A freeze warning is in effect throughout North Central Florida this week and is expected to last through Friday night. Blue Grotto Farm is planning to protect its crops with water from its on-site spring.
Blue Grotto Spring has been operating as a dive resort in Williston for about 50 years. The spring’s clear water and steady 72-degree temperature allows the farm to produce year-round, said owner Dave Myler.
Myler bought the property as an investment in August 2013 and established a hydroponic farm: a method of growing plants without soil.
Instead, the farm's crops thrive in volcanic rock that has been heated and expanded like popcorn, known as perlite, that acts as an alternative to soil.
The farm uses water pumped from an underwater cave in Blue Grotto Spring. The water is assessed by a computer, enhanced with nutrients and sent through a system of tubes to efficiently spray the plants.
After a period of experimentation and some setbacks, Blue Grotto Farm sold its first large harvest of lettuce last week to a wholesaler.
The farm covers more than half an acre and has about 23,000 plants, Myler said. Of the 18,000 heads of lettuce, about 3,000 will be harvested each week. Tomatoes, cucumbers and herbs are also growing rapidly.
Myler said he will expand his hydroponic operation by one acre and will be adding space for free-range chickens, beehives and berries.
By this fall, the expansion will be well underway and Blue Grotto Farm will offer a prepaid produce plan to customers who will receive fresh produce from the farm each week for 20 weeks.
To ensure the plants survive the cold weather, several different methods are used.
The lettuce is sprayed with water and protected by a layer of ice. The ice keeps the lettuce at 32 degrees even when outside temperatures and wind may be significantly lower.
About 1,000 tomato plants grow in tarp-covered tunnels, which trap some heat. The seedlings and herbs in the greenhouse are safe and sound under bright, warm lights. The lights are kept on 24/7 regardless of weather.
Marvin Botts, Blue Grotto's hydroponics manager, said the first step when faced with a dangerous frost is filling the pots with spring water. He even pours water on the ground to create a warm mist that heats the air in the tomato tunnels.
Botts created a geothermal heat exchange unit to also aid in heating. He said the device acts like a car radiator. Spring water is poured into coils, and a fan blows the warm air rising from the coils into the tomato tunnels. When the temperature drops to 20 degrees or below with wind chill, a propane heater is used as a last resort.
Botts said the hydroponics operation, combined with spring water, produces healthy plants without interference from pests and with little waste.
Myler and Botts hope to fully automate the watering system and create a way to reclaim the water to eliminate waste entirely.
Botts said he avoids synthetic nutrients, but the nutrients added to the water are inorganic, like phosphorous and nitrogen. He hopes to design a system to process organic matter — like cow manure — on the farm to make the produce completely organic.
“It’s not organic in the strictest sense, but it is natural in the strictest sense,” Botts said.
Ben Collingsworth, the farm’s hydroponics technician, said it takes about 12 days for a seed to become a plant. After three weeks in the greenhouse, lettuce is transplanted to hydroponic towers. After another six weeks, the lettuce is ready to be harvested.
Most of what Myler has learned about hydroponic farming he has learned on the job. He started the farm early last year but had to completely restart the project in October after insects, fungus and poor planting conditions ruined the crops.
Collingsworth was there through it all. He said the process was intimidating, but he was optimistic for the future.
Now, he said, “Things are looking up.”