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weed seeds stretching

How To Prevent Stretchy Cannabis Seedlings

Long, stretchy seedlings with little foliage tend to be a sign of light deficiency. In this article, we’ll show you how to quickly deal with stretchy weed seedlings.

Are your cannabis seedlings growing tall, with long stems and few leaves? This is a common problem that, when not addressed quickly, can kill your seedlings. Luckily, it’s easy to deal with.


Cannabis seedlings develop long, stretchy stems when they’re lacking light. In an attempt to get more light and keep growing, the seedlings put all their energy into developing a long stem rather than foliage. This is a natural survival mechanism that, in nature, helps the plant grow taller than others around it in order to soak up as much light as possible.

Stretchy seedlings are a really common problem among first-time growers. There’s a lot of information online encouraging growers to keep their seeds in the dark after germinating and planting them to encourage root growth. Unfortunately, this usually just starves the seedlings of light and immediately encourages them to stretch.

Another common cause of stretchy seedlings is using the wrong grow lights. Many growers pop their seedlings under their regular grow lights at a distance to compensate for the light’s high wattage. As a result, the seedlings end up lacking light and stretch.


If you notice your seedlings growing long and stretchy, you’ll want to act quickly. When caught early, you can usually avoid causing your plants any serious harm. If you’re too late, however, your plants may die from the lack of light.

First, you’ll want to help your plants stand upright. To do so, tie them to a wooden skewer or, better yet, try replanting them in deeper soil, leaving only the top 3–4cm of stem sticking out of the soil.

Next, you’ll want to address your lighting situation. The best solution for growing healthy cannabis seedlings is to position 40W compact fluorescent lamps (CFLs) roughly 5–7cm from the tops of your seedlings. One lamp usually gives off enough light to support around 3–4 seedlings. Just keep an eye on your seedlings to ensure they don’t get too close to the light source. This is a recipe for light/heat stress.

After installing your lights, your seedlings should start developing thicker, bushier foliage. After a few weeks, they should develop some full-fingered leaves, at which point you can switch to stronger lights to support your plants during their vegetative growth phase.


• Don’t overwater: Droopy, yellow leaves and limp stems are a sign you’re watering your seedlings too much. Remember, seedlings have very small roots that’ll drown in overwatered soil. Your soil should be damp, but never soaked.

• Too much heat/light: Seedlings are very sensitive, and too much light can be just as damaging as too little. Burnt, crinkled, or upward-folded leaves are classic signs that your seedlings are receiving too much light/heat. Follow the lighting instructions we mentioned above to ensure your little ladies don’t suffer from light stress.

• Avoid nutrient burn: Seedlings can easily die if given too many nutrients. If in doubt, avoid feeding your seedlings until they’ve entered the vegetative growth phase and developed a few full-fingered leaves.


A lack of adequate light is the #1 cause of long, stretchy weed seedlings. Once you’ve germinated your seeds, make sure your seedlings get plenty of low-wattage light to support steady growth and healthy foliage. By following this tip, and the others mentioned in this article, you can achieve healthy seedlings of a desirable size—every time!

Grow Q&A: Help! My Pot Seedlings Are Stretching

Dear Dan, Sprouting seed has been easy for me, and transferring it to soil has been fine too. My problem is they all grow straight up 6 inches or more and then the weight of them makes them fall over. I have a plant light and run it according. What is the issue am I not planting seeds deep enough or is it something else? – Joshua B.

Dear Joshua,
My initial diagnosis is that your light is too far away from your plant tops. This is usually the reason that seedlings will stretch and then fall over. Lower your light closer to your seedlings and you should see this problem disappear.

If your seedlings are still alive, try carefully removing the plant from your container and replanting it with much of the stem buried in more soil. Wet your soil, flip your container over with your fingers protecting the stem and then gently remove the plant with the wet soil attached. Replant the sedling in a deeper container (or the same container if you can and wish) burying the stem almost up to the first leaves. Some light airflow from a fan can also help build up the stems and make them stronger and able to carry the weight of the plant above.

Why are my cannabis seedlings so tall?

Question: Why are my young marijuana seedlings getting tall and dying? They're growing all stretchy with long stems, and aren't making new sets of leaves.

These cannabis seedlings are growing tall and thin (and falling down) because they need more light.

Answer: When marijuana seedlings are growing tall and thin like that, it means they need more light.

"Leggy" seedlings need more light

When young marijuana seedlings are starving for light, they often show signs of lots of other problems, but if they're getting really tall without making any leaves, it's a sure sign it needs a brighter environment.

To increase the amount of light, you either need to get stronger grow lights (what grow lights work for growing cannabis?), or move your current grow light closer to your plants.

Some growers bury the extra stem to make seedlings short again, which works, but as long as you start giving your seedling light it will do a "push up" and rise back up, strengthening its stem in the process! Here's what to do right away…

Get 1-2 CFL bulbs and keep 2-3 inches away from the tops of your seedlings (be careful not to let seedlings grow into the light!)

Get 2 x 40W 'daylight' CFLs (can support 1-4 seedlings)

You can get more light later when the plant is making buds, but getting 2 CFLs should stop the stretching so you have a few more weeks.

After adding light, you'll see the new growth is much bushier and closer together, but the original stems will not get new leaves. Some growers will bury plants like these up to the point where there's leaves, but there's nothing wrong with just growing plants out as long as you have the height!