Early Planted Hemp
Most all of the varieties of industrial hemp that have been grown in North Carolina so far have been varieties that are daylength sensitive. This means that when daylight decreases below 12 hours, the hemp will initiate flowering and cease vegetative growth. How short the day needs to be to initiate flowering varies from one variety to another. This was very evident when we first started comparing seed and fiber varieties from Europe and Canada. The Canadian varieties tending to start flowering almost as soon as day length started to decline after June 21st. This limited the amount of vegetative growth available for those varieties to produce high seed yields. We suspect that those varieties will need to be planted early to maximize vegetative growth to support seed production.
But what happens if we plant too early? Will short days trigger flowering prematurely, limiting yield potential in seed or CBD varieties? We were somewhat lucky in the first two years that seed and clones were generally not available for planting too early. This year we are planting two of the major CBD varieties used in North Carolina in a planting date test. The varieties are BaOx and Cherrywine. Below are pictures of these two varieties transplanted on May 1. The pictures were taken on June 6, 2019. You can see that many of the Cherrywine plants almost immediately went into flowering where the BaOx plants show the desired vegetative growth we would want at this stage of the game. It will take time to determine how early we can or possibly want to plant for various varieties. Some growers are not interested in planting early because they do not want to deal with larger plants at harvest. We may also find that changing the length of light in the greenhouse may alter when these varieties tend to start flowering in the field due to daylength.
It is interesting that some of the Cherrywine plants that went into flowering appear to be putting out vegetative suckers as shown below.