8/3/2023

Soaking cannabis seeds as part of the germination process is something to consider in certain circumstances. The value of such a practice is dependent on a few variables. So like many other cannabis cultivation questions, this one seems to pop up from time to and also, like many other cannabis-based questions, is one with a spectrum of answers depending on certain variables. The key principle behind soaking cannabis seeds is one of simplicity, to soften the outer seed coat (shell). After soaking a cannabis seed, the shell will be much softer. Therefore it makes the initial step (imbibition) water absorption much more likely.

Imbibition: Water And Seed

Imbibition is a vital process in plant biology, involving water absorption by dry seeds. By absorbing water and activating the embryo, this process initiates seedling development, eventually leading to the emergence of a new cannabis plant. Without successful imbibition, the seed would remain dormant and unable to sprout. As the seed imbibes water, it triggers metabolic processes within the seed, activating key enzymes. These enzymes break down stored nutrients, such as carbohydrates and proteins, into simpler forms that the growing embryo can utilize for energy and regulation of growth. As the imbibition process progresses, water absorption leads to an increase in the volume and mass of the material. In seeds, this swelling helps to rupture the protective seed coat, allowing the embryo to emerge and initiate growth. Imbibition triggers metabolic processes within the seed, activating enzymes that break down stored nutrients into simpler forms for the developing plant. As the enzymes start breaking down the stored nutrients, this metabolic activity triggers the release of plant hormones, particularly gibberellins.

Gibberellins are a plant hormone class that promotes various aspects of seed germination, including the elongation of the embryonic shoot (hypocotyl) and the mobilization of stored reserves in the endosperm or cotyledons. Some of these hormones can produce volatile (odorous) phases, meaning that one seed/plant can help trigger developmental or regulatory changes around the seeds/plants. Some of these hormones can produce volatile (odorous) phases, meaning that one seed/plant can help trigger developmental or regulatory changes around the seeds/plants.  

So Why Would You Soak Cannabis Seeds?

Growers cite several reasons for soaking seeds. Although many growers will only soak seeds that are older and/or are not germinating, it remains true that there are some inherent pros to soaking seeds, as listed below.

Advantages of soaking seeds include:
• Enhance germination rates
• Faster germination
• More uniform germination
• Determining viability rate
• Reduce handling and unnecessary damage/abnormals
• Enhanced germination rate and speed

The rationale behind soaking seeds for speed and increased germination rate is one of logic. For instance, if seeds are not germinating, they are perhaps a little old; soaking them can help increase the number of seeds that ‘pop’. Furthermore, by default, some commercial growers will soak all their seeds in a weak bleach solution.

For example, this is a nice sterilisation method, and it can also help soften the shell further and increase the chance of triggering imbibition. This can help with the speed of germination and germination uniformity (germination at the same time). This is crucial when hundreds of plants are sown for consistency and same-week harvest.

Viability

Although it is not backed up by any science, seeds that sink vs those that float are said to indicate the viability of the seeds. However, it is not wise to determine viability with this practice alone. Most agricultural departments around the world do not recognise this method at all. Therefore, it should not be taken too seriously. In this context, viability refers to the state of the embryo – is it still viable – able to grow, or is it completely dead?

Reduced Damage

Some growers say that soaking seeds results in less ‘damaged’ seeds. A phenomenon rarely spoken about amongst cannabis seed enthusiasts is what’s known in other species as abnormal seeds or simply ‘abnormals’. This is a small percentage of seeds that germinate but then stop growing, often due to abnormal genomic structure, a lethal mutation, or can even be due to damage to the seed itself. Damaged seed coats can cause the embryo to abort during the earlier stages of germination. Soaking seeds may help prevent the growth-arrested associated with damaged seed coats.

Cons Of Soaking Seeds

Like many things, doing every part of a process correctly is usually the key to success. The disadvantages of soaking seeds are focused mainly on things that can go wrong due to human error or improper materials. The latter is mainly to do with the water used to soak seeds. Firstly, however, the main disadvantage of soaking seeds is disease onset.

Soaking Seeds Can Cause Disease

Using water only as a soaking agent can lead to the spread of disease. Water can be easily inoculated by accident, especially fungal/mold-type organisms, thus infecting your seedlings. The nature of the seed coat is to protect the embryo inside, so softening it more aggressively can allow infection to take hold before the plant can defend itself. Also, suppose the seeds have a surface ‘infection’ – microbes on the seed coat that could be pathogenic. In that case, there is a chance by soaking the seeds, you encourage the infection straight into the emerging seedling. The rationale is that if not soaked and planted, there is a better chance of the infection not occurring due to the competitive nature of the microbe world. Soil-planted or even, in some cases, inert planted seeds can avoid infection due to beneficial microbes outcompeting pathogenic ones. Also, the slower infection rate can allow the plant a little time to start its immune response. Of course, this is easily avoided by using a disinfectant in the water.

Water Quality For Soaking Seeds

Although some things can be added, such as phytohormones, bleach, hydrogen peroxide etc, using water with an improper balance of minerals can stunt germination. Some tap water can contain chloride-based salts and other minerals, which can interfere with the germination process. This should be avoided if soaking seeds. At least boil the water and let it sit for 24 hours. This will help reduce the issue but does not always; it depends on the starting levels of each mineral/salt. Ideally, use source water that is filtered, distilled, deionised, RO, rain or even spring water.

Water Quality For Soaking Seeds

Using the wrong concentration of added chemicals listed above can also mess up germination if soaking seeds. Nearly any substance can be toxic to living organisms if in too high a concentration; this can be true of plants too. For example, using bleach to cleanse the seeds at too high a concentration will kill the embryo inside. Hydrogen peroxide and bleach are used as precautionary measures to reduce the risk of fungal or bacterial infections on the seeds during the soaking process. They have mild antiseptic properties that can help disinfect the seeds and prevent the growth of pathogens that might be present on the seed surface or in the water.

Here Is A Step-By-Step Guide On How To Soak Cannabis Seeds

Step 1: Gather Materials

• Cannabis seeds
• Clean water (preferably room temperature)
• Optional: Household bleach or hydrogen peroxide (food-grade 3% solution)
• Measuring utensils (if using bleach or hydrogen peroxide)

Step 2: Prepare the Water

Fill a container with the desired amount of water.

Step 3: Add Optional Disinfectant (Bleach or Hydrogen Peroxide)

If you add a disinfectant, use extreme caution and ensure appropriate concentration. Use a very dilute final concentration of approximately 0.1% to 0.5% for bleach. For hydrogen peroxide, use a 3% food-grade solution in a very dilute concentration, around 0.5% to 1%. Avoid using higher concentrations, as they can harm the seeds.

Step 4: Mix the Solution (if applicable)

If you add bleach or hydrogen peroxide, gently mix the water to ensure even distribution of the disinfectant.

Step 5: Add the Cannabis Seeds

Carefully place the cannabis seeds into the water. Ensure that the seeds are fully submerged. Allow the seeds to soak in the water for a specific duration. The soaking time can vary depending on the seed variety and the recommendations of the seed supplier. Typically, soaking times range from 12 to 24 hours.

Step 6: Prepare the Water

After soaking, carefully drain the water from the container. Use a sieve or mesh to separate the seeds from the water. Plant the soaked cannabis seeds in their desired growing medium.

Step 7: Provide Optimal Growing Conditions

Place the newly planted seeds in a warm, well-lit environment with consistent moisture. Monitor and adjust the environmental conditions to support healthy seed germination and seedling growth. 

Conclusion

It's essential to note that using clean water for seed soaking is generally sufficient for most growers. If you use bleach or hydrogen peroxide as a disinfectant, follow recommended concentrations and guidelines carefully to avoid harming the seeds. Proper seed handling, sanitation, and optimal environmental conditions during germination are essential for successful and healthy seedling development.

This article is from Seedsman.

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