Growth stages from seedlings to harvest.

Seedlings

When a seed sprouts, the white taproot emerges. Soon afterward, the cotyledon, a.k.a seed or seedling leaf, appears. The seed leaves spread out as the stem elongates. Within a few days, the first true leaves appear, and the little plant is officially a seedling. This growth stage lasts for three to six weeks. During seedling growth, a root system grows rapidly while green aboveground growth is slow. Water and heat are critical at this point of development. The new, fragile root system is very small and requires a small but consistent supply of water and warmth. Too much water will drown roots, often leading to root rot and damping-off. Lack of water will cause the infant root system to dry up.

As the seedlings mature, some will grow faster, stronger, and appear healthy in general. A little heat now will help nurture small seedlings to a strong start. Other seeds will sprout slowly and be weak and leggy. Cull sickly, weak plants, and focus attention on the remaining strong survivors. Seedlings should be big enough to thin out by the third to fifth week of growth.

Seedlings need at least 16 hours of light daily. They require less intense light now and grow well under fluorescent tubes for the first two to three weeks. Compact fluorescent and HID light can also be used. The compact fluorescent light should be 12-18 inches and the HID 3-4 feet above seedlings for best growth.

The seedling stage is over when rapid foliage growth starts. Rapid growth above ground is the beginning of the vegetative growth stage. Plants need more room to grow; transplanting into a larger container hastens development.

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Vegetative Growth

The seedling growth stage lasts for about two to three weeks after seeds have germinated. Once a strong root system is established and foliage growth increases rapidly, seedlings enter the vegetative growth stage. When chlorophyll production is full speed ahead, a vegetative plant will produce as much green, leafy foliage as it is genetically possible to manufacture as long as light, CO2, nutrients, and water are not limited. Properly maintained, cannabis will grow from one-half to two inches per day. A plant stunted now could take weeks to resume normal growth. A strong, unrestricted root system is essential to supply much needed water and nutrients. Unrestricted vegetative growth is the key to a healthy harvest.

A plant’s nutrient and water intake changes during vegetative growth. Transpiration is carried on at a more rapid rate, requiring more water. High levels of nitrogen are needed; potassium, phosphorus, calcium, magnesium, sulfur, and trace elements are used at much faster rates. The larger a plant gets and the bigger the root system, the faster the soil will dry out. The key to a strong vegetative growth and a heavy harvest is supplying roots and plants with the perfect environment.

Vegetative growth is maintained with 16 or more hours of light. Cannabis will continue vegetative growth a year or longer (theoretically forever), as long as an 18-hour photoperiod is maintained.

Cannabis is photoperiodic-reactive; flowering can be controlled with the light and dark cycle. This allows indoor horticulturists to control vegetative and flowering growth. Once a plant’s sex is determined, it can become a mother, clone, or breeding male, and can be harvested or even rejuvenated.

Note: Plants show early male or female “pre-flowers” about the fourth week of vegetative growth. Cloning, transplanting, pruning, and bending are all initiated when plants are in the vegetative growth stage.

Flowering

Cannabis must flower and produce seeds and successfully complete its annual life cycle. Cannabis is a dioecious plant, being either male (pollen producing) or female (ovule producing). However, hermaphrodite (bisexual) plants with both male and female flowers can also occur. In nature, cannabis flowers in the fall, after the long hot days of summer. Plants are normally either male or female. Cannabis produces male or female pre-flowers after four weeks of vegetative growth.

Growth patterns and chemistry change during flowering: stems elongate, leaves grow progressively fewer blades; cannabinoid production slows at first the accelerates; and flower formation is raped at first and then slows. Nutrient needs change as growth stages change. Plants focus on flower production rather than vegetative growth. Green chlorophyll production, requiring much nitrogen slows. Phosphorus and potassium uptake increase to promote floral formation. Shortly before the flowering stage, growers change to a “super bloom” fertilizer formula with less nitrogen and more phosphorus and potassium.

Induce flowering in greenhouses, outdoors, and indoors by giving plants more hours of total darkness and fewer hours of light. Give cannabis 12 hours of uninterrupted darkness and 12 hours of light to induce visible signs of flowering in two weeks or less. This program is effective in all but the latest pure sativa strains. Growers with a vegetative room illuminated 18-24 hours a day and a flowering room with 12-hour days and 12-hour nights, create environments that mimic the photoperiod in summer and fall. With this simple combination, growers crank out a crop of outstanding buds every six to ten weeks all year long.

Inducing flowering in cannabis grown from seed with a 12/12 day/night photoperiod will cause plants to show sex, male or female. Once the sex of the plant is guaranteed, males are almost always harvested before they shed pollen, and females are coaxed into higher yields. Once the photoperiod is set, disrupting it will cause plants to suffer stress. If they suffer enough stress, hermaphrodite tendencies increase.

Water intake of flowering plants is usually somewhat less than in the vegetative stage. Adequate water during flowering is important for plants to carry on internal chemistry and resin production. Withholding water to “stress” plants well actually stunt growth and diminish yield.

Removing large fan leaves to allow more intense light to reach small buds or to stress plants is crazy! Large leaves are necessary to keep plants healthy. Indoors and in greenhouses where the hours of darkness are controlled, cannabis flowers for six to ten weeks or longer. This is a very short time. Hacking off branch tips to initiate more budding sites diffuses floral hormones and retards growth. Remove only leaves that are 50 percent or more damaged by diseases, pests, and cultural practices.

Upon pollination, one of the many, tiny grains of pollen from the male (staminate) flower pod, lands on a pistil of the female (pistillate) flower. Female flower tops are a mass of calyxes with each calyx harboring an ovule and a protruding set of pistils. Actual fertilization takes place when the grain of male pollen slides down the pistil and unites with the female ovule deep within the female calyx. Once fertilization takes place, pistils turn brown and a seed forms within the seed bract.

Seeds are the result of this sexual propagation and contain genetic characteristics of both parents. In nature there is a 50/50 chance for a seed to produce a male or female plant. Once fertilized with male pollen, female plants put the bulk of their energy into producing strong, viable seeds. When flowers are full of ripe, mature seeds, the female will die, having successfully completed her life cycle. The male completes his life cycle and dies after producing and dispersing all of his pollen into the wind, in search of receptive female pistils.

Harvest

Growth stops at harvest and the THC content cannot increase. It will stay the same or decrease after harvest. Proper handling is the key to retaining THC potency. Prolonged periods of light, temperatures above 80 degrees Fahrenheit, friction from fondling hands, and damp, humid conditions should be avoided because they all degrade the THC.

The THC chemical is produced in leaves, flowers, and stalked glandular trichomes, lovingly referred to as “resin glands” or simply “trichomes”. Stems and roots may smell like they should be smoked, but contain few mind bending cannabinoids, if any, and the resin is not very psychoactive. Male plants contain much less THC and are harvested before they pollenate females. Female plants are harvested when trichomes show peak ripeness. Leaves are harvested first.

Step-by-Step

  • Step One: Stop fertilization 7-10 days prior to harvest.
  • Step Two: If sprays have been applied during the last week (not recommended), mist plants heavily to wash off residue and then gently shake off excess water. DO NOT wash buds if bud mold is a threat.
  • Step Three: Some growers report that giving plants 24 hours of total darkness before harvest makes the buds a little more resinous.
  • Step Four: Harvest in the morning when THC content is at its peak. Harvest either entire plant or a single branch at a time.
  • Step Five: Drying- some growers hang their entire plant upside down for convenience although this is a bit slower. You may also hang individual branches.

Cannabis growth stages. The growth stages from seedlings to harvest. Growth stages of cannabis. Growth stages.