by Ed Rosenthal
These clones are being repotted into larger containers so their growth isn’t stunted.
These plants were grown outdoors from seed early in the season so they could be sexed just a little before the longer days kept them in the vegetative stage. They were shielded from pests and cool overnight temperatures using a clear plastic tarp that was removed each morning.
STARTING SEEDS
Gardeners using standard seeds can expect 1/4 to 1/3 of the seeds they plant to reach maturity. Fresh seeds are usually viable, with high germination rates. Seeds more than two or three years old may not germinate as well. Older seeds may have a higher percentage of weak plants, and slower germinating seeds are more prone to attack from molds and bacteria.
Intact, dark brown or grey seeds are most likely to germinate. Whitish, light tan, or cracked seeds are usually not viable. Most guide books suggest that growers select the largest seeds in a batch for planting, but the size of the seed is genetically as well as environmentally determined and does not necessarily relate to its germination potential.
Marijuana seeds germinate best in a warm, room temperature range of 70-80° F (21-26° C), temperature. At lower temperatures, germination proceeds slowly, and seeds are subject to attack by fungi and bacteria.
There are two methods of germinating marijuana seeds.
The first method is to place the seeds between the folds of a wet paper towel or cloth until a shoot breaks the shell, and then place them in the growing medium.
Moisten the paper towel or cloth with water until it is almost saturated. Place the marijuana seeds on the towel and fold it over. Put the folded towel or cloth on a bowl or plate and cover it with plastic wrap. Check the seeds once or twice a day for signs of germination. When it is apparent that the taproot is emerging, place the seed in the prepared growing media at a depth of about .025 inch (0.5 cm). Keep it moist.
To keep the environment disease free, treat the water with a 0.5% solution of hydrogen peroxide. Drugstore hydrogen peroxide is 3%, so mix one part hydrogen peroxide for every five parts water to create a 0.5% solution. Dilute compost tea also protects germinating seeds and seedlings because it contains living organisms that fight pathogens and aid root growth.
PLANTING IN PLACE
Alternatively, seeds can be germinated directly in the ground or planting medium, or in small cups or containers using soil or planting mix, in peat pellets, rockwool cubes or other germination mediums.
Pasteurized or sterile mediums, such as vermiculite or rockwool, and most indoor planting mixes are excellent for seed starting. You can keep the water pathogen free by using a 0.5% solution of hydrogen peroxide or you can protect the roots using compost tea or root-protecting organisms such as mycorrhizae, or both.
Paper or styrofoam cups are convenient germinating containers. Lightweight cups are ideal containers for plants that are germinated at one location and then moved to another location. Containers made from straw, rice or paper can be placed directly in the ground or into a larger container without disturbing the roots.
“"You know all the rules by now And the fire from the ice Will you come with me? Won't you come with me? What I want to know is—Will you come with me?"
Lyrics: Robert Hunter & Jerry Garcia "Uncle John's Band"
Use mature uncracked seeds that are dark tan and brown.
Germinating in rockwool blocks also avoids having to remove rooted plants from the medium. Rockwool starter sheets fit in standard 10” x 20” (25-50 cm) horticultural trays and are divided into either 50 or 72 cubes. Seedlings should be attached to larger growing blocks or sheets about a week after germination.
Four-inch diameter cubes can hold the plants for two to four weeks without inhibiting growth.
Whether seeds are germinating indoors or outside, the planting medium must be kept moist during the entire period. Seeds dry out quickly during this process, and dry medium results in dead seeds. If you can, place a dome over the trays or cover them outdoors with clear plastic film. The sun can dry the surface of the soil very quickly, so it is often easier to germinate in the shade outdoors and then transplant. This is more of a problem in the late spring when the light becomes more intense, and high temperatures promote evaporation.
1. The stem is emerging. 2. The seeds have germinated. Their taproots have just emerged. They should be placed in the planting medium before the roots get longer. 3. The stem has just pierced the soil and reached the light. 4. The cotyledons are opening, pushing the seed cover aside. 5. The cotyledons have opened and the first true leaves have appeared. 6. The leaves are open and the seedling is ready to begin fast growth. 7. These seedlings were started in a seedbed. I prefer individual containers so the roots aren’t disturbed at transplanting. 8. Each seedling has been labeled and will carry its ID until harvest. These seedlings are a bit stretched but will strengthen their stems if given more light and perhaps cooler temperature.
Seeds usually germinate in three to ten days. Germination time is affected by the seed’s age and health and the media temperature. First the root emerges. Shortly after the stem emerges from the seed and shoots above the soil line. It orients itself perpendicular to gravity. Folded on top of the stem, a pair of embryonic leaves called cotyledons unfold and begin to supply the plant with the sugars it needs for growth and respiration. Cotyledons are rounded single blades and look nothing like mature marijuana leaves.
As soon as plants germinate, they require light. If the light is not intense enough, the stem stretches, reaching for it. You can start seeds under either standard T-8 or T-5 fluorescents or under CFLs. Place them about 6" (15 cm) above the canopy. Space High Output (HO) T-5s and high watt CFLs about a foot (30 cm) above the plants. You can also start the plants under Metal Hallide (MH) or High Pressure Sodium (HPS) high-intensity discharge lamps or place the seedlings under them soon after germination. HPS 600w and 1000w lamps should be placed about 1.5'-3' (45-90 cm) above the canopy if they are air cooled, and about 3'-4' (90-120 cm) if not. You can germinate seedlings under HPS or MH lamps, or place them under the lamps shortly after. They can also be moved outside.
Outdoors, the sooner after germination you plant the seedlings, the faster they adapt to the environment. Place them outdoors at the same time of the season as tomatoes and corn are planted. However, depending on your latitude, the dark period may be too long early in the spring, forcing some varieties to flower prematurely. For more on this, see the sections on varieties and flowering.
These seedlings’ elongated stems are the result of too dim or too little light, or too high a temperature.
SEEDLING VULNERABILITIES
Seedlings are at their most vulnerable stage immediately after they germinate. Stem rot, a fungal infection, attacks when the medium is kept too moist or when roots are deprived of oxygen. This can happen when the soil or planting mix is too fine, so it holds too much water but not enough oxygen. This condition is exacerbated by over watering; fine soils don’t need to be watered as often as media with more porosity. As with germinating, compost tea or a 0.5% hydrogen peroxide solution prevent both fungal and bacterial infections in seedlings.
Dry mediums damage both roots and canopy leaves. The time between first signs of wilt and irreparable damage from dehydration is very short for young plants, which don’t have much of an infrastructure reserve. Dry conditions cause the leaves to wilt as they use the available water in the cells and lose turgidity. If the conditions are caught in time, the plants recover as soon as they are irrigated. This situation is time sensitive and should be corrected immediately.
Mice, pet birds, dogs and cats have all been noted to have a fondness for marijuana sprouts and young plants. These animal friends should be protected from temptation by installing a barrier. Another problem with pets, especially those that live both indoors and out, is that they may be carrying insect pests into the garden.
Seedlings given too little light in too warm an environment stretch their stems. The long, slender shoots subsequent
ly have problems staying upright and become top-heavy. The long, thin stem indicates that these plants need more light. To correct stretch that has already occurred, support the seedlings using toothpicks, chopsticks, skewers or thin bamboo stakes.
Too little sun can be a problem for young plants, but so can a withering sun. Seedlings have more problems with this when they are set outside in late spring or during the summer. You can help plants adjust to intense sun by starting to transplant them first in a shaded area or under screens. They can be moved to full sun gradually over five days or so. You can also protect the plants by spraying anti-transpirants on them before they are placed outdoors. These substances place a barrier between the leaf and the sun and slow transpiration so the plants don’t wilt. New leaves that grow in the sun will grow longer mesophyte/palisade cells that absorb more light before it reaches the chlorophyll. They position the chlorophyll so it receives less light, protecting it from the more intense environment. New leaves will not have the sensitivity to UV light that destroys indoor-grown leaves placed outdoors. Seedlings started outdoors easily adjust to the bright sun.
Reservoir system: these containers are large enough to support fast growth of one stem plants to full maturity.
To transplant, first put a small amount of soil or planting medium in container. Place the transplant on top of the medium, then pour soil around the roots and stem. When the container is filled, gently compress the mix so that it holds the plant firmly. Stretched stems can be buried a little to keep the plant stable.
Fill the container with enough planting mix so the transplant sits about 0.5" (12 mm) below its original position. Place transplant. Add planting mix to 0.5" (12 mm) above transplant, pat soil down. Add more if necessary.
If it is inconvenient to plant at the moment, seedlings and cuttings can be placed in the refrigerator, not the freezer, to stop their growth. You can store them in the vegetable crisper of the refrigerator for a week or more. Keep them in a moistened plastic bag with the temperature above 40° F (4° C) to prevent cell damage. This treatment does not adversely affect the plant’s later growth and, in fact, is an easy way to harden up plants that are placed outdoors later.
PLANTING SEEDLINGS AND CLONES
Seedlings and clones are ready to transplant when they have developed a network of roots and several sets of leaves and are able to cope with and take advantage of the environment.
Plants grow large quickly. This transplant will double in size in about 10 days.
If the plants are being transplanted into soil or planting mix, place the entire rootball in the medium just slightly deeper than the rootball’s height so it is covered with soil. The roots will grow from the small ball in all directions, downwards and outwards.
Roots concentrate their growth in permeable areas of the growing medium that contain water, nutrients and oxygen. Whether nutrients are held in the soil or provided using a nutrient-water solution, roots absorb them as simple salts. Microorganisms in the planting media digest complex organic nutrients and then release them in a water-soluble form available to the plants. As the plant draws up the nutrients from the water, the planting medium gradually releases more that dissolve in the water. Enriched planting mediums and soils contain high levels of organic amendments or compost that support seedling growth and will not need supplementation for at least a week.
To save space, plants can be transplanted to progressively larger containers:
•8 oz. (0.25 l) containers support root growth for 7-10 days after germination.
•16 oz. (0.5 l) containers support root growth for 10-20 days, but a 32 ounce (10.9 kg) container will support faster growth.
•1 gallon (3.75 l) containers support plants for 15-30 days.
By eliminating males from the equation, breeding becomes much easier. However, when females are crossed for breeding over several generations, breeders are inadvertently selecting for hermaphroditism. The reason is that females that produce the most pollen have a tendency towards hermaphroditism. When this is compounded over several generations, the plants are more likely to carry the hermaphrodism trait.
As a practical matter, breeders have found more success in crossing plants than in self-crosses. The self-crosses result in more hermaphrodites. They also say that gardeners should expect about 5% of the plants from feminized seed to be hermaphrodites or males. This is the result of multigenerational crossing. First generation feminized seeds have fewer hermaphrodites. Even so, gardeners still have to inspect and sex the plants.
Some mediums support plants longer. A few are made with time-release formulas that last the entire growing season.
The length of time that a planting mix or soil can support growth depends on several factors. The most important ones are: size of the space that the roots have to grow, nutrient levels of the mix, and growth rate of the plant.
Generally speaking, when growing in soil or planting mix, the canopy of the plant will grow to equal the size of the roots or be at most one third larger. Soils rich with organic fertilizers that break down gradually and soils with time-release fertilizer may need little or no additional fertilizer.
A plant with a 10' (3 m) diameter canopy will have a root system 6-10' (2-3 m) in diameter. The same ratio applies to a plant with a canopy 2 feet in diameter; its root system will range from 1.3 – 2'.
In contrast, hydroponic plants can grow considerably larger than the size of the root zone because easy access to water and nutrients encourages roots to grow much more densely. As long as the roots have access to water and air they will colonize the growing medium very densely.
The canopies of hydroponically grown plants cover an area from the diameter of the container to three times as wide depending on how well you supply the plant with its essentials. If two plants are growing under identical conditions, except for the container size, the one in the larger container will yield more. Contrary to urban myths, there is no harm done in growing a plant in a container larger than is required. However, growing plants in containers that are too small slows growth and stunts the plant.
Starting the seeds in one-gallon containers or transplanting to that size gives the young plant’s roots enough space to spread out while it is being sexed. After sexing, the plant can be placed in an appropriate-sized container.
Plants probably grow a bit faster without being transplanted from container to container. However, the light and space saving more than compensates for the lost growth. By graduating plants from smaller to larger containers, light is being used most economically because it is focused on plants rather than the floor.
LIGHTING, TEMPERATURE, CO2 AND NUTRIENTS FOR SEEDLINGS AND CLONES
After cuttings have rooted, the clones begin to grow new stem and leaves, starting at the apical meristem, the very top of the growth tip. After seeds germinate, they develop a taproot and the first true leaves emerge. In both clones and young plants, the new growth indicates that they are now ready to develop under full light indoors. Once placed in the garden, the new growth adjusts to the light intensity.
During marijuana’s early growth, the plant needs little special care. The plant adjusts to its environment and grows at the fastest pace limiting factors allow. Most seedlings and clones survive the perils of early growth and, within a matter of weeks, develop into vigorous young plants.
SEXING THE YOUNG PLANTS
Sexing, the process of identifying the gender of your plants, is discussed in more detail in Flowering. But since there are few things more important to careful gardeners than being sure their crop is protected from unwanted pollination. Sexing the plants as early as possible is a good idea, even at the seedling stage.
1. Sometimes a flower grows on young plants at nodes below the top of the canopy. This seedling has a stigma indicating a female flower. 2. This is a hermaphrodite. It has both male and female flowers. These plants should be removed from the garden. 3. These are unripe male flowers. As they open, the heads move from drooping to upright. When the pe
tals open the pollen is released into the wind. These plants should be removed from the garden as soon as they appear.
Be sure to force your plants to flower before they get too tall.
Clones and plants grown using feminized seeds are almost all female, but they still have to be sexed. Plants grown from standard seed are either male or female, in a roughly 50-50 ratio. Unless you are planning to breed plants, males have no use in the garden and are detrimental to the crop if their flowers are allowed to open and pollinate the female flowers. Pollination not only creates seeded bud but lowers the effective potency and usable weight. By eliminating males, no resources or effort are spent caring for plants that won’t yield a quality crop of sinsemilla—a term that comes from the Spanish phrase sin semilla literally “without seed.”
Rather than wait until late in the season to determine sex, there are methods you can use to sort the plants much sooner. Male plants are likely to be taller and more vigorous than females early in life, so gardeners are often disappointed when their favorite plant turns out to be male; however, plant morphology is a very difficult way to figure out the sex.
Two good ways to determine sex are:
•Look at the nodes of the young plant where the leaf petioles and the stem are joined. Sometimes a small, single male or female flower grows at this point. The plant is the same sex as this single flower. Some varieties indicate more than others, so while this method can be helpful, it cannot be used to determine every plant’s sex.
•Another way to determine sex is to induce early flowering. However, forcing the whole plant to flower requires 10 days as it switches to flowering cycle and 10 days to switch back to vegetative growth. Use cuttings instead: take a cutting of each young plant that you wish to sex and mark each plant and the cutting that was taken from it. Place cuttings in a planting mix or a cup with water under a flowering light regime of 12 hours on, 12 hours off. Cuttings will begin to flower and indicate sex within 10 days. Giving them more darkness—16 hours of darkness and eight hours of light per day—speeds flowering by a few days. They will indicate faster if you keep the cuttings in darkness for three days before placing them under a reduced light cycle. The cuttings and the plants from which they came have the same sex.