This is how we maximize lettuce cultivation in our vertical farm:
1. Seeds: We grow large quantities of lettuce, so we prefer pelleted seeds to speed up sowing. Coated with inert materials, they’re larger, rounder, and easier to plant individually, speeding up the process. We also use them for basil and other herbs.
2. Varieties: Because we grow outdoors, choosing the right lettuce varieties for each season is essential. We choose heat-tolerant Batavia in summer, oak-leaf and romaine in spring, and Lollo in winter. Each variety tolerates different temperature and humidity conditions.
3. Substrate: Since aeroponic towers don’t use soil, we start our seedlings in agricultural rockwool, a growing medium made primarily from melted basalt (volcanic rock) spun into fibers. Rockwool is an inert, initially sterile substrate that retains moisture while providing excellent aeration for developing roots, making it ideal for hydroponic and aeroponic cultivation.
4. Pests: Caterpillars are our main lettuce pests, especially in spring and autumn. We control them naturally using Bacillus thuringiensis (Bt), a naturally occurring bacterium that targets young caterpillars, typically applied once a week for three weeks during periods of caterpillar activity.
5. Birds: Birds love nibbling on lettuce! We deter them using hanging reflective CDs and a bird-of-prey scarecrow. We also provide birdbaths with fresh drinking water.
6. Yields: Fast-growing varieties that reach maturity in 4 weeks can produce 624 heads per tower annually with 12 harvests! Varieties that need 6 weeks can yield approximately 450 heads annually under continuous production.
7. Nutrients: Our lettuce receives all its essential minerals through a water-soluble nutrient solution. Macronutrients include nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur. Micronutrients include iron, manganese, zinc, copper, boron, and molybdenum. These minerals are supplied in dissolved, plant-available forms for efficient root absorption.
Vertical farming in Martinique, in the French West Indies. Just a few months after installing 52 aeroponic towers, this farm is now thriving with a wide variety of fresh vegetables and herbs. Located in the Caribbean, it’s the first phase of a project that will expand to 180 towers, in collaboration with our local partners @bds__farm
This soilless growing system is completely automated including nutrient dosing and irrigation cycles. It only takes 10 minutes to assemble an aeroponic tower, and from there, everything runs on autopilot until harvest. The nutrients are automatically dosed at a 1:300 ratio, and the nutrient-rich water is stored in a gravity-fed tank. This gravity tank automatically tops off the tower reservoirs, while float valves inside each reservoir regulate the flow to maintain a consistent water level of 74 liters. This water also acts as a weight to anchor the towers, helping keep them stable during strong winds and storms. All the low-wattage submersible pumps are connected to a central digital timer, running on cycles of 3 minutes on and 12 minutes off, 24 hours a day, amounting to only 4.8 hours of electricity usage daily. That means that during the time the plants are not being irrigated, they spend 80% of their time with their roots hanging in the air. This oxygen-rich environment supports efficient nutrient uptake, healthy root development, and faster crop growth.
6 flowers we grow vertically without soil on aeroponic towers. Vertical farming is often associated with lettuce, leafy greens, and herbs, but aeroponic towers can grow so much more. Adding flowers throughout the farm creates a beautiful environment while also supporting the insects and pollinators that are part of the ecosystem.
This is how we grow 18 purple cauliflowers vertically on an aeroponic tower:
1. Tower Assembly: It takes about 10 minutes to assemble one aeroponic tower, including the reservoir, growing sections, submersible pump, irrigation tubing, and the top shower cap that distributes nutrient solution through the tower. From there, everything is on autopilot.
2. Rockwool: Since there is no soil, the plants are grown in agricultural rockwool, a soilless substrate made from basaltic rock that is melted and spun into fibers. It provides excellent water retention while still allowing plenty of oxygen around the roots.
3. Transplanting: In this video, we are growing Amethyst purple cauliflower. Because cauliflower plants become very large, we plant only two per level on opposite sides. With 9 levels, that gives us 18 plants on one tower.
4. Automatic Irrigation: Once transplanted, irrigation is fully automated. The bottom reservoir refills with nutrient-enriched water as needed through irrigation lines connected to a gravity-fed tank.
5. Irrigation Cycle: The submersible pump runs 3 minutes ON and 12 minutes OFF continuously, totaling about 4.8 hours of irrigation per day.
6. Aeroponics: During the OFF cycle, the roots remain suspended inside the tower in an oxygen-rich environment. This helps support efficient nutrient uptake and rapid growth.
7. Pest Management: The main pests we deal with on brassicas like cauliflower, cabbage, and broccoli are caterpillars. As a preventative, we apply Bt (Bacillus thuringiensis), a naturally occurring bacterium used in organic farming that stops caterpillars from feeding after they consume treated foliage.
