Water
Mint prefers moist soil via infrequent, deep watering, but it will adapt to its environment. Mulch the soil with 2 inches of straw or wood chips to prevent evaporation. In the heat of the summer, water when the top inch of soil is dry. Mint in containers will need more water than mint planted in the ground.Fertilizer
If planting in the ground, there is no need for fertilizer. As long as your soil is of average health, mint will get the nutrients it needs. Since mint is such a bountiful grower, over-fertilizing can lead to an invasive, flavorless plant.If planting in a container, fertilize after transplanting (or annually once new growth emerges) with a balanced liquid fertilizer, and again after pruning 4-6 weeks later with a balanced slow-release fertilizer. Repeat once more 4-6 weeks before the last frost date in your region.
Overwintering
Mint is hardy to zone 4, meaning it can survive temperatures down to -30˚. However, you'll want to take some steps to ensure the plant survives bitter cold days and comes back thriving in the spring.In the fall, prune the plant down to the ground and cover with a thick layer of organic mulch such as compost or shredded leaves. This will help prevent disease and pests from taking up residence in your plant and emerging in the spring.
When gardening in containers, your zone decreases by at least one full zone due to the lack of insulation compared with in-ground plants (i.e. if you garden in zone 6, treat your containers like you're in zone 5). If that drops your zone to 4 or below, consider moving your containers to a protected area like inside a garage or shed. You can also sink the entire pot into the ground, cover with mulch, and dig out in the spring to help insulate the roots during the cold season.
