by Nebula Haze
Sometimes you want to start your cannabis seeds or clones directly in their final container. This saves time transplanting from smaller containers to big ones. However, when weed seedlings are growing in a big pot, they are easy to overwater so you need to make sure you’re watering plants properly. Read on to learn exactly what to do.
These cannabis seedlings were started in big 5-gallon plant pots. Follow the watering instructions in this tutorial to water seedlings in a big pot (like this) so they grow fast and healthy!
Learn how to grow happy, healthy cannabis seedlings even in a really big pot!
Quick summary: The key to watering cannabis seedlings in a big pot is to give just a little water at a time, and wait a few days between waterings. Once the seedling grows bigger, it drinks more and can be watered normally. Today’s article will explain exactly what to do, and I also included the exact seedling watering schedule that I use.
Note: Cannabis seedlings may grow a little slower at first when you start them in a too-big container (though good watering practices should overcome this). However, once they “get going”, cannabis plants in big pots tend to grow faster and bigger than ones in smaller pots.
Why cannabis growers should avoid overwatering seedlings
Overwatered cannabis seedlings get droopy, grow slowly, turn yellow, and may show signs of nutrient deficiencies. This can happen even if everything else you do is perfect.
This cannabis seedling was overwatered. Look at the dark and wet soil. This young plant can’t drink that much yet. The overwatering is why the seedling looks yellow, droopy, and unhealthy.
This overwatered cannabis seedling doesn’t have deficiencies, but it is already 4 weeks old and has barely grown. The cause is overwatering. Often when a cannabis seedling stays stunted or doesn’t get bigger, the grower needs to give water less often.
Learn more about how to help overwatered cannabis seedlings.
How to water cannabis seedlings or clones in a too-big container
When starting seedlings in a big container (for example, a 3-gallon plant pot or bigger), it’s important to slowly give just a little bit of water at a time until your seedling “grows into” its pot size. This prevents overwatering, which can dramatically slow down cannabis seedling growth.
This cannabis seedling is in a big pot. However, if you water it properly it should grow fast and healthy without getting overwatered.
By watering the right amount in the cannabis seedling stage, you can speed up growth significantly, especially during that first week or two.
For new seedlings, you should give water in a small circle around the plant instead of saturating the whole container.
Give seedlings only a little water at a time, and pour it in a small circle around the base of the cannabis seedling.
Small marijuana seedlings can’t drink more water than this!
Don’t give water again until the top inch of the potting mix is dry to the touch (which should be less than a few days if you did your job right). This makes sure your seedlings get a perfect mix of air and water so it grows as fast as possible.
Make sure to give water slowly in a small circle around seedlings until you get runoff water out of the bottom of the container. This makes sure that water is getting to your plant’s roots but isn’t over-saturating the container.
After the plant has started to “grow into” its container, the top inch of potting mix will start drying out quickly (less than a few days). At this point, you can start normal cannabis watering practices which means you saturate the whole growing medium until you get about 20% runoff water.
Example for 5-gallon Fabric Pot with Soil
This is an example schedule for watering seedlings in 5-gallon fabric pot. This should work well for most seedlings in most pots betwe 3-10 gallons because seedlings typically drink about the same amount of water. However, if you have a really well-draining grow medium like 50/50 coco/perlite, you may need to water a bit more at a time, or a bit more often, as these tend to dry out faster. As always, pay attention to what your seedlings are telling you.
- Day 1 – Give 2 cups (500ml) water per seedling
- Day 3 – Give 2 cups (500ml) water per seedling
- Day 6 – Give 2 cups (500ml) water per seedling
- Day 8 – Give 3 cups (750ml) water per seedling (every 3 days after this)
- Day 11 – Give 3 cups (750ml) water per plant
- Day 14 – Give 4 cups (1 liter) water per plant
- Day 17 – Give 4 cups (1 liter) water per plant
- Day 20 – Give 5 cups (1.25 liter) water per plant
- Day 23 – Give 6 cups (1.5 liter) water per plant
- Day 26 – Give 6 cups (1.5 liter) water per plant
- Day 29 – Give 8 cups or 1/2 gallon (2 liter) water per plant
- Continue giving 1/2 gallon (2 liters) per plant every 3 days. You may need to give more at a time or more often as plants get bigger. If you’re getting a lot of runoff out the bottom (more than 20%) or plants droop after watering, it means you should be giving less water at a time. If plants get droopy before being watered, you should give more water at a time, or water more often.
Note: This is the schedule that I use for a 5-gallon fabric pot, but your environment will affect how much plants drink. If plants are in hard-sided pots as opposed to fabric pots, you may need to water less often or give less water at a time.
Learn more about how to care for cannabis seedlings
Summary: How to water cannabis seedlings or clones in a too-big container
Beginning Stage
This is for when you’ve just planted your cannabis seeds or clones in a too-big container. By giving your young plants less water at a time following the steps below, you prevent overwatering which can slow down seedling or clone growth in a too-big container.
- Pour water slowly in a small circle around the base of the seedling (I first pour my water into a solo cup so that it’s easy to pour water around each plant).
- The circle should be ~2 inches in every direction from the base of your seedling (or if your seedlings are bigger, about the width of the leaves).
- Every time, make sure to continue watering slowly in a circle until you get runoff water out of the bottom of the container. Make sure to remove runoff water so it doesn’t get re-absorbed through the bottom of the container.
- Don’t water again until the top inch (up to your first knuckle) is starting to feel dry to the touch.
Regular Watering Stage
Once your marijuana plants have established healthy root systems that can support the size of your container, you can start watering as normal.
- Once the top of the growing medium is drying out quickly, in less than 2-3 days, you’re past the beginning stage.
- Switch to normal watering practices. This means that you are watering the entire container until you get 20% runoff every time. Then don’t water again until the top inch (up to your first knuckle) is starting to feel dry to the touch.
Important: Always wait until the top inch (up to your first knuckle) is starting to feel dry to the touch before watering your plant again. This prevents both overwatering and fungus gnats.
Transplanting for faster growth
Transplanting means that you start your plants in a relatively small container, and then transplant the plants as needed so that their roots never run out of room.
Transplanting will provide your plants with faster growth if done right. This is because transplanting allows you to set up an environment where your roots are getting access to plenty of water and air. However, transplanting can stress your plants (and slow down growth) if not done properly. When transplanting, it’s important to carefully move plants so that their roots are not disrupted in any way. This means moving plants before they get root-bound, and creating a hole in the potting mix of their new container so the plants can be placed right in without disturbing the roots.
If you plan on starting your plants in a small solo cup and transplanting your plants to bigger containers as needed, take a look at this transplanting guide.
While transplanting makes it easier to give your young plants access to plenty of water and air, it can stress the plants if not done right, and it can also be too much work for some growers. So many growers start their plant in its final container.
When seedlings or clones are started in a large container, it can be difficult to get enough air to the roots until the plant is bigger and drinking a lot. This is because when the potting mix gets soaked, the seedling roots just won’t be able to drink it fast enough, and the roots will end up sitting in stagnant water with very little access to oxygen. The growing medium has to dry out on its own, which can take a while, and your plant will be droopy and overwatered until the roots start getting access to oxygen again.
Some growers start their seedlings or clones in a bigger pot, or even the final container they plan to use. While this can slow down the growth of young seedlings, you can minimize this effect by watering young plants correctly when they’re started in a too-big container.
