At Trichome Technologies, we use two basic seed germination techniques: for small seed germination needs, say 100 seeds or less, we use large 24 × 36 × 8-inch clear Tupperware containers. We drill one ¼-inch hole for drainage in the bottom and two ¼-inch holes for airflow in the lid. We place light diffusers in the bottom of the container, which allows 3-inch rockwool cubes to drain. With the lid closed, it is the perfect environment.
A light diffuser is a plastic sheet of small ½-inch squares. It is used in overhead lighting to direct light straight down. They are available from most hardware and lighting stores, but do not use chrome-plated plastic diffusers—only white. The chrome will come off when exposed to nutrients, etc.
Germinating pads are placed underneath to provide heat—the temperature should be kept at 78°F. Some cultivars prefer higher or lower temperatures, ranging from 70–80°F, but whatever the temperature, it must remain constant. Anything higher or lower than these parameters is not ideal for seed germination. Place a thermometer or digital temperature probe in the medium so you can constantly monitor the temperature and keep it exactly where you want it.
Seeds germinating with the white taproot emerging. Plant the taproot facing down when the time comes and be gentle, they can be easily damaged.
Seedling emerges. The two broad leaves are called cotyledons, and the two small leaves emerging are the first true leaves of the baby cannabis plant.
Photos: Mel Frank
Determining Cannabis / Marijuana Plant Sex
Determining plant sex early is important for good growing. You must identify plant sex as early as possible during the vegetative stage. Males must be quickly removed and destroyed / properly disposed of before they produce pollen or else your crop will go to seed. If you’ve started from clones of a known female sex, then you’re assured that the plants will be female (unless plant stress causes hermaphrodites).
Female Pre-Flowers
Adult Female Flowers
Female pistillate flowers have a teardrop shaped bract with two tiny, thin, white stigma protruding.
Pre-Flowers on Male
Adult Flowers on Male
Male staminate flowers form tiny oval ball-like clusters that extend from the stem on their own stem like micro bunches of bananas.
For lighting, 4-foot cool white fluorescent fixtures, with 2 bulbs per fixture and 2 fixtures per propagation chamber, are used. We prefer 3-inch Grodan rockwool cubes with 2-inch diameter pre-made plug holes in the center. We place a soilless mix of equal parts fine sifted potting soil, perlite, and vermiculite, with a little horticultural sand mixed in to aid drainage and oxygenation. Instead of using rockwool cubes for germination, use the same soilless mix in small 3-inch containers. Seeds are pre-washed in a 2% bleach solution for one minute to eliminate fungal attacks, and then dried off. We then lightly score them on the edge with a nail file and place them in a jar of distilled water (at 78°F) for 24 hours. Seeds are then placed between 4 folded paper towels and moistened with distilled water. Finally, they are placed onto Pyrex plates with Pyrex lids on top. The plates are placed in chambers to maintain a constant temperature utilizing germination / heat mats (keep temperature approximately 78°F).
Cotyledon visible on a seedling that just emerged. It produced 3 pounds six months later.
Photo: Mel Frank
Germination chamber.
The seeds will germinate in 2 to 7 days. There are some cultivars that take up to 14 days, but this is rare. Water them daily, but do not soak, and never let them dry out—always keep them moist. After sprouting, decontaminate a pair of rubber-tipped tweezers with alcohol, dry thoroughly, and gently place sprouts, with the white tip pointing down, ¼-inch into flushed, pH-adjusted, and pre-moistened soilless mix in rockwool cubes. Carefully cover them with medium and water them with distilled water only. After 7 days, water with ¼ strength fertilizer—vegetative mix.
Place the chambers over germination / heating pads to elevate temperature inside, then raise or lower the chambers to achieve optimum temperature. Try to keep the temperature at 78°F. Seedlings need oxygen, so monitor moisture levels several times a day and open chambers to allow fresh oxygen in. The cubes are now ready to be placed in the decontaminated chambers. Chambers can then be placed over, not onto, germination pads and under lights.
When the sprouts start to appear, take the covers off the chambers. Continue to provide 16–18 hours of fluorescent lighting, kept at approximately 6–8 inches above seedlings, for 2–3 weeks. Use ¼ then ½-strength nutrients or fertilizers until the average seedling is 4–6 inches tall; then transfer them to 600-watt, MH HID lighted chambers. For the first 24 hours, the MH HID must be kept 3–4 feet from seedlings, then lowered to the proper height of about 1–2 feet. Throughout the seedling stage, all lights must be on for 16–18 hours and off for 6–8 hours, depending on your chosen lighting regimen.
Propagating Clones / Germinating Seeds Intended for Outdoor Growth
When propagating clones or germinating seeds intended for outdoor growth, you must germinate using a 12-hour on / 12-hour off light cycle for the first 30 days. Then, you can switch to a 16-hour on / 8-hour off light cycle. Clones must be taken from a plant that is on a 16/8 light cycle and kept on that cycle until they’re ready to be placed outside. After that, the light cycle must be adjusted to approximate outside lighting conditions and the plants must be hardened off before finally being placed outside permanently. This terminology is explained further in the cloning chapter. The purpose of all this is to simulate springtime lighting conditions. If you placed the clones / seedlings that had been acclimated to an 18-hours on / 6-hours off photoperiod directly outside, they would immediately begin to flower for a couple of weeks before reverting back to vegetative growth, which is a waste of limited, valuable time. However, if you want short plants, you can place them directly outside after an 18/6 photoperiod late in the growth season, and they will begin to flower immediately and continue until they are finished. In other words, they won’t revert back to vegetative growth, thus allowing you to harvest earlier in the summer, rather than waiting until fall. The goal is to replicate the springtime light cycle that exists outside at the time you are planting, after hardening off. This principle applies to both clones and seedlings to be placed outside. You are trying to replicate true daylight hours, not sunrise / sunset. The best way to achieve this is to add two hours to the time of your local official sunrise and sunset.
When cloning for sex, you take a single clone from an early veg plant like this, and then flower the clone in your flowering chamber to get an early determination of the veg plant’s sex.
Photo: Ed Borg
Hay bale garden.
Photos: K
Cannabis is a dioecious plant, meaning that the female and male flowers develop on separate plants. That said, monoecious plants—those that have both male and female flowers on one plant, also known as hermaphrodites—also commonly exist. It is often difficult to determine a marijuana plant’s sex in its first seven weeks of vegetative growth. Male plants can grow taller and more rapidly than females, but as a rule there is no way of differentiating between male and female in the very early stages. Under normal conditions, cannabis seeds produce an approximate ratio of 50% male and 50% female plants.
Grow huts such as this one are perfect for cloning or starting seeds, and are readily available and easy to put up and take down.
Determining a plant’s sex requires close visual inspection using a jeweler’s loupe and good lighting, or a loupe with a built-in light. You must understand where preflowers form and exactly what male and female preflowers look like. Typically, the first preflowers appear eight to ten weeks after seed germination with the formation of undifferentiated primordial flowers along the main stalk at the nodes (also known as “crotches” or “intersections,”) where the fan leaves, petiole, and branches stem from and meet at the nodes, behind the stipule (leaf spur). If you are lucky, upon first inspection you will find a preflower tucked in among these plant parts.
When the primordial flowers first appear, they are undifferentiated sexually. The tiny preflower is typically 2–10mm in length and is a determining indicator as to whether the plant will be found to be male or female. Males can sometimes be difficult to identify for a novice, but you must be vigilant and eliminate all males at the first opportunity (unless you are breeding).
Male preflowers are typically very small, ranging in size from 2–7mm. They develop in multiple forms. According to Mel Frank, one variation is flat, spade-shaped, and raised on a short stalk; another is pod-shaped and extremely tiny (2–3mm), either with or without a stalk; and a third variation is teardrop-shaped, stalkless, and easily confused with the female preflower (without its stigmas). Any plant expressing the third type of preflower should be kept for later reinspection.
Female primordial flowers appear as normal (albeit very small) female flowers / bracts / stigmas, the exception being that they form singularly, and never in multiples or as buds. Occasionally only the bract casing (protective seed pod) appears without the V-shaped fuzzy white stigmas present. Upon inspection, if you see a well-developed female flower with the stigmas (pollen-catching appendages) extended to form a V-shape at two or more nodes toward the top of the plant, this is the first indicator that the plant is female. Once you have experience examining, identifying, and interpreting preflowers you will see that if the preflower is raised or has a stalk, it is a male; female preflowers are without stalks.
If you have never identified preflowers you should wait another one or two weeks before discarding the suspected male plants, allowing time for a second inspection. If the first sexing is proved correct by the later preflower formation, you can then begin to eliminate males as and if you wish. If you are unsure of your determination, you can label all of the plants and wait until the flowering cycle begins to make absolutely sure, but you must eliminate the males as soon as possible to prevent seeded buds.
Your next option is to clone for sex (see the full explanation of this in the cloning chapter). This works very well for indoor and outdoor plants. Simply remove a branch / clone and place it in proper propagation conditions under a 12/12 photoperiod. Preflowers will form, along with roots, and indicate plant sex without subjecting the original donor plant to the undue stress of having light prematurely reduced. You must always check and recheck the plants throughout the flowering cycles. Females can sometimes become hermaphrodites and form random male flower clusters within the female flowers. The male flowers can pollinate the female flowers and will produce seeds.
Important: as stated before, if this is your first try at plant sexing, it is recommended that you label all plants either male or female and learn from any misidentification, rather than by mistakenly eliminating any females. Learn from trial and error. Be vigilant. Check and recheck.
Environmental Influences on Plant Sex
It has been scientifically proven that plant sex can be influenced during the early stages of vegetative growth. The sex of your seedlings is predisposed to gender chromosomes encoded in its DNA. While certainly not a golden rule (each cultivar reacts slightly differently), nor with a 100% effective success rate, the following explanations and steps are to aid you in producing the sex of plants you desire (male vs. female). Some seed companies use a simple technique with gibberellic acid sprays to produce feminized seeds. The sprayed female plants produce male flowers / pollen. That, in turn, is used to produce feminized seeds. However, factors such as the environment can also influence gender. Environmental stresses—i.e., erratic lighting schedules, excessive heat or cold, over- or under-fertilization, etc.—will produce a high percentage of males and hermaphrodites. It is important that you introduce these environmental changes at the three-pairs-of-leaves stage and continue for two to three weeks before returning to normal conditions. Other methods of producing pollen from a female plant are: 1) erratic lighting schedules, 2) excessive heat or cold, and 3) over- or under-fertilization, all of which will produce hermaphrodites that will produce pollen that will then produce feminized seeds.
In order to improve your chances of getting the desired result when germinating seeds, follow this table:
Factors For More Males or Females
*E.g., an increased level of nitrogen and lower level of potassium for the first two weeks increases the number of female plants.
Seed Germination with Landrace Hindu Kush
Step 1: Use your chosen germination method.
Step 2: Once seeds germinate, plant them in seed cups.
Step 3: Keep a close eye on temperature and humidity.
Step 4: Seedling emerges.
Step 5: Seedlings grow towards the light.
Step 6: Cotyledon and first true leaves are visible.
Step 7: More growth and more leaves.
Step 8: Two weeks later.
Step 9: Two-and-a-half weeks later.
Step 10: Entering the vegetative stage.
Young roots.
Photo: Samson Daniels
Temperature Guidelines
Keep medium at optimum temperature of 70–78°F
Keep air temperature at 75°F
Do not exceed 80°F for either the medium or the air temperature
Watering Guidelines
Do not over- or under-water
Do not dry out the growing medium
Never have standing water under cubes
Keep cubes moist, yet maintain good drainage
Beforehand, pH balance your medium: adjust rockwool cubes and soil to 5.8 to 6.8
Tips
Remember: young roots are very delicate
Keep records and label all seeds and seedlings
There is more to successful germination than getting a seed to sprout. Know the complete germination cycle for your cultivar. When accelerated growth occurs at 3–4 weeks, the vegetative stage of growth has begun.
If you want to know our other methods, for large scale cultivation / production, you will have to wait for the next book from Trichome Technologies which will cover major industrial-scale grows.