What marijuana plants need

Have you been thinking about growing marijuana plants, but hesitated because it seemed hard? Growing a weed plant is easy; it’s growing a healthy one that’s the challenge.

You can’t learn how to grow the best weed plant from a single article, but you can learn some of the basics. I’m going to teach you what weed plants need to produce the best harvest. 

Basic facts about marijuana plants

Two of the most confusing aspects of growing marijuana is knowing what weed plants need and how much of it to give them. In fact, most growers fail at this many times before they eventually grow healthy plants. Truth is, it takes a lot of time and effort to yield optimal results.

Download my free Grow Bible to learn all about growing healthy weed plants!

However, when you learn the fundamentals, you’ll reach that point much faster. 

Weed plants have needs 

Generally speaking, cannabis plants grow fast without much help. However, they still benefit from well-balanced nourishment.

The proper nutrients can strengthen the plant, increases their resistance to diseases, and accelerate their growth. They also help weed plants produce high yields of those potent buds we enjoy.

In other words, a weed plant flourishes when it has everything it needs to thrive. But what are those “things”? 

If you are a first-time grower, you need to know the answer to this question. These “things” are important because they aren’t just required for growth; they decide how successful your plant can be.

A lack or excess of any of them can cause your plants to stress. From experience, I can tell you, a stressed-out plant is a lot harder to grow. 

6 Things healthy marijuana plants need

Knowing what your plants need is the first step to growing healthy weed plants. Thankfully, these needs can be easily placed into six categories. Once you learn these six ‘things,’ you can provide them in proper amounts.

Adequate water

Water is the foundation of life. As we know, all living things depend on this element for nourishment. This is especially true in marijuana plants as water plays a variety of crucial roles for sustainability. For example, water is what gives a weed plant its vigor and flexibility. It also regulates the plant’s internal temperature.

Adequate watering
Adequate watering

It should be no surprise that a weed plant will suffer when it gets too much or too little of this element. 

Looking for some watering tips? Check out our ultimate guide on watering your marijuana plants!

I cannot overemphasize the importance of proper watering.

  • Overwater: the roots can choke as they struggle to get oxygen. 
  • Underwater: the plants become thirsty and unable to regulate their temperature.

So, before you start growing, learn the correct way to water your weed plants to avoid newbie mistakes. The good news is watering problems are often easy to fix. 

Correct temperature and humidity

The right temperature and humidity play a huge role in the growth of healthy cannabis plants. During the germination period, you want a gentle, stable heat. As the plant grows into maturity, the ideal temperature floats between 68 and 78 degrees Fahrenheit.

Correct temperature and humidity cannabis plant seedling stage
Correct temperature and humidity cannabis plant seedling stage

In hot temperatures, weed plants can lose a significant amount of moisture, which can lead to stress. In contrast, very low temperatures can cause the plant to stop absorbing and circulating vital nutrients. The same goes for humidity. That’s why one of the best ways to grow healthy weed plants is to simply monitor temperature and humidity levels.

If all of this seems daunting, don’t let it scare you. A weed plant can grow in any environment. This entire article is about producing the best possible results.

If you are concerned about providing the optimal temperature and humidity for your plants, you can start with strains that are most likely to survive less than optimal levels.  In the wild, weed plants naturally adapt to their environment. As a result, some strains can withstand ‘extreme’ temperatures better than others. 

Marijuana strains for extreme environments

blue cheese strain

Buy Blue Cheese seeds

  • 80% Indica 20% Sativa
  • THC levels up to 19%
  • Fast-flowering grow in- and outdoors
  • Delivers a strong indica effect
  • Feminized seeds for guaranteed bud
purple haze

Buy Purple Haze seeds

  • 30% Indica 70% Sativa
  • THC levels up to 20%
  • Great yield & easy to grow
  • High energy long-lasting buzz
  • Feminized seeds for guaranteed bud

Good soil

Before you start growing marijuana, you need to find the best possible soil. If you start off with the wrong soil, you can end up with weak and sick plants. Look for the potting soil with the following traits.

Balanced pH Level

The right pH value in the soil helps the roots absorb more nutrients. For marijuana plants, the ideal acid-basic balance is anywhere that is close to 7. But even the best soil can exhibit imbalances in the pH level once it is overcrowded with nutrients. Therefore, growers must be vigilant in regularly checking pH levels to ensure the soil is optimal for the roots.

Good drainage

When choosing the right soil, we should also consider how well it drains water. As we know, the roots will have a hard time taking in oxygen when there’s too much water. But at the same time, we don’t want soil that is so loose that water easily runs through it, leaving little for the plant to drink. 

a young marijuana plant growing on soil
Good Soil

That’s why you want to stay away from clay and sand-based soils. A potting mix with perlite can help with drainage.

The proper amount of nutrients

Nutrients are crucial for a marijuana plants’ production of big, dense buds. On top of that, a lack of these elements slows down growth and makes plants susceptible to pests, molds, and diseases. On the other hand, an excess can alter the pH level of the soil or causes nutrient build-up that prevents root absorption.

Bergman's marijuana nutrient set
Right Amount of Nutrients

There are two types of nutrients:


These nutrients provide your plants with their most basic needs. As a result, marijuana plants consume a lot of these to support their rapid growth. The macronutrients include nitrogen, phosphorus, and potassium.

Each mineral plays a significant role throughout the life cycle of the plants at different times. So, to get the best results, learn how to adjust and balance their amounts.


Although not consumed as heavily as the micronutrients, these minerals are also essential to a marijuana plant.  Some examples are calcium, manganese, zinc, copper, and iron. Very few of these minerals are used by the plants; however, a deficiency or excess can be a serious problem.

Just like temperature and humidity, certain marijuana strains are better able to survive nutrient problems. Here are a few strains to try if this aspect of growing seems challenging. 

Marijuana strains least likely to suffer from nutrient problems:

White Widow Autoflower

Buy White Widow seeds

  • All our autoflowers are feminized
  • 60% Indica 40% Sativa
  • THC levels up to 19%
  • Very easy to grow plants
  • Euphoric high with powerful mental buzz
Jack Herer marijuana strain

Buy Jack Herer seeds

  • 40% Indica 60% Sativa
  • THC levels up to 20%
  • Highly resistant to diseases
  • Long-lasting energetic buzz
  • Feminized seeds for guaranteed results

The right amount of light

The cannabis plant is relatively self-sufficient because it can make its own food. However, to make that food, weed plants require a good amount of light to convert carbon dioxide into sugars. Therefore, not enough light is detrimental to growth. 

A weed plant that does not receive enough light will stretch to get closer to its light source. When this happens, you’ll end up with thin plants that have very few leaves.

proper lighting technique
Proper Light

On the other hand, too much light can burn and weaken leaves. The good news is, you can easily control the amount of light that your weed plants receive. If you are growing indoors, simply adjust the distance of the light.

Outdoors, this could be a little difficult to control, but you can position your plants so that they receive direct sun for optimal exposure.

Aside from nourishment, light is also crucial for your plant’s transition through its lifecycles. This matters because you need to know when it is time to harvest. 

Download the Free Harvest Guide for more on harvesting marijuana.

Sufficient air

When you are growing weed plants outdoors, you probably aren’t thinking much about airflow. However, indoors, a well-ventilated grow room is a must.

Ventilation and air flow
Proper ventilation and air flow

If healthy plants with huge buds are the goal, then you must ensure there is enough fresh air. As a bonus, this also helps in minimizing the overpowering scent those weed plants will produce.

Carbon dioxide

In addition to airflow, indoor growers must also monitor carbon dioxide levels. Weed plants require carbon dioxide to maintain their overall health. As mentioned above, this element is converted to sugar, which the plants convert to energy.

Therefore, a good amount of carbon dioxide is essential for them to thrive.

To get sufficient amounts of this element, most growers install CO2 generators in their grow area. Doing so usually results in larger, higher-yielding buds

Growing indoors can be challenging for beginner growers, but it’s easier if you start out with the best strains. These strains are great for growing indoors. 

Marijuana strains best for beginner indoor growers:

buy super skunk autoflowering seeds

Buy Super Skunk seeds

  • All our autoflowers are feminized
  • 80% Indica 20% Sativa
  • THC levels up to 14%
  • Very easy to grow plants
  • Skunky smell with relaxing full-body high
buy sour diesel autoflowering seeds

Buy Sour Diesel seeds

  • All our autoflowers are feminized
  • 40% Indica 60% Sativa
  • THC levels up to 20%
  • Great for new growers
  • Energy-driven psychedelic high

Why having a healthy weed plant is important

When growing anything, you probably want it to be healthy. The main reason is that a healthy plant is easier to grow than other options. However, when growing a weed plant, the need for a healthy environment is even more critical. Chances are, you will be consuming the flowers of your weed plant, and you’d like those to be the absolute best.

The good news is anyone can successfully grow marijuana. Over time they can become an expert. 

Growing a healthy weed plant is merely a combination of the right knowledge and practice. Before you start growing, do your research and learn everything that you possibly can.

Then jump right into it and start applying that knowledge to your plants. 

With a lot of patience and practice, you and your plants will get better. 
Make sure to get your seeds before the season starts!
Check out my marijuana seed shop!


What are autoflowering plants?

Autoflowering marijuana plants are weed plants bred to enter the flowering stage without the assistance of light. Not only does this speed up the process of growing marijuana, but it also creates smaller, easier to manage plants. Learn more about autoflowers in this article.  

Is it easier for beginners to grow outdoors?

Growing marijuana outdoors has different challenges than growing indoors. For example, you cannot control light, temperature, or humidity and it is harder to keep pests away. However, the costs to grow outdoors is less. Learn more about growing outdoors in this article.  

Are there nutrient products designed for weed plants?

Yes, there are! I recommend Bergman’s Plant Food.  However, if you are unable to purchase cannabis-specific nutrients, you can use products that are designed for tomatoes.

Avatar for Robert Bergman

Robert Bergman


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

65 comments on “What marijuana plants need”

  1. Hi there,

    Thanks for your message. We currently only ship to the US, unfortunately. But hopefully when things change in Mexico, we may eventually consider shipping there as well!

    Kind regards,

  2. im gonna read the downloads i downloaded few important sections and will tell a comment about your book about knowing info thats important to anyone on what we need to know I hope i do good im scared I adopted a friend nice female very sweet and loves my presence in the room and attention i need know more bout her care shes in bud and how much do i water her and light and dark how much hours on and off all that I need know asap

  3. My weed plant is starting to turn dead looking in spots. My friend says its getting too much water. Has been raining alot lately. What must I do to save my plant?

  4. My plants are just entering the seedling stage. Grand Daddy Purple. They are growing great. Watering ever 3 days approx (when dry 2” down and pot is light). Using light grow nutes with pro-tekt and some Cal-mag. LED lights about 24” from plant tops. Everything looks god and plants are growing faster every day. The only issue (and may not be an issue), is lime green almost like stripes on one plant. Actually growing better than other. Just lighter green stripes on this one. Any ideas what this could be? Thanks so much for your help.

  5. Can you use fish liquid based fertilizer for marijuana plants and if yes when do you put it on the plant or in the soil.

    • I would really like to learn how to grow marijuana indoors I would love to have a grow book or Bible to teach me step-by-step what I need I have good seeds just need to know what else I need step-by-step if you can help please help me thank you

  6. I have a plant that starting to develop 1 Really Green curled up leaf? It has 1 leaf and starts out dark green curled up in ball then shoots out but it’s 1 leaf?

  7. I haven’t grown since the mid 80’s and im sure some things have evolved!i also raise poultry and take the chicken droppings and soak in water. After a week or so i decant the liquid and dilute it 10:1 and use it in a spray bottle. Try it, it works well!

  8. Hey I am so new to this an need to know if my plant is OK or not it grew the first two real leaves bout 5 days ago an now there is one more leaf an I thought they come in 2 at a time is this normal

  9. A pleasant and helpful article for a new grower like me. I learn some tips to grow cannabis from this article and apply them while growing cannabis. I started growing cannabis three months ago after I got my MMJ card from the OnlineMedicalCard and got a good percentage of female flowers in my harvest.

  10. I’m thrilled to tell you I’ve got three plants in the vegetation phase. I went with the white widow beginner package. Tomorrow I’m planning CO2 generating with dry ice and hot water. So far my little grow hobby is thriving. Thanks for all your guides and valuable information

  11. I want to grow two plants at a time I’m thinking a 4 X 4 tent with a 1000 watt full spectrum led Not sure though if my tent and light are correct. I’m researching before I buy.

    • Gayle,

      A 4×4′ tent is perfect for 2 plants and you can achieve max yield by growing just 2 plants in that space. Air circulation will be good, and there will be space for the plants to branch out. I have grown 1.5 LB. in a 4×4′ tent. Genetics is the key to successful growing.

      visit our seed shop for the best genetics and guarantee on the W3. 🙂

      Happy growing

  12. Robert,
    your site on how to harvest is not working. Can you tell me what I have to do.

    Jim Jacobs

    • Jim Jacobs,

      I am not aware of a how to harvest site. We have a Blog, a Support forum and a seed shop. Pwerhpas you should just join us at support.ilovegrowingmarijuana.com

  13. Hi guys, I’ve been with ILGM for about 4-5months. All of my seeds have germinated & produced great results for my outdoor grow(Southern Hemisphere). I am now looking forward to beginning to grow indoors. Is there a beginner set-up? Or tent/light package available for a novice who only wants to grow 1plant at a time & keep the grow as basic as possible? Thank you & happy growing !

  14. Got my blueberry auto flowering seeds about 2 weeks ago and set them in damp paper towel 4 days ago and all 5 germinated! I have high expectations.

  15. Where do I measure temperature and humidity? Is it at the top of the canopy or down by the top of the planting pot?

    • Yes measure the canopy on both sides & also measure about 1-2feet under the canopy & make sure there is plenty of air flow through the garden.Lockey

  16. Can you manage the soil’s ph by using PH balanced water on a regular basis? I have the ability to regulate my water’s PH

    • John,

      Yes and No. By using properly PH 6.5 you can manipulate the dailt 1st drink. The best way to insure proper PH in soil is to add Dolomitic Lime. Happy growing. Com see us in the forum – I❤️GM

  17. Salts are tough on yields. Fertilizers contain salts . Get top yields by reducing salts.
    MKP is rated lowest in Salts out of all soluble blends of fertilizers.

    Compare Salt Levels of Popular Soluble Fertilizer formulas


    Fertilizer Formula Salt Level
    High to Low
    Potassium chloride 120.1
    Urea 46-00 74.40
    UAN 32 71.10
    Potassium nitrate 13-0-46 69.50
    Potassium Thiosulfate KTS 0-0-25 68.00
    CAN 17 65.00
    NABTA-LIB 12-6-24 60.05
    NABTA-LIB 15-15-30 51.40
    NABTA-LIB 20-20-20 50.15
    Magnesium Sulfate 44.80
    Potassium sulphate 0-0-52 42.60
    NABTA-LIB 15-30-15 40.99
    NABTA UrP 17-44-0 30-40*
    Diamonium phosphate 29.20
    NABTA MAP 12-61-0 26.70
    NABTA MKP 0-52-34 8.40

    The Salt Index is based on the relative comparison to sodium nitrate. The Salt Index is the measure of the Salt
    concentration that fertilizer induces in the soil solution.
    Because Nabta MKP 0-52-34 (mono potassium phosphate) is Sodium free, Chloride free, and Lead free, it is possible to apply both as a drip/drench or as a foliar…. or both.. If you want to impress your friends with extra large buds apply MKP. Nabta MKP is Pharmaceutical grade, Food grade and Ag grade.

  18. Alan,
    they will form strong stems! 🙂
    You need a small oscillating fan as soon as your seeds pop and become seedlings. Thie fan will gently vibrate the seedlings and

  19. Karen,

    I don’t see where you mentioned an issue. “No flowers” You won’t see flowers for23-4 weeks from switching to 12/12, and then bud will develop from there.

    It might benefit you to join our support forum. We have many friendly and knowledgeable members always will to help and share. See you there 🙂

  20. Help! I purchased a growth chamber from DEALERZ.COM and it is designed to support growth of 6 plants, but I was concerned that 6 plants would be too crowded in the closet, so only grew three. It’s been six weeks and I have beautiful plants, but no flowering stage. Switched over to 12 hours of light and 12 hours of dark 5 days ago. Pruned plants because they were too close to LED light. Proper nutrients added weekly based upon instructions that came with growth chamber. What am I doing wrong? Any help would be appreciated.

  21. Mark,

    It is evident that you have either burnt the tips with light or over fertilized your plants. It is hard to give you an informed decision with so little information.

    I suggest that you join our support forum and, we will be able to help you our. When you join; Look around for topics with burnt tips. We have friendly members and expert staff always willing to help.

    Happy growing 🙂

  22. I received my seeds in a timely manner, well packaged and discreet. I decided to start with just two seeds since I am new at this. I placed my two seeds in two peat pots containing “germinating” soil. I has one seed that looked like it had been crushed, (the external shell was cracked and displaced. I soaked the two seeds in plain water. The “cracked” seed sank in about an hour so I planted it right away. The second seed sank in about 5 hours so I planted it right after it sank. 4 days later both seeds are up and making leaves!! It’s like having a new additions to the family!! I have a plan to create my own grow box with a few items that I have on hand or can easily get. I hope to keep this site posted on the progress. Here goes…can’t wait.

  23. I have the three pack of boosters, but I don’t know when to use them. Could you help me out by making me a simple list of when I should change over to the next fertilizer. Thanks

  24. I need a step by step guide to design layout grow set up. I’m looking for a complete guide that will show me how to build the grow site with dimensions and sizes and material list. I plant to grow 36 -72 plants. Do you know where I can get that information?

  25. CFlL is a cheap way to provide minimal but, adequate light to your plants. On the other hand; If you invest in 125w-200w CFL lamps you will do fine. Smaller CFL lamps can be used for the vegetative phase. I prefer 400-600w digital lamp system from Ippower

  26. Hi Robert
    Alwayse enjoy receiving mail from ilgm. Recieved my seeds haven’t germed them yet still preparing my room, seeds are dark and Shiney but they look overly small to me I hope they germ ok, should have my room ready in a week or so then I’ll germ have a great night.

  27. my indoor plants are about 24″ high and some of the leaves are turning yellow. What do you think is the problem?

  28. Chayanne,

    I can only assume that you are about our nutrients; “marijuana Booster”. There are 3 parts to Robert’s Nutrient system.
    1.Grow Booster – For use in the vegetative stage of your grow.
    2. Flower Booster – This is for the bloom phase of your grow; From transition to about 4-6 weeks in flower.
    3. Mass Booster – This is used to bring out the optimum amount of oils,and to bulk up the weight mass which is ocurs at the end of a successful grow.

    • Part 2…

      You use each part as directed during the phase of grow you are currently in. You never mix any of the 3 concentrates tog ether without water.
      Remember; Always mix your nutrients and additives in the amount of water measure that is called for in your particular grow schedule.

  29. e,
    You can add Bloom Booster when you start flowering. Follow the dorections on the bottle.
    I suggest you join our support forum, so that we may share more information from many expert growers.

  30. Pete,
    It is a good idea to change from blue to red light spectrum for best results; But not absolutely necessary. 🙂 Please join our support forum for many ideas and support from a wide range of knowledgeable members.