hemp cultivation overview
While hemp could be considered as a weed, it would be a mistake to assume that it requires no fertiliser as is often suggested by people who have read the famous book "the Emperor Wears No Clothes" by Jack Herer and consider themselves to be instantly converted into hemp farmers as a result of this.
The cost of seed (around £5.00 per kg) and the density needed (around 35kg per acre) makes hemp one of the more costly crops to cultivate (barley seed is around 33p per kg) and so getting things right from the beginning is extremely important.
Hemp requires fairly precise fertilization. A fertilization scheme that is too high or too low will lead to lower yields. The total Npk requirement per hectare is 110 kg of Nitrogen (N), 80 kg of phosphate (P) and 140 kg of potassium (K).
2: soil type and seedbed preparation
It has often been said that hemp will grow anywhere and this is true. However, for a hemp crop to attain commercially viable yields, soil preparation is critical.
Hemp seed is delicate in form and carries little energy in itself. Therefore, it needs to grow fast and uninhibited.
The best way to prepare the seedbed is treating it like cultivating sugar beets. The structure should absolutely not be too coarse, but also not too fine, which would cause the soil to drift rapidly. The seedbed should also be level and compressed.
The soil type and weather conditions determine the way in which the soil should be prepared for seeding but generally the land should be ploughed during the winter (chisel ploughed if compacted), power-harrowed prior to drilling (late April - early May) and rolled straight after drilling.
There are 26 different soil classifications in the UK and so many locations will have a unique preparation process to be followed. Local knowledge is very useful in this regard.
Even though hemp grows well at low temperatures, HempFlax (our recommended seed supplier) recommends not seeding the crop too early. Preferably, the soil should have a temperature between 10° and 12° Celsius. A week later won’t matter much and is still better than a week too early under poor conditions. Seeding early does not automatically lead to a higher stem yield.
The first two weeks after seeding are crucial for the cultivation. Hemp should emerge fast, between 10 and 14 days. Then, the crop can easily conquer emerging weeds and the growth is off to a good start.