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Growing Seedlings in the Flex Micro

How to jumpstart seedling growth for growing in the Flex Farm

Materials needed:

  • Measuring Cup
  • Measuring Spoons
  • TDS Meter
  • pH Test Kit
  • pH Down
  • Nutrient A & B
  • Potable Water (Pitcher or Hose)
  • Seeds
  • Rockwool
  • Black Nursery Trays (perforated & non-perforated)

Growing Seedlings in the Flex Micro

The Flex Micro was designed with seedlings in mind. This tool allows the development of strong, healthy and fully developed seedlings that can be transplanted into the Flex Farm or Flex Acre. 

Once seeds are sown and the tray is placed in the Flex Micro, the growing process becomes mostly hands-off—simply monitor your tank's water, nutrient, and pH level (takes around 10 minutes per week!). 

IMG_7475In this picture, there are herbs, tomato, pepper and cucumber plants in the bottom shelf, while microgreens grow in the middle shelf. 

Before planting seeds, review and follow these steps:

  • Flex Micro Setup: Ensure that your Flex Micro is set up and operating correctly according to the Flex Micro Setup Guide.

Always place a non-perforated tray in any unused tray slots to keep the irrigation system fully contained and minimize the risk of contamination and help prevent algae growth. 

  • Lights: Each tier features its own dedicated light control. Keep the light on continuously for any tier with uncovered, actively growing plants. Use the switch at the top right back corner of each tier to turn the light on or off as needed.

If a tier does not have actively growing plants, or if trays are still covered with humidity domes during germination, be sure to turn off the light for that tier. This will help prevent algae growth and make post-harvest cleaning much easier.

  • Pump: Your pump should be set to be on for 15 minutes every 8 hours (refer to Flex Micro Setup Guide for more details).

We recommend checking your Flex Micro tank’s water, nutrient, and pH levels at minimum twice each week. These routine checks and adjustments usually take just 5–10 minutes. Start by checking all levels—water, nutrients, and pH—note any adjustments needed, then make those changes.

Tip: If you need to add more than a few gallons of water, slightly increase the amount of pH Down and Nutrients A & B you add, as adding water raises pH and decreases nutrient concentration.

  • Water Level: Add water each week and ensure the tank water level does not fall below the bottommost indent in the tank. 

pH and Nutrient Level: Follow the Checking & Adjusting your Nutrients & pH Guide.

  • pH = 5.5-6.
  • Nutrient = Base TDS + 350.

To test the pH and nutrient levels in your Flex Micro water, remove the tank lid plug and insert your TDS meter into the water, and/or use the vial from your pH test kit to collect a water sample.

Germination & Development

After planting seeds, you need to mimick the correct environment for germination. This is done with humidity, and without nutrient-rich water and light. Each plant variety may take more time to germinate than others. Follow these steps:

  1. Stack a perforated nursery tray inside of a non-perforated nursery tray before planting seeds. 
  2. Saturate rockwool with water. Pour any excess water from tray. 
  3. Plant seeds. 
    1. Each plant variety has a different seeds-per-hole recommendation. For lettuce and other leafy greens, basil, brassicas, rainbow greens, edible flowers, and fruiting plants, plant one seed per hole. For other herbs, plant 2-3 seeds per hole. Some seed packets may list other recommendations.
  4. Cover tray of seedlings with a clear humidity dome and remove the non-perforated nursery tray.
  5. Place the tray of seedlings in the Flex Micro. 
    1. The light should be off. 
  6. Seed varieties vary in time to germination. Check your seedlings once per day and spray them with water to promote humidity.
  7. Germinated seeds look like they have a stem curling from the seed. Here's an example of lettuce seeds germinated after 2-3 days of growing. You can see the seedling curling out of the seed casing.They were planted on a Wednesday and moved into the Flex Micro on Friday.  
  8. Once all seeds have germinated in the nursery tray, remove the humidity dome. IMG_7351
  9. Turn on the lights and confirm the pump is running. 
  10. The seedlings can grow in the Flex Micro for 1-2 weeks. 

    IMG_0950
  11. Transplant your seedlings into the Flex Farm or Flex Acre once they have developed their two true leaves! 

The rockwool may turn green while in the Flex Micro. While algae is normal in hydroponics, you can limit it's growth by keeping your total dissolved solids count close to your target number, and by cleaning the system regularly.