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Is your young weed plant hanging out limp? Is your plant perhaps standing on the windowsill and almost falling over? This is because your weed plant is not getting enough light. Young weed plants in particular are not able to tolerate much and have a growing hunger for light. This is why growing weed without a lamp is not recommended. Still want to grow a weed plant in the window? Then read this article about what you should pay attention to and why light is so important for growing weed.
What is Stretching of weed plants?
Two events can be defined for stretching weed plants. The first, however, is completely natural: a weed plant can suddenly become much larger in the first weeks of the flowering phase. However, this is not what we mean by stretching. Weed plants stretch in the seedling phase (when your plant has just germinated) when there is too little light available.
Stretching can be seen as gasping for light. The fibers in the young stem suddenly become much longer, causing the stem to stretch and become limp. Your weed plant may start to droop or fall over. And all this while you think you're watering enough. Lack of or too much water is not to blame. Darkness is and giving more light is the answer.
Compare this healthy young weed with the stretched plants in the introduction photo. A short weed plant like this is much stronger and can be achieved with enough light.
Weed Plant on the Window Sill
You might not think so, but glass absorbs and reflects light. This reduces the amount of daylight coming in through glass. Especially when sunlight shines on your windows at an angle, glass reflects all those much-needed sun rays.
Weed plants are tropical plants. Sativas in particular, with their thin leaves, really need buckets of light to grow healthy and tall. But whether you are growing an indica or sativa, at the end of the day the light behind the glass is not enough to get the maximum potential out of a weed plant.
The wind direction of the window, restrictions in free view, the season and with it the height of the sun in the sky all determine how much or how little light actually falls on the leaves of your weed plant. So there are quite a few factors that will cause your weed plant to not get as much light as if it were standing in a tropical region in the blazing sun. That's why growing weed in a window is not a good idea.
Still want to grow a weed plant on the windowsill? If you succeed, the potential yield decreases significantly!
Pregrowing
There is, however, a difference between growing a weed plant on a windowsill and pre-growing a weed plant in front of a window. With pre-grown, the goal is to give your weed plant a head start. This is done by placing the plant in a safe environment (without wind, rain or pests) during its most vulnerable period. This allows the young weed plant or seedling to grow strong.
At least, that's the idea. If you are going to pregrow a weed plant on a windowsill facing north in December, you will see that within a week of germinating your weed plant will start to go limp. Your plant will first grow a lot taller and then fall over. This elongation is what we mean by stretching.
Preventing stretching
If your weed plant has fallen over after stretching, there is unfortunately nothing you can do about it. But now that you know the cause, fortunately you can prevent it. So what do you need to do this?
Germinated? Then your plant needs direct light.
Light! Young weed plants really don't need as much light as adult plants, but it is for a reason that no weed plants grow in Lapland. And it can get as high as 30 degrees Celsius in the summer there. But the sun is relatively low in the sky and tropical one-year plants such as weed do not stand a chance. You can proceed in two ways.
Pregrowing with a grow lamp: the right lamp
The best way to do this, after germinating your cannabis seeds, is to pregrow the weed plant with a grow light. A grow light doesn't have to be a 1000 watt jet. In fact, a designated energy saving lamp is usually the best choice. There are special lamps with a blue glow that you can also buy at the garden center. Whether you choose a fluorescent tube, energy saving lamp or special LED lamp: as long as the grow light is intended for growing young plants. The wattage depends on the chosen lamp and the distance to the young plant. Often a fluorescent lamp of 2x24 Watt will do the trick. A grow light of 2x55 Watt gives enough light for a larger area. And if you replace the lamps with flowering lamps you can also let a small weed plant finish flowering in the winter months.
Read all about pregrowing weed.
Pregrowing on the Windowsill: germinate at the right moment
Don't have a grow light or don't think it's worth the investment? No hard feelings. :) In that case, please pay attention to the following points:
- Germination period - Do not germinate before April or after July. For growth and flowering you will need sufficient sunlight later. Autoflowers also do not get enough sunlight during the winter months. If you germinate at the end of April, your weed plant can grow for 2 to 3 weeks before it is allowed to go outside after Ice Saints.
- Choose the sunniest window - Preferably take a south-facing window with an open view. A large second floor window or attic window is usually a better choice. A tree or fence quickly casts a shadow on a living room or kitchen window.
- The closer to the glass the better (but not up against it) - The further you place the young plant away from the window, the less light. So slide your little plant more toward the window, but not against it. Then the heat from the glass can cause the leaves to "burn" or become dry.
- Not for life - Pre-growing on a sunny windowsill is okay, but don't leave your weed plant there for her entire life. For best results place her in a greenhouse or outdoors in a sunny spot.
So light is crucial. But exactly how much light does a weed plant need after pregrowth? We have written an extensive blog about this: Why pre-growing weed can increase the yield
Weed Plant Stretches Under Grow Lamp
A weed plant can stretch under a grow lamp if the light intensity of the lamp is not sufficient. This intensity can be increased in several ways. It is not only a higher wattage lamp that can offer a solution. Reflectors and even the colour of the grow box make a difference. But the most important factor in preventing stretching and increasing yield is adjusting the height of the lamp correctly.
The ideal height of the grow lamp above a weed plant is to look for the limit between too high and too low. If the lamp is too high above the plant, the plant will stretch towards the light. If the lamp is too close to the plant you run the risk of burnt leaves and buds. That is what you want to avoid. But how close can you hang the lamp? There is a method of calculation, but here are the guidelines.
HPS / MH grow lamps height
- 150 Watt - 20-30 cm
- 240 Watt - 25-35 cm
- 400 Watt - 30-48 cm
- 600 Watt - 35-64 cm
- 1000 Watt - 41-79 cm
If you want to be on the safe side, you can use the following rule of thumb for HPS and MH: Height of the grow light = 10% of the wattage in centimeters. So a 600 watt lamp can be hung 60 centimeters above the weed plant.
Height LED-lamp weed
Although the temperature of a LED fixture is often lower, LED has a higher light pressure than HPS and MH lights. As a result, leaves can bleach and burn due to the amount of light. With LED panels, there are more factors than the best height for the grow light. For example, which LED lights are in the panel and is the fixture cooled? We do have a guideline for you.
- 200 Watt - Around 30 cm
- 300 Watt - Around 40 cm
- 400 Watt - Around 50 cm
- 450 Watt - Around 60 cm
- 600 Watt - Around 80 cm
Read all about calculating light intensity in this blog. Especially useful when growing weed with LED-lamps!
CFL grow lamp height
These lights are great for pre-growing weed plants and making cuttings, but they don't provide enough light to grow giant plants. You can place CFL bulbs as close to the plant as you can, but keep an eye on the heat generation. If you can keep your hand at that distance from the lamp for 30 seconds, you won't have to worry about burning your weed plant either.
Weed plant hangs limp, now what?
If your seedling is now hanging limp, but not yet dead, you should first take a look at what exactly is going on. If you have read the article, you will see that young plants often get too little light. But if you have been watering too much or too little, you also have to take care of that. Only water the plant when the soil feels dry.
You can use a stick to give your young plant support. Place the stick next to the stem of your seedling and gently insert it into the soil. If you damage the young roots as well, it will end quickly. You can use soft twine to attach the seedling to the stick. After your plant has found the support it is important to give it more light. Move your plant to a brighter location or put it under the grow light. Within a few days your plant will begin to recover. The stick will remain necessary up to and including the growth phase, because the stretching has stretched the fibers. In the growth phase your plant slowly but surely gets more hold.