The joy of germination is watching a seed pop, bring forth a tiny sprout, and grow into a highly productive mother. However, kicking off cultivation does not always turn out this way. Sometimes, the seed coat protecting embryo is also the one that instigates a complicated, long-running germination process. This annoying delay can be amended, though, by scarifying the seeds.
All plants come from the noble and humble seed. It contains all the essential elements necessary for the growth and development of a new plant. Contrary to popular perception, the seeds are not all tiny and round; they come in various shapes, sizes, and textures.
Seeds consist of three main parts: seed coat, endosperm/cotyledon, and embryo.
- Seed Coat. As the name implies, it is the protective shell that encases the other parts of the seed. It is typically thick and strong enough to shield the seed from environmental factors and premature germination brought about by exposure to water.
- Endosperm. The seed receives its needed nourishment through the endosperm, a tissue surrounding the embryo that forms after fertilization. It is, in essence, a reservoir of starch, oil, and proteins that allow the embryo to develop.
- Embryo. The seed embryo develops from a fertilized zygote and contains the first forms of a plant’s roots, stem, and leaves. Until it is ready to become a seedling, a mature embryo depends on radicle, plumule, and one or two cotyledons for sustenance. During this “waiting period,” it engages in cellular respiration and other critical metabolic processes to prepare for germination. Provided that all the essential elements of germination are present, it starts consuming the endosperm until it is ready to sprout out of its container.
Germination will commence when the right balance among these three crucial components are present:
- Water. Mature seeds are often extremely dehydrated, so it is necessary to obtain water from an external source to trigger protoplasmic activities. Through a process called imbibition, it absorbs enough water to activate enzymes that encourage metabolism. Furthermore, the water also increases permeability and weakens the coat until it breaks open.
- Oxygen. In a process is called aerobic respiration, oxygen breaks down glucose to produce enough energy for the seed to germinate and the seedling to grow.
- Temperature. Heat affects the rate of imbibition, metabolic reactions, and respiratory activity. Ideally, the air temp should be between 20-22°C (68-71°F). Meanwhile, the growing medium should be a degree or two higher, at around 23-25°C (73-77°F).
Causes Of Delayed Or Failed Sprouting
An imbalance is one of the worst enemies of cultivation. Even with good seed viability, unfavorable conditions prevent or disrupt sprouting:
- Unsuitable Moisture Levels. Seeds thrive in a moist environment, but too much water restricts the presence of oxygen and thereby impede sprouting. To avert excessive dampness, maintain a 70% relative humidity.
- Oxygen Deficiency. Apart from too much water, a tightly compacted soil or planting seeds too deeply into the medium can also cause oxygen deficiency.
- Excessive Heat. Seeds are inclined to germinate in warm environments. However, high temperatures can cause heat stress and seed aging due to the decrease in essential enzymes – either of which can kill the seed or reduce its ability to germinate.
- Impervious Seed Coat. The pod is the modulator of seed-environment relationships as most of the elements required for germination such as water and oxygen externally sourced. Some seeds have a thick husk to protect the embryo from unfavorable weather conditions. However, an impervious shell also affects absorption causing it to remain dormant.
- Direct Germination In Soil. Planting a seed deeper than 1 cm increases the risk of oxygen deficiency and prevents the cotyledons from emerging. Moreover, watering the soil can bury the seed deeper. Instead, germinate the seed kitchen paper, jiffy pellets or peat plugs used for rooting cuttings first before transplanting to the soil.
- Incorrect Orientation. A seedling will not sprout if the seed not properly oriented. The crater or the crown must always face upwards as it serves as a hinge when the tip opens to let the root out.
- Multiple Seeds Per Container. Germinating several seeds in the same pot does not immediately affect the seeds. However, once the seedlings spout, the root system could get entangled.
- Age Of Seed. The quality of seeds degrades with age and are unusable as even slightest pressure can cause it to crack. On the other hand, immature seeds, often green and white in appearance, are a waste of time as its germination rate is low and extremely slow.
Stick with dark seeds that are firm to touch. Also, conduct a float test to determine viability. Discard the seeds that stay on the surface and germinate the ones that sink to the bottom.
Scarifying For Fast Germination
Favorable conditions are sometimes not enough for germination. An unusually tough shell can stop water and oxygen from reaching the embryo and promote growth. Consequently, many of these seeds end up discarded.
A seed with tough husk is the plant’s way of ensuring survival. It allows the small kernel-like DNA vessel to endure freezing winter spells, getting submerged in floods, and journeying through the acid-filled digestive tract of a mother plant. In some instances, some seeds take years to germinate even when exposed to ideal environmental conditions. Scarifying seeds help lessen the length of time it takes to sprout. There are three ways to accomplish this – mechanical, thermal, and chemical.
Scarifying seeds has its inherent benefits, but it is also not without disadvantages and risks:
- Can be done to any cannabis seed with a hard shell
- Relatively easy to do
- Jumpstarts germination in 24 to 48 hours
- Only requires cheap, accessible materials
- Applicable to small and large-scale operations
- Saves time and money
- Uniformity as all seeds germinate within hours to a day of each other
- First few attempts are often prone to error, exposing seeds to irreversible injury
- May require a time-consuming trial-and-error approach to know which scarification methods work best
- Not beginner-friendly.
How To Scarify Seeds
Between the three methods of scarifying seeds, no one is better than the other. More than the technique, the result depends on the execution, the strain, and thickness of the shell. To boost the chance of success, though, ensure that the internal portions of the seed – embryo, endosperm, and cotyledons – are not in any way damaged.
Studying cannabis seed anatomy before scarifying the first time is crucial as the structure varies per species. Recording the results of every method and other details is also helpful in finding out which works best.
More popularly known as “nicking,” this approach involves the use of sharp or abrasive tools such as a nail clipper, nail file, sandpaper, or knife to abrade or weaken the seed coat. Only a few outer layers of the small cannabis seed should be scraped for water and other soil nutrients to penetrate the embryo, so perform this technique with utmost care and precision.
There are various ways to go about mechanical scarification. Some of the most widely used procedures are:
Sharp Tool Or Nicking Method
- Nail clipper or small knife
- Cannabis seeds
- Locate the seed’s hilum – a scar marking the seed’s former attachment to the placenta – and prepare to nick the side opposite to that.
- Take a nicking tool of your choice and make a shallow cut on the marked end of the seed.
- Keep chipping within that small area away until its lighter colored layer shows through.
- Stop nicking the shell and place the seed in a bowl of tepid water.
Sandpaper In A Jar Method
- 1 piece of sandpaper
- Clear jar with cover
- With the rough side facing inwards, roll the piece of sandpaper into a cylinder.
- Insert the rolled-up sandpaper inside the jar.
- Place the seeds inside the jar and seal the lid.
- Shake the jar moderately until the seeds’ outer covering has lost its luster.
- Take the scarified seeds out of the jar and store in a container filled with room temperature water.
Two Sandpaper Method
- 2 pieces of sandpaper
- Lay sandpaper sheet one – rough side up – on a flat surface.
- Place a few seeds on the sandpaper and spread evenly in one layer.
- Take the second sheet of sandpaper and place it over the seeds.
- Gently move the top sheet back and forth a few times to apply friction on the seeds.
- Transfer the seeds to a bowl filled with room temperature water.
Sandpaper Tube Method
- 1 piece of sandpaper
- Adhesive tape
- With the rough side facing inwards, roll the piece of sandpaper into a narrow tube. Make sure that the cylinder’s circumference is small enough that both ends can be covered with the thumb and middle or index finger.
- Tape the rolled-up sandpaper to keep it from unrolling.
- Seal bottom end with the thumb and put the cannabis seeds in.
- Cover the top end with the middle or index finger and shake the sandpaper cylinder moderately.
- Take the scarified seeds out of the jar and put in a container filled with tepid water.
Hot Water Scarification
Also called “wet heat treatment,” the hot water approach is one of two heat scarification methods. Unlike the dry heat technique which is best performed with fire-adapted plant species, the use of heated water is ideal for small seeds like that of cannabis as it provides a fast, uniform administration. Moreover, this approach is safer than nicking as it has a lower likelihood of harming the seed’s embryo.
- Pot or beaker
- Room temperature water (5-6 times the volume of seeds)
- Pour the water into the pot/beaker and heat to approximately 70°C (158°F)
- Remove the pot/beaker from the heat source.
- Place the seeds in the pot/beaker and let the water cool down to room temperature.
- Allow the seeds to soak in the same water for another 12 hours.
Scarification can occur naturally when birds and small animals eat seeds. The acids in the digestive tracts weaken the pods, resulting in seeds that are ready for germination once released together with the birds’ stool. The process can be mimicked by replacing gastric juices with concentrated sulfuric acid or other solutions.
Because sulfuric acid is a dangerous product that must solely be handled by professionals with the right equipment, and cannabis seeds only have moderately tough coats, vinegar is the more appropriate liquid material to use. Also, as not to destroy a whole batch of seeds, run a pilot test with a few in varying durations, and evaluate which produces seeds that germinate best.
- Small glass container
- Baking soda
- Pour some vinegar in the container.
- Soak a small batch of seeds in the liquid for 30 minutes to an hour.
- Rinse the seeds with water and baking soda to neutralize the acid.
- Soak the seeds in room temperature water until the seeds start to swell noticeably.
Germinating Scarified Seeds
Germination should be easier and smoother after seeds have been subjected to appropriate scarification methods. Whether it is through nicking, sandpaper scuffing, hot water soaking, or acid treatment, if done correctly, the seedling should emerge within 24 to 48 hours. Put the by-products to the test using any of these germinating media:
Perhaps the simplest of the lot, this technique entails soaking the cannabis seeds in warm water. Be cautious of oversoaking, though, as to prevent the seeds from experiencing oxygen deprivation.
- Ceramic cup or mug
- Plate or dish (must be big enough to cover the cup/mug)
- Warm distilled water
- Pour the water in the cup/mug and place the seeds inside.
- Cover the container with a dish or plate to trap the heat and prevent light from entering.
- Remove the seeds from the water as soon as the taproots start to emerge from the seed coat.
- Transplant the young cannabis in its permanent medium after.
The use of kitchen paper towel as a sprouting medium is arguably the most widely employed method on the list. Just keep in mind, never to leave the temporary abode to dry out. Also, seeds properly scarified are bound to pop within a day or two, so be ready to transplant the young rooted plant right away as soaking for too long run the risk of damaging its little radicle.
- 2 sheets of paper towels (non-porous)
- 2 plates or dishes
- Boiled water
- Wet the kitchen paper towel to make it moist.
- Lay one paper towel onto a plate or dish. Drain the excess water.
- Place the seeds onto the damp towel and cover with the other sheet.
- Use the other plate or dish to shield the covered seeds from light and prevent the heat from escaping.
- Remove the seeds from the damp paper towel immediately once the taproots have sprouted.
Germinating a scarified seed in the soil, although not as popular as the previous modes, isn’t a bad idea if it will be its permanent home. Do not sow the seeds more than 1 cm deep, though, to prevent oxygen deficiency.
- Plant pot
- Fill the pot with soil without packing it too tightly.
- Pour water into the soil until it’s completely saturated.
- Bore a shallow hole into the wet soil with a pencil or any long object.
- Place the scarified seed into the hole and cover it with dirt.
- Keep the pot in a place with room temperature.
Hydroponic growing methods have gained popularity in recent years, and rockwool germination is no exception. One of the main advantages of germinating seeds in rockwool cubes is the ability to transfer the medium directly onto the soil without disturbing the seed. Less contact with the seed translates to minimal stress on the plant.
- Rockwool cubes
- pH-balanced water
- Heat pad
- Humidity dome
- Soak the rockwool cubes in the water solution for an hour.
- Shake the cubes gently to get rid of any excess water. Do not squeeze the medium.
- Using a match or similar object, create a small hole at the center of the cube that is twice as deep as the length of the seed.
- Place the seed inside the hole and gently cover it with rockwool.
- Repeat these steps on a few more cubes and place them on a tray.
- Place the heat pad underneath the tray to keep the water and cubes within ample temperature.
- Cover with a humidity dome to create a warm and moist environment.
- Monitor the moisture levels of the cubes at least once a day by spraying them with just enough purified water to keep them damp.
- Once the seedling has penetrated the surface of the cube, carefully remove the seed coat from the germinated embryo.
Tough Seeds Need Tough Love
Slow or failed germination because of thick seed coat is natural. Nonetheless, through scarification, a highly effective method of speeding up sprouting, preventing or lessening instances of this normal yet troublesome occurrence is possible.
Thicker-than-usual pods can be remolded through nicking, abrading, or soaking in hot water or acid solutions. These methods, though seemingly harsh, allow water and oxygen to penetrate and make their way to the embryo which, in turn, will trigger germination Once in a viable state, cannabis cultivation is back in business fast and strong, proving a bit of tough love is necessary at times.