by Nebula Haze
Tired of weird germination methods? Start your cannabis seeds directly in the final container to simplify the beginning of your grow. However, it’s easy to overwater seedlings in a big pot, so growers must water cannabis seedlings carefully to avoid overwatering.
Follow the watering instructions in this tutorial to water cannabis 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 container!
Quick summary: The key to watering cannabis seedlings in a big pot is to give just a little water at a time, and not too often. Once a 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.
Water seedlings in a small circle around the base.
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
- Afterward – Wait until top of soil is dry, then give enough water for 10% runoff
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.
Seedlings don’t drink much yet
How to water an “adult” plant (over 30 days old)
- Get 10% runoff every watering – Give enough water that you get about 10% extra runoff water out the bottom. Don’t let plants sit in water on a regular basis, otherwise the roots or base of the main stem may start to rot. The easy solution is to always remove the runoff water. A big syringe or wet vac works great to remove runoff water. Put a little piece of plastic or a couple stacked coins under the tray in the back, as a slight incline causes the runoff water to naturally pool forward for easy removal. Learn more about how to easily water plants and remove runoff water.
- Let top of soil dry before watering again – If growing in soil, let the top inch dry to your first knuckle, before giving water again. If growing in coco, wait until the top looks mostly dry. Not sure whether plant needs water? Try picking up the pot a little. Pots feel surprisingly light when they need water. If the pot feels heavy like it’s got bricks inside, the plant already has plenty of water.
Note: If you’re trying to avoid getting runoff, for example you’re growing in a “just add water” soil, continue giving 1/2 gallon (2 liters) per plant every 2-3 days. You may need to give more at a time or more often as plants get bigger, especially during the water-hungry flowering stretch period.
Learn more about how to care for cannabis seedlings.
Instead of a watering can, I use a battery-powered liquid transfer pump to water my cannabis plants.
Watch out for…
- Too much runoff – If you’re getting a lot of runoff out the bottom (more than 20%), it means you should be giving less water at a time. There’s not much benefit to putting that much water through the grow medium, as it can increase the chance of overwatering, and also washes out some of the nutrients. Plus it’s just more work for you to remove all that extra water.
- Plants feel weirdly light – Sometimes growers get warned so much about overwatering they unintentionally give plants too little water. Most of the weight of a plant comes from the water, so here’s a way to check for that. If you ever pick up your plants, and it feels weirdly light, that’s a sign it needs more water, or more water at a time.
- Drooping after watering – Some sensitive plants droop immediately after watering, which can be normal. But they should quickly bounce back, happier than ever. However, if you water plants thoroughly and they are still drooping 24 hours later, it likely means they were overwatered. They might need less water at a time, and/or more time between waterings.
- Droopy before watering – If plants get droopy before being watered, they likely used up their water before you gave them more. If plants regularly are drooping before watering, and seem happy after watering, you should give more water at a time, or water more often.
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, like a cup, and then transplant the plants as needed so that their roots never run out of room.
Transplanting provides your plants with fast growth if done right, but transplanting can stress your plants (and slow down growth) if not done properly.
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.
However, if you want to avoid the work of transplanting and the chance of stressing plants, start seeds straight in your final pot. As long as you follow today’s tutorial, your seedlings will grow fast without getting overwatered, and you never have to move them.
Happy growing!
Nebula Haze, Co-Founder of GrowWeedEasy.com
