Yellow Leaf Edges on Hydroponic Lettuce? Here's What Might Be Causing It

1. Nutrient Deficiency (Especially Calcium or Potassium)

When leaf edges turn yellow or crispy, it's often a sign of missing essential nutrients—particularly potassium (K) and calcium (Ca). These minerals play vital roles in water transport and cell development.

How to fix it:

• Check your nutrient solution formula—make sure it includes secondary elements.
• If you’re using filtered or RO water, consider supplementing with a separate Cal-Mag solution.

2. EC Too High or Too Low

If the EC (Electrical Conductivity) is too low, your plants may not absorb enough nutrients. But if it's too high, it could cause "nutrient burn," usually starting at the leaf edges.

How to fix it:

• Adjust your EC based on the plant's growth stage. For example, buttercrunch in the mature stage prefers 1200–1800  µS/cm
• Use clean water with the appropriate hardness.

3. Uneven Light Distribution

When light doesn’t spread evenly, some outer leaves may get too much light and get damaged. On the other hand, areas with poor light exposure may show signs of deficiency and yellowing.

How to fix it:

• Adjust the distance and angle of your grow light to cover the entire growing area.
• Rotate your hydroponic system or the plants themselves regularly.

4. Root Problems

Blocked or diseased roots reduce the plant’s ability to absorb nutrients, which can cause yellowing starting at the leaf edges.

How to fix it:

• Check the root color and smell—they should be clean and white.
• Clean your system and refresh the water every 7–10 days.

Conclusion

Don't panic if your lettuce leaves are turning yellow at the edges!

Just go through these common factors—nutrients, EC level, light, and roots—and make small adjustments.

Your LetPot system is more than capable of growing beautiful greens when the basics are looked after consistently 💚

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