Asparagus is a perennial crop that, once established, can produce spears for 15 to 20 years or more. This long lifespan means the initial planting phase is a significant long-term investment. Success depends on proper site selection and planting at the correct time, which is crucial in Michigan’s variable climate for developing a strong root system before summer heat.
Optimal Planting Times Based on Michigan’s Climate
The ideal time to plant asparagus crowns in Michigan is in early spring, specifically as soon as the soil becomes workable and is no longer waterlogged. This period generally falls within the month of April across most of the Lower Peninsula. Planting dormant, one-year-old crowns during this window allows them to establish new roots before the plant begins its active growth cycle.
Crowns thrive when planted as the soil temperature consistently warms, usually reaching about 50°F. While the Southern Lower Peninsula may reach this threshold earlier, northern regions and the Upper Peninsula will plant later. Planting early avoids late winter cold and ensures root development occurs before late spring heat encourages rapid top growth.
Michigan’s distinct regional climates mean the precise planting date varies, but the principle of planting early remains constant. Sandy, well-drained soils often warm up and dry out faster. Gardeners with heavier clay soil must wait longer for the ground to dry sufficiently, as planting in saturated soil can lead to crown rot.
Planting crowns four to six weeks before the average last spring frost date is a reliable guideline for many Michigan gardeners. This timing ensures the crowns are settled while still dormant, giving them a head start on the season. Fall planting is generally less recommended for crowns in Michigan’s cold winters, making the early spring window the most successful approach for long-term establishment.
Preparing the Permanent Asparagus Bed
Because an asparagus bed can last for decades, preparation of the permanent planting site is crucial. Asparagus requires a location that receives full sun exposure and demands excellent drainage. Crowns are highly susceptible to root diseases like Fusarium wilt in saturated conditions.
If the native soil is heavy clay, planting in a raised bed or mounding the soil can significantly improve water runoff, protecting the crowns. Amending the soil with generous amounts of organic material, such as well-aged compost or manure, improves both drainage in clay and water retention in sandier soils.
Eliminating all perennial weeds is necessary and should ideally begin the year before planting. Weeds are difficult to remove once the crowns are planted and will compete fiercely with young asparagus for nutrients and moisture. A soil test is highly recommended to adjust the pH level to the preferred range of 6.5 to 7.5, which helps suppress disease-causing fungi.
Planting Crowns for Successful Establishment
Asparagus is almost always grown from one-year-old crowns rather than seed, as crowns reduce the wait time for the first harvest. Crowns should be planted into a trench 6 to 10 inches deep, with deeper trenches used for lighter, sandy soils. Rows should be spaced four to five feet apart to allow mature ferns adequate room to grow.
A small ridge of soil should be built down the center of the trench, and the crowns are placed on top of this ridge. The fleshy roots must be carefully spread out and draped down the sides of the ridge, ensuring the growing buds are pointed upward. Crowns should be spaced 12 to 18 inches apart within the trench to give each plant sufficient space for future growth.
After placing the crowns, cover them immediately with only two or three inches of soil, leaving the trench partially unfilled. This initial, shallow covering protects the crowns while allowing them to draw warmth from the sun. The soil should be gently firmed down, and the area should be watered thoroughly to settle the soil around the roots.
First-Year Care and Harvest Patience
Care immediately following planting focuses on preventing competition and promoting deep root development. Diligent weed management is necessary in the first year because young asparagus plants cannot compete effectively with weeds for resources. Hand-pulling or shallow cultivation is preferred to avoid damaging the developing roots of the new crowns.
As the first shoots, or ferns, begin to grow several inches tall, the trench should be progressively filled with soil. This gradual back-filling process should continue throughout the first season until the trench is entirely filled and level with the surrounding ground by late summer. The process encourages the plant to form a deeper crown, which is beneficial for winter survival and long-term production.
Watering is important during dry spells in the first year, particularly in Michigan’s sandy soils, to ensure the crowns establish a strong, deep root system. The primary aspect of first-year care is adhering to the “three-year rule” for harvesting. No spears should be harvested during the first growing season, as all energy must be channeled into crown and root development to support future harvests.