To the uninitiated, 'stretching' may evoke images of a jogger warming up before a run, but in the world of cannabis cultivation, it takes on a distinctly different meaning. The "stretching phase" of cannabis growth is a crucial period during which plants rapidly increase in size, laying the foundation for fruitful yields, but if not managed correctly, too much stretch can be problematic. Understanding the intricacies of this phase, from its timing to the changes it brings, is vital for every cannabis grower.
Unravelling The Enigma Of Stretching
The stretching phase in cannabis cultivation is when the plant experiences a significant growth spurt. But it's not just about getting taller. The term 'stretching' is derived from the plant's dramatic increase in height, making it appear as though the plant is stretching toward the sky like an ambitious yogi reaching for an advanced pose. Along with this vertical growth, the plant also develops new leaf nodes, a foundational aspect in the future formation of cannabis buds.
The Stretching Phase And The Plant's Lifecycle
Before we go any further, it’s important to note one thing: A lack of sufficient light can cause stretching, as the plant reaches up to outcompete surrounding flora to get enough light to survive. This can be a problem, especially for young plants in the seedling stage. In this article, however, we will discuss the intentional flowering stretch. This phase occurs as a necessary part of the lifecycle of cannabis plants.
The stretching phase commences as the cannabis plant transitions from its vegetative growth stage to the flowering stage. In photoperiod strains, a shift in the light cycle instigates this transition. It will typically last for the first couple of weeks of cannabis flowering but can sometimes last three or four weeks, depending on genetics and environmental factors.
In indoor cultivation, the light schedule typically changes from a vegetative growth schedule of 18 hours of light and 6 hours of dark to an equal 12/12 hours of light/dark for the flowering period. In an outdoor setting, Mother Nature takes the reins as the long summer days start to shorten, signalling the plant to enter the flowering phase and, thus, the stretching period.
Plant hormones play a key role in the flowering stretch of cannabis. The levels of these hormones are regulated by the amount of daily light exposure when cultivating feminised cannabis seeds. As the plant perceives a decrease in daylight hours, this triggers hormonal shifts that promote increased cell division and growth, thereby initiating the flowering stretch in cannabis.
Duration Of The Stretch: A Time Of Transformation
The stretching phase generally lasts one to three weeks, but it's not a universal timeframe. The duration is highly dictated by the plant's genetics and the environmental conditions it's exposed to. Certain strains are genetically predisposed to have a more prolonged stretching phase, while others may complete this phase relatively quickly. Understanding your plant's needs and traits can help you better anticipate and plan for this stage.
Indica vs Sativa: A Tale Of Two Stretches
Like many aspects of plant growth, genetics greatly determines not only the length, but the extremes of the flowering stage. Cannabis plant varieties, mainly Indica and Sativa, showcase distinct differences in their stretching phase. These two major cannabis varieties each have unique growth characteristics and patterns. Indica strains, often compared to the 'wallflowers' of the cannabis world, are usually shorter and bushier, with a stretching phase that is less pronounced and tends to be of a shorter duration. Although it varies from strain to strain, the Indica stretch will be around two weeks and see up to a 50-100% increase in size. Take a look below at the two varieties. Although both are in flowering, you'll see the difference between the bushier Indica on the left, and the lankier Sativa on the right:
On the flip side, Sativa strains are like the ones dancing shamelessly in the middle of the dance floor. They tend to be taller and thinner and have a longer, more pronounced stretching phase. These long-legged ladies of the cannabis world can sometimes surprise unprepared growers with their vertical ambition. The stretching phase with Sativas can last three or four weeks, longer in some cases, and sees plants double in size, or in some cases, more. So, if you're a 'low ceiling' grower, remember that Sativas may not be your best bet!
Of course, most strains nowadays are the product of crossbreeding, and as such may have both Indica and Sativa in their lineages. This leads to differences in the traits and varies from strain to strain, but an Indica-dominant variety will often tend towards a shorter and bushier structure, with Sativa-dominant varieties tending towards the opposite.
Five Stretching Strategies: Navigating The Growth Spurt
1. Know Your Grow
This one applies more to indoor growers, but if you’re concerned about having adequate headroom in your grow space to accommodate the stretch, opt for cannabis strains with a lower plant height. Indicas and indica-dominant varieties tend to finish shorter than their sativa cousins and can take the agony out of the stretching phase. For those growing in outdoor gardens or indoor growing situations where height doesn’t present a problem, the stretching phase is your chance to let your plants run amok and boost yield potential. Too much of a stretch can be detrimental to yields, but manage it just right, and you could increase your harvest.
Remember, when choosing your genetics, you can check the approximate plant height on the product page on our website. Always be sure to do this so you know what to prepare for.
2. Space Your Plants Out
During the stretching phase, one fundamental consideration is ensuring your plants have enough space. Since the plants are growing rapidly, they'll need ample room to flourish. Cramped spaces can hinder growth, impede airflow, inhibit light, and even encourage the spread of pests or diseases.
3. Manage The Glow
Light management is another critical aspect during stretching. Positioning your grow lights too close, or too much light intensity, can cause light burn while placing them too far away can lead to excessive stretching as your plants strain towards the light source. In other words, don't force your plant into a game of "how low can you go" or "reach for the sky."
The light spectrum is also important here. If you’re looking to avoid the stretch getting out of hand, the type of light and spectrum can be your friend.
LED Lights: These lights don’t tend to have too profound an influence on stretching, but the more red in the spectrum, the more likely the increase in stretch. It’s not guaranteed, but at least anecdotal evidence indicates this. On the other hand, the blue light spectrum has been said to help limit stretching potential by enhancing compactness and encouraging bushier rather than taller plants. If you’re lucky enough to be rocking LEDs, you may be able to adjust the colour spectrum to either favour or hinder stretching. Follow the manufacturer’s instructions on LED lighting for correct distancing, usually somewhere between 12-18 inches away, but this could be greater depending on the power of your LEDs.
HPS (High-Pressure-Sodium) Lights: If you’re looking to maximise stretching in your plants, it’s thought that HPS lights encourage this due to their yellow and red spectrum. Use your hand to determine good light distancing – if your hand is close enough to the light to feel a burn, so will your plants. Adjust the light height so your hand won’t feel excessive heat from the bulb. This is a safe distance for your lights.
Note: This test doesn't apply to LED lights.
4. Stay On Top Of Airflow And Temperature
You should have fans in your grow room to create good airflow and minimize the risk of mold. But those fans serve another purpose – strengthening stems. A light breeze across the plants can develop stronger stems while keeping heat and humidity – two factors contributing to plant stretch – from building up under the canopy.
5. Train For Gain
Stress training techniques like Low-Stress Training (LST) and High-Stress Training (HST) can be employed to manage plant height and ensure even light distribution. These techniques, such as topping and fimming, won’t slow or stop the stretch but will help to manage it. Using the SCRoG method can also give you a degree of stretch management – by tucking tips under the screen once about 5cm of the tip has grown through, you can tame the upward trajectory of your plants to a degree.
Vigilant monitoring of your plants during this phase can help spot early signs of any issues. Regular check-ins ensure your plants are stretching healthily and can prevent potential problems from escalating. Consider yourself the personal trainer of your cannabis plants, always watching, always ready to motivate and correct.
In the grand scheme of cannabis cultivation, the stretching phase is akin to adolescence - a critical period of rapid growth that lays the groundwork for future productivity. As the cannabis plant stretches its limbs and prepares to bear flowers, understanding this phase's intricacies becomes vital for any grower. So, as we tend to our stretching cannabis plants, we're nurturing them and growing alongside them, expanding our knowledge and expertise. Remember, a well-stretched cannabis plant is akin to a well-prepared athlete – both are primed to perform at their best.
