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Correcting Nutrient Deficiencies

How to read yellowing, stunted, or purple leaves in your Flex Acre and correct the cause without burning the crop

Follow the instructions in this article when your weekly scan turns up plants that do not look right. Work the steps in order, as the first one clears the problem more often than any nutrient does. Follow the steps in Keeping your Flex Acre Clean before you begin.

Gather Tools:

  • pH Meter
  • pH Up
  • pH Down
  • The Single Nutrient your Crop is Short On
  • 5-Gallon Bucket
  • Mixing Tool

What am I looking for?

  1. Look for yellowing leaves on the plants your scan flagged.
  2. Look for stunted growth.
  3. Look for purple discoloration.
  4. Record what you see before you change anything, as you will compare against it daily.

The weekly scan and the pruning of dead or yellowing leaves belong to Wiping Light Bars & Pruning your Plants (Part 5 of 5). Use this article once that scan turns up a symptom you want to correct.

Why do I check the pH first?

  1. Take your pH reading once your nutrients have stabilized for 1 hour at minimum.
  2. Compare the reading against the 5.7 to 6.2 range for lettuce and herbs.
  3. Add pH Down in increments of 1 to 3 tablespoons when your reading sits above that range.
  4. Add pH Up in increments of 1 to 3 tablespoons when your reading sits below that range.
  5. Stir thoroughly with the mixing tool.
  6. Allow your Flex Acre to cycle for 60 minutes at minimum once your adjuster is stirred in.
  7. Re-test your pH once the 60 minutes have passed.
  8. Repeat the increments until your reading sits in range.

A pH outside that range locks the nutrients already sitting in your Tank, so your plants show deficiency symptoms even though the nutrient is there. That makes pH the most common cause, and the first thing to rule out. As an example, a reading of 6.3 on lettuce takes about 1 tablespoon of pH Down. Use the pH Up, pH Down and nutrients supplied by Fork Farms. They are matched to your Flex Acre. The full dosing procedure and the reason for the 60 minute wait live in Adjusting your pH after Dosing (Part 4 of 5).

What if my pH is in range and the leaves still look wrong?

  1. Name the one nutrient your crop is short on.
  2. Hold off on any dose until you have named it.

This article does not name a nutrient for you, as the same symptom can come from more than one shortage. A full feed of Nutrient A and Nutrient B at a 1:1 ratio is a separate task, and it belongs to Mixing Nutrients for your Flex Acre (Part 3 of 5), which also carries the rule that keeps those two parts out of the same bucket. Bring one bottle to your Flex Acre for a correction, not both.

How do I correct it without burning the crop?

  1. Mix a small batch of that one nutrient in your 5-gallon bucket, at a lower concentration than a full weekly dose.
  2. Stir the batch thoroughly with the mixing tool.
  3. Pour the batch into the pump side of your Tank.
  4. Allow your pump to cycle for 10 minutes at minimum once the batch is in the water.
  5. Record the nutrient and the amount you added.
  6. Check the affected plants every day for improvement.

CAUTION: MIX THE CORRECTION BATCH AT A LOWER CONCENTRATION THAN A FULL DOSE. A FULL-STRENGTH BATCH CAN BURN THE CROP.

Correcting one nutrient at a time is what lets you read the result. If you change two things at once, you will not know which one your plants responded to. Your correction belongs in the same weekly entry as your PPM and pH, which Logging your Flex Acre Tasks & Readings covers.

Your correction is in the water and your crop is back on its weekly rhythm—well done!

Next: Wiping Light Bars & Pruning your Plants (Part 5 of 5) — to compare the affected plants against what you recorded today.