.