Underwatering Weed Plants & Overwatering Solutions

When it comes to over or underwatering your marijuana plants, there are a number of factors that will determine how much and how often you should be watering them.

These factors include the size of the plant, the size of the container your plant is growing in, the canopy, the root level, the temperature of the grow room, the humidity level, and which stage of growth your plant is currently in.

Larger plants generally need more water than smaller plants, and larger containers won’t need to be watered as extensively.

You will need to water more during hot weather, but if the humidity level is high, then you won’t need to water as much.

When plants are in their final stages of the flowering phase, they consume less water and therefore you will need to water them less than normal.

If you water your plants incorrectly, the roots of your marijuana plants could dry out or start to rot. In either case, the effects are detrimental to the health of your plant.

Signs of improper watering

Signs of improper watering your cannabis plant


If you are watering your plants too much, their roots will start to drown. There won’t be any discoloration to indicate a problem, but the leaves will begin drooping and the overall look of your plant will be tired and unhealthy. There might also be chlorosis or yellowing of the plant’s leaves. Make sure you don’t confuse drooping plants with wilting plants, as they are caused by two opposite problems. Drooping leaves mean the entire leaf is curling, not just the tips of the leaves.

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With overwatering, the growth of your plant will be extremely slow, or it might even stop. This all happens because of the anaerobic condition that develops from an overwatered plant. The roots have no use for carbon dioxide, but plenty of use for oxygen. Too much water can moisten the valuable air pockets where oxygen is stored, making less oxygen available for the roots to absorb. The roots will consequently function incorrectly and won’t be as potent as before after a while. They will also fall victim to pathogens much easier.

If your plant is experiencing these symptoms, the cause is probably due to the frequency of your watering schedule combined with a planting mix that is unable to drain the water effectively. Perhaps it is only because of drainage holes in the container since they are essential to keeping your plants’ roots from drowning. The soil itself could be made up of too small particles, meaning they are packed together more tightly and don’t let water flow through as easily.


Your plants will wilt (rather than droop) and will experience slower growth if they aren’t receiving an adequate amount of water.

How to fix improper watering

How to fix improper watering

A good rule of thumb to water your plants properly is to wait until the soil is drying (but not yet completely dry) and then water it enough to last it until the next scheduled watering.


You should always wait to water until the top layer of the soil (one inch deep, or to your first knuckle) is completely dry. Then water the soil only until there’s approximately 20 percent of it draining from the bottom of your plant’s container. If you notice the soil remaining damp for a significant amount of time, either the drainage needs to change or your amount of watering needs to change.

Sometimes growers simply lift up the pot their plant is growing in to see if it feels light or not. If it feels light to them, most of the moisture is gone and, therefore, the time for watering their plant has come. At first this might be difficult for people new to this method, so you can compare it with another pot that you fill with the same growing medium – but don’t water it. This will help you know what a “light” pot should feel like. When you do this, you can lift the actual pot with the plant in it up to see if it is similar in weight to the dummy pot. After some experience with this you should no longer require the dummy pot to know if your plant needs watering or not.

If your plant is exhibiting signs of overwatering, you should try to solve the issue immediately. First of all, if your plants are growing in containers, you should make sure that the drainage holes are clear and working well. If there aren’t any drainage holes to begin with, cut them with a knife, drill, or heat-based tool. Drainage holes are crucial for your plant’s root health.

If that is clearly not the problem, test out the soil to see if the particles are too small. Do this by watering the mix and seeing whether the water drains out freely. If it doesn’t or comes out quite slowly, the problem is probably the particle size of your soil or planting mix. It is considered to be draining too slowly if it takes more than a minute or two for you to see water coming out of the bottom. If this is indeed the problem, you can solve it by simply watering your plants less often. In the future, go with coarser soil or planting mixes that are more aerated. Keep in mind that it is especially difficult to avoid overwatering your plants if they are small but are growing in a large container.

If you are growing your plants outdoors, it could depend a lot on the natural type of soil in the area. Clay-based soils or soil that experiences heavy rainfall will not drain well. On the other hand, sandy soils might have drainage rates that are too fast. Know your soil and adjust your watering routine accordingly. The most basic way of combating an overwatering problem is to add in time between each scheduled watering, then allowing your plant some extra time to absorb smaller amounts of water until it appears happy and healthy again.

Another simple way of increasing the oxygen and decreasing the amount of moisture in any soil-based growing medium is to poke holes into the soil with a pen or pencil. This will allow the soil to aerate (have more oxygen).

For hydroponic system growers, signs of overwatering are really signs that there is a root problem. This could mean root rot is not allowing them to absorb enough oxygen, or there is not enough oxygen that has been dissolved in the water. You can use an air pump or air stones to solve this problem.


If your plants are not getting enough water, you will need to adjust your watering schedule in a different way. This problem is easier to fix that an overwatering problem – you simply need to water your plants more. If they are starting to wilt, feed them more water. When first starting to fix the problem, don’t use water that has been enriched with any fertilizer, since that will not help. Instead, use pH-balanced water that is plain to re-hydrate your plants. Once they have stopped wilting and look like their normal, upright selves, you can go back to using the fertilizer enrichment.

The tricky thing about underwatering is that you might not identify it at first, since slowed growth is sometimes difficult to notice. They will, however, undergo a noticeable spurt of growth if they begin receiving higher amounts of water (assuming they also have enough nutrients to begin with).

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Robert Bergman


Robert Bergman is an Amsterdam-based marijuana grow expert who has years of experience from small grows to massive operations ... See profile

32 comments on “Underwatering Weed Plants & Overwatering Solutions”

  1. I have learned the best way to water your plants is to use a scale.
    You need to find your reference points. Note 3 points.
    1 pot with fresh mix when you open a new bag. (Good start point/avg)
    2 is wet (after runoff stops).
    3 is dry .

    Example: 3 gal pot with fresh promix weighed 7 pounds. After full watering and runoff stops, pot weighs 12-14 pounds. When dry pot weighs 5 pounds( @4 pounds see slight wilting)

    On my calendar I mark in the mix I’m using(ph+ec),pot weight wet and dry and the runoff numbers(ph+ec) when I water heavy and mid+final flushing.
    With practice you will find your range(amt of water vs days between) don’t go too dry(light) nor consistently too wet.
    Monitoring these will also give you an early sign when something is wrong. ( pot stays heavy not using water, runoff ph too low/ec too high)
    There’s a good video on YouTube about watering more frequently with smaller amounts. He believes that keeps the nutrient more balanced.

    • Don,

      Impossible to tell from your brief statement. I suggest you join us at support.ilovegrowingmarijunana.com. We have many helpful and friendly members as well as expert staff to guide you. 🙂

  2. We planted in a forest environment May 22, 2017 (plants 2-3 inches in “red cups..).” We dug the wide holes and did all necessary prep. Water crystals really helped us maintain rainwater when necessary in the woods/wilderness. All plants are doing well (5-6 feet with flowers). Problem,One strange bit of nibbling on the wood appears to be from a “beaver…” because we’ve found piles of cut trees. Any comments on whether beavers bite pot “stems,” but don’t eat the greens?

    • Greatads,

      It might be that they just do not like the taste or somehting in the plant is noxiuos to them. Good question.

  3. Here’s my story….started plants Inside under light and moved them outside into ground May 11. Nice 6 foot plants, lots of foliage. Now Sept 7 no buds. What happened??

    • Ron,

      You gave me little information to go on. NO idea what seeds you used, no idea of grow methods or anything else. There are many factors. that could be your issue. I have never heard of a plant not flowering outdoors unless it is a Male.

      Also; In May, the days are still getting longer. So you really have only been getting shorter days needed in flowering photo period for 2-3 months. A sativa takes 4 months in flower approx. IN May and June daylight is more than 14 hours or thereabouts. Plants do not create buds until they start to receive only or less than 12 hours of light per day.

      Join our forum and ask around. Many experienced growers who are always willing to share.

  4. My husband sprayed vinegar/water on our plants last night to help with the ph cause we were out of ph up and with in hours my leaves were drooping how can i fix this? My stems on each plant still has bulbs that look like they are coming out. Help

    • Rosesforeman,

      I am saddened by your account of what happened. Let me try to put some thoughts in a simple order.

      1. vinegar is aicidic
      2. ph up is alkaline
      If you needed a home remedy for ph up; you use baking soda “sparingly”. Get commercial stable ph up, asap.

      spraying anything on your plants is risky. Spraying vinegar, an acidic solution, is a bad idea.

      I hope you can come and join me and our support community at ilovegrowingmarijuana.com. We will help you grow successfully from start to finish. I promise! 🙂 – I❤️GM

  5. Has anyone tried a “grow box”…indoors? Growth is so slow I’m wondering if the system keeps the soil too damp?

    • Temple,

      I advise you to check with the seller of the grow box. This is an article to help growers to understand the watering a plant. Perhaps it would help you to join our support forum. 🙂 We have many knowledgeable and helpful members there and some use grow boxes.

  6. a friend told me….like tomato plants…..weed plants do not like the water to hit the leaves. Do you agree?

  7. So I have 1 plant that needs to go to flower. I also have 3 that are a few weeks old. I’m growing in a med sized closent. What do I need to do?

    • Jay,

      Flower then all. If you have some plants a few week in veg’, then you can flower them all. If your grow methods are sound, then you will be a
      Happy harvester”! 😀

      • It seems that a lot of you are making this process harder than it really is. I grow a couple of plants at a time for personal use only. I simply soak my seeds 48 to 72 hrs in shot glasses. I plant directly in my 5 gal containers under 2 t5 lights approx. 18 hrs daily. After a couple of weeks I switch to my 400 watt HPS lighting. I water when the plants need a drink ( mostly depending on size) I check them on a regular basis and don’t mess with them much. Watch over trimming as they grow and just let them do their thing. I built a 8×8 grow room with A/c and heat and keep all my numbers in check (temp, humidity etc). I don”t think my yields are large enough but, my quality is excellent. It just seems some are creating problems by over tinkering. Keep it simple, these are smart weeds you’re growing. Hope this helps.

  8. I watered my pot plant in now the leaves are dropping down in wilted I don’t no if it under water or under watered the soil is moist what do I do if I need to show you tell me help please

    • Your OVER WATERING. YOU CAUSE stem rot GET SOME H2 O2 hydrogen peroxide mix 2 t spoons a gallon STRAY ON EVERY STEM to prevent stem rot. If you put too much on or if too stronge it burn the bark. So LESS but more OFFEN the key.. Once a week for a couple of weeks just get spray bottle STOP WATERING .. 2 weeks let them really fro out. Try a leaf spray cool water after a week in EVENING see how they respond. Once they dried out start with 1/2 the water you were giving them. The co op growers are almost GIVING AWAY their last year harvest 30 OZ top bud, including colas. Most are harvesting right now IN July or AUGEST, one to 1.5 pound plants s tarted outside in Feb and March. So we could have big outside plants ready to harvest in another 30 days

      You can too have colas so huge the top 10 inches weigh almost 1/2 pounds WET. I just love 4 to 6 ounce dry colas. REMEMBER. Smaller buds are easier to get into grinder. They are so damn STICKIE you have black finger tips from all the resin

      HOW MANY people so you know who have seen a MALE CANNABIS PLANT in full blum…. I never have… If it has balls, it has got to go.

  9. Hi,plz help,I did buy 2 type npk ,for vegetation stage 20 ,5,5 for flower stage 20 ,20,20
    Do u think is OK?can u tell me withch dosage in the time I should use ,for indoor with 800w hps 2 m square

    • jason buy his book its just up there on the right hand side, or would you rather he just nip over to your growroom&grow them too?infact he may aswell trim&smoke it for you aswell..