The pennyroyal (Mentha pulegium) is a perennial herb that comes from the mint family. Its oil is often used in a perfume. The pennyroyal plant is known for its ability to repel fleas, ants and even mosquitoes. In fact, sometimes the pennyroyal plant is referred to as the mosquito plant. Pennyroyals are not picky and can be grown easily.
Wait to plant your pennyroyal plant until the spring. Pennyroyal plants grow well when temperatures have reached 45 degrees F, but haven't gotten hotter than 80 degrees F.
Choose a location where your pennyroyal plant will get partial shade.
Test the pH of the soil where you want to plant your pennyroyal. According to Purdue University, pennyroyals grow well in most soil types, but they prefer a pH between 4.8 and 8.3.
Dig a hole 1/4 inch in the ground. Drop in a pennyroyal seed and cover the rest of the hole back up with soil. Continue this in rows with the seeds spaced 6 inches apart.
Water your pennyroyal seeds so that the soil is wet, but not muddy. Keep the soil moist until your seeds are growing well. Then water on a regular basis.