marijuana stretch

How to Control Stretching of Cannabis Plants?

Cannabis plants grow very well without a lot of maintenance during their vegetative stage. They put out pretty green leaves and prepare for the reproductive or flowering stage. There isn’t a lot to do during the growing stage, but the flowering stage definitely requires maintenance. From pests to diseases to stretching, there can be too many headaches to count. If you’re wondering how to control stretching of cannabis plants, this article will show you simple steps that will help you harvest great yields.

It’s not that the plants don’t stretch during the vegetative stage – they do – but it’s a lot more during the flowering stage. Stretching is nothing but a natural spurt of growth and is common for all cannabis plants. However, it works only if it’s moderate. Stretch too much and the plants start putting out buds that are airy and tiny.

On the other hand, when plants don’t stretch too much and grow sideways, you get healthy buds. This means that one must control stretching to prevent loss of yield, not to mention quality. Stretching occurs due to multiple reasons out of which genetics plays a role too. This is why some plants that remain small and compact will also produce offspring that grow in a similar fashion. Even lanky plants will only give you plants that grow tall and lanky.

So, is all hope lost, you ask? No… You can control stretching in various ways, so let’s take a look at them.

What happens when plants stretch?

Stretching is not that big a deal if you’re growing plants outdoors. Like other plants, cannabis plants also enjoy growing outdoors and you don’t have to worry much at all. Sometimes, the plants can stretch too much even when outdoors, but you can control them using training methods like LST. For the most part, stretching occurs when the plants are indoors.

As mentioned already, stretching invites problems and instead of growing plants that grow compact with thick buds, you’ll have a bunch of plants growing upwards. They become spindly and tall and stop focusing on the buds while diverting all their attention on stretching. When this happens, the quality of the buds take a hit and you’ll lose quite a bit of the yield too.

Why do cannabis plants stretch?

Stretching usually occurs indoors. If the plants aren’t genetically inclined to stretch, they could be stretching due to the lights. If the distance between the plants and the lights is too much, the plants start growing upwards in search of more light. In an effort to go close to the source of light, the plants experience a growth spurt that’s otherwise known as stretching.

Stretching also occurs when there are too many plants in a grow room. If the grow room is overcrowded, the plants have no other option other than competing with each other for light. Last but not the least, the type of light you use matters too. Whether they are HPS or LED lights, plants tend to stretch if there’s a lot of red and orange light. You can prevent this by supplementing blue light along with the red lights during flowering since it encourages thicker stems and branches.

You also need to provide a strong source of light. For instance, if you’re growing a couple of plants with only a 100W CFL as the light source, the plants will start stretching since the light isn’t powerful enough. It’s recommended that you provide at least 50 to 70W of light per square foot. Anything less than this will most definitely encourage the plants to stretch to their maximum.

How to prevent stretching of cannabis plants

1. Choose the right strain

Okay, this is the first thing you need to do because you can do everything and the plants will still stretch if it’s in their genes. And, this will happen even if you grow clones or plant seeds! Thus, find the right strains.

Most Indica strains tend to grow sideways rather than upwards. At the same time, many Sativa strains are notorious to grow upwards searching for light and are adept at producing airy buds. Of course, you’ll see that they are many exceptions. Not all Indica plants grow sideways and not all Sativas grow tall and lanky. However, since most of them do, choose Indica strains – Cream Cookies Auto, for example – that grow in a uniform fashion so that the light can be distributed evenly to all plants.

Cannabis plants grow very well without a lot of maintenance during their vegetative stage. They put out pretty green leaves and prepare for the reproductive or

How to Prevent and Fix Stretching in Cannabis Seedlings

Long, stretchy stems are one of the most common problems growers face during the seedling stage. Luckily, there are a few simple ways to prevent and fix stretching in cannabis seedlings.

Fix stretching in cannabis seedlings, and prevent it from happening again.


Just like baby humans, cannabis seedlings are super fragile and need plenty of tender loving care to flourish. Unfortunately, many growers run into the same issue during the early stages of their cannabis plants’ lives; their seedlings grow long, stretchy, and weak stems. This, in turn, can lead to a host of issues that put your crop at risk of delivering subpar results.

Below, you’ll learn how to prevent and fix stretching in cannabis seedlings.

Understanding the Seedling Phase

Seeds are like little genetic time-capsule bombs. What this means is that they only have one job, and only get one chance to pull it off. They are pre-programmed to survive. A seed self-contains absolutely everything a future plant needs to get started. Once activated with moisture and darkness, it will trigger germination, and once that gets going, there is no turning back.

A seedling does not need any food for the first good few days of its life. From its genetics, it is already backpacking all the essential nutrients needed to embrace the miracle of life. Seedlings have a little reserve to help establish themselves in their growing environment.

In optimal conditions, the seed shell, or husk, will crack open and a taproot will pop out, immediately digging further down in search of a water lifeline. Soon, you will see a sprout rise from the under the soil, spread out its first baby leaves (cotyledons), and then you will start noticing the first set of true leaves. Leaves have an equally important job as the taproot, but they are in search of another food source – light. Quite literally, a plant uses light to digest what it brings up from the soil.

Easy Start

The Perfect Light Conditions for Cannabis Seedlings

To grow healthy seedlings, it’s important to give them the right amount and type of light as soon as they break out of their shells. Cannabis seedlings like to receive around 16 hours of light per day at an intensity of 375 lumens and 4000 lux.

To meet these requirements, we recommend using one 12W CFL bulb per 1–2 seedlings. Keep the bulb 5–7.5cm (2–3in) from the top of the seedlings and monitor their growth carefully, making sure the plants don’t make contact with the bulbs.

Growing your seedlings under lights with a high percentage of red light may cause them to stretch. Blue light, on the other hand, helps to keep internodal spacing to a minimum and encourages plants to grow nice and stocky from the get-go.

What Causes Abnormal Stretching?

Abnormal stretching in the seedling phase is a sign of stress. By far, the most common situation that causes seedlings to stretch and topple over is light deprivation.

In the same way taproots dig for water and nutrients, the top part of the plant will stretch vigorously if it’s not receiving enough light. It’s a survival mechanism in which a plant uses up all its stored energy to rise above competing flora. In the case of indoor growing, there is no competition, but the seedling will perceive it this way. For instance, leaving the pot under a windowsill in the shade will likely trigger this behaviour. Things can get even more dramatic under artificial light.

This may seem a bit confusing for new indoor growers, as they may think they are providing more than enough light to their plants. But consider the following: Positioning a 200W metal halide (MH) bulb relatively far from the pot will be less effective than a 20W CFL bulb placed a few inches from the leaf surface. Even though CFLs are much weaker than MH, light intensity drops significantly the further away plants are from the source.

Moreover, seedlings have very small, and few, leaves. The total surface area available to absorb light is very small. So, in essence, that 200W bulb will be radiating over a very large area, but the seedling can only use a minute fraction of it. The CFL positioned right over the plant, on the other hand, will be able to give most of its 20W directly.

Other Potential Causes of Stretchy Cannabis Seedlings

Besides light deprivation, there are a handful of other factors that could be causing your cannabis seedlings to stretch. One common cause of leggy seedlings is poor nutrient content in the soil.

More precisely, cannabis seedlings benefit from nitrate-derived nitrogen. Unlike ammoniacal nitrogen, nitrate-nitrogen is a lot easier for plants to absorb and fuels shorter, bushier vegetative growth. If your seedlings are stretching despite ideal light conditions, we highly recommend checking the ammoniacal nitrogen content in your soil and fertiliser.

Another cause of leggy seedlings is heat.

While cannabis seedlings like warm, humid conditions, too much heat can cause a plant’s leaves to grow slower than its stem, resulting in tall and stretchy growth. To promote healthy seedling growth, we recommend keeping the temperatures in your grow room or dome at 19–20°C during the day and roughly 13°C at night.

Finally, cannabis seedlings can also stretch if they’re receiving too much or not enough light per day.

While some growers opt to keep their seedlings under 24 hours of light per day, we recommend sticking to 16 hours. Seedlings are fragile, and giving them too much light can cause stress and stretching. Remember, those dark hours are just as important for your young plants to develop healthy roots and respire.

How to Keep Cannabis Seedlings From Stretching and Falling Over

Stretchy cannabis seedlings can be a pain to handle and transplant. Their stems can be very fragile, and once they start vegging, their foliage can be off-centre due to the weird stretch they underwent as seedlings.

For best results, we recommend replanting your stretching seedlings deeper into their soil, correcting your lighting, and checking the nitrogen levels in your soil and/or fertilisers (as mentioned above). Once you’re confident you’ve created the right environment for your seedlings, pop them back under their lights and monitor their growth. Over time, the buried overgrown stem should sprout roots.

If possible, you may want to consider growing your seedlings outdoors under direct sunlight. There is simply no substitute for Mother Nature, and seedlings in direct sunlight will grow healthy, strong stems with short internodes. Once your plants have developed 2–3 mature leaves, feel free to move them indoors, making sure to keep their lights at the right height to prevent any further stretching.

If you have to grow your seedlings indoors, use the setup described above to ensure they get enough direct light at the right intensity.

Soon, you should notice your seedlings developing healthier growth. Short internodes and compact, green foliage are all signs that your seedlings are growing perfectly.

Note: Some growers try tying their stretchy seedlings to a stake. We do not recommend this method, as it doesn’t do anything to combat the weak, overgrown stem or the difficulty it’ll present further along in the grow.

Thinning Your Cannabis Seedling Crop to Prevent Stretching

Thinning is a common agricultural technique that’s often forgotten among cannabis growers. As the name suggests, thinning is all about reducing competition among your plants by “thinning” out the population.

Cannabis plants grow very quickly and will naturally compete with one another for space, light, and nutrients. So, while you may have been taught to think that more plants will naturally translate into bigger, better harvests—that might not be the case. In fact, many experienced growers opt to cull their weakest seedlings and only grow those plants that show the healthiest growth. This way, they focus their efforts on the plants most likely to produce the best flowers.

Thinning also helps growers maintain an even canopy across their grow room, which makes better use of a limited amount of light and space. Finally, thinning can help you avoid pests and other plagues, as you’ll be less likely to end up with a crowded grow space.

To thin your plants, simply keep a close eye on your seedlings throughout the first 1–2 weeks of their life, and only keep those specimens that show the healthiest, fastest growth.

Are your cannabis seedlings growing long, stretchy stems? Here's how to prevent and fix stretching during the cannabis seedling stage. ]]>