Marijuana seedling problems

When your marijuana plant is a seedling, it is in its most important and most vulnerable stage of life. This means you will need to be well acquainted with the potential marijuana seedling problems that could occur so as to ensure a healthy beginning and future of your plant’s life.

‘Water and heat are critical at this point of development. The new, fragile root system is very small and requires a small but constant supply of water and warmth.’

Jorge Cervantes

The most common seedling are overwatering, underwatering, nutrient problems, temperature, and lighting issues. These are all preventable conditions that an educated or experienced grower will effectively avoid, but as a new grower you can also prevent them from occurring just by doing your homework.

Read our cannabis germination guide to ensure you’re germinating your seeds properly.

Overwatering seedlings

Although we refer to it as “overwatering,” the problem itself comes from a lack of oxygen rather than an overabundance of water. Hydroponics systems, where plants are literally “planted” in water, work perfectly fine as long as there is enough dissolved oxygen in the water. If you are growing your seedlings in a container as many growers do, overwatering can be seriously risky to your marijuana plants. You will know your plant has been overwatered if it is drooping but not wilting.

If your little seedling is in a large pot, the chances are good that you are going to have an overwatering problem. Seedlings don’t absorb very much water, and a large container requires lots of time to fully dry out. Instead of planting your seedling in a large container from the beginning, start it out in a smaller container until they have grown significantly. You can then transplant it to a larger container.

If you don’t have a choice any longer because the seedling is already growing in the large container, then you are going to need to adjust your watering method. Simply water the plant a small amount of water, and pour it over the seedling in a circle pattern.

Makes sure the top inch of soil (up to your first knuckle) is totally dry before you water the next time. Don’t worry about water runoff with a small seedling until it has grown significantly.

Your plants will actually grow faster if they are put in a smaller pot, so make sure you are choosing a pot that is the best size for them and then transplant as they increase in size.

Download my free marijuana grow guide for more about watering.

That being said, it is also not helpful to have a large seedling in a pot that is too small for it. This is more about the size of the root system than the size of the plant above the soil. Your seedling might become root bound (when the roots have wrapped themselves around the outside of the container, therefore not allowing water to escape through).

Root bound plants often exhibit strange symptoms, including drooping and nutrient deficiencies, but also strange and unpredictable ones like interesting patterns of discoloration.

Often drainage (or, rather, a lack of drainage) is the problem when it comes to overwatering. If the water is unable to move freely through the soil and out the bottom of the container, you will run into overwatering health problems. Soil that is clay-based will not allow water to move freely through it, so avoid this type of soil when choosing your planting mix.

You should also make sure that there are enough drainage holes at the bottom of whatever container you are using, and that these drainage holes are not jammed or clogged and therefore preventing proper drainage.

Perhaps the simplest cause of overwatering to fix is watering too frequently. You need to allow the soil to have enough time to dry, so as to give your roots an adequate and consistent amount of oxygen. Oxygen in water is absorbed rapidly by the roots, meaning they will also need to have pockets of air within the soil to survive. If you choose a lighter, more airy amendment for your potting mix (such as Perlite), it will retain more oxygen than a thicker or heavier soil.

You can add as much as thirty to forty percent Perlite to the mix to ensure maximum oxygen retention.

Another way to increase the amount of oxygen in your soil is to use containers that allow air to come in through the sides as well as the top.

Smart Pots or Air Pots are examples of such containers. Another way to combat overwatering issues is simply to water your plants less than normal during colder periods of temperatures. Their growth, processes, and water intake all slow down at lower temperatures, so don’t forget to adjust accordingly.

Underwatering seedlings

Symptoms of underwatering include wilting, improper growth, and a lack of moisture in the soil. Although it happens less often than overwatering, it is still a serious problem that could negatively impact your seedling. It happens especially with beginners who have been warned – ‘never overwater your plants,’ so they overcompensate in the opposite direction.

If you combine underwatering with an overdose of nutrients, it will cause the seedlings to turn dark green, stunted, twisted, and new growth will be discolored.

Because there is a constant water loss in plants’ leaves through the transpiration process, they need to always have some presence of moisture to ensure proper functions and processes.

If the roots can’t absorb any water, the plant processes will simply stop, and the growth will be significantly slowed or stopped. If roots are ever allowed to fully dry out, they will actually begin to die.

While it’s a less common problem than overwatering, underwatering can be far more serious when it comes to negative health effects. If you look at the soil and you see that it has begun to separate from the container, this means that it is far too dry to be healthy for your plant.

Underwatering is an especially grievous offense when it is combined with an overdose of nutrients.

If this has happened to your plants, it is at least a simple fix: just add more water. Start watering them more regularly, and they should start to bounce back quickly and relatively easily.

Even if the soil mix is “hot” (which means that lots of nutrients have been added), your plant should have a good chance of adapting to it with an adequate supply of water.

Nutrient problems

You will recognize nutrient problems in your seedlings if their leaves are yellow, crispy, spotted, or have other forms of discoloration. Your marijuana seedlings should be green at all times – it’s as simple as that. The nutrient problems might come from too many nutrients, too few nutrients, the wrong kind of nutrients, or something else.

If your plant exhibits symptoms like tip burn and dark leaves, it probably has nutrient toxicity of some sort. After a while of untreated nutrient toxicity, you will start to see other symptoms, such as yellow lines located on the seedling’s lower leaves.

If your plant has a nutrient deficiency, then its leaves will probably look pale or yellowing, and you might also see signs of other leaf discoloration. A nitrogen deficiency is almost always at fault, and this will make the leaves include brown with the yellow and will go soft and will fold before they become crispy and drop off the plant. Don’t be deceived if the yellowing leaves are actually located at the top (newer growth only) – if this is the case, then it is unlikely that nitrogen is the nutrient at fault. A nitrogen deficiency generally affects the oldest leaves at the bottom of the plant before it reaches the other leaves elsewhere.

Problems with bugs can resemble nutrient deficiencies at first, so be careful to identify the symptoms correctly.

Your seedling’s nutrient problems might come from a “hot” potting mix, meaning it has lots of nutrients in it. This can simply be solved with adequate watering and waiting until the seedling has “grown out of it.”

If your soil is slow release soil, such as Miracle-Gro soil, it can cause nutrient burn and will eventually damage your final yield and bud development in the flowering phase. Don’t ever use a slow release soil.

Download my free marijuana grow guide for more on nutrient burn

Seedlings don’t need many nutrients, so don’t overload them with them. As long as you have started with a high-quality potting mix, you shouldn’t add more nutrients until at least after the first few weeks of growth.

Nutrient toxicity can develop very quickly (within one night!) if you dump your plants with lots of nutrients all at the same time. When starting to feed your seedling nutrients, you should always use just half of what is recommended on the provided nutrient schedule. Check how your seedlings are reacting to it, and then you can increase the dose from there.

If your seedlings have a nutrient deficiency, it is most likely that a nitrogen deficiency is to blame. A nutrient deficiency of any kind could come from using a soilless medium that doesn’t have any added hydro nutrients, which are necessary for a hydroponic growing system. Another cause in a soil-based growing system could be that the grower isn’t adding in nutrients when the plant has used up the soil. Nutrients in soil don’t just sit there forever; they are absorbed and used by the plant, meaning you will always need to add in some more as time goes on.

Also read “A quick crash course in nutrients“

One of the most common causes of nutrient deficiency is feeding your seedling or plant the wrong type of nutrients. You need to make sure the right type of mix and use the right mix during the correct stage of life. Use a vegetative formula for your plant’s beginning part of life, and a “bloom” formula for the flowering and budding stage.

Once the plant is fully grown you will need to start thinking about flowering and harvest time.

Our free little Harvest Guide will help you determine the best moment to cut your plants.

Another common nutrient problem with marijuana plants is a pH imbalance. Make sure to always maintain a balanced pH level, and you should be aware of the fact that the pH level will fluctuate. Improper watering (see above) will also cause a nutrient deficiency if left too long. Planting your seedlings in a container that is too small will lead to them becoming root bound, which will cause your seedlings to display symptoms of nutrient deficiencies. Problems with bugs can resemble nutrient deficiencies at first, so be careful to identify the symptoms correctly.

High temperatures

If your plant is experiencing too high of a temperature, the leaves will start curling at the edges until they look like tacos or canoes. They will also wilt and start showing spots.

Make sure to keep a constant eye on the temperature of your grow room, or know the weather to see if you will need to install any special equipment to keep the air temperature of your plants down. Seedlings are happiest when the temperature is somewhere between 68 degrees and 77 degrees Fahrenheit. Make sure to use your own thermometer to double check this. You should also be sure not to position your grow room lights too close to your plants, so you can avoid burning on the closest parts of the plants.

Improper lighting

Burnt leaves, crinkled leaves, tall seedlings that are falling over, and lots of stem spaces between nodes are all symptoms of too much or too little lighting. Plants that are too tall have experienced too little light while plants that look burnt or fried have had too much light.

TIP: Looking to buy seeds? Visit the ILGM marijuana seed shop.

Buy quality marijuana seeds

• We ship daily to all U.S. states for FREE!
• Our seeds are guaranteed to germinate
• Guaranteed Delivery
• Get 24/7 Grow Support

BUY SEEDS

Whether it’s too much or too little, improper lighting can cause some serious problems for your marijuana seedlings. Luckily, it’s usually an easy fix: just move the lamps closer to or further away from your plants. If you are growing your plants outdoors, try covering them up on extremely hot days, and make sure every bit of your plant is exposed to direct sunlight. If they are exhibiting signs of lighting problems, you can fix the problem early on by adjusting the lights, and this should be enough to get your seedling back on their “feet.”

Marijuana plant symptoms

Leaf symptoms:

• Discoloration
• Yellowing
• Crispy texture
• Spotted
• Tip burn
• Burnt edges
• Pale leaves
• Death of leaves
• Slowed growth

Plant symptoms:

• Wilting
• Drooping
• Algae growth
• Improper growth
• Slowed growth
• Dark green
• Stunted growth
• Twisted growth
• Discolored new growth
• Other discoloration

In general, your seedlings are going to want a moist environment, warm temperatures, and some light. They aren’t going to want much for nutrients. As long as you follow these points, your seedlings should be perfectly happy and healthy.

Also read “Symptom checker – Identify marijuana plant problems“

Remember that plants with strong genetics have less chance of getting sick and are less vulnerable to diseases, deficiency, pests and environmental stresses. So make sure to buy marijuana seeds from a trusted seed bank.

FAQ about marijuana seedling problems

Why are my seedlings turning yellow?

Seedlings mostly turn yellow when they have nutrient problems. They could be lacking enough nutrients, getting too many nutrients, or getting the wrong kinds of nutrients.

Why are my seedlings growing so slow?

They might be lacking the essentials they need to grow into healthy plants. Make sure they have proper lighting, warm temperatures, a moist environment, and enough nutrients.

Why are my seedling leaves curling down?

Seedling leaves curl downwards when they are exposed to temperatures that are too high. Make sure the temperature in your grow room ranges somewhere between 68 and 77 degrees to avoid such problems. 

Thanks for reading. Please leave comments or questions below and don’t forget to download my free grow bible

Robert