the art of

growing cranberries

Cranberries are a low running, perennial vine and grow in 2 to 5 acre plots referred to as cranberry beds. In different parts of the United States, farmers refer to plots of cranberries differently; Wisconsin - marsh or bed, Massachusetts - bog, or Oregon/Washington - field. Currently, Wisconsin farms grow over 60% of the world's cranberries. 

Manitowish Cranberry Co has seven different varieties of cranberries, some ripening sooner than others, so harvest can be started earlier in the fall. There are over 100 varieties of cranberries, although there is very little taste or visual difference. Our farm has cranberry beds that were planted in the 1960s and are still high yielding, but other low-producing beds are replaced with higher yielding varieties developed by research universities or private propagators - a process known as bed renovation. It takes 3 to 5 years for the newly planted vines to reach their yield potential. 

Contrary to popular belief, cranberries grow dry – not in water. We use an irrigation system for two main purposes - frost protection and soil moisture. Frost protection is important during the early summer months when cranberry buds are emerging. Early season frost damage could cause a loss of the entire crop. Throughout the growing season, we monitor the soil moisture using remote sensors. When the soil reaches a specific threshold, the irrigation system turns on automatically. Cranberries are fully flooded two times per year - for harvest and in winter. 

cranberries 101

Mid-April to September 

growing season

During the growing season nutrient quantities, water levels, pests, and pollinators are closely monitored – all keys to a successful harvest for Wisconsin’s official state fruit. Since cranberries are native to northern Wisconsin and thrive in low, wetland environments, very few “inputs”, such as pesticides or fertilizers, are needed to grow cranberries, especially when compared to other crops such as corn and soybeans. We apply fertilizer to give plants the right nutrients they need to thrive based on the previous year's plant and soil nutrient results as well as our own field observations. Lastly, with our Integrated Pest Management Plan, we’re able to methodically search for and remove inch-worm types of pests that may cause damage to the berries. 

As the growing season progresses, the plants’ new growth begins to set flowers, which turn into tiny berries by late July. Every year, we “hire” (rent) 600 honey bee hives – about 30,000,000 bees! – to pollinate millions of cranberry blossoms. You can actually hear the “hum” of the bees doing their important work. Our careful management of our science-based growing practices directly correlate to a sustainable farm with healthy vines, nutrient-dense soil, clean water, and bountiful harvests. 

Late-September to Mid-October

The Most Beautiful Harvest

Harvest begins in late September when the berries turn a crimson red color. Cranberry beds are slightly flooded  with water so the berries can be removed from the vine using a special machine, called a harvester. Water is pulled from nearby bodies of water using energy-efficient electric pumps. The harvester is a tractor with a custom fabricated implement that gently combs through the vines to knock the berries off.  The harvester travels at 3 miles per hour and takes roughly 45 minutes per cranberry bed.

Collecting Berries

Once the berries are floating off the vines, they are corralled to one end of the bed using two tractors (one on either side of the flooded bed) and long, floating booms. The boom fully encircles the berries, pulling the berries closer to the berry pump for removal from the bed. The booms are very similar to ones used for containing oil spills in the ocean. 

After the berries are corralled, the berry pump sucks them out of the cranberry bed using a specialized piece of equipment that separates any floating cranberry leaves or grass from the berries. The berries then fall into a waiting dump truck, and leaf litter is pumped into a separate dump truck (which is later sold as cranberry leaf compost). Each berry truck can haul 24,000 pounds of fruit and takes roughly 7 minutes to fill. This specialized harvest implement has been one of many impactful upgrades to efficiency in cranberry harvesting. What used to require 7-8 people in the berries, now requires just 3-4 people standing on the edge of the bed.

                            No fruit is harmed during this process. The pump is so gentle that the same model is also used to transport live minnows at fish hatcheries from one pond to another.


Receiving and Cleaning Station

The cranberry-filled trucks move fruit from the field to an on-site bulk pool, which can hold 120,000 pounds of fruit, prior to being cleaned. Cranberries then travel up a conveyor belt into the receiving station. Once inside, berries are washed again, mechanically sized, graded, and binned (put into large wooden crates) before being loaded into semi trailers to be taken to a freezer in central Wisconsin. 

  • Each bin holds 1,200 pounds of berries. 
  • It takes just 45 seconds to fill and label each bin.
  • Each semi trailer can hold 44 bins. 
  • Each bin is weighed, labeled, and can be traced back to which bed it came from.

Every bin of cranberries is tested at our on-site lab using Ocean Spray standards for quality, color, firmness, moisture level, and size. This is the last step before the fruit is made into Ocean Spray Craisins®, juice, sauce, and other cranberry products. 

November to April

Winter Season

After harvest is complete, vines turn from green to dark purple and go dormant for the winter months. Once winter arrives, we flood the cranberry beds to freeze a solid block of ice above the plants. This acts as a blanket from bitter cold temperatures. When spring arrives and the days become warmer, cranberry vines come out of dormancy causing the cranberry buds to emerge and the growing season begins again.

Perhaps, surprisingly, winter is a busy season on the farm. During this time, we: 
  • Perform equipment maintenance on machines and implements
  • Design and fabricate new equipment and tools – most specialized equipment is built in-house, such as the berry pump, planting machines, and ditch cleaning attachments
  • Review and write nutrient and pest management plans
  • Review budgets and prepare for capital improvement projects
  • Attend nutrient management training, pesticide applicator training, and industry research conventions

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