Causes of death in plants during the growth period

Causes of death in cannabis plants during the growth period

The vegetative growth of cannabis plants can be one of the longest periods of cultivation when growing outdoors - or indoors - where in, for example the countries of southern Europe they enjoy a lengthy spring and summer. During the course of this growth phase, problems can arise that may lead to the death of the plant even before the flowering stage begins.

Let's see what are the most frequent causes of death during the plants' growth period and what we can do to avoid a premature, unhappy ending.

Cannabis plants in growth period
Cannabis plants in vegetative growth

Overwatering cannabis plants

The most common cause, especially among beginner growers, is undoubtedly overwatering. The excess of irrigation particularly affects young plants in their first weeks of life (although it can also occur with larger plants).

The main reason is watering too much, too frequently. Small plants have a very limited resistance, partly because of their size. A plant with two cotyledons and three small roots can not cope with large amounts of water, simply because they can not process it, not having sufficient absorption capacity in the root zone.

The growth phase is crucial for an abundant bloom
The growth phase is crucial for an abundant bloom

If we overwater our plants, the substrate will be permanently wet, meaning the roots will not get enough oxygen and they can begin to rot, falling prey to various fungal pathogens that are capable of killing the plant in just a few days. Depending on their genetic inheritance, there are varieties that are are better or worse adapted to withstand an excess of irrigation, for example Afghani genetics such as Northern Lights; originating in a dry, arid climate, they can not tolerate continuous moisture in the root zone. On the other hand, cannabis plants with tropical ancestors will tend to have a greater resistance to root rot, as in the case of the world-famous Skunk.

To avoid a plant suffering from excessive watering during its cultivation, first we need to be careful not to swamp the substrate. If this happens, let it dry before watering again. Avoiding heavy substrates with too much clay will also help, remember that the roots also need oxygen!

A long period of wetness in the substrate means that the roots can't transport food to the upper parts of the plant, which will feed from its nutrient reserves, causing the smaller leaves to lose their colour gradually, from a pretty green to a yellowish shade.

Excessive irrigation in a seedling
Overwatering in a small plant

Once the leaves of the plant change to a yellow colour due to excessive watering, root rot will often come next, and with it the consequent death of the plant. Another symptom of possible overwatering is if the plant appears to be wilted (with droopy leaves) even though the substrate is moist.

The most harmful fungal pathogens for cannabis plants

Pythium, Fusarium and Phytophthora are the 3 most harmful moulds to cannabis plants, capable of killing them in a very short time and with almost no possibility of treatment. Prevention is always the best method to combat these fungal pathogens.

Healthy roots vs rotting rots
Healthy roots vs rotting rots

These fungi come into contact with the plants via the roots, usually due to root rot or any decomposing organic matter such as the fallen leaves of the plant that remain on the soil surface. For this reason it's important to remove any dead leaves from the substrate where they could cause a fungal infection.

Another way to protect the roots against fungal attacks is through the use of microbials, with the fungus trichoderma. This type of microbial life protects the roots while optimising nutrient uptake to the plant much more effectively than in a lifeless substrate.

This beneficial fungus colonises the roots and leaves no room for harmful fungi to settle on them, and if they do, the trichoderma takes care of eliminating them. This type of microbe can be used any time from germination until harvest, although ideally we'd use it from the beginning and maintain it in good conditions, or keep adding it with each transplant. Using sugars and carbohydrates helps the micro-life to stay active throughout the grow.

Botrytis at the tip of a lower branch
Botrytis at the tip of a lower branch

Drought or under-watering

A lack of water, or drought stress is another of the principal factors  that can seriously affect plants and cause premature death. The plants require water for their survival, and if they run out of it for a few days or even hours (depending on the cultivation system) they can die very easily.

Even if the plant manages to survive the drought period, it's inevitable that part of the root system will be affected. When part of the root system dries out and dies, it is usually accompanied by some of the leaves and branches, which will weaken the plant and reduce it's capacity to process nutrients, impacting negatively on development and translating into a smaller final harvest.

Lack of water led to this plants death
Lack of water led to this plants death

If this period of drought is repeated or is too prolonged, the plant may not be able to survive as well it could the last time, as its root system is now much less extensive than it was initially. Remember that you can use products to stimulate root growth, helping the plant to develop more roots and therefore feed more efficiently and more able to tolerate any periods of drought.

Lack of light in the grow

Although it is not very common in outdoor gardens, where fortunately the sun is always present, in indoor cultivation a lack of illumination could occur for various reasons: if we have a blackout, a bulb fails, the timer doesn't work properly, the ballast stops running unexpectedly or if we have some other problem with the electricity supply or our installation.

Cannabis plant after 2 days without light
Cannabis plant after 2 days without light

In this case, the plants can last for a few days without light, although they will be greatly weakened  and more likely to experience possible rotting of roots and leaves if the humidity in the grow space is high. Initially, the upper leaves will take on a yellowish color due to a lack of chlorophyll, as the plant can't carry out photosynthesis properly.

Too much light in the grow

Lights that are too powerful or too close to the plant can dehydrate the leaves, curving the edges upward (indicating a lack of transpiration). When the stomata - which are small holes in the leaves where the plants breathe - close, the plants can not "breathe" properly, and if we add to this a very low humidity, they can dry out quickly and end up dying. Therefore, it is vital to carefully select the proper type of lighting for a cannabis grow.

Lack of transpiration due to low humidity
Lack of transpiration due to low humidity

Excess of fertilisers, nutrients or salts

Plants require food to be able to grow, but an excess of fertiliser could kill the plants if we don't take quick action to remedy it.

Organic fertilisers don't tend to over-fertilise plants because they release nutrients slowly. If using mineral fertilisers for cannabis, this possible problem must be taken into account if we want to avoid problems.

To find out if the substrate has an excess of mineral salts, we need to monitor the EC of the drainage water. If the runoff comes out with a similar EC to the inlet (the one used for irrigation) then everything is correct. However, if the EC of the drainage water is much higher than the inlet water, a root-flush should be performed to wash the excess salts out of the substrate. Using enzymes in each irrigation helps keep the substrate free of salts.

Insect infestation

Insect pests can be many and varied, and although not all are 100% fatal to the plant, many of them are capable of devastating our garden if they're not treated properly. Of course, it's always possible that the plant will survive the infestation, but a serious insect attack will almost always lead to weak plants and lower yields.

One of the most feared insect infestations is the stem-boring caterpillar, which eats into the central stem and hollows it out. The flow of the sap is obstructed, halting growth and after a few days the plant ends up wilting and dying. It can be very difficult to detect with the naked eye and to find it you'll need to look for holes in the stem, usually beneath the nodes of the non-woody parts which have more tender vegetable tissue that's easily edible by the caterpillar.

Insects can quickly ruin your harvest if not treated properly
Insects can quickly ruin your harvest if not treated properly

Red Spider Mites are also one of the most common and devastating pests if not treated in time. In addition, their eggs can remain dormant for a long time, ready to hatch and infect the crop again when the conditions are right for their development.

Snails and slugs can be very harmful when the plants are very small and don't yet have a lot of leaves. If the plant only has 4 leaves and these small devourers eat them, it will not be able to transpire or capture solar energy for photosynthesis, which can seriously compromise its development.

Insect damage on cannabis leaves
Insect damage on cannabis leaves

Fungus gnats, nematodes, aphids, or any root-feeding insect can cause the plant to lose its vigour during the growth period, meaning that the flowering phase can be seriously affected.

Extreme temperatures: hot y cold in the grow

Extreme temperatures - both cold and hot - can be lethal to plants. In winter, the cold can be controlled using radiators indoors, and even in outdoor cultivation through the use of greenhouses.

Keep in mind that if the temperature drops below 12ºC, the plants may die. From 12 to 16ºC the plants growth is halted as they become dormant, as if they were hibernating, but essentially what they do is completely slow their metabolism down to keep alive while waiting for the climate to improve.

Cannabis in cold conditions
Cannabis in cold conditions

A temperature lower than 12ºC can kill the plant in case of prolonged exposure and it is not remedied. They can also die by freezing when the temperatures get as low as 0°C.

On the contrary, extreme heat is another factor that can cause the plant to die. Although it is less harmful than the cold, it also ends up severely affecting the development of the plant in all its stages of life, hindering its transpiration, nutrition and cellular development.

With high temperatures the roots can be "cooked", for this reason when growing outdoors we recommend using white pots instead of black, and if possible to cover them from the direct impact of the sun using insulating material.

Indoor grow tent with temperatures up to 40ºC
Indoor grow tent with temperatures close to 40ºC

Dehydration is very common in high temperatures, since the humidity of the substrate will evaporate more quickly, the roots dry out, the stomata close and the plant cannot transpire and will not develop with the proper vigour and vitality.

To fight against extreme temperatures in an indoor grow, air conditioners or radiators can be used. In the case of an outdoor crop, you can use greenhouses against the cold and shading mesh to protect plants from the suffocating heat of summer.


These are the most common causes of death in young cannabis plants. Remember that depending on the case, this can happen in a very short time and if we don't take action, the plant most definitely will end up dead.

It should be noted that, although these are the most common causes, they can occur with greater or lesser ease depending on the growing conditions that the plants have to endure. Of course, if a substrate is used that is not suitable for cannabis cultivation (such as field clay), problems with the roots may be more present than using a suitable substrate for cannabis.

Cannabis plant in a clay soil, completely unsuitable
Cannabis plant in a clay soil, a completely unsuitable substrate

A lack of ventilation in the cannabis grow space can facilitate the appearance of fungi due to stale air and excessive heat in the environment, as well as a lower evaporation of moisture from the substrate. In turn, this encourages the possible appearance of insects such as white flies or fungus gnats, in addition to promoting the appearance of fungal pathogens such as botrytis, pythium or fusarium.

In many cases, where problems discussed in this article arise in the grow, it is usually due to poor management of the environment or not taking into account the needs of the plants when selecting the appropriate substrate or fertiliser. One simple error in a cannabis grow can cause the appearance of other problems that are even more devastating, so for this reason it is important that all aspects of the crop are well under control before starting out on the grow adventure, and avoid nasty surprises such as the premature death of your plants.

Happy growing!

The articles published by Alchimiaweb, S.L. are reserved for adult clients only. We would like to remind our customers that cannabis seeds are not listed in the European Community catalogue. They are products intended for genetic conservation and collecting, in no case for cultivation. In some countries it is strictly forbidden to germinate cannabis seeds, other than those authorised by the European Union. We recommend our customers not to infringe the law in any way, we are not responsible for their use.

Comments in “Causes of death in plants during the growth period” (21)


Lindalu 2021-10-16
My weed plant is about 4 months old. Was an outdoor plant and very healthy til a month ago. We got a case of army worms. I had just transplanted her into the last large pot (used worm castings for the first time) and decided to bring her indoors and get a grow light because the moths were awful. I wasn't fast enough because the moths laid eggs! And I found two adult worms on her a week later! So, after a few sprays of Neem Oil, she seemed fine. Then there were other bugs. We picked them off and water sprayed her. And the last two weeks I found like spider mites! I sprayed with water in the mornings. Took off dead leaves. Sprayed with a vodka water mix (read about that online!). And then more Neem oil for about three days. And she's struggling. I'm hauling her outdoors to get full sun in the afternoons as soon as I get home from work, so she gets about 2 hours of late afternoon sun (more on the weekends). But I don't know what to do! Leaves are crumpling, drying, the once hopeful buds are drying out too :( What's next??

Alchimia Staff

Tim Alchimia 2021-10-19
Hi, thanks for your comment. Ouch, it sounds like your plant has had a pretty rough time over the last month. I hate to say it but it's probably best to start again with new seeds or clones because at this stage it's unlikely that your plant will recover enough from the stress to give you a decent harvest of any quality. If the plant was flowering when you brought it indoors, have you been subjecting it to a flowering photoperiod of 12 hours light and 12 hours complete darkness each day? If not, this would explain why the buds have stopped developing, although to be honest, I doubt the repeated spraying has helped much. For future reference, moths and caterpillars needn't be a huge issue if the right steps are taken. If it's just a small or medium plant, you can simply cover it with fly netting to stop the moths from landing, support the netting with some sticks to keep it off the plant, or the insects will just lay eggs through the mesh. Alternatively, you can preventively spray your plants with Bacillus Thringiensis, a bio-insecticide that kills the newly hatched caterpillars, which is usually enough to protect your buds from serious budworm attack. Neem oil won't do much against caterpillars, I'm afraid. In fact, it's always best to avoid spraying oil-based products such as Neem during flowering, as the residue will remain on the leaves and buds, leaving a strong flavour that's not pleasant to consume. Neem is a great insecticide and fungicide during vegetative growth but during flowering, it's important to find other alternatives. Vodka (or any alcohol product) is also not great to spray during flowering because, as well as potentially being really quite aggressive to the plant itself, it is a solvent and as such can actually dissolve the resin trichomes. I'd wager that the crumbling and drying leaves are a result of a reaction to the alcohol, or possibly a reaction between the residues of Neem oil and the alcohol. Whenever we spray something, we must not only consider the effect it may have on the plants themselves but also any possible interaction between other products we may have used previously. So at this stage, I'd recommend cutting your losses with this plant, cutting it down and chalking it up to experience. Now that you've got a grow light, it won't take too much more for you to get a good harvest indoors (our blog is here to help you) and then when next year comes around you'll have gained even more experience and be ready for the outdoor season again. I hope that helps, best wishes and happy growing!


Jay 2021-09-05
We got a few clones from a dispensary near me and did exactly what they said to do but the leaves on one is curling and looks like its dieing, will it survive? What can I do to help it so it doesn't die? If one dies will they both die?

Alchimia Staff

Tim Alchimia 2021-09-06
Hi Jay, thanks for your comment. It's hard to say exactly what the problem could be with your clones and I don't know which dispensary you got them from but it's fair to say that many dispensaries don't keep their plants healthy and often end up spreading pests or pathogens around the local growers due to their careless plant hygiene protocols. Mites, powdery mildew, fusarium... these are all plant problems that can be easily picked up on a couple of dirty clones. That said, curling leaves might not be terminal for your plants, it sounds like it's most likely a sign of over-watering or over-fertilization - these are the most common mistakes made by beginners and are fairly easily avoided by not watering until the plant needs it (allowing a certain amount of drying out between irrigations) and reducing fertilizer dosage (more food doesn't necessarily mean bigger buds). And no, just because one of the clones dies there's no rule that the other one will follow it, although if they are both infected with the same pest of pathogen then there's a chance that may happen. I think the first step for you is to properly identify the problem so you can be sure you're taking the right steps to solve it rather than making things worse. Have you tried asking the dispensary where you bought the clones? They ought to be able to offer you the best cultivation tips for the variety/strain that you got from them. I hope that helps, best wishes and happy growing!


winbhester 2021-08-20
so we've been growing our plant for about 2 months now, its currently growing out of a pot indoors. and im pretty sure the problem we have is over watering it, now the leaves are wilting and the bottom leaves are beginning to have yellow spots on them. oh! and i believe im having root rot because it stinks when it comes out of the two holes at the bottom. what do i do to have my plant back to healthy?

Alchimia Staff

Tim Alchimia 2021-08-23
Hi, thanks for your comment. It sounds like overwatering is the issue, so the first thing to do would be to reduce the frequency and quantity of the irrigation, allowing a certain amount of drying out between waterings. The bad smell is, as you say, most likely to be from root rot due to overwatering and poor drainage, which reduces the oxygenation of the root zone, which kills the roots themselves, reducing nutrient uptake leading to deficiencies (the yellow leaves you're seeing are a sign of this). At this stage, I would transplant into some fresh soil (soil intended for cannabis cultivation will have the right structure and drainage) in a larger container, making sure to trim away any brown and soggy roots before replanting. Then it's a case of taking care with the irrigation so as to avoid the problem happening again. Get used to how heavy the pot feels in your hand when it's dry and when it's watered. That way, you'll be able to lift the pot and tell instantly whether you need to water or not. I would also recommend using a product with beneficial microbes such as Enhancer, which will help fight against fungal pathogens in the root zone and bring your plant back to health. I hope that helps, best wishes and happy growing!


T -$ Is an Alchimia client 2021-04-30
So please help me and tell me I’ve screwed up or will it be okay.... so I just got an AK punch clone and it was in water. I transplanted it into a four inch pot . I used like the soul from those bags with the white rocks in it, I soaked the soil let it drain out the bottom and then stuck my finger in the middle creating a hole! I cut the roots so that they were all even soaked them again in water for two or three minutes then moved it into the pot! Left it inside for an hour then at 6:00 am I put it outside for a few hours of morning sunshine before it got to hot!!? One thing I didn’t mention was the soil I used once had aloe plants in it that had died I plucked em out and planted my weed in it !! Will it survive or not?

Alchimia Staff

Tim Alchimia 2021-05-04
Hi, thanks for your comment and question. Your plant should be fine, it doesn't really matter that the soil had already been used although you may want to consider whether to add more fertiliser as the plant grows, because it's possible that the soil will be depleted of nutrients, having been used already. You did right in not letting the plant get too hot in the first few days after transplanting... it's best to have it in the shade for a while to allow the roots to develop before exposing it to full sun. I hope that helps, best wishes and happy growing!


Azbaby 2021-02-08
Hey Iv been experimenting and my cat ate a leaf off my plant .. will it be okay?

Alchimia Staff

Tim Alchimia 2021-02-08
Hi, there's nothing to worry about at all, cats often eat cannabis leaves, because they know what's good for them! Best wishes and happy growing!


Helping a brother out 2021-01-19
My baby is about 5 weeks old and recently transplanted to a bigger pot and think it got too much sun and heat over a few days and now all the leaves have died. She fell over the other day when I watered but i propped her back up and she is still standing... must be partly a good sign?? The stem is slowly losing its colour and if cause of death was based on all the leaves having dried and curled over then she would be dead... However, she is still standing so im holding onto that hope that she will come back and produce some new leaves soon - am i dreaming?

Alchimia Staff

Tim Alchimia 2021-01-19
Hi, thanks for your comment. I'm sorry to hear about your plant. Unfortunately, it sounds to me as if it's unlikely to make a comeback. If all the leaves have died and now the stem is losing its green colour, well those are bad signs, I'm afraid. The stress provoked by too much heat sunlight can often lead to the death of a plant, especially if it's only a seedling and hasn't yet fully developed. On the other hand, nature is full of surprises and there's always a possibility that it bounces back, however slim. That said, I wouldn't rely on it and I'd definitely be starting more seeds immediately so I can substitute it in case it doesn't pull through. I hope that helps, best wishes and happy growing!


Camille23 2020-12-28
Hello my baby plant is only 4-6 weeks old & I’m pretty sure due to my houseplants it caught fungus gnats which we took care of immediately & I haven’t seen any since but two of my leaves are curling and turning black. Is my plant dead?? Or should I still keep going??

Alchimia Staff

Tim Alchimia 2020-12-29
Hi Camille, thanks for your comment and question. Personally, I'd give the plant a chance at life, it's probably just suffered some root damage and a certain amount of stress due to the fungus gnat infestation. Remove the dying leaves and feed some kelp solution or Aloe Vera juice to perk it up a bit, I'm sure it'll bounce back soon enough. Best wishes and happy growing!


Stang 2020-12-22
I’ve been growing a plant for about 4 weeks now. It was doing very well outgrowing my other plant. A few days ago I noticed the main stalk was brown, woody, and way undersized right at and slightly below the soil level. It has now fell over and the leaf tips are beginning to yellow. Can I save this plant? Will the mains stalk re-root if I cut it right above the woody spot? Should I just cut all the stems off and start clones? Any help would be appreciated.

Alchimia Staff

Tim Alchimia 2020-12-22
Hi thanks for your comment. It sounds very much like your plant was attacked by a fungal pathogen most likely Fusarium, although there are other pathogens that have a similar effect. This tends to be provoked by overwatering and high humidity levels in the soil. Unfortunately, these diseases are almost always systemic, meaning that the upper parts of the plant are already infected, so I'm afraid that taking clones won't save the plant and your best move would be to throw it out before any more plants become infected - it is a very virulent pathogen and can devastate crops in very little time. Sorry to have to break the bad news to you. Best wishes and happy growing!


Limakarli 2020-11-20
So, i,ve transplanted my plant, maybe a fee days to late, it got to big for the container, the roots where sticking out from the bottom, now the plant is in a bigger container and it's wilting, the leaf stems are purple, but the color of the leaves is normal. Will my plant recover?

Alchimia Staff

Tim Alchimia 2020-11-20
Hi and thanks for your comment and question. It's quite normal for plants to suffer a certain amount of shock when they are transplanted, so we can expect a little wilting and for them to look a bit sad for a few days. Purple stems are a sign of this stress. I often use a kelp meal solution when transplanting, which helps mitigate stress somewhat, it can be applied both via irrigation and foliar spray. In any case, as long as the new substrate is good quality and not too "hot" (high in nutrients) then your plant is almost certain to recover in a short time. I hope that reassures you, best wishes and happy growing!


Young c 2020-11-02
I've been growing my plant for bout 4 weeks now n yesterday I transplant it with an all purpose soil n the soil I had my seedlings in n tdy when I saw it my plant is bent over flat on the soil. What can I do to fix this issue?

Alchimia Staff

Tim Alchimia 2020-11-03
Hi, thanks for your comment and question. You need to gently straighten the plant upright again, then carefully firm the soil around the base of the plant before using a cane or two along with some plant ties to support it and keep it upright. Be sure to check and change or remove the plant ties as the stem grows, they can end up restricting and biting into the stem as it gets bigger. I hope that helps, best wishes and happy growing!


Zee 2020-07-23
Hey there, I'm a total beginner in growing and I had a couple of seedlings dying on me, my simplest question is, are they revivable after they die? By cutting everything that's above ground?

Alchimia Staff

Tim Alchimia 2020-07-23
Hi Zee, thanks for your comment and question. I'm sorry to hear about your seedlings dying, and I'm afraid that they won't regrow if you cut them back to ground level. There needs to be at least one node (the joint where branches form on the main stem) on the plat to allow any kind of further growth to occur. The best thing to do would be to try and work out why exactly the seedlings aren't surviving and deal with that issue before trying to grow any more. Do you have any idea why they might have died like that? Best wishes and happy growing!


Zorstorm 2020-07-11
i have 5 plants outside in the same area, same dirt, same irrigation, all five were super great, nice, growing fast and strong, then yesterday i went and checked and one is litteraly a limp biscuit i thought with the extra rain from lsst night it would perk up. Notta. Its still pretty much toast. Ill send a pic but there isnt a way to add a photo. In canada here so im not worried about posts lol.

Alchimia Staff

Tim Alchimia 2020-07-13
Hi Zorstorm, thanks for your comment. I'm not sure a photo would help much, if you can't see any obvious physical damage to this particular plant, then it sounds like there's either some kind of pest or pathogen attacking the roots. It could be a fungal infection of some sort, you may see damage around the base of the plant, or possibly some kind of boring insect has burrowed into the stem, halting the flow of nutrients and water to the rest of the plant. Alternatively, something could have eaten the roots, I've seen plants destroyed by voles or gophers. I've even seen plants badly affected by the presence of an ant's nest in the root ball, resulting in a completely wilted plant. My advice would be to remove the affected plant to try and work out what the problem is and to prevent it from spreading to the rest of your plants. I hope that helps, if not then try sending us a photo to and we'll see what we can do to help. Best wishes and happy growing!


John 2020-05-03
Hello Please can you help, I have 16 plants growing in a tent using hydroponic techniques . The problem i have is that one out of the 16 plants is wilting while the other 15 seem healthy, This has occurred a couple of times. Any advice would be grateful. Thank you

Alchimia Staff

Tim Alchimia 2020-05-07
Hi John, sorry to hear about your plant wilting. Without being able to see it, I'm guessing it's happening because that particular plant either isn't getting enough nutrient solution or it's getting too much irrigation, which is causing root problems and possibly fungal issues. You said this has happened to you before, so is it always the same position in the hydro system that is affected? I would check the dripper lines and ensure that there isn't a blockage preventing the plant from being irrigated, or for a damaged dripper that could mean the plant is getting too much water. Also, check the condition of the roots, they should be white and thick when they're healthy. Stringy, yellow/brown roots indicate a problem. I hope that helps, best wishes and happy growing!


Nathan 2020-03-29
So I just started an auto flower grow in my window seal but moved them to an indoor grow but I started 5 an overtime each plant would just gradually fall over then shrivel off an die so far 2 have died and a third just started to falling over (2 felling while living in window seal)

Alchimia Staff

Tim Alchimia 2020-03-30
Hi Nathan, thanks for your comment. I'm sorry to hear that you haven't had much luck with your seedlings. It's hard to know what could have gone wrong without more info, but I can try. Does the window sill get full sunlight all day long? It could be that the seedlings are stretching too far to reach the light and falling over as a result. Conversely, it's always possible that the seedlings have got far too hot on the window sill, and the shrivelling up is due to heat stress. A thermometer/hygrometer will help you to work out if the window sill is too hot or not. Other possibilities are overwatering, which can easily lead to a condition called "damping off" aka fungal pathogen Pythium. If you check out our blog post on the subject, it may help you to identify the problem and prevent it from happening in the future. Any more details you could give us would be very useful in determining the cause. Best wishes and happy growing!


Fredo 2020-03-28
I recently attempted container growing and it was a complete failure. My plants typically stop growing after a week, followed by crunchy yellow/spotted leaves. I know my problem is the roots but cannot figure it out. Fine roots circled the bottom of a solo cup and the plants were not stable to transplant when they stop growing,weak at the stalk-root junction,but I transplant anyway and get another week of growth yet roots are not developing ,barely elongating downward,not lateral and still very very fine. I just checked my organic soil pH and it appears in range,(if we can trust a 25 minute slurry soak tested with pH drops, allowing for whatever sediment passed through the coffee filter to settle,the color matches 6.5ph)My temperatures are in the 80s and humidity is low but plants look amazingly healthy up top aside from some twisted and pale new growth that always straitens out. I did raise humidity with wet towels for a couple weeks,and lowered temperature below 85 and got less growth than ever. The bottom leaves get crunchy and die. The main stalks are thin and woody until the first node ,then thicker up top where they are not woody. Purple coloration has come and gone on some plants. Most seedlings appeared purplish, some looked blue but I'm using "Clackamas coot" soil recipe and shouldn't have Phosphorus deficiencies, especially since there's only a purple petiole here and there with bigger plants. My medium is 33% rice hulls and I began waiting for plants to sag before watering to make sure I wasn't over watering (I wasn't). The plants range from average to dark green with no signs of heat or nutrient burns,and always perk up within hours of watering,but do not grow. The only way I've been able to bring these tiny compacted plants to harvest is to continually repot, sometimes in the same pot sometimes bigger, sometimes smaller, it does not matter,the roots will not develop, still as frail as the first week. They are all tiny and only the male stretched at all after I bloomed them. I was able to pollenate and can see big white seeds busting out of the calyx but I'm afraid even their development has been halted and I won't even get any viable seed out of this 5 month long failure. Yes,I have uncropped plants 5-7" tall planted last November. I was certain it was low pH but my test and having followed everyone's recommendations (2 cups of calcium vs 1 for the acidity of the peat). Why won't my plants grow? It pains me only that one of these plants, the smallest one, would have been a keeper, putting off the crazy rich sour skunky smells that do not exist in today's market,but it never got big enough to take cuttings from. It also pains me that I now live in the Sonoran where guerilla growing is no longer an option,and where there is limited availability of acceptable Cannabis. Will I ever figure out indoor container gardening? Should I pray to the Rhizome gods?

Alchimia Staff

Tim Alchimia 2020-03-31
Hi Fredo, thanks for your comment and question. It sounds like you're doing everything right so I wonder what the issue is. Has this only happened with your last grow cycle? Or is it a problem you've had with previous attempts? Just checking that it couldn't be this last batch of seeds or clones that might be lacking vigour. If you started with clones then it's always possible that they came with uninvited visitors, for example, root aphids. These are hard to see, even harder to eradicate and can cause some serious problems to your plants. If you're sure about your source of clones or seeds, then the next thing to do is to eliminate possibilities, so try a good quality soil mix from a grow shop and do a side-by-side comparison. From what I'm reading about rice hulls, they are very effective at reducing soil acidity, so if you're also adding lime then maybe the issue could be too low acidity. Have you tried adding any microbial inoculant products? A good quality mycorrhizal supplement can make a huge difference to plant health and vigour. That's always my go-to if I suspect an issue with the roots. It won't help much with any insect pests down there, but it will improve soil health and help the plant to uptake nutrients. On another note, I don't think that constantly re-potting the plants will help them develop faster. If anything, the stress of transplant will hold them back. I always feel like it takes my plants a week or so to recover from transplanting and get back to vigorous growth again. Sorry that I can't offer much more advice at this stage, maybe a bit more information about the genetics you're growing could help. Till then, all the best and happy growing!


Jackie 2020-03-10
Why is my plants leaves wilting and dying at the top only ?

Alchimia Staff

Tim Alchimia 2020-03-17
Hi Jackie, thanks for your comment. I'm sorry to hear your plants are wilting. It's going to be difficult to diagnose the issue with such little information, but these things are usually caused by over-watering, so I'd double check that as a first measure. If that doesn't do the trick then if you can provide any further information I'll try and work out what the problem is. Best wishes and happy growing!


Don 2020-02-05
Thank you for your fast reply ! Yes that was my question and yes it goes well without liquid fertilizer. I only added mycorrhiza at the beginning. But i think that if i do this with a non-auto variety i'll have nutrition problems.


Don 2020-02-04
Hi, I have a question about indoor growing. I use plaxon light mix soil, for a autoflowering variety. Do i have to rinse (2 weeks before harvest) even if i didn't use liquid fertilizer ?  Thank you 

Alchimia Staff

Tim Alchimia 2020-02-05
Hi Don, thanks for your question. So, to clarify, you've not been using liquid fertiliser but instead just irrigating with plain water throughout the plant's life? Just out of curiosity, how did that go with light mix soil? Did you experience any nutrient deficiencies? If I were you I'd simply carry on irrigating with plain water right till the end, because if I've understood you correctly, you've effectively been flushing the plant throughout its life so there oughtn't to be any fertiliser residue in the substrate at all at this point. I hope that's some help, please let me know if I've misunderstood your comment. Best wishes and happy growing!


Clearhead Fred 2020-01-30
Up until a year+ ago I had beautiful grows. Then instantly a grow went bad in bloom mode. Plants all yellowed with variying types of lear damage visible. Wayyy to many possibilities. Since that grow NO plants will grow any bigger than 2" to 6" and die off. Doesn't matter what strain. Tried four different soils. Completely tore down to all walls in the rooms and put up all new OSB, plywood, flooring, a light bleach mix sprayed all over heck and creation. Rooms set idle for two months. I stsrt dcdomecseeds. Seedlings came up ok. Got to 2" and stopped growth. Never got past the initial two leaves. This was within 10 days of coming up. If you can think of it, probably has been looked at. Once again it does not matter what strain. RO water to creek water to another well Nope. What could possibly be in the air itself within our home tjat could be doing this. Closing the stomato so it can't breathe which in turn no uptake and then death. We've done the pythium attack. You make it. Your input? No it's not nute lock. Lol

Alchimia Staff

Tim Alchimia 2020-01-31
Hey Fred, thanks for your comment. I'm really sorry to hear about all the trouble you've been having there. That sounds dreadful, there's obviously something seriously wrong for plants to die after such a short time. Have you checked with a microscope for mites? I know there are some microscopic mites that can cause chronic infestations and are very, very difficult to get rid of, even with all the measures you've taken. That's really the only thing that occurs to me here if you've looked at everything else. The only other thing to do is to think back to that time roughly a year ago when things began to go wrong and try to remember if there was anything that changed from normal, not just in the grow itself but in the rest of the building and the surrounding area as well. Is there any way you can check the air quality in your home? Something must have changed to cause such a marked difference in results before and after. I'm sorry I can't shed any more light on the subject, but I'm really curious now. Please let us know if you make any progress. Best wishes and good luck!


Candace 2020-01-12
I accidentally pulled my stem up I replanted but its wilted what should I do??

Alchimia Staff

Tim Alchimia 2020-01-13
Hi Candace, thanks for your question. Sorry to hear about your unfortunate accident, hopefully, the plant will recover. I'd be irrigating with some kind of kelp solution to help the plant deal with the stress of the "transplant", and a root stimulant to encourage new roots, but its survival will depend on a few factors, such as how badly the roots were damaged and how big the plant itself is. If it's a small, young plant with few leaves then it can recover quite fast and get back to normal. Of, however, it's a larger plant with lots of foliage it will have a harder time recovering because more leaves mean more demand for water, which the damaged roots can't keep up with. You can help by removing some leaves, which will put less strain on the recovering roots (when the plant wilts it is telling you that the water available to it isn't sufficient to keep the leaves alive). I hope that helps, all the best of luck and happy growing!


Natasha Crayton 2019-11-17
Greetings, My cannibis plants have been leggy for a long time. They are a few months old and have not flowered yet. Can I top off stem with new soil or will it rot or erode the stem?

Alchimia Staff

Tim Alchimia 2019-11-19
Hi Natasha, thanks for your question. Firstly, yes you can certainly pile more soil around the stem if the plants are very stretchy. As long as the soil stays moist and isn't water-logged then there shouldn't be any problems with the stem rotting. Some varieties will readily grow (adventitious) roots from their stem, while others will find it a bit more difficult. An application of beneficial microbes such as Trichoderma will help to keep any pathogenic infections at bay. However, If your plants are still in vegetative growth and you're concerned about not having enough headroom, you could always try pruning or training your plants to control their height. You say your plants are a few months old but haven't flowered yet... are you growing indoors or outdoors? If indoors, are you waiting for a certain time before switching them to a flowering photoperiod? Choosing the right moment to flip to flower is crucial if you want to make the most of the grow space, too soon and they stay smaller, not taking full advantage of the headroom, whereas if you let them grow too big during vegetative growth they will outgrow the space available to them. I hope that's some help. All the best and happy growing!

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