(Recommended) Start seedlings in smaller container until they’re growing vigorously, then transfer to a larger container If seedling is already in a big container, there’s still hope! When watering, give just a little water at a time in a small circle around the seedling. Then allow the top inch of your medium to mostly dry before watering again. Once the plant is growing vigorously, start watering as normal (with extra runoff water coming out the bottom every time) These small cannabis plants (below) were put in big pots, and were given enough water to support a much larger plant. The plants couldn’t drink all the water that was given to them and as a result, their roots weren’t able to get the oxygen they needed and started “drowning.” Once the roots are out of commission, the leaves start drooping.
One way to prevent this from happening is to make sure your plants are in an appropriately sized container for each stage of their life; this is done with transplanting. First, you need to get a general idea of the final container size which will be based on how big you want your plants to grow. The less often you transplant, the bigger the final size pot you’ll need because the roots will tend to grow out and cover the whole container if left too long. You can help avoid problems with roots getting rootbound by using a fabric pot (also known as a “Smart Pot”) or an air pot. Final Container for Desired Plant Size – General guide (the less often you transplant your plants, the bigger final size you’ll need) 2-3 gallon container. But what size pot should you use for your seedlings? For fastest growth rates, it’s better to plant young seedlings or clones in a very small container, like a disposable plastic solo cup. For new seedlings and clones, use a small container if possible.
Easy transplant guide – some popular transplant guideline: Solo cup -> 1 gal -> 3 gal Solo cup -> 1 gal -> 5 gal Solo cup -> 2 gal -> 5 gal Solo cup -> 1.5 gal -> 3 gal -> 5+ gal. There is no perfect transplant guide, but the one above should give you a general idea of where to start. Why don’t you want to go from a solo cup to a 5 gallon pot? Young plants won’t be growing very fast yet, so they also won’t be using much water. When you completely saturate a big container that slow speed means that the plant won’t be able to drink all the water. Since so much of the water is contained in the middle without access to air, it won’t be able to dry out by evaporation. This means you’re left with a huge container full of wet potting mix. The young cannabis plant roots will quickly use up all the available oxygen that’s been dissolved in the water, and then the roots will sit in water until the water slowly evaporates on its own. Some containers such as smart pots and air pots allow air in from the sides, which can help dry the growing medium faster, but it’s better to use proper technique from the beginning. Planting in too big a container is sometimes called “overpotting.” It’s possible to get around this with special watering techniques (for example by giving plants just a little bit of water until they start “growing into” their containers) but starting plants in small containers and transplanting as needed can be a more straightforward way for some growers. Overpotting plants is also a waste of growing medium and nutrients, especially if the plants never get big enough to fully use their containers. This OG Tahoe Kush seedling was overpotted, though this can be overcome by the grower just giving a little bit of water at a time until the plant starts growing vigorously. At that point, the grower can provide more and more water until they’re finally watering normally. More information about container size and transplanting here: https://www.growweedeasy.com/germinate#what-size-pot. While using a too-large container can cause problems for seedlings, so can too-small of a container. Seedlings are happy in a small container like a solo cup for a while, but as they get bigger, their roots need more room. The roots tend to wrap around the outsides of the container, encasing the middle part so that water can’t get out. This is known as the plant being “root bound.” If the seedling isn’t transferred to a bigger container in time, it can cause symptoms of overwatering, nutrient deficiencies, wilting, and sometimes very strange and unpredictable symptoms. These plants were left in a too-small container for too long. Because they were drinking so fast, the grower watered them frequently – too frequently! This combination of being root bound and overwatering caused the plants to suffer. A too small container, combined with overwatering – these conditions can cause some strange symptoms that often look like a nutrient deficiency. Pink leaves, red discoloration, rusty spots and edges… While it make look like these cannabis seedlings are experiencing nutrient deficiencies, all these symptoms are actually caused by a combination of overwatering plus a too-small pot. When the roots aren’t happy, the plant isn’t able to uptake nutrients properly and cannabis seedlings can show a wide variety of strange problems. It’s usually not a good sign when cannabis leaves start “crossing their fingers” like this (instead of having all the leaf tips spread out). While this can happen naturally every once in a while, you know for sure that you’re having a problem if the crossed fingers are combined with discoloration of the leaves. The following cannabis plant was also overwatered and had no drainage.
Notice how dark the soil is and the green algae growing all along the top of the soil – these are more signs the plant has been overwatered for quite a while. You should never water your plant when the soil on top is still wet, and if you notice lots of algae growing on top of your soil, it may be a sign that you’re overwatering on a regular basis.
Leaving the top of the soil wet is also the number one reason growers get fungus gnats. No Drainage (or poor drainage) Cannabis roots need oxygen to thrive, and therefore they will have trouble if the roots are “drowned.” If water cannot run out the bottom of the container, it will pool at the roots, which causes overwatered plants. Always start with a good growing medium that drains well – never use a clay based soil which holds onto way too much water.