Hemp, also known as industrial hemp, is a remarkable and versatile plant with a rich history dating back thousands of years. It is a variety of the Cannabis sativa plant species that is primarily cultivated for industrial and commercial purposes. In this blog, we will delve into the many facets of hemp, from its cultivation and characteristics to its numerous applications and the sustainability benefits it offers.
Cannabis Sativa L. a.k.a HEMP.
Cannabis sativa L. is an herbaceous plant belonging to the Cannabaceae family. This plant species has many vernacular names and is known by many people as marijuana and hemp. Despite being native to Central Asia, this plant’s capacity of adaption to different climates lead to its spread all over the world.
In 1753, Carl von Linné mentioned the word Cannabis for the first time. This word comes from the Latin canna that means “reed” and bis that means “twice”, which means literally “reed with two sexes”. At present, there are many local or vernacular names and various synonyms to name Cannabis. It is also known as hashish, marijuana, weed, Acapulco gold, ace, bat, bhang, log, hemp, Indian hemp, Colombian, doobie, dope (Cannabis), ganja, hydro, Jamaican, jive (sticks), joint, Maui wowie, Mexican, Panama gold, Panama red, pot, firecracker, ragweed, reefer, sativa, sinsemilla of California, spliff, Thai stick, etc. Those names and designations stay different depending on the region, country and culture.
Biologically, hemp belongs to a family and genus of plants with wide chemotypic diversity. The genus Cannabis (hemp and marijuana) is part of the Cannabaceae family of plants, which includes a total of 170 species. It is commonly accepted and recommended that Cannabis sativa is a single species, with four subspecies, namely indica, ruderalis, sativa and afghanica. Interestingly, a primary ingredient of beer, Humulus (hops), is also from the Cannabaceae family, making hops and cannabis genetic cousins.
Hemp is distinguished from its close relative, marijuana, by its low content of THC (tetrahydrocannabinol), the psychoactive compound responsible for the euphoric "high" associated with marijuana use. In most countries, hemp must contain less than 0.3% THC to be legally cultivated. This key difference ensures that hemp does not produce the intoxicating effects of marijuana, making it suitable for industrial purposes without the potential for misuse.
The Botany of the Hemp Plant.
Plant Structure: Hemp plants are typically annual, erect, and dioecious, meaning they have separate male and female plants. The plant is known for its stout, aromatic, and upright stature, with a tall, slender stem that can reach heights of up to 20 feet or more.
Roots: The root is taproot with a length of up to 30 cm, but the lateral roots reach 20 to 100 cm. In addition, in peaty soils, the lateral roots are more strongly developed, and the main root grows to a depth of 10–20 cm. The growth rate of the root system is quite slow in the initial stages of vegetation, in contrast to the aerial part of the Cannabis plant, which grows intensively and rapidly.
Seeds: The seeds are smooth, greyish ovoid or spherical in shape, 2.5 to 3.5 mm long and 2.5 to 3 mm in diameter. Each seed contains two cotyledons rich in reserves (protein and oil), with an albumen considered particularly small compared to other plant species.
Stalk: The plant has a fluted stem that can reach 1 to 4 m with a diameter ranging between 1 and 3 cm. The variation of height and diameter depends on the sub-species, environment, soil and climatic conditions. The internal part of the stalk is known as the hurd and the external covering is known as the bast fibers.
Leaves: The Cannabis leaves are stipulate and opposite, with palmate (five to seven unequal), elongated and spiny segments with toothed margins. Towards the top of the axis, the leaves become alternate and are inserted on the stem in an opposite arrangement every 10–30 cm. These plants have cystolithic, tectorial and resin-secreting hairs; the latter have a voluminous base ending in a cluster of several cells, with each one secreting resin.
Flowers: The flowers of hemp are small, fine and greenish-yellow in color. They have glandular hairs that make them fragrant and sticky. At post-germination, young male and female plants cannot be distinguished. It is only during the last phase of growth, when flowers start appearing, that sex determination becomes possible. The female flowers have no petals and consist of two long white, yellow or pink stigmas. The female flowers appear in pairs in the axils of small leaves named bracts, these bracts contain numerous glandular trichomes where cannabinoids, mainly THC, accumulate. On the other hand, the male flowers have five sepals of approximately 5 mm length, with yellow, white or green color. The male plants develop small pollen sacs that serve to fertilize the female plants with hairy, resinous stigmas.
Agricultural and Growth Cycle
Hemp is a fast-growing crop, requiring approximately 100 to 120 days to mature. For industrial hemp grown for fiber or seed production, the maturity period may be shorter, typically around 60 to 90 days. These cultivars are often selected for their rapid growth and early maturation to optimize fiber quality or seed yield. In contrast, hemp plants cultivated for CBD (cannabidiol) production may have a slightly longer maturity period, often ranging from three to four months. These cultivars are typically bred for high cannabinoid content rather than rapid growth, so they may require additional time to develop and accumulate cannabinoids in the flowers.
Germination:
The journey of a cannabis plant begins with germination, the process where the seed awakens from dormancy and sprouts its first roots and embryonic leaves. During this stage, seeds require moisture, oxygen, and warmth to activate enzymes and trigger growth. Germination typically takes 1 to 7 days, depending on factors like seed quality and environmental conditions.
Seedling Stage:
As the seedling emerges from the soil, it enters the delicate seedling stage. This phase is characterized by the development of its initial root system and cotyledons (embryonic leaves) and requires a nurturing environment with gentle lighting, adequate humidity, and careful watering. Seedlings are vulnerable to overwatering and damping-off, a fungal disease that can hinder growth. Maintaining a balance of moisture and airflow is crucial during this stage, which usually lasts 1 to 3 weeks.
Vegetative Stage:
With a strong root system established, the cannabis plant enters the vegetative stage, a period of vigorous growth and foliage expansion. During this phase, the plant focuses on photosynthesis and nutrient uptake to support its development. Providing ample light (natural or artificial), proper ventilation, and a balanced nutrient regimen rich in nitrogen is essential for optimizing growth. The vegetative stage typically lasts 2 to 8 weeks, depending on genetics and desired plant size.
Pre-flowering Stage:
As the vegetative stage nears its end, cannabis plants undergo hormonal changes in preparation for flowering. This transitional phase, known as the pre-flowering stage, is marked by the emergence of pre-flowers and shifts in growth patterns. For photoperiod-dependent strains, pre-flowering is triggered by the onset of shorter daylight hours. Indoor growers can induce pre-flowering by adjusting the light cycle to a 12/12 schedule (12 hours of light, 12 hours of darkness).
Flowering Stage:
The flowering stage is perhaps the most anticipated phase of the cannabis growth cycle, as it is when the plant produces flowers (buds) rich in cannabinoids like THC and CBD. Female plants typically develop larger, resinous flowers compared to males. The duration of the flowering stage varies depending on the strain, ranging from 6 to 16 weeks. During flowering, cannabis plants require specific light conditions, proper airflow, and nutrient adjustments to support flower development and cannabinoid production.
Harvesting:
Harvesting is the culmination of the cannabis growth cycle, marking the moment when flowers have reached peak maturity and cannabinoid content. Timing is critical, as cannabinoids degrade over time and exposure to environmental factors. Growers may monitor trichome development using a magnifying tool to determine the optimal harvest time. Harvesting involves cutting down the plants, trimming the flowers, and drying them to preserve potency and prevent mold.
Drying and Curing:
After harvesting, the cannabis flowers undergo a drying and curing process to remove excess moisture and enhance flavor, aroma, and potency. Drying typically involves hanging the trimmed flowers upside down in a cool, dark, and well-ventilated space for 1 to 3 weeks. Once dried, the flowers are cured in airtight containers, allowing for gradual oxidation and flavor development over several weeks to months.
Sustainability Benefits of Hemp
One of the most significant advantages of hemp cultivation is its positive impact on the environment, making it a sustainable and eco-friendly crop choice. Here are some of the key cultivation benefits of hemp:
Low Environmental Impact:
Hemp cultivation requires minimal pesticides and herbicides compared to many other crops. Hemp is naturally resistant to pests and diseases, reducing the need for chemical inputs. Hemp has a relatively short growth cycle, typically maturing in 3 to 4 months, which allows for multiple harvests per year in suitable climates. This rapid growth rate minimizes the environmental footprint of cultivation.
Soil Regeneration:
Hemp has deep roots that penetrate the soil, helping to break up compacted soil and improve soil structure. This enhances soil aeration and water retention, reducing erosion and promoting overall soil health. Hemp is a phytoremediator, meaning it can absorb and detoxify contaminants from the soil. It has been used in phytoremediation projects to clean up soil contaminated with heavy metals, pesticides, and other pollutants.
Carbon Sequestration:
Hemp is a highly efficient carbon sequester. During its rapid growth phase, hemp plants absorb large amounts of carbon dioxide (CO2) from the atmosphere through photosynthesis, helping to mitigate climate change. The carbon stored in hemp biomass remains locked up even after harvesting, as hemp products continue to store carbon throughout their lifecycle. This makes hemp-based materials a carbon-negative or carbon-neutral alternative to traditional materials.
Biodiversity Conservation:
Hemp cultivation can support biodiversity by providing habitat and food sources for pollinators and beneficial insects. Hemp flowers are rich in pollen and nectar, attracting bees, butterflies, and other pollinators to agricultural landscapes. Hemp fields can serve as wildlife corridors and refuges for native plant species, enhancing ecological diversity and supporting healthy ecosystems.
Water Efficiency:
Hemp is a drought-tolerant crop that requires relatively little water compared to water-intensive crops like cotton. Hemp can thrive in arid and semi-arid regions with minimal irrigation, reducing pressure on freshwater resources. Hemp's deep root system can access water stored deep in the soil, making it more resilient to drought conditions and reducing the need for frequent watering.
Sustainable Agriculture Practices:
Hemp cultivation aligns with principles of regenerative agriculture and agroecology, promoting soil health, biodiversity, and ecosystem resilience. Hemp can be grown using organic farming methods without synthetic fertilizers or pesticides, further reducing environmental impacts and protecting ecosystem integrity.
Conclusion:
Hemp, with its rich history, sustainable cultivation practices, and diverse range of applications, stands out as a valuable and eco-friendly resource. Its potential to reduce environmental impact, enhance biodiversity, and provide sustainable alternatives in various industries makes it a plant of immense significance in our increasingly eco-conscious world. As we continue to explore and harness the capabilities of hemp, we can look forward to a future where sustainability and innovation go hand in hand, leading to a more environmentally responsible and resilient society.