By Jo Kapke
Asparagus (Asparagus officinalis) is one of few perennial vegetables suitable for growing in Minnesota gardens. The first edible spears emerge from the soil as ghostly tips sometime in April or May. Once an asparagus bed is established, it can provide you with delicious and tender harvests for 15 years or more.
An asparagus bed should be located in full-sun and well-drained soil. Asparagus is most often planted as one year old “crowns.” The crowns need to be planted in a furrow that can be filled back in once the spears begin to grow. Several varieties of asparagus grow well in Minnesota including Millennium, the Jersey series and the Washington series.
Now—for the hardest part—the waiting! Asparagus spears can usually be harvested beginning two years after crowns are planted or three years after seeds are planted. As the spears grow, they mature into “ferns.” The ferns are left to build the energy the plant needs for the following season. Continued watering and weeding of an asparagus bed is important to ensure the plants are healthy for the next season. Ferns can be removed once totally brown and dry in late fall, early winter, or when the weather warms the following spring.
Asparagus is harvested from late April through late June in Minnesota. Asparagus spears can grow up to 2 inches a day given the right conditions! One clue to know when to stop harvesting the spears is if they are consistently less than the width of a pencil. The spears are best harvested when they reach 6-8 inches long. The spears can be snapped or cut with a knife at the soil surface.
Once asparagus reaches the kitchen, it is easy and quick to prepare and can be enjoyed in many different ways; even raw.
For more information about asparagus, visit this University of Minnesota Extension site.
The Minnesota Asparagus Project—a collaboration between the Sustainable Farming Association and the University of Minnesota—provides extensive information about growing asparagus, especially on a large scale, in their web handbook found here.