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How to Help Yellow Cannabis Seedlings

Having a problem with your cannabis seedlings? Here’s a quock tutorial to help you identify the problem and get it solved right away so you can get back to growing marijuana!

What Causes Cannabis Seedlings to Turn Yellow (or Show Other Symptoms)?

  • Poor Watering Practices – When it comes to seedlings, the most common problem is overwatering. Leaves may turn yellow if roots stay wet for long periods of time (“wet feet”) and may also show a wide variety of other symptoms, spots and nutrient deficiencies. Less commonly similar symptoms can be caused by underwatering but it’s more rare because small plants don’t drink much. Learn how to water your cannabis plants.
  • Bad Soil – If soil is thick and muddy, your seedlings will grow poorly. Good cannabis soil drains well and is rich and light.
  • Not Enough Light – Seedlings get long and stretchy with big spaces between sets of leaves, often with yellowing. What type of grow lights are good for cannabis plants?
  • Too Much Light – Parts of the plant closest to the light is turning yellow or brown. Learn about light burn.
  • Too Hot or Dry – This can cause leaves to turn into tacos, crinkle up at the edges, and sometimes turn yellow if it gets too bad! Learn about heat stress and controlling temperatures!
  • Incorrect pH – If pH is too high or too low the plant may show nitrogen or other deficiencies. Learn about controlling pH to prevent nutrient deficiencies. As long as your plant is getting nutrients and doesn’t appear droopy, 9/10 times the nutrient deficiency is actually being caused by the incorrect ph!
  • Not Enough Nutrients (rare) – If growing in soil, it’s very unlikely your seedling will use up all the nutrients in the first few weeks. However, if growing in coco or hydro, it’s important to give seedlings suitable nutrients from the beginning or they will immediately start turning yellow from the bottom up.

Examples of Unhealthy Cannabis Seedlings

Overwatering – Common cause of droopiness and yellow leaves

Another example of a deficiency that’s actually caused by overwatering

Chronic overwatering in thick soil led to the following yellow leaf symptoms. The main thing that alerts you to the fact that the yellowing is caused by overwatering is the fact that the seedling is droopy. It’s very easy to overwater young plants when you have a small seedling in a big container. When that’s the case, don’t soak the whole growing medium. Water in just a circle around the plant until its leaves are up and growing fast. At that point you can start watering more thoroughly 🙂

The strange yellow and red growth in this picture has been caused by giving the plant too much water, too often. Overwatering can often causes what appears to be nutrient deficencies in young plnats! Older plants tend to just droop, but especially seedlings can have really odd reactions to root problems.

This soil is thick and thoroughly saturated with water. As a result the young seedling roots can’t get any oxygen and it’s stopped growing, with the first set of leaves starting to turn yellow. Overwatering will stunt young plants and keep them small!

This “soil” is more like mud. The plant roots are drowning from lack of oxygen, causing severe wilting.

Not Enough Light – Tall or “Stretchy” Seedlings

Seedlings stay yellow if they never get any light

Too Much Light – parts of plants closest to the light are turning yellow

Heat Stress – Causes leaves to fold into tacos and edges to turn up

These two seedsling are suffering partly from overwatering, and partly heat

After being subjected to overwatering plus a heat wave, the leaves of the following seedling started cuppping upwards and turned lime green. The stems and veins of the leaves were turning red. You can see the soil is still dark and wet because the plant stopped drinking after developing root problems.

Not Enough Nutrients

Not enough overall levels of nutrients usually only happens to cannabis seedlings in coco or hydro where the grower didn’t provide any extra nutrients. It’s rare for a young seedling in soil to be able to use up all the nutrients in soil in the first few weeks. In coco or hydro you should be providing nutrients (at seedling strength) from the very first watering because otherwise it only has the nutrients that were contained in the seed.

How to Help Yellow Cannabis Seedlings Having a problem with your cannabis seedlings? Here’s a quock tutorial to help you identify the problem and get it solved right away so you can get back to

Yellow Seedling Leaves – Why Are My Seedlings Turning Yellow

Have you started seedlings indoors that began healthy and green, but all of a sudden your seedling leaves turned yellow when you weren’t looking? It’s a common occurrence, and it may or may not be a problem. Keep reading to learn more about yellowing seedling plants and how to treat them.

Yellow Seedling Leaves

The first thing to establish is which of your seedling leaves turned yellow. When seedlings emerge from the soil, they put forth two starter leaves called cotyledons. After the plant becomes more established, it will begin producing differently shaped leaves that are characteristic of its species.

The cotyledons are designed to get the plant started in the very beginning of its life, and once it’s producing more leaves, these aren’t really needed anymore and will often yellow and eventually fall off. If these are your only yellow seedling leaves, your plants are perfectly healthy.

Why are My Seedlings Turning Yellow?

If it’s the larger, more mature leaves that are turning yellow, you do have a problem, and it could be caused by any number of things.

Are you giving your seedlings the right amount and intensity of light? You don’t need to buy a fancy grow light for healthy seedlings, but the bulb you do use should be trained about as close as possible directly over your plants and attached to a timer that keeps it on for at least 12 hours per day. Make sure you do give your plants a period of darkness too, of at least eight hours.

Just as too much or not enough light can cause yellowing seedling plants, too much or too little water or fertilizer could also be the problem. If the soil around your plants has been completely dried out between waterings, your seedlings are probably just thirsty. Overwatering, however, is a very common cause of sickly plants. Let the soil begin to dry a bit between waterings. If you’re watering every day, you may very well be doing too much.

If water and light don’t seem to be the problem, you should think about fertilizer. Seedlings don’t necessarily need fertilizer so early in their lives, so if you’ve been applying it regularly, that may be the problem. Minerals from fertilizer can build up very quickly in seedlings’ small containers, effectively strangling the plants. If you’ve applied a lot of fertilizer and can see white deposits around the drainage holes, flush the plant gradually with water and don’t apply any more fertilizer. If you haven’t applied any and your plant is yellowing, try a single application to see if it perks up.

If all else fails, plant your seedlings in your garden. New soil and steady sunlight might be just what they need.

Have you started seedlings indoors that began healthy and green, but all of a sudden turned yellow when you weren't looking? It's a common occurrence, and it may or may not be a problem. Read this article to learn more about yellowing seedlings.