Asparagus is a perennial vegetable that signals the start of spring’s harvest season. Michigan is one of the nation’s leading producers of this crop, with Oceana County often recognized as the “Asparagus Capital of the World.” The exact timing of the harvest is a variable event, dependent upon the unique environmental conditions of the season.
The Typical Michigan Asparagus Harvest Window
The arrival of fresh Michigan asparagus generally occurs in a predictable window each year. Growers typically begin harvesting in early to mid-May, marking the beginning of the state’s first green vegetable crop. The season remains in full swing throughout May, which is officially celebrated as Michigan Asparagus Month.
The harvest season is relatively short, usually lasting between six and eight weeks. This means the availability of fresh Michigan asparagus generally extends through late June. While the season can occasionally start as early as mid-April, a cold spring can delay it well into May.
Factors Determining Asparagus Emergence
Soil Temperature
The timing of asparagus emergence is governed by environmental factors that break the plant’s winter dormancy. The primary trigger is the warming of the soil where the perennial crowns reside. Spears typically begin to push through the ground once the soil temperature consistently rises above 50°F (10°C) at the depth of the crown.
Air Temperature
Air temperature also plays a role in determining the start date. Warm spring air temperatures accelerate the growth once the underground buds have been roused from dormancy. A very warm spring can bring the first emergence date forward by several weeks, while a cool start to the season can delay it.
Soil Moisture
Adequate soil moisture is another factor influencing the timing and vigor of the emerging spears. The crowns require a period of cold to prepare for growth. The combination of rising temperatures and sufficient rainfall creates the ideal environment for the spears to rapidly develop.
Harvesting Methods and Season Duration
Spear Growth and Picking
Once the spears begin to emerge, their growth rate is fast under ideal conditions of warm days and nights. A single spear can grow up to a half-inch per hour, sometimes adding as much as ten inches daily. This rapid development requires harvesters to walk the fields frequently, often multiple times a day, to pick the spears before the tips begin to fern out.
Harvesting Technique
In Michigan, the harvest is predominantly done by hand. The spears are typically “snapped” or cut slightly above the soil line. Snapping the spear results in a tender, entirely edible product with little to no woody base, which is common for the fresh market.
Season End
The commercial harvest period is not indefinite, as the plant must be allowed to replenish its energy reserves. Growers practice “stopping the harvest,” ceasing all cutting usually around the Summer Solstice or by July 1. The remaining spears are allowed to grow into tall, fern-like stalks. These stalks photosynthesize and send energy back to the underground crown to fuel the next year’s crop.
Post-Harvest Care and Storage
Maintaining Freshness
Once acquired, asparagus requires immediate refrigeration to maintain its crisp texture and flavor. Asparagus spears continue to respire and lose moisture quickly after being harvested. Refrigeration slows this process, preserving the vegetable’s quality.
Storage Method
For optimal short-term storage, the ends of the spears should be trimmed by about an inch. The bunch can then be placed upright in a container with one to two inches of cold water in the bottom. Covering the tops loosely with a plastic bag helps create a humid environment, preventing the spears from drying out. When stored this way, the asparagus can retain its peak quality for several days.