Create a sterile seed bed
- power harrow and compact
- Current practice (spray off weeds and worms after ca 6 weeks (weeds appear after ca 2 weeks))
- repeat as weather permits
- Better to plant native perennial rye grasses such as, Mt View and Jackaroo and Cocksfoot such as Megatas and Lazurly and clovers Stormwhite and Weekawhite
1kg hemp seed has 52,500 seeds (winnowed but size ungraded)
For fibre plant 40kg/ha for seed plant 20kg/ha
At 40kg per hectare = 40 * 52500 = 2.1 million plants ie 210 plants per sq metre
- Tractor 76HP
- spreader for fertiliser
- 2m wide powered harrow with compacting roller and seed drill
- Boom spray
- Sickle bar mower
- (Yeoman plough 5 to 7 tines)
- (offset discs draw bar pulled)
Hemp processing machines
- hammer mill and silo
- bagging and storage.
Geopolymer hempcrete printing machines
Planting end November Tasmania.
At this stage you will get probably 2 months of vegetative growth and
then the plants will go to seed. Ideally for fibre you plant European
varieties in late September. Once the plants are making heads the
fibre just starts to toughen and by the time seed is ripe you have
quite a lot of dead hemp, making harvesting and processing more
difficult. I would advise planting a separate smaller plot for seed,
planted at a lower density (40Kg per ha min for fibre/20Kg per ha for
seed). It’s critical to plant soon after the seed bed has been
prepared to get good seeding, planting at 40 Kg ha. This is a rate
recommended in the European literature after years of planting rates
of 65 – 80 Kg per ha. I am recommending this lower rate to everyone as
they’ve found that there are no greater yields planting at higher
density, however letting the hemp get ahead of weed emergence is
BASIC CATEGORIES OF CANNABIS AND THEIR FIELD ARCHITECTURE
Cannabis sativa is an annual wind-pollinated plant, normally dioecious and dimorphic, although sometimes monoecious (mostly in several modern European fiber cultivars). Figure 2 presents the basic morphology of the species. Some special hybrids, obtained by pollinating females of dioecious lines with pollen from monoecious plants, are predominantly female (so-called “all-female,” these generally also produce some hermaphrodites and occasional males). All-female lines are productive for some purposes (e.g. they are very uniform, and with very few males to take up space they can produce considerable grain), but the hybrid seed is expensive to produce. Staminate or “male” plants tend to be 10%–15% taller and are less robust than the pistillate or “female” (note the comparatively frail male in Fig. 3). So prolific is pollen production that an isolation distance of about 5 km is usually recommended for generating pure-bred foundation seed. A “perigonal bract” subtends each female flower, and grows to envelop the fruit. While small, secretory, resin-producing glands occur on the epidermis of most of the above-ground parts of the plant, the glands are very dense and productive on the perigonal bracts, which are accordingly of central interest in marijuana varieties. The root is a laterally branched taproot, generally 30–60 cm deep, up to 2.5 m in loose soils, very near the surface and more branched in wet soils. Extensive root systems are key to the ability of hemp crops to exploit deep supplies of nutrients and water. The stems are erect, furrowed, and usually branched, with a woody interior, and may be hollow in the internodes. Although the stem is often woody, the species is frequently referred to as a herb or forb. Plants vary enormously in height depending on genetic constitution and environment (Fig. 4), but are typically 1–5 m (heights of 12 m or more in cultivation have been claimed).
Fig. 2. Cannabis sativa. This superb composite plate by artist Elmer Smith, often reproduced at a very small scale and without explanation in marijuana books, is the best scientific illustration of the hemp plant ever prepared. 1. Flowering branch of male plant. 2. Flowering branch of female plant. 3. Seedling. 4. Leaflet. 5. Cluster of male flowers. 6. Female flower, enclosed by perigonal bract. 7. Mature fruit enclosed in perigonal bract. 8. Seed (achene), showing wide face. 9. Seed, showing narrow face. 10. Stalked secretory gland. 11. Top of sessile secretory gland. 12. Long section of cystolith hair (note calcium carbonate concretion at base). Reproduced with the permission of Harvard University, Cambridge, MA.
Fig. 3. Photograph of Cannabis sativa. Left, staminate (“male”) plant in flower; right, pistillate (“female”) plant in flower. Fig. 4. United States National Institute of Health, University of Mississippi marijuana plantation site, showing variation in plant size. A tall fiber-type of hemp plant is shown at left, and a short narcotic variety (identified as “Panama Gold”) at right.
There is great variation in Cannabis sativa, because of disruptive domestication for fiber, oilseed, and narcotic resin, and there are features that tend to distinguish these three cultigens (cultivated phases) from each other. Moreover, density of cultivation is used to accentuate certain architectural features. Figure 5 illustrates the divergent appearances of the basic agronomic categories of Cannabis in typical field configurations.
Fig. 5. Typical architecture of categories of cultivated Cannabis sativa. Top left: narcotic plants are generally low, highly branched, and grown well-spaced. Top right: plants grown for oilseed were traditionally well-spaced, and the plants developed medium height and strong branching. Bottom left: fiber cultivars are grown at high density, and are unbranched and very tall. Bottom center: “dual purpose” plants are grown at moderate density, tend to be slightly branched and of medium to tall height. Bottom right: some recent oilseed cultivars are grown at moderate density and are short and relatively unbranched. Degree of branching and height are determined both by the density of the plants and their genetic background.
Highly selected forms of the fiber cultigen possess features maximizing fiber production. Since the nodes tend to disrupt the length of the fiber bundles, thereby limiting quality, tall, relatively unbranched plants with long internodes have been selected. Another strategy has been to select stems that are hollow at the internodes, with limited wood, since this maximizes production of fiber in relation to supporting woody tissues. Similarly, limited seed productivity concentrates the plant’s energy into production of fiber, and fiber cultivars often have low genetic propensity for seed output. Selecting monoecious strains overcomes the problem of differential maturation times and quality of male (staminate) and female (pistillate) plants (males mature 1–3 weeks earlier). Male plants in general are taller, albeit slimmer, less robust, and less productive. Except for the troublesome characteristic of dying after anthesis, male traits are favored for fiber production, in contrast to the situation for drug strains noted below. In former, labor-intensive times, the male plants were harvested earlier than the females, to produce superior fiber. The limited branching of fiber cultivars is often compensated for by possession of large leaves with wide leaflets, which obviously increase the photosynthetic ability of the plants. Since fiber plants have not generally been selected for narcotic purposes, the level of intoxicating constituents is usually limited.
An absence of such fiber-strain traits as tallness, limited branching, long internodes, and very hollow stems, is characteristic of narcotic strains. Drug forms have historically been grown in areas south of the north-temperate zone, often close to the equator, and are photoperiodically adapted to a long season. When grown in north-temperate climates maturation is much-delayed until late fall, or the plants succumb to cold weather before they are able to produce seeds. Unlike fiber strains that have been selected to grow well at extremely high densities, drug strains tend to be less persistent when grown in high concentration (de Meijer 1994). Drug strains can be very similar in appearance to fiber strains. However, a characteristic type of narcotic plant was selected in southern Asia, particularly in India and neighboring countries. This is dioecious, short (about a meter in height), highly branched, with large leaves (i.e. wide leaflets), and it is slow to mature. The appearance is rather like a short, conical Christmas tree.
Until recent times, the cultivation of hemp primarily as an oilseed was largely unknown, except in Russia. Today, it is difficult to reconstruct the type of plant that was grown there as an oilseed, because such cultivation has essentially been abandoned. Oilseed hemp cultivars in the modern sense were not available until very recently, but some land races certainly were grown specifically for seeds in Russia. Dewey (1914) gave the following information: “The short oil-seed hemp with slender stems, about 30 inches high, bearing compact clusters of seeds and maturing in 60 to 90 days, is of little value for fiber production, but the experimental plants, grown from seed imported from Russia, indicate that it may be valuable as an oil-seed crop to be harvested and threshed in the same manner as oil-seed flax.” Most hemp oilseed in Europe is currently obtained from so-called “dual usage” plants (employed for harvest of both stem fiber and seeds, from the same plants). Of the European dual-usage cultivars, ‘Uniko B’ and ‘Fasamo’ are particularly suited to being grown as oilseeds. Very recently, cultivars have been bred specifically for oilseed production. These include ‘Finola,’ formerly known as ‘Fin-314’ (Fig. 6) and ‘Anka’ (Fig. 7), which are relatively short, little-branched, mature early in north-temperate regions, and are ideal for high-density planting and harvest with conventional equipment. Dewey (1914) noted that a Turkish narcotic type of land race called “Smyrna” was commonly used in the early 20th century in the US to produce birdseed, because (like most narcotic types of Cannabis) it is densely branched, producing many flowers, hence seeds. While oilseed land races in northern Russia would have been short, early-maturing plants in view of the short growing season, in more southern areas oilseed landraces likely had moderate height, and were spaced more widely to allow abundant branching and seed production to develop. Until Canada replaced China in 1998 as a source of imported seeds for the US, most seeds used for various purposes in the US were sterilized and imported from China. Indeed, China remains the largest producer of hempseed. We have grown Chinese hemp land races, and these were short, branched, adapted to a very long growing season (i.e. they come into flower very slowly in response to photoperiodic induction of short days in the fall), and altogether they were rather reminiscent of Dewey’s description of Smyrna. Although similar in appearance to narcotic strains of C. sativa, the Chinese land races we grew were in fact low in intoxicating constituents, and it may well be that what Dewey thought was a narcotic strain was not. Although some forms of C. sativa have quite large seeds, until recently oilseed forms appear to have been mainly selected for a heavy yield of seeds, usually recognizable by abundant branching. Such forms are typically grown at lower densities than hemp grown only for fiber, as this promotes branching, although it should be understood that the genetic propensity for branching has been selected. Percentage or quality of oil in the seeds does not appear to have been important in the past, although selection for these traits is now being conducted. Most significantly, modern selection is occurring with regard to mechanized harvesting, particularly the ability to grow in high density as single-headed stalks with very short branches bearing considerable seed.
Fig. 6. ‘Finola,’ the first cultivar of Cannabis sativa bred exclusively for grain. (Courtesy of the breeder, J.C. Callaway, Univ. Kuopio, Finland.) Fig. 7. ‘Anka,’ the first registered North American bred cultivar of Cannabis sativa. This variety is best suited for grain production. (Courtesy of the breeder, P. Dragla, and of the Industrial Hemp Seed Development Company, Chatham,