How to Increase Yields Through Better Space Allocation
By James Eaves
Cannabis yields can be substantially increased by allocating space more efficiently between vegetation and flowering rooms. Consider a simple case where the same room is used for both vegetation and flowering to grow a single variety with a four-week vegetation and an eight-week flowering period.
By James Eaves
The room can hold 500 m2 of flowering plants, and each m2 produces 1,000 grams of flower. For each week, Table 1 indicates if the room is being used for vegetation (V) or flowering (F). The table shows that each 12-week harvest produces 500,000 grams of cannabis, or an average of 5,952 grams per day (500,000 grams/84 days).
Because vegging plants take up less space, the room is under-utilized for four weeks each harvest. The 500 m2 can be fully utilized by separating the room into three smaller rooms – one small vegetation room and two larger flowering rooms. The vegetation room should be large enough to produce enough plants to exactly fill a flowering room. So, the optimal size of the room depends on the maximum expected size of a flowering plant compared to that of a vegging plant. If a flowering plant takes up three times the space of a vegging plant, then space is fully utilized with a single 71.4 m2 vegetation room and two 214.2 m2 flowering rooms. Table 2 illustrates the production cycles for this scenario.
Each harvest is 51 per cent smaller than the single room case, but each occurs 67 per cent faster. The result is that the average yield per day (after the first harvest) increases to 7,653 grams from 5,952 grams (214,300 grams/28 days), or a 28.6 per cent increase.
The benefit of dividing the space depends on what impacts the relative space used by vegging and flowering plants. If, for instance, the genetics or the growing strategy caused the relative size of flowering plants to be 1.5 rather than three times larger than vegging plants, then the optimal size of the vegetation and growing rooms would be 125 m2 and 187.5 m2, respectively. In this case, the resulting average daily yield would be 6,696 grams per day (187,500 grams/28 days), or 12.5 per cent higher than the single room case.
One benefit of using a single room is that the grower will spend less time and labour moving plants from a vegetation room to a flowering room, which can take several days depending on the size of the room and the amount of automation involved. Staying with the previous example, imagine it took three days to breakdown the 125 m2 vegetation room and put a 187.5 m2 flowering room online. In this case, to appropriately evaluate average daily yields, we should add an additional three days to each harvest cycle (187,500/(28 + 3)). This combined with the relatively smaller flowering plants reduces the improvement from dividing the 50 0m2 room from 28.5 per cent to just 1.6 per cent.
Government regulations can also have a large impact. For example, employee movements in and out of rooms must be electronically logged, and the resulting additional time caused by that process adds up. If employees spend, in aggregate, an average of three additional minutes a day moving themselves and objects in and out of a room, that adds up to 18 lost hours a year. Moreover, each room is required to have at least two aisles wide enough to allow for a wheelchair to turn around. Each time a new room is built, a higher proportion of space is lost to aisles.
When plants are spaced too closely they compete for light, causing growing spurts that can lower the plant value. The further apart vegging plants are spaced, the lower the benefits of having separate vegetation and flowering rooms. Nonetheless, what constitutes too close depends on factors like genetics, lighting and training, all of which can be manipulated by the grower.
By developing a deeper understanding of growing decisions, space allocation and profit per m2, the grower can optimize space allocation and make better choices like what strains to grow. Companies that thrive will be those obsessed with operational efficiency, to which space management is central.
Note: This article summarizes an article researched by James Eaves and Mitch Galton from Fluence Bioengineering.
James Eaves is a professor of management and entrepreneurial finance at Université Laval. He received his Ph.D in Agricultural Economics from the University of California, Davis. His research focuses on profitability for growing in control environments.