Cannabis Seedling Issues And Ways To Resolve The Issues

Many Marijuana growers complain about issues like yellowing leaves and slow growth in the seedling stage. Such issues need to be eliminated right away as they eventually hamper the yield quantity.

In this article, I will walk you through some of such common problems and share ways to get rid of them so that these do not negatively impact the growing journey and, most importantly, the yield quality.

However, before we dive into the issues, let us discuss healthy cannabis seedlings and the factors that affect their health.


Healthy Cannabis Seedlings

When the cannabis seed spreads its leafy hands and legs and grows out of the shell, you will see two tiny structures that look like leaves. These are called cotyledons and are not leaves in the true sense. They support the plant till the true leaves appear.

The true leaves are bright green, and should they appear burnt at the edges or yellowing, you should keep an eye for the plant’s health.

Factors That Affect The Health Of A Cannabis Seedling

Relative Humidity And Temperature

You must ensure the correct temperature and humidity so that the seedling grows well. These factors must not be too much, or some problems might be.

Keep the humidity at 70-80% and the temperature around 21 to 23 degrees centigrade.

Proper Light Intensity

Light burn is a common issue that seedlings face. Thus, adjusting the light is very important. Dim the light if you see that you feel the light is too much.

If the seedlings are growing too high, you can place the light closer to the seedling or increase its intensity.


Water is very important. You must give your seedlings the correct amount of water as both underwatering and overwatering might kill the seedling.

You can start watering with 100 ml of water and slowly increase as the plant grows. Make sure to test the pH using a pH testing strip.

Common Problems That The Marijuana Seedlings Face And Their Solutions


Seedlings constantly lose water through the process of transpiration, and you must replenish this water to prevent drying out and dying. Therefore, you should take care to keep the plant roots moist.

Mixing cocoa fiber or vermiculite with the soil is another way to ensure that the water is retained in the soil.


Both oxygen and water are crucial for the seedling’s growth. When you water the seedlings more than necessary, the seedlings don’t get the required oxygen, and their leaves start getting droopy. In a few days, you will see that they have turned yellow due to a lack of oxygen.

You can fix these issues by making drainage holes on the bottom of the container, and it will help if you do not leave the plants under running water. You can also enhance drainage and oxygenation by adding perlite into the growing medium.

Some also prefer using smart pots or other self-watering containers. If you are a hydro-grower, ensure that one-third of the roots are out of the water to ensure that the seedlings get oxygen.

Over Or Under Lighting

I cannot stress enough the importance of correct lighting. The seedlings might start getting longer if there is too little light. If they are closer to the light than they need to be, their leaves will burn.

The distance between the light and the plant needs to be adjusted in such cases. CFLs can be used other than LEDs or HPS to avoid these issues.

More Than Needed Heat

Your plant might also suffer from heat stress due to low humidity, strong fans, and excess temperature. In such a case, you might see the soil cracking and it becoming dry. The leaves might fold like tacos and become dry and crispy if the plant suffers from heat stress. The leaves might also turn yellowish. Therefore, You should correctly maintain the temperature and humidity levels.

I like putting my hands under the light to check these levels. If I feel a lot of heat, then, of course, the plants are feeling them too. Then I increase the distance between the lights and the plants. The fans also should not be very strong.


Nutrient issues that show symptoms like slow growth, yellow tips, and burnt tips happen due to overfeeding your plant. You should not feed your plant with too many nutrients in a short period, and many also add amendments that can create a nutrient burn.

To handle this issue, it is best to water the plant with plain water to wash off the extra nutrients. However, you must check the pH level of the water. The ideal pH level of the water must be 6.0 to 7.0 if you are growing them in soil. When using clay pellets, hydroponics, or coco peat, keep the pH level from 5.5 to 6.2.

You must regulate TheThe pH level as and when required and be monitored every day with basic testing strips.

It is best not to feed the seedlings for the first ten to fourteen days to avoid feeding more. If you are using good quality organic living soil, do not use the soil before the biological activities are reduced. A month or six weeks of the resting period will be enough for that.

Handling Common Seedling Issues

Your seedlings will show signs and symptoms of the issues it is facing. You need to understand them to treat it properly.

Light Distance

Though there isn’t any standard distance between the seedlings and the lights, you can determine the correct lighting distance based on the type of light.

MH or HPS Lamps: 25-40 Cm.

CFL Lamps: 5-10 Cm.

LED: 75 Cm, 40% light Intensity.

Plastic Dome

If you have germinated in a germination chamber, you must have used a plastic cover to lock the moisture. You must remove the cover when the cotyledons appear.

Downward Curling Leaves

Exposure to higher temperatures causes the seedling leaves to curl downward; a steady temperature of 20 to 25 degrees centigrade and correctly watering the seedling would be beneficial in such a situation.

Yellowing Leaves

Yellowing of the leaves can be due to overfeeding the seedling with nutrients, feeding wrong nutrients, or having fewer nutrients present in the soil. If you see such symptoms, pause for a few days before you start feeding again.

Light Usage

For the first couple of weeks, the cannabis seedling was under fluorescent light (15-20 W). When the first set of true leaves completely develops, you must put it under a LED or MH lamp. 18hrs of light is best for cannabis seedlings.

Slowing Down Of Growth

There might be several factors for slow growth, ranging from proper lighting to extreme temperature or humidity. Lack of nutrients might also slow down the growth of your marijuana plants. Therefore, you must check all these factors for slow seedling growth.

Good Substrate Mix

A light nutrient mix is the best to ensure healthy growth for the plant during the initial weeks. Mix perlite and coco fiber with the soil to create your substrate mix. It would be best to take proper care to ensure that the substrate mix allows proper oxygenation and good water retention.

Finishing Thoughts

Marijuana plants are fragile and delicate in their seedling stage. Keeping your plants in good health during this stage will grow into robust plants, ensuring a good yield. The above factors will help you in doing so.

However, you must also choose a good strain and the best quality seeds for a great harvest. I suggest buying strains from the top online cannabis seed-selling website, Homegrown Cannabis Co. They have the best variety of stabilized, healthy seeds bred with care.

I hope you have enjoyed reading the guide. Here’s wishing you a great harvest. Ciao!

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