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Table of Contents

Growing Cannabis Seedling Stage of Growth

In this three part cannabis growing cannabis section we will detail the three main stages of cannabis growing. In this article we will detail, growing cannabis seedling stage of growth. We will walk your thought getting the best growth in this stage of the cannabis life cycle to get your cannabis plants off to the best start possible. If you are looking for information on germinating your cannabis seeds for the first time we recommend reading this article first. 

The cannabis seedling stage of growth is very important as it will be getting your plants off to the best and most healthy start possible. Any issues during this time can seriously slow down the time to harvest your crop. Even worse is if something happens to kill your young seedlings before they ever get growing well. 

In this article we will help you to avoid these issues and get the best growth possible. 

Cannabis Seedling Just Coming Up
Cannabis Seedling Just Germinating

Getting Everything Needed ready for Healthy Seedlings

To get the best growth in the cannabis seedling stage, it is important to make sure everything is set up correctly before the seeds even break ground. This includes getting the right growing medium and containers to get the plant growing quickly and avoid any issues. 

Picking the Correct Containers for your Seedlings 

When picking containers for cannabis seedlings you will want to pick a container that is not overly large in size. The containers should be large enough to let the plant grow for about 2 to 3 weeks in the cannabis seedling stage. It should also not be larger than to need watering after about 3 days. In other words it should at the very least dry out after about 3 days from the last watering. The size of your container is very important as you will want a good wet, dry cycle of about 3 days. 

After watering your seedlings the container should not hold water for more than three days and should dry and need more water. If the growing medium in the container stays wet for any longer than this, you risk more diseases, and rot root that will kill your seedlings. 

We recommend this article for more in depth information on selecting the perfect containers for your cannabis

Cannabis Seedlings in Soil
Cannabis Seedlings in Soil

Picking the Correct Growing Medium for your Seedlings

Most likely even more important than picking containers is picking the correct starting medium for the cannabis seedling stage of growth. The best cannabis mediums are sterile, have the proper PH for cannabis and have excellent drainage for the cannabis seedling stage. 

Cannabis Seedling In Rockwool
Cannabis Seedlings in Rockwool

There are many mediums that you can use for cannabis, however we will review the best ones to get the most healthy start with cannabis seedlings. 

  • Pre-made Soil Starting Mediums: These mediums have the advantage that they already come pre-made to get the best growing results. They will be sterile, have great drainage, and have all the proper nutrients for your cannabis seedling to get them to the vegetative stage of cannabis growth. They will also have the correct PH range for your cannabis seedling, so no adjustments will need to be made. 
  • Rockwool: Another excellent medium to use for the cannabis seedling stage of growth. This medium will hold just the right amounts of oxygen and water, it also has great drainage and is 100% sterile. Growers using this medium will have to adjust the PH of this medium as it is slightly too acidic. Growers will also have to provide nutrients, in the correct amounts as rockwool will contain no nutrients for your cannabis seedlings. 
  • Coco Coir: Made up of dry coconut husks, this medium is also sterile and will come with the correct PH for your seedlings. Unlike rockwool this is an organic starting medium for your seedlings. It will have just as good drainage for your seedlings and will hold water well while still allowing oxygen to your plant root zone. Like rockwool growers will need to provide nutrients for the seedlings, give them complete control over how nutrients they will receive and how much. 

How Long Will it Take for the seedling to break the medium?

Typically it will take anywhere from 3 to 5 days for the seedling to break free from the medium. Growers will first see the tops of the cotyledon leaves of the seedling. These are the first leaves that the plant will have as it pushes free of the growing medium. They will slowly make their way out of the medium and grow straight to the light. 

When do my Cannabis Seedlings Need Light?

As soon as you see the cotyledons coming from the soil, you will want to provide a good lighting source for your young plants. If the seedlings do not have a good lighting source right away they will start to stretch looking for a lighting source. This will tend to cause cannabis seedlings to start to fall or bend over, and if this can be corrected with a better lighting source it can cause them to grow slower. 

Cannabis Seedlings Under Light

Temperatures and Humidity for Cannabis Seedlings

Your new seedlings are very delicate when they first germinate you will want to provide them with correct temperatures and humidity right from the start. Growers should keep them somewhat warmer than they would need in a vegetative stage of growth, in the range of 73.4F (23C) to about 77F (25C). This is a good temperature for the seedlings to get a good start growing. As for humidity this can be the same as growing in vegetative, approximately 45% RH to 50% RH, it can be dropped after the plant grows it first sets up true leaves. 

How to improve Seedling Growth?

First, making sure that the new plant has everything that it needs to thrive, such as water, correct temperatures, humidity, lighting, and nutrients. Giving your seedling all these things in the proper amounts will get your plants off to a great start in the cannabis seedling stage. After young seedlings break the medium they need very little in the way of nutrients, however as the plant starts to first grow their first true leaves, giving them the correct amount of nutrients to continue growth will also improve the growth of your young seedlings.  

How do you speed up seedling Growth?

Two of the most important ways to speed up seedling growth will be to provide your new seedlings with enough light, not providing them with enough light can seriously slow down cannabis seedling growth. Also making sure the plant has the proper temperatures above, will also speed up growth, having seedling temperatures that are either too hot or too cold will slow the plants growth down considerably. 

Another way to help speed up seedling growth is to add natural growth hormones to the growing medium. These can include Kelp, B1 vitamins, and Superthrive. These are also great for speeding up growth in the cannabis seedling stage. 

Cannabis Seedling First Set of Leaves
First Set of Leaves Cannabis Seedling

Cannabis Seedling Stage Day by Day

In this section of the article we will give you a day by day once your cannabis seeds break the ground and start to grow. 

Cannabis Seedling Stage: Day #1: 

Growers will start to see their tops of the seedling pushing out of their selected growing medium. The cannabis seed shell may be still attached to the seedling as it pushes from the medium. There is no need to remove it at this point and may even damage the seedlings. They will still be yellowish in color and will need lighting at this point to continue good growth. 

Cannabis Seedling Stage: Day #2: 

The cannabis seedling will start to straighten up and the seed will shed its shell still attached if needed. It will start to grow taller up to the lightning or sun. 

Cannabis Seedling Stage: Day #3: 

The seedling will continue to grow taller and the first set of young leaves called cotyledon leaves will grow out, with its first tiny true set of leaves in between them. They should also now start to become green in color.

Cannabis Seedling Stage: Day #4:

Your young seedling should have stopped stretching upward towards the light by now. If they have not stopped we advise that you add more or stronger lighting to keep the plants from stretching too high and falling over. If they do fall over this is fine and they will eventually stand back up again once the stem gains more strength. 

Cannabis Seedling Stage: Day #10:

The seedling should now be growing out their two true sets of leaves between the cotyledon leaves. All the leaves should be green and healthy by looking. Over the next couple of weeks your seedlings will start to grow faster as they grow more and more true leaves to take in energy from your lighting sources. 

What is Damping off and How Can it Affect Cannabis Seedlings?

When starting cannabis seeds you may run into a plant disease referred to as “damping off”. This is a plant disease that will only attack young cannabis seedlings. It is caused by excessively damp conditions in your growing medium that allow for the fungal infection to take root and grow in your young seedlings. It can also be more prevalent in cooler soil conditions. 

Once this disease is present in your crop of seedling, the plant’s stem will die at a certain point on the stem itself causing the top of the young plants to fall over and die. This can happen very quickly if you are not careful, this disease can kill a whole crop of seedlings overnight. 

How do Cannabis Seedlings get Damping Off Disease?

Since this is a fungal disease it can be present in the growing medium before the seed is planted. It can also be on the seed itself before it is planted, infecting the cannabis seed and the growing medium. Once the seedling falls over the disease is already in the late stages and there is no way that the plant can be saved. This is why it is so important to have a good clean and sterile starting medium for your cannabis. 

How to Prevent Damping Off Disease in Seedling?

The easiest way to prevent this disease is to allow your growing medium to dry out well between waterings. As mentioned above it is best to allow the growing medium to dry out completely after at least three days to stop damping off from starting to grow. Another important preventative is to create a good air flow over the plants, using a small fan to move air over your plants in the cannabis seedling stage. 

What to do if your plant is Stunted after Germination?

Sometimes growers will have a seedling that does not have its proper cotyledon leaves or first set of true leaves between the cotyledon leaves. It is really up to the grower at this point on what to do. Normally the plant will have much slower growth, but will eventually start to grow again after a week or two. This will put the plant far from any other seedling you happen to be growing. You can either let it keep growing or pull it up and destroy it. 

How long does the cannabis seedling stage take?

In the cannabis stage of growth it normally will last until your plants get their first true set of leaves. The plant will get its cotyledon leaves, a set of single leaves that look more like true cannabis leaves, and then a set of true cannabis leaves. These leaves will be normally a group of three leaves or five leaves together. At this point the plant will enter into its vegetative stage that will be written about in our next section of our growing cannabis series. 

Final Thoughts

The cannabis seedling stage of growth is sometimes the hardest part for new cannabis growers. It’s when the new plants are the most delicate, and when the most things are able to grow wrong. Once they go wrong in this stage, most of the time there is no coming back and the tender seedlings will die and the grower will have to start again. We hope this article will help you to identify and prevent these issues, for healthy seedlings. 

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