Living in Minnesota's cold winter climate is no excuse not to include herbs in your garden plan. When it comes to cooking, it's impossible to beat the flavor of fresh herbs. Many herbs can be dried and used to brew a delicious pot of tea. Even though Minnesota's winters can be challenging, raising herbs is possible, and isn't much different than growing herbs in warmer climates. In fact, most herbs will thrive in Minnesota's cold winters and warm, dry summers. Plant herbs after the last frost of the season.
Harden off herb plants before planting them outdoors so the plants will be acclimatized to the chilly Minnesota air. For the first two days, place the plants in a sheltered area, such as a covered porch, for three to four hours. For the next two days, move the plants into a sunny spot for three to four hours. Over the course of the next few days, gradually increase the time so that the herbs are outside all day. The herbs will now be ready to be planted.
Choose a sunny spot for the herbs. Most herbs require at least six hours of sunlight every day. Plant herbs away from cold winds. Most importantly, choose a spot where the soil drains well, as herbs won't grow in soggy soil.
Prepare the soil at least a week before you plant the herbs. Use a shovel or tiller to cultivate the soil to a depth of 10 to 12 inches. Spread 3 to 4 inches of decomposed manure or compost on top of the soil, and rake it in thoroughly. If the soil doesn't drain well, incorporate 4 to 5 inches of peat moss into the soil in addition to the manure or compost.
Use a trowel to dig a small hole for each plant. Herbs should be planted in the soil at the same depth that they were in the container. Planting herbs too deeply can cause the plants to rot.
Water the plants immediately. Keep the soil slightly damp until you notice new growth, which indicates that the herbs have taken root. After that time, herbs should be watered only when the top of the soil is dry.
Spread 2 to 3 inches of organic mulch, such as pine needles, dry grass clippings or shredded grass around the herb plants, but don't bury the plants. Organic mulch will keep the soil warm, control weeds and retain soil moisture.
Harvest the herbs on a warm, sunny day, when the aromas and flavors will be at their best. The buds should be just barely opened.
Place a thick layer of mulch over the herb plants after the first freeze of the winter. A 6-inch layer of straw or bark will protect the roots of the herb plants during the freezing Minnesota winters. Don't remove the mulch until after the last frost in spring; then remove the mulch so the plant can grow freely. Apply fresh mulch around, but not on, the plants.