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Troubleshooting Hydroponic Plant Problems

Having problems with your hydroponics garden? Troubleshoot your hydroponic plant problems with our nifty, user-friendly hydroponics resource: a troubleshooting guide to help quickly diagnose and treat whatever ails it.

Our Beginner’s Guide To Hydroponics is on sale for a short time. Check it out!

Hydroponic lettuce setup

Our guide is easy to use: just look up your problem by the “main symptom”, and you’re on your way to the solution!

First, we review the “Big Picture” for possible obvious problems, then we take you to the troubleshooting tool.

Are you a beginner? Here’s a hydroponics guide for beginners.

First Check The “Big Picture”

Start by taking a quick look at the “big picture” of your hydro system. Unless you have an obvious insect or disease infestation going on… your
problems most likely have been caused by poor growing conditions. Run through these obvious solutions first:


  • Is the temperature between 60-90°?
  • Is there a 10° drop when the lights go out for the night?
  • Is the RH (relative humidity) between 50-70%? (50-60% is best)


  • Do you have adequate air exchange, or is it stagnant and stale in there?
  • Is the stale air being vented out somehow?
  • Do you have a fan gently stirring the leaves 24/7?


  • Are you using HID lights? (Fluorescents and most LEDs will not support fruiting/flowering).
  • Is the lamp too close or not close enough?

The nutrient system

  • Check the reservoir. What temp is the grow juice? Should be below 85°; under 80° is optimal. Check the ph and concentration.
  • Is there enough solution, or is the pump sucking air during cycles?
  • If you suspect any feeding/watering problems, drain the reservoir and start a new batch of nutrient solution. 

Keep in mind that plant problems are seldom straightforward, and it’s too often the case that opposites (like under and over-watering or feeding) can produce similar symptoms. We all have to put on our Sherlock Holmes hat when it comes to diagnosing our plants!

Troubleshooting Guide For Hydroponic Plant Problems

Okay, you’ve run through all the essentials and found no quick fixes? Try our hydroponics resource for troubleshooting below.

1. Critters

Have you found any insects in your garden (crawling, flying)? Identify and treat them by visiting our pests page.

2. Icky Coatings

If your plants or medium have a slimy or fuzzy green, white, black, or grey coating, you probably have a fungus or mold problem. Read on:

  • Sooty grayish to white fuzz = “gray mold” (see Common Plant Diseases)
  • Powdery white spots that grow to cover the whole plant = “powdery mildew”
  • White cottony masses in the crooks of the stems = mealybugs
  • Webs = spider mites
  • Shiny trails = snails or aphids
  • Greenish tinge on top of the growing medium = algae 
  • White “salt crystals” or residue on top of the growing medium = salt and mineral buildup. [Flush the pots well with clean water].

3. It’s in the leaves

  • Wilted leaves: over or under watering; too dry or too hot (try watering with clear water). Wilt Disease: curled up, dried out, and dead leaves
  • Curled up leaves: check for thrips and aphids (learn more about getting rid of aphids)
  • Droopy Leaves: that means temp could be too high (cool it down), or there’s not enough fluid (check that system is delivering enough solution). Another cause could be that the nutrient solution is too strong (flush plants with clear water only for a week, then restart with a new batch of nutrient solution]
  • Spots: white or silvery spots could be thrips again, or powdery mildew. Tiny yellow speckles could be spider mites
  • Yellow leaves: nutrient imbalance (check that ph not too alkaline), or you could have overwatered. Also, check for whiteflies. Note: yellow leaves are normal when the crop reaches the end of life. Time to uproot and start over.
  • Leaf Drop: Sudden temperature change/shock (like when setting out new seedlings); cold wind/dry air. Overwatering could be another reason. Or, mealybugs or whiteflies.
  • Tip burn: If the tips of leaves are brown, the nutrient concentration is too strong (flush with clean water and mix a new batch). Hot dry air can also burn.
  • Burn patches on leaves: Too close to the lights (light burn)
  • Leaves distorted or crinkly: could ve a virus or aphids

4. Blossoms and fruit

  • No blossoms: temperature too low
  • Blossoms drop: climate problems (too hot, improper light, too humid or too dry), as well as overwatering. Make sure there is a 10° temp drop at night when the lights go out. Learn more about Blossoms not getting pollinated.
  • Fruit drop: If the fruit yellows and dries up while still small, check nutrient solutions: it could be poor nutrition. Or, the light could be too low, or the wrong kind of lighting.

Hydroponic Tomatoes Problems

Here are some common tomato problems and how to fix them.

Misshapened/deformed fruits
Deformed tomatoes (catfacing)

This is also called “Catfacing”:

  • overall temperature is too low
  • insufficient day-night temp drop
  • poor pollination
  • light too low
  • humidity too high. 
Blossom end rot, or black spots on fruit
Blossom end rot on tomato

If it’s on both small and large fruits, there’s a calcium deficiency (mix new batch of nutrients).

If on only the large fruits, your plants are too dry (increase irrigation).

There is no cure for blossom end rot, only prevention.

Cracking tomatoes
Cracking tomatoes

If your tomatoes are cracked, there’s either not enough or too much water.

High temperatures can have this effect too.

You can still eat these tomatoes, as long as the cracks don’t become too deep and/or rotten.

5. Seedlings

  • Collapse: root rot or “Damping off”; usually too cool, dark and damp.
  • Spindly Growth: If the seedlings grow very tall and spindly, there’s not enough light. You would
    think it would be the opposite, but it’s not. When the light is too dim or too far from the seedlings, they strain towards the light, making them almost unusable for transplanting. Give your seedlings strong and close lighting if you want stocky, sturdy baby plants.

General Growth Problems

  • Bolting: Lettuce, broccoli, and radishes bolt to flowers and then seeds because of  too warm temperatures (they figure it’s spring, and time to make flowers!) Make sure these plants get plenty of light in their early growth stages and then keep them cool closer to harvest
  • Stunted or slow growth: Too cold, underfeeding, or overwatering
  • Spindly, skinny plants: Insufficient light
  • Rotting stems/leaves: Excessive humidity, overwatering, or disease/fungus

Troubleshooting hydroponics plant problems is easy if you can check things off a list. I hope our guide was helpful to you.

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peggy wilson

Wednesday 17th of May 2023

I have plants outside on east side...gets sun till 1 or 2 pm. start ok but now wilting.


Wednesday 17th of May 2023

Are these hydroponic plants?

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[…] Learn about possible hydroponic plant problems. […]


Tuesday 4th of January 2022

I have grown several batches of lettuce in rock wool and have good germination but once the cotyledons emerge the lettuce plant continues to slowly grow its stem longer without producing anymore leaves until it eventually falls over and dies days later but the cotyledons and long stem are still green, what issues could this be? They are grown under 4 UV lights in pH adjusted water soaked rock wool cubes, any information you could lend would be greatly appreciated, thanks.