Cannabis goes through several stages of growth – germination, seedling, vegetative, pre-flowering and flowering. Each stage of growth is controlled by seed genetic qualities, or the hours of daylight and darkness plants receive. Each stage of growth has specific needs including light, air, water, nutrients and growing medium.
Depending upon seed genetics and environment a cannabis plant can take from 3 to 9 months to grow from seed to harvest. Indoor and greenhouse growers can plant seeds with the proper genetic qualities and control the environment of their grow rooms to harvest, after a few weeks as well as all year round. Outdoor growers can plant seeds tha grow best in their climate. Your level of knowledge and expertise about cannabis cultivation is directly propornal to the quality and volume of the gardens you harvest.
Cannabis cultivated indoors, in a greenhouse or outdoors has the same basic needs for growth – light, air, water, nutrients, and a growing medium. Each type of cannabis – regular, feminized, photoperiod and auto-flowering require slightly different cultivation techniques. Growers who supply these basic needs at the proper time so that cannabis plants suffer no stress harvest more high quality cannabis flowers.
The difference between regular, feminized, photoperiod and auto-flower cannabis
Cannabis sex is the first setp to distinguish different types of cannabis. In nature cannabis grows as individual male and female plants. Today, feminized cannabis seeds that grow only female plants are available too.
Regular cannabis grows individual (separate) plants with either male or female flowers. Male plants are grown from seed. They are removed from the garden so that cannabinoid-potent female plants remain.
Feminized cannabis is treated and altered so that only female flowers grow. Feminized cannabis is very popular because all the seeds are feminine and grow cannabinoid-potent female plants.
Photoperiod cannabis will remain in the vegetative growth stage when they receive 16+ hours of light per day. Long nights and short days trigger flowering. Photoperiod cannabis flowers outdoors in the autumn when nights grow long and days short. Indoor growers typically give flowering plants 12-hours of complete darkness and 12 hours of light to flower.
Photoperiod cannabis can be regular or feminized.
Auto-flowering cannabis flowers about three weeks after seed germination regardless of day and night length. Auto-flower cannabis flowers during the longest days of summer when growing contitions are the best. Productive indoor growers give autos 20-hour-long days and 4 hours of darkness.
Auto-flowering cannabis can be regular or feminized.
Hermaphrodites (acutally intersex) cannabis contains both male and female flowers on the same plant. Hermaphrodite plants may be of interest to cannabis breeders. I stay away from intersex cannabis plants because the male flowers pollinate all the female plants that are exposed. These genetically unstable plants produce seed-laden flowers. I also advise against planting these seeds.
The two charts below show seed to harvest time for each stage of growth for photoperiod and auto-flower cannabis.
The Effects of Stress on Cannabis Growth
This backyard garden full of healthy Stinky Pinky and StinkBud plants from Oregon´s SoFresh Farms are grown from seed and have suffered virually no stress – the result is a heavy harvest of quality cannabis flowers.
Cannabis needs energy to grow. Each stage of growth – seed, seedling, vegetative, pre-flowering and flowering – must have enough energy to achieve a cannabis plants’ genetic potential.
Seeds store energy in the form of food. Seeds must be fully developed with a hard outer shell and adequate stored food (energy) within to grow into a strong healthy seedling. Seedlings must grow in a perfect environment so that roots and foliage develop to full potential. Vegetative plants need a perfect environment too. They must grow long enough to manufacture more branches, leaves and flower budding sites. Big healthy vegetative plants grow more and heavier flowers. A six-month-old female yields 3-4 times as much as a four-month-old if planted the same day.
Environmental stress includes wind, temperature extremes, inconsistent and dim light, drought and excessive water, compact and poor-draining soil, disease and pest attacks, and nutrient deficiencies. Any and all stress slows plant development and growth. Stress diminishes plant energy and reduces harvests.
Athletes provide an excellent example. A 15-year-old athlete has not developed to their fullest potential. Bones, muscles and mind need further growth. At 25 years of age the same athlete is fully developed psychically and mentally. They have grown up in a healthy nurturing environment. The athlete has eaten a healthy diet, trained for a specific sport and is able to achieve peak performance. Cannabis is the same.
Weak growth during any stage of development will result in a diminished harvest. The first few weeks of growth require extra attention to seed and seedling needs.
Cannabis Seed Germination
Germinating seeds is easy, but requires close attention to air temperature, substrate moisture content and temperature.
During the first growth stage the seed germinates, establishes a root system, grows a stem and a few leaves. After 3-7 days regular and feminized plants enter the seedling growth stage that lasts about a month. Auto-flowering seedlings start flowering after about three weeks of (seedling) growth.
At germination moisture, heat and air activate hormones within the durable outer coating of the seed. Hormones signal more cells to form and increase in size. The embryo expands, nourished by a supply of stored food (energy) within the seed. Soon, the seed’s outer coating splits, a white rootlet grows downward probing for nutrients and a sprout with two opposing rounded seed leaves (cotyledons) pushes upwards in search of light.
Seed Germination
- Air temperature range:
a. Extremes: 70-90ºF (21-32ºC),
b. Indoors: 72-79ºF (22-26ºC),
c. Ideal: 78ºF (25ºC) - Humidity 100%
Cannabis Seedling Growth
These flats of seedlings show the first set of rounded cotyledons and the first set of true leaves.
The single root, called a taproot, from the seed grows down and branches out, similar to the way the stem branches out aboveground. Tiny hair-like roots and rootlets develop to draw in water and nutrients. Roots also serve to anchor a plant in the growing medium. Proper seedling growth ensures adequate energy for growth in the form of stored food.
Regular seedlings should receive 16 hours of light to grow more female plants and maintain strong healthy growth.
This little auto-flower seedling got a fair start on life. At 21 days from germination, it already has three sets of leaves and is developing a fourth. The first tiny female flowers started to show a few days later.
Auto-flowering plants require special care during the seedling growth stage. They must grow very, very fast during the first 3-4 weeks of life. Auto-flowering plants must grow as much foliage as possible so that they will be able to produce more flowers on big plants. The root system must grow rapidly without impediments now and throughout life. Abundant branch and foliage growth translate into more and heavier flowers at harvest.
Seedling Growth
- Air temperature range:
a. Maximum: 55-85ºF (13-30ºC),
b. Indoors: 72-77ºF (22-25ºC),
c. Ideal: 75ºF (24ºC) - Substrate temperature range:
a. 65-70ºF (18-21ºC),
b. Ideal 68ºF (20ºC) - Humidity Range:
a. Maximum: 60-70%,
b. Ideal: 60%
Cannabis Vegetative Growth
Strong, healthy unabated rapid growth is the key to a healthy, heavy harvest.
Vegetative growth is maintained in regular (male and female) cannabis by giving plants 16-24 hours of light every day/night. A point of diminishing returns is reached at 18-20 hours and the extra hours of light provide much less benefit.
Auto-flowering cannabis produce best when they receive 20 hours of light daily in all growth stages – seedling, vegetative and flowering.
Strong healthy roots are vibrant white with little fuzzy hair-like “feeder roots” found mostly near the tips.
Roots take on specialized functions as cannabis plants mature. The center and old mature portions contain a water transport system and may also store food. The tips of the roots produce elongating cells that continue to push farther and farther into the soil in search of more water and nutrients. The single-celled root hairs are the parts of the root that actually absorb water and nutrients. Without water, frail root hairs dry up and die. They are very delicate and are easily be damaged by light, air and clumsy hands if moved or exposed. Extreme care must be exercised during transplanting.
The stem grows through elongation too, producing new growth buds along the stem. The central or terminal bud carries growth upward, side or lateral buds turn into branches or leaves. The stem serves to transport water and nutrients from the delicate root hairs to the growing buds, leaves and flowers. Sugars and starches manufactured in the leaves are distributed through the plant via the stem. This fluid flow takes place near the surface of the stem. If the stem is bound too tightly by string or other tie downs, it will cut the flow of life-giving fluids, thereby strangling and killing the plant. The stem also supports the plant with stiff cellulose, located within the inner walls. Outdoors, rain and wind push a plant around, causing much stiff cellulose production to keep the plant supported upright. Indoors and in greenhouses, with no natural wind or rain present, stiff cellulose production is minimal, so plants develop weak stems and may need to be staked up, especially during flowering.
This beautiful cannabis plant was started early, now on 12 July 2019, it will double in size by the time the first female flowers form
Leaves manufacture food (carbohydrates) for the plant. Chlorophyll, the substance that gives plants their green color, converts carbon dioxide (CO2) from the air, water and light energy into into carbohydrates and oxygen. This process is called photosynthesis. It requires water drawn up from the roots, through the stem, into the leaves where it encounters carbon dioxide. Tiny breathing pores located on the underside of the leaf, called stomata, funnel CO2 into contact with the water. In order for photosynthesis to occur, the leaf’s interior tissue must be kept moist. The stomata open and close to regulate the flow of moisture, preventing dehydration. Cannabis leaves are also protected from drying out by an outer skin and resin. The stomata additionally permit the outflow of water vapor and waste oxygen. The stomata are very important to the plant’s wellbeing and must be kept clean to promote vigorous growth. You can liken dirty, clogged stomata to you running a race with a sack over your head. Dumb idea!
Strong vegetative growth is essential so that cannabis plants will have enough foliage and a large enough root system to support many dense flowers. If plants suffer stress during the vegetative growth stage, roots do not develop properly and cannot supply enough nutrients to foliage and flowers. In nature, cannabis spends most of its life in vegetative growth. Cannabis has enough time to develop properly and store energy so that big flowers will grow.
Vegetative Growth
- Air temperature range:
a. Maximum: 55-85ºF (13-30ºC),
b. Indoors: 65-85ºF (24-30ºC) – Ideal 75ºF (24ºC) - Soil temperature range 65-75ºF (18-24ºC)
- Reservoir temperature range: *65-75ºF (18-24ºC), Ideal: 68ºF (20ºC), *59-75ºF (15-24ºC) DWC
- Humidity range: 40-70%, Ideal: 60%
Nighttime temperatures can drop to 55ºF (13ºC) with little noticable change in growth in outdoor plants. Indoor plants grow best when nighttime temperatures decrease less than 10ºF (5ºC).
Cannabis Pre-flowering and Sex
Little male cannabis flower pods full of pollen are developing on the stem at the base of a leaf and a new growing shoot. A low-power hand-held microscope makes identifying male flowers easier.
Female stigmas grow from seed bracts and appear as a pair of white fuzzy hairs. The first female pre-flowers appear after about 8 weeks of vegetative growth under normal conditions.
Regular and feminized pre-flowers on cannabis grown from seed appear about the fourth week of vegetative growth, eight weeks from seed sprouting. Pre-flowers on regular and feminized cannabis generally appear between the fourth and sixth node from the bottom of the plant. Cannabis plants are normally either all male or all females. Cannabis is predominantly dioecious, imperfect flowers – satminate “male” and pistillate “female” flowers occur on separate plants. Each sex has its own distinct flowers. Pre-flowers will distinguish a plant as male or female. Growers remove and destroy the males (or use them for breeding stock) because they have negligible levels of cannabinoids (THC, CBD, CBG, etc.) and produce little foliage. Female plants are cultivated for their high cannabinoid content, including CBD, THC and CBG, and abundant foliage. Industrial hemp is cultivated for its long resilient fibers or for industrial seeds rather than foliage or cannabinoid-rich flowers.
Branches on auto-flowering cannabis plants are often fairly close together on the stem.
Auto-flowering cannabis starts flowering after about 21-25 days of chronological growth. Pre-flowers set and soon flowers develop. After 60-70 days the flowers are ready for harvest. The entire auto-flower plant life cycle, sprouted seed to harvest, is complete 70-90 days regardless of daylength.
Cannabis Flowering
Early flowering male pollen pods are developing quickly. This male plant has abundant foliage.
This Amnesia Haze female is in the early stages of flowering.
A few male flowers will open ahead of the rest and start shedding pollen. If growing regular photoperiod plants or unstable varieties, keep an eye out for males that open early.
This beautiful crop of flowering females from Original Breeders League is 3-4 weeks from harvest.
Male Stink Bud in full bloom.
This mature Swazi Landrace top is a mass of flower buds with classic narrow leaves found on many sativa varieties.
Mid-to-late-season regular and feminized cannabis varieties starts to flower when daylength drops below 14 hours. Depending upon your latitude, flowering starts about mid-summer as nights become progressively longer.
Short-season Kush and Afghani varieties typically start flowering the first week of August and are ready to harvest in mid-to-late September. Check with seed sellers for specific flowering times in your latitude.
The length of the night signals cannabis that their annual life cycle is coming to an end. At flowering plant functions change. Leafy growth slows and flowers start to form. Flowering is triggered in most commercial varieties of cannabis by 12 hours of darkness and 12 hours of light every 24 hours. Outdoors, nights become longer gradually, and flowering is initiated during a period of 3-4 weeks. In controlled indoor and greenhouse environments, days and nights are changed abruptly to 12 hours. Flowers appear in 10-14 days. Plants that originated in tropical regions that have less variation between day and night often start flowering under more light and less darkness.
Flowers form during the last stage of growth. Left un-pollinated, female flowers continue to grow larger and produce more cannabinoids. When fertilized with male pollen, female flowers develop seeds. Typically, unpollinated female plants develop dense heavy flowers with high levels of cannabinoids.
Flower
- Air temperature range:
a. Maximum: 55-85ºF (13-30ºC),
b. Indoors: 65-85ºF (24-30ºC),
c. Ideal: 75ºF (24ºC) - Soil temperature range: 65-75ºF (18-24ºC)
- Reservoir temperature range: *65-75ºF (18-24ºC), Ideal: 68ºF (20ºC),
*59-75ºF (15-24ºC) DWC - Humidity range: 40-60%, Ideal: 60%
Nighttime temperatures can drop to 55ºF (13ºC) with little noticable change in growth in outdoor plants. Indoor plants grow best when nighttime temperatures decrease less than 10ºF (5ºC).
Sinsemilla Cannabis
Unpollinated, female cannabis flowers are often called “sinsemilla” Spanish for without seeds. Sinsemilla cannabis flowers continue to swell and produce more resin while waiting for male pollen to successfully complete their life cycle. After weeks of heavy flower and cannabinoid-laden resin production, CBD, THC and CBG production peak out in the unfertilized sinsemilla flowers.
CBD and THC production develop simultaneously in lockstep. The CBD to THC ratio is predetermined by genetics. The plants must be grown in a stress-free environment to achieve the full genetic potential.
This frosted Zin auto-flower was harvested the day the photo was snapped. This cluster of flowers is an example of THC-rich auto-flower varieties.
Female flowers on auto-flowering cannabis start to form about a week after pre-flowers are visible. During this time, autos continue to grow at a rapid rate when properly maintained in a stress-free environment. Flower formation is slow at first and gains momentum during the following weeks. Flowers continue to form and swell until peak resin production is reached. The short life span makes it imperative for growth to be fast and strong so that the plant can develop completely and store enough energy to produce heavy dense flowers.
