Medically Reviewed by
Jason Crawford

Article Last Updated on January 14, 2023

Getting your watering can and watering your weed plants may seem like the easiest thing there is, but the truth is that some growers, especially those new to cannabis cultivation, find it a bit hard to determine the right amount of water their plants need as well as the frequency of watering. If this is your first time growing in a cannabis grow tent and you’re wondering how you can develop a proper watering schedule, we’re here to help you out. However, if greenhouse cultivation appeals to you more, read through our guide and find out how much water greenhouse cannabis plants need.

It’s obvious that plants need adequate amounts of water to thrive, together with an adequate room temperature for growing, enough nutrients, and proper humidity levels. Since overwatering or underwatering your cannabis plants can lead to various growing troubles like nutrient deficiencies, nutrient burn, development of mold and mildew, and so on, adequately watering your plants is the key to growing healthy and thriving weed plants. 

This article will focus on exactly that, giving you the proper information to develop a watering schedule for your plants so they can thrive instead of just survive.

How Much Water Should You Pour Into Your Cannabis Plants?

As plants grow, it’s obvious they’ll need more water. Different stages in the life cycle of cannabis plants require different amounts of water (as do different varieties of weed), so watering your plants should be done according to the needs of the plants. 

Because Sativas originated in warmer environments, they’ve evolved to be taller and conserve water, while Indicas are bushier and shorter and don’t conserve as much water as Sativas. To figure out the appropriate amount of water for your weed plants is, you need to look into the variables covered below.

Cannabis Growth Stages

The life cycle of cannabis plants consists of 4 growth stages:

  • Germination stage;
  • Seedling stage;
  • Vegetative stage;
  • Flowering stage.

Depending on the maturity of the weed plants their watering schedule will differ. Even before your seed germinates, it needs water to sprout. After the sprouting period, it’s time for transplanting the seed in a growing medium, which means that it’s time to establish a proper watering schedule.

Seedlings consume less water than plants which are in the flowering stage, so growers should mist or lightly moisten the substrate in the first stages and use a watering can only after the plant reaches the vegetative stage. The plant will give you signals when you need to water it, meaning, the soil mix will be completely dried out and you’ll need to add more water for it to keep thriving.

The Growing Medium

Which growing medium you choose to use will greatly impact how much water your plant needs. The cannabis plant thrives in airy soils that drain well, and planted in pots that allow proper drainage. If planted in the wrong soil and pot, as the soil dries, the roots pull in oxygen, therefore the plants are overwatered and they “drown.” 

Growing mediums that retain water are the cause of nutrient deficiencies, rotten roots, mold, pests, and other problems in cannabis plants. To ensure proper drainage, add perlite to the soil mix which will aerate the soil mix and promote the growth of a healthy cannabis plant.

The Size of the Container

The size of your planting pot will affect how much water you need to add to your plant. A small plant in a large container won’t thrive, and this also goes for a huge plant in a small container. The way growers start their seedlings is in smaller pots, and pot them in larger containers as they grow.

Temperature, Light, and Health of Cannabis Plants

Other conditions also affect how much water a cannabis plant needs. The plants which are exposed to more light and heat will probably require more water and nutrients, compared to cannabis plants growing in colder temperatures. Moreover, a thriving plant will need more water compared to one that’s fighting a disease or pests.

How Do You Know if Your Cannabis Plants Need Water?

To determine whether your weed plants need to be watered, look into the following signs. Thirsty cannabis plants will droop and appear lifeless which may sometimes be confused with overwatered plants. 

Overwatering is even worse than underwatering your cannabis plants. Overwatered plants generally have a deep green color and bent downwards, which is how you’ll differentiate between them and underwatered plants. 

Underwatered plants appear like they’re yellowing, wilting, and their soil is completely dry. Slightly underwatered plants will recover a few hours after watering. Finally, your best option is to check the growing medium – if the soil is dry, add water, if it’s wet, wait a day or two. 

How to Water Your Marijuana Plants?

The aim when hydrating your plants is to give them enough water for the plants to thrive, but not overwater them. What do we mean by that? The amount of water needed to provide the root system adequate hydration is generally about 25–33% of the pot capacity.

In order to better water your plants, first water the middle of the pot and then the edges of the container. This method will encourage your roots to reach the edges of the container they’re potted in, and drive the nutrients that are at the top of the medium to reach the roots.

Keep in mind that the excess water that sometimes collects at the bottom of the pot can be a perfect breeding ground for the development of bacteria and fungi, so you may end up with rotten roots. Therefore, it’s important that you throw the excess water away after it collects.

Essential Tips for Watering Marijuana Plants

When watering plants, it’s essential that you follow these tips:

  • Avoid leaving your marijuana plants in runoff. The drainage holes let the water drain from the soil so the plants don’t stay in more water than they need. After the water drains and collects in the pot tray, you should dump it immediately to avoid the development of mold (or the plant getting infested by pests or bacteria). 
  • Keep the PPM (the amount of nutrients present in your medium) and the pH levels of the water balanced to prevent the lockout of nutrients (plants being unable to absorb the adequate nutrients). Hydroponically grown weed, or weed grown in coco coir, should have pH levels lower than 5.5–6.1, while weed grown in soil needs pH levels between 6.3–6.8.

How to Water Cannabis Plants When You’re Away From Home?

Keeping your cannabis plants hydrated is essential, especially when you’re not at home. Below, you’ll find relevant information on how to keep your cannabis plants alive even if you’re away.

  • Ask a friend to water your plants for you but make sure they know all they need to know about overwatering and underwatering, to avoid root rot and nutrient lockdown.
  • Make a DIY drip system which will give your plant enough water over time.
  • Create a makeshift greenhouse which will recycle the water that plants release and rain it back down inside the soil.
  • Purchase a sophisticated irrigation system which has timers and controllers (to provide adequate amounts of water to the plants on demand).
  • Purchase a slow drip system with an attached timer to keep your plants hydrated.

Flushing Marijuana Plants: An Essential Step Before the Weed Harvest or When Marijuana Plants Experience Nutrient Imbalance or Lockout

In order to have a quality harvest, flushing your weed plants is a vital step before harvesting and curing them. Keep in mind that different growing mediums have different flushing timeframes. 

For example, growing in soil requires you to flush 7-10 days before harvest, growing in rockwool and coco requires a 7-day flush period, while growing in hydroponics requires a 5-7 days flush period before you harvest your weed plants.

Flushing is also a good idea when your plants have too many nutrients, improper pH levels, too much water, salt buildup, or other stresses. The excess buildup will be removed by flushing the plants which will help restore the pH balance in the soil and bring your plant back on the thriving track.

Final Thoughts on How Often You Should Water Cannabis Plants

While there’s no ready-made option for how often you should water your weed plants, a good motto to go by is to “water well but not too often.” To cultivate healthy cannabis plants make sure they have enough nutrients, proper pH balance in the growing medium, proper humidity levels, and adequate amounts of light. Pair this with watering your cannabis plants as needed and you’ll have thriving plants and a great yield.

A passionate advocate for the benefits of cannabis. Fraser Horton, who has a background in botany and a strong love of nature, has spent years researching how cannabis affects the body and mind. He established Leaf Nation in 2020, where he has devoted himself to educating people about the legalisation of marijuana and its safe and responsible use. Fraser is committed to highlighting cannabis’ potential for improving wellness and working to dispel the stigma associated with its use.


The information presented on this page is provided as a public service to aid in education and is derived from sources believed to be reliable. Readers are responsible for making their own assessment of the topics discussed here. In no event shall Leaf Nation be held reliable for any injury, loss or damage that could happen if using or abusing drugs.