How to


How to Germinate Cannabis Seeds

Seeds help to protect plant embryos until optimal conditions for growth and development are met. This is the central idea behind germination. Marijuana plants can survive in challenging environments and migrate in the form of seeds around the globe, thanks to germination.

An excellent example of the viability of this process is Super Lemon Haze, the world-famous sativa cleverly bred by Arjan Roskam and his team using cuts of Super Silver Haze, the robust indica Northern Lights #5, 1970’s stalwarts Skunk #1 and Haze, and the well-travelled Lemon Skunk which made its way to Amsterdam via Las Vegas. All made possible by successful germination of seeds from different parts of the world and even across the decades!

Germination can be tricky and determined by variables that can be controlled, such as maintaining optimal conditions in as clean an environment as possible. Other variables can be out of the cultivator’s control, such as the health and age of the seed, sprouting time, and the conditions of the plant’s habitat, which informs the seed’s initial formation and quality. Keep in mind that even under the utmost care and using the best equipment, some seeds may still fail to germinate.

Principles of Germination

A batch of marijuana seeds of a single strain contains many expressions of the cannabis plant’s characteristics in each seed. These include growth vigour, terpene profile, cannabinoid concentration, resistance to pests and disease and whether or not it responds well to training that increases yields. The cultivator who selects desirable traits for their crop can continue growing those attributes into the future.

Cannabis seeds require moisture, stable, warm temperature and darkness in order to germinate. Absorption of moisture and oxygen in its surroundings will stimulate several key metabolic activities – chemical processes integral to maintaining life – such as cell division and enlargement, production of enzymes and growth hormones (among others). These determine the development of the embryo inside the seed into the first white root to emerge from the seed, known as the taproot.

A consistent temperature of between 22 and 25 Celsius (71 to 77 Fahrenheit) is ideal for the germination of cannabis seeds. The production of enzymes that break down the outside seed coat (allowing the taproot to break through) is significantly influenced by temperature and can be prevented from being produced if the temperature is too high or low. This principle can also be applied to a seed’s exposure to light, as too much light can deter germination processes.

When taproots have sprouted, and the seedlings are ready to be transplanted, make sure to plant them in their next containers at a shallow depth of 0.5-2.5cm. Furthermore, the most critical aspect of successful germination and keeping seedlings alive is making sure they have enough moisture. Regardless of the seedlings’ final planting media, it is vital that they are kept moist (but not saturated) throughout the entire process.

Methods of Germinating Cannabis Seeds

While there are many ways a cultivator can germinate their cannabis seeds, the basic principles outlined above will remain the same. Let’s take a look at some of these germination methods.

At-home Germination with Kitchen Towels and Plates

One of the most straightforward ways of germinating seeds is the paper towel method. Absorbent blotting paper or even cotton wool pads can be used, although there is the risk of roots growing directly into them. Nitrile gloves are recommended, but some may find it interferes with the “feel” of the seeds.

1 . Moisten a paper towel with sterilised water until it is almost saturated. Be careful not to overdo it in this step, as excess water will prevent the embryo from absorbing oxygen and drown it. If any extra water can be squeezed out of the towel, it is too much.

2 . Place cannabis seeds on the towel, keeping seeds several cm apart. Fold the towel over or place a second damp towel over the seeds. Place the kitchen towel(s) upon a flat surface such as a sterilised plate.

3 . Cover the plate with plastic wrap or a second plate. This will keep the moisture from evaporating and will keep the seeds from drying out. Keep the plate somewhere the temperature can be a stable 22-25C, such as under incandescent lights or on top of a heating pad. If using a windowsill, be sure to monitor the temperature for fluctuations between day and night.

4 . Check the plate twice daily for signs of germination. To avoid damaging the taproots, try not to disturb the seeds or the plates. Germination is an extremely delicate procedure. Avoid touching the seeds altogether, as pathogens and bacteria that can kill the nascent seedlings may transfer from fingers to the seeds.

5 . When signs of germination can be identified (taproots emerging from the seed shells), make holes at depths of 0.5-2.5cm in the chosen growing medium. Very gently move the germinated seeds into these holes and situate them with the taproot pointing down.

6 . Keep the growing medium moist but not completely saturated. Remember that moisture is the key to metabolic processes that will stimulate the growth of the seedling.

A germinated cannabis seeds sitting on soil

The Glass of water Method

An even easier approach than using paper towels and plates is to simply submerge seeds in a glass of water. Use room-temperature water (18-22C) and do not keep seeds submerged for more than 5 days as they may drown. Keep glasses in a warm and dark place.

Please be extra careful when removing sprouted seeds from the glass. Any seeds that haven’t sprouted after this time can be removed from the glass and placed in paper towels to finish the process.

Easy Germination Using Starter Cubes

The risk of damaging newly sprouted seeds is reduced when seeds are germinated using starter cubes. They are perhaps the easiest, safest way to germinate cannabis seeds. Additionally, they can be easily transplanted to larger pots or containers filled with potting soil, coco coir or the medium of choice as soon as the seedlings are established.

Simply plant the seed in the pre-made hole on the surface of the cube, gently pinch the hole closed, water and keep it moist and warm! Very little preparation is needed, and the grower can get started as soon as their cubes arrive.

Starter cubes come in many forms: the grower can choose between Rockwool cubes, jiffy pellets and rapid rooters, to name several well-known options. The cultivator can decide which to use based on their growing needs after their young plants have sprouted. Rockwool cubes have been proven to work well in hydroponic systems, jiffy pellets work best with soil or coir, and rapid rooters are optimal across the board.

Avoid Transplant Shock by Planting Directly into Soil/Growing Medium.

Consider planting cannabis seeds directly into the soil or the chosen growing medium in order to avoid the risk of shock-by-transplanting. Transplant shock manifests in otherwise healthy plants as stunted growth, loss of crucial early leaves and cotyledons (the first leaves to appear after the plant emerges from its seed) or, in the worst cases, death.

Seeds planted directly in the soil or growing medium waste no energy adjusting to changes in their environment as they are already in their final destination (so to speak).

Cultivators who plant directly into soil or growing medium will benefit from watering in root growth hormone or root-protecting organisms such as mycorrhizae as soon as seedlings crack their seeds and start to emerge in order to supplement root growth as early as possible.

Post author
Martin is a production horticulturist with experience in commercial cannabis cultivation and sustainable farming from his time with Emerald Cup Award-winning farmers Esensia Gardens in northern California's Emerald Triangle.
See more from Martin

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