Spacing is an important factor to consider before your season starts, as it will determine how many plants are needed of each variety. When you are growing hemp for CBD extraction or smokable flower, you want to grow the plants in rows much like tobacco or Christmas trees. This is much different than food and fiber industrial hemp which is grown like a grain with very close plant spacing and harvested mechanically.
The number of plants you order depends on both row spacing and inter-plant spacing. While you might be tempted to crowd as many plants into the field as possible, there are many considerations in determining how best to lay out your fields.
More space between the plants allows for maximum sun exposure and optimal wind flow. Sunlight and airflow help prevent disease. For optimal flower production, you want direct sunlight to hit as much of the plant as possible. Whether that means plants are more widely spaced to allow the entire mound to get sunlight or the plants are more closely spaced to force the plants to grow together and maximize the sunlight hitting the “blanket” of foliage, different varieties react differently to the range of possible layouts. The more distance you have between rows also allows for easier access to the plants to scout for weeds, pests, and problems and possibly even allows for ATV travel through the field,
One common practice is to allow 6 feet between rows and 4 feet between plants. This can allow row and plant access all season, balanced against plant to plant coverage of the field. Plants that can tolerate closer spacing include smaller varieties, faster finish(early-flowering) varieties, any late season planting and auto-flower types. Auto-flower is very new to commercial cannabis and even newer to industrial hemp. Make sure you ask your breeder for proper spacing on any auto-flower plants you purchase.
Remember that there is no single way to grow hemp that works in every situation. Testing out multiple layout designs with plants spaced further apart or more closely together can help you determine what works best for your cultivation systems. Consider the costs and benefits of a denser planting approach versus a more widely spaced approach in terms of weed-prevention, stability and resistance to wind, etc and make certain that you learn what works for you during the season.
Planting strategy also depends on when during the season you’re planting. Planting earlier in the season (May) allows fewer plants to grow larger and produce a potentially-larger yield. However early planting can put the plants at greater risk of adverse weather, pest and disease pressure. Planting later in the season(mid-June to Mid-July) with less time for vegetative growth means that the option to space the plants more closely together to get the same quantity of flower/biomass. Later planting also reduced risk of damage by early summer storms and reduced the overall crop time so that there are simply fewer opportunities for things to go wrong. The total yield is dependent on multiple factors, but the total yield per acre is still close to 2,000 lbs at 4 foot, 5 foot, 6 foot, and 4 by 6 foot.
For example: a field that was planted late in Colorado with 4 foot by 6 foot spacing. The plants were 5 weeks from harvest which filled in most of the row space, the plants peaked over 4 feet tall, and still left enough of an aisle to get an ATV down.
Closer Spacing (4-5ft)
Wider Spacing (5-6ft)
In our examples below, we use a perfect square to make it easier to understand the spacing and numbers. The acre plot example is 210ft by 210ft and all rows, plants, and mulch are to scale. The plants are laid out in a staggered format in the row to allow for maximum spread of every plant within its row. In the 4 feet infographic below, the center of one row to the center of another is 4ft and the center of one plant to another is 4 foot running down the row. The black rows are 2 feet across, which is common for what a raised bed mulch application would be. You could do a wider spread mulch at 5 and 6 feet row spacing but 2 feet is feasible, common, and cheaper. It also helps keep all these numbers easy to compare.
4 Foot Centers
- Good for fast finish or more compact varieties.
- Needed to maximize plant coverage if planting later in the season.
- This layout requires 2,704 plants which is 940 more plants and a 35% increase over the total plants on 5 feet centers.
- If the plants only get 3 feet wide the rows will still be accessible for scouting. However, if they reach 4 feet across the rows will be hard to navigate.
- The gold dirt aisles here are 2 foot wide.
5 Foot Centers
- This is one of the most common layouts.
- Good middle ground spacing for all varieties.
- This layout requires 1,764 plants which is 539 more plants and a 30% increase over the total plants on 6 feet centers.
- If the plants only get 4 feet wide the rows will still be accessible for scouting. However, if they reach 5 feet across the rows will be hard to navigate.
- The gold dirt aisles here are 3 foot wide.
6 Foot Centers
- Good for early planting, long season, and big varieties.
- This layout requires 1,225 total plants and almost 20 fewer rows than 4 foot spacing.
- Even if plants get 5 feet wide, there would still be room to access the plants in the aisles.
- The gold dirt aisles here are 4 foot – wide enough for an ATV for most of the season.
There you have it! If you need help with spacing your hemp plants or have any other questions, feel free to email our team: firstname.lastname@example.org