Cannabis plant stretching is basically the growing vertically of cannabis plants during the early flowering stages, which is seen in a lot of sativa and sativa dominant hybrid plants. This is something that usually is seen during your third or the fourth week, and some may even grow a bit longer.
This is something a lot of cultivars try to avoid all the time, since this can definitely cause issues with growing in certain media, but also makes the plants spindly and tall, reduces production, and they will then outgrow the area, and their buds will start to be airy in terms of growth, so it’ll spoil all of the plants that are there, and also will not create a good, even canopy, and you won’t be able to get the most efficient growth possible.
It's a nightmare when this happens, and you’ll then have to adjust your entire space for flowering to accommodate all of this, and it may cause a harvest, but it’s usually worthless. How do you fix this though? How do you keep this reasonable, especially during those first few weeks, so that they don’t do that.
First, consider genetics.
You want to choose ones that are good for your space to grow. Indica plants will not stretch as much, with the exception of the OG Kush, which is a stretchy cultivar, since this is something that has specific genetics to this.
Choose ones with a shorter veg period
This may seem obvious, but if you want to make sure that your plants don’t stretch, you’ll want to choose one that has a veg period that’s a little bit longer. Those that have an 18/6 schedule, and then moved to a 12/12, it will start to flower. You want to go for shorter vegetative periods, since this offers more room int eh ten to go upwards, so that you don’t have to worry about the plant stretching as much.
Think about Temperature
Usually, most growers will use HPS lamps when flowering, since they are a part of the warm light levels of colors, which means that they’re more red, and they mimic autumnal light colors in order to help with flowering.
However, this does also induce the action of stretching in many cannabis cultivars. You should try to continue to use metal halide kinds of lamps to help with vegetative growth over the next couple weeks of flowering. You should try to go for blue light spectrums, to help with better internode spaces, and also to reduce stretching while also keeping the plants at logical height levels. Usually, after a few weeks of the 12/12 types of lighting, you want to then change the MH to HPS in order to continue the correct flowering. You can also use LED lamps of a variable spectrum to save you a bit of headache as well.
Look at temperatures
Finally, you want to make sure that you are not giving them too cold of a temperature. You want to try to make sure that the growing temperature isn’t too much between daytime and nighttime. This is because it will cause the plant to create gibberellin, which means that it will stretch a lot more.
Usually, research says that the stretching takes place mostly in the first couple hours of the morning, so if you reduce the temperature a little bit for a few hours during daybreak, and also reduce it just a little bit at night, it can help with this. It can also be fixed with cold dump to help keep things cold and stop the stretch.
