How does temperature affect compost tea brewing?

Temperature profoundly affects every aspect of compost tea brewing, influencing its microbial activity and safety. Optimal temperatures of 55-80°F (13-27°C) promote the growth of beneficial organisms while inhibiting the growth of pathogens. I monitor temperature continuously while brewing using floating thermometers. Microbial populations crash outside of this narrow range, or dangerous bacteria take over and destroy the batches.

Microbial reproduction slows significantly in cold temperatures. Below 55°F, bacteria division rates drop by 50%, and extended brewing is required. I recommend adding aquarium heaters during winter brewing to maintain a temperature of 68°F. Insulating your containers will limit heat loss from container walls. Do not rush your cold brews. Inadequate time produces weak and ineffective tea.

Temperatures above 80°F threaten pathogen eruptions. Balancing high heat and good species - thermophilic (heat-lovingly) bacteria compete with beneficial species. I handle heat by dunking brew buckets in a cool water bath. When emergencies arise, frozen water bottles can be rotated frequently, every 4 hours. When tea is brewed at a temperature above 90°F or hotter, discard the tea. The tea could potentially harbor pathogens.

Adjusting to seasonally consistent results is critical in brewing. Summer brewing requires an early am start time and shade cover, winter supplemental heating, and is time-consuming. Brewing temperatures are logged with microbial counts in a journal. This data is helpful to establish the temperature for precise brewing times as the season changes. If these controls are implemented, there is a greater opportunity to produce consistently high-quality tea throughout the year.

Read the full article: Compost Tea Brewing: The Ultimate Guide