As a cannabis grower, predicting the height of your plants is an important factor when setting up your garden and choosing the best practices that work for you.
Cannabis plants can grow as small as 1 ½ feet tall and up to 34 feet tall.
As you can see, the range of plant sizes is wide. Growers have some degree of control over how tall their cannabis plants can grow. Some growers may prefer smaller plants to fit in cramped spaces, while others may seek larger plants to maximize their outdoor yield.
Carefully planning your garden, from the types of seeds you buy to the cultivation methods you use, can help you grow a marijuana plant that is the perfect size for your growing environment and specific needs.
Indoor vs Outdoor Gardens
One of the most important factors to consider when estimating the size of your marijuana plants is their growing environment. Do you plan to grow indoors or outdoors?
With indoor cannabis cultivation, you have the ability to control nearly every parameter of its environment including temperature, humidity, and light. In addition, using special cannabis training techniques can help manage a plant’s height while increasing yields.
Common plant training techniques include:
Low-stress training (LST): LST involves bending and tying down branches and stems to create an even canopy and better light distribution.
A screen of green (SCROG): Using a screen, cannabis plants can be trained to grow horizontally instead of vertically so that you can create an even canopy. This technique is usually reserved for tall-growing Sativa strains.
When growing cannabis outdoors, growers have some control over the height of the plant, but mainly rely on the natural elements (sunlight, temperature, humidity). Generally, plants can grow considerably taller than indoor plants, if they get enough direct sunlight and root space.
For outdoor-grown cannabis, container size and root space are critical. If the root space is too small, plant growth can be stunted.
Sativa vs. Indica vs Autoflowering Strains
Genetics also plays a critical role in the growth pattern of a cannabis plant. While you can control many environmental factors that can reduce or extend the height of your plant, its height will ultimately depend on its genetic composition.
Generally, Indica strains grow short and squat, while Sativa strains grow tall and thin under the same growing conditions.
Of course, there are exceptions to the rule. It is important to research your strain to determine its expected height and grow it accordingly.
Autoflowering strains are a variety of cannabis that differ from traditional photoperiod plants that require the light cycle to switch from its vegetative to its flowering stage. Autoflowering strains automatically switch to their flowering stage after a specific amount of time, not a change in the light cycle.
On average, auto-flowering strains can grow between 1.5 and 3.5 feet tall, perfect for small spaces.
Vegetative vs Flowering Stages
Cannabis plants have a unique growth cycle that can be divided into their vegetative and flowering stages. During the vegetative stage, the plant is focused on foliage growth. During its flowering stage, it is focused on bud growth.
Plants that are allowed to spend a longer time in their vegetative stage tend to grow taller than ones that spend a short time in this stage. The length of time that your plant spends in its flowering stage depends on its genetics and growing environment.
In indoor gardens, growing cannabis plants too tall can make them reach too close to your grow lights, which can cause the harsh light to burn your plants and buds.
Many growers choose to switch from their vegetative stage to the flowering stage when the plant has reached about half the size of its desired height. During the flowering stage, plants can nearly double in size, on average.