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Picking the perfect fertilizer is hard. I personally dread it; and try to avoid using nutrients by starting with the ideal growing environment and high-quality genetics.
However, there comes a time when every grower needs nutrients, especially when you are just starting out. I will help you pick your ideal fertilizer by sharing some of the best out there (in addition to my personal favorite: Bergman’s Plant Booster).
Fertilizer can help produce a healthy, flourishing plant but there are other methods as well. I’ll explain how to boost CO2 as well as how to fertilize your plants safely. Knowledge is key, so keep reading to learn how to choose your perfect fertilizer or skip ahead to the section that you need.
The best marijuana fertilizers:
Homemade vs. professional
If you are thinking about fertilizers, you will need to first decide on one thing.
Homemade or professional?
Of course, you can always make your own nutrients with your preferred mixture, but usually it is much simpler to buy pre-made nutrients. Keep in mind that marijuana plants have a wide assortment of needs.
Professional systems can prevent you from making any unforeseen mistakes with chemical reactions that may happen if you accidentally mix the nutrients the wrong way. You also won’t have to worry about deciding what to feed your plant and the necessary ratios. They already have all of that taken care of, which is especially helpful for beginners.
If you still want to DIY, try making your own soil instead, but you don’t have to risk it.
Tip: make sure to download my free Grow Bible and learn how to make your own soil mixture
There are so many awesome marijuana products created by well-experienced growers worldwide. Why make things hard?
Instead of reinventing the wheel, focus instead on choosing the best system when growing marijuana or what you’d like your growing medium to be.
WARNING: Stay clear of any fertilizers that are advertised as being “slow release” or “extended.” While these systems may be good for regular plants, they are most likely going to cause an array of issues when growing marijuana.
When choosing nutrients, how you grow is what matters.
Once you decide how you want to grow your plant, whether in soil, coco coir or hydroponics, make sure to buy products that fit that growing method. Some products are good for growing in more than one medium and some are only for a specific medium.
Need help finding your supplies?
Here’s a link to my favorite online nutrient store.
Want to know the best way to waste money on fertilizers?
Not water your plants correctly.
Fertilizers aside, without a proper watering technique, soil plants will never thrive. Newbie marijuana growers often make the mistake of watering their plants far too often.
So, before we discuss fertilizers, let’s talk about watering.
Here’s how to water plants in soil:
- Keep at least the first top inch of the soil feeling dry.
- Add nutrients to your water; flush with water only once every two weeks.
- Let about 20% additional water drain through the bottom when you water.
- Repeat the first step.
Be sure you are always adding the proper amount of nutrients, and that you have chosen the right fertilizer for your growing stage. The following fertilizers are viable options for plants that are growing in soil:
Bergman’s Plant Food
Bergman’s Plant Food is a great product that ensures you have a good mixture of all the needed nutrients.
Here’s why it is perfect for cannabis:
Healthy marijuana plants require three elements for firm roots and vibrant flowers with high yields: Nitrogen (N), Phosphorus (P) and Potassium (K). You will often see these values displayed on packaging as NPK.
Nitrogen is important for leaf growth while phosphorus aids in bud growth. Potting soils are already mixed with these three elements which will aid the plant for up to three weeks. But as the plants grow, they will need additional nutrients.
Bergman’s plant food contains the perfect mixture of these three elements.
Once your plant starts developing leaves, you will need to give it a 20% balance of phosphorus, potassium and nitrogen. If you are growing indoors, you’ll want to dilute this formula to one-quarter or one-half strength. When marijuana plants are grown indoors, they do not handle full strength dosages well, and it could cause the leaves to droop due to shock.
You can feed your plant each time you water, although it isn’t completely necessary. Twice per week will usually suffice. However, outdoor plants naturally get fresh air, and their roots have free range to spread out and grow, so they often do not need as much.
One of the best things about Bergman’s plant food is that it is easy to use.
The product comes with a watering and feeding schedule for both soil and hydro. Go here for all the products, but also check out the individual products for their benefits and use.
Fox Farms Trio
Fox Farms is a top pick for newbie marijuana growers. With it, you can grow any marijuana strain and never need more additives. They have both the hydroponic and soil versions so be sure to get the correct one. This can also be used with coco coir growing as well.
There are three bottles, (you may be able to get them as a package), and you’ll need all three. They are called “Grow Big,” “Tiger Bloom,” and “Big Bloom.” Available at this online store.
This set is really easy to use.
Just follow the directions on the bottles. Fox Farms is really all you need to get your marijuana to bloom just right.
Perlite and Vermiculite Marijuana Fertilizers
For soil growing you can make things nice and easy by buying a smart pot to grow your marijuana in and add a mix of Fox Farms Happy Frog soil with about 30% perlite for starters. Humbolt soil is also a good option.
If you choose hydroponic growing, add perlite or vermiculite in a combination of about 50 percent fertilizer to a mixture of water and peat moss.
Want professional-level soil?
Always use perlite or vermiculite. They are produced when mica is heated proportionately to 1,400- and 1,800-degrees Fahrenheit. When heated the minerals enlarge and become porous. This creates white pellets that retain air.
Why do these pellets matter?
They can also take in almost four times their own weight in water. They are why many commercial solid potting soils do not become tough and lumpy when dry.
The minerals in them naturally create magnesium, calcium, and potassium and will eventually infuse into the soil.
This is great because the mixture continuously feeds the soil with nutrients.
After some time, the pellets of both fertilizers become immersed in a mixture of the minerals discharged into the soil. Perlite, vermiculite and other media are available at Growershouse.
Yes or No to Miracle-Gro?
If you’ve grown anything, you’ve likely heard of Miracle-Gro.
It’s one of the more popular formulas on the market, as well as a household name when it comes to plant fertilizers. Just about anyone you ask has heard of it and most likely used it for gardening “regular plants.”, but it is not the best for marijuana growing.
Why should you avoid Miracle-Gro?
One reason it is not recommended is that the solution gives too much nitrogen during the flowering stage. As mentioned above, a proper balance of all nutrients is essential to growing a healthy marijuana plant.
Miracle-Gro simply doesn’t have the right balance.
If you use Miracle-Gro, you will be using the same formula for the entire life span. Now in the beginning stages, it may work fine. However, the requirements for a marijuana plant shifts significantly between the seedling stage and when it starts making buds. It should make sense that you would switch your formula, too.
So, while its reputation would make you think it is a great, easy option, our suggestion is to stay clear of using Miracle-Gro.
So, maybe cost is a concern for you, or you are new to marijuana growing and need a simple solution. In either case, you should check out Grow and Bloom fertilizers by Dyna-Gro.
Whether you are growing your marijuana plant in soil, coco coir or hydro, this is an effective solution. Dyna-Gro is available at this link.
Here’s how to use it:
Use Grow while the plant is in a vegetative stage. During the flowering stage, use Bloom. After that, just follow the instructions on the bottles! You can use these throughout the entire growing cycle from seedling to harvest time.
Urine as a Marijuana Fertilizer?
So, we already know that nitrogen is necessary for marijuana growth and development. Well, human urine contains large amounts of nitrogen.
Yes, your urine is a healthy fertilizer for marijuana!
Now you don’t want to just go and urinate directly on the plants or even on the ground around it, as this could kill them. Instead, mix a commercial plant food with one full bladder worth of urine per each gallon of water. You will have to use this solution immediately to avoid any toxic ammonia from forming.
Humans aren’t the only good fertilizer makers.
Chicken manure also is an excellent marijuana fertilizer. Organic slow release chicken manure compost increases yields and promotes healthy plants. Learn about the benefits of ChickenFuel compost.
Let’s say you live in an area where the soil is too acidic for marijuana growing. You can use plain wood ashes to help restore the proper pH. Just mix a shovelful of wood ashes per 5-gallon bucket of water to the soil. If that is not an option, you can also try lime (available at most garden stores) for the same results.
Although I recommend professional fertilizers for the best results, composting also provides a natural alternative.
Let’s be honest,
Composting isn’t the first form of fertilizer that most people would think of. It also doesn’t bring about the most pleasant thoughts either.
Here’s the deal, however,
Animal manure and leftover food from your kitchen create some bountiful, thriving marijuana crops.
Animal poop and vegetables/fruits are recycled back into the earth the same as any other organic thing would, and along with that goes all the nutrients contained within it. These nutrients will be absorbed by your plant.
Using compost as fertilizer can be done anywhere. If you are in an area where the soil is lacking, it will enrich the soil. Read the article How to make marijuana compost for more information
After your first pile of compost is created and starts decomposing, you can start building another one. You need a pitchfork to turn the compost so as to get everything blended really well. Do this often, preferably daily to reduce the amount of time it takes to transform from a state of decay to dirt.
There’s another reason to regularly turn the soil.
You want to avoid spontaneous combustion.
This happens when heat created by microbes feeding on rotting material (under some form of pressure) dries, then catches fire, burning everything up in the process. This is the last thing you want.
Be aware that certain foods will decay much faster in hot temperatures. Also, give your compost about three full months to transition into rich soil.
Not excited about soil?
Some people prefer to grow their marijuana in water. This is what is called “growing your plant hydroponically”. With this method, you will need fertilizers that are designed for hydroponic growing. There is no room for loose particles that could clog your pumps, tube and any other hydroponic equipment you may own.
General Hydroponics Flora Series Nutrient Trio
This highly suggested nutrient system is a great start for both beginners and advanced growers. You can also use this in coco coir and soil as well. The awesome part – they sell a “performance pack” which includes a pH balance test kit along with all that you need to start growing. Find it at this link.
General Hydroponics FloraDuo
If you want to narrow it down to two bottles instead of three, there is General Hydroponics FloraDuo. This line is great for learning the different stages your plant will go through and what it needs to flourish.
You’ll start with the first bottle, a high nitrogen formula, then once you are at a certain point in the growing process, you will start using the second bottle. The second bottle has a higher concentration of Phosphorus and Potassium.
You don’t have to bother memorizing proper nutrient proportions, simply follow the instructions.
Following the feeding schedule is very simple. Keep the pH of your water between 5.5-6.5, and this product is known to breed good results fairly quickly. General Hydro Nutrients are available at this link .
Another great system for your hydroponic marijuana growing needs is Botanicare.
Bloom and Grow can be used for the entire growing experience. However, for the more experienced marijuana grower, these formulas let you play around and make adjustments to the calcium and nitrogen levels.
Look, there’s nothing wrong with custom blends.
The system was created to be tweaked. Following the instructions exactly may not provide the most desirable results, so if you want to try this system, you need to have the right knowledge and be ready to experiment. Botanicare is available at this link here
The Advanced Nutrients line is more on the expensive side, but several growers love it.
The truth is you really don’t need the expensive products to get the results you want. You will most likely get just as good – if not better – results with the less pricey products mentioned above. While this line certainly is not necessary for satisfactory marijuana growth, it is worth a try if you don’t mind paying a premium for it.
I’ll say it again:
Advanced Nutrients is pricey. However, you can save a little money if you only use what you need.
Here’s a link to a calculator that measures that for you:
Growing in coco coir, or coconut coir can have similar advantages to growing in a hydroponics system. Coir is the fiber that comes from the coconut husk, and it’s used in a variety of products (i.e., doormats) as well as by gardeners.
Didn’t know you can grow marijuana in coco coir?
Well, any food that can be grown hydroponically is also good for coco coir growing. You’ll want to use a smart pot.
Coco Coir is an easy-to-use growing medium, but it requires a specific type of nutrient.
Successful coco coil growers remember to:
- keep the pH between 5.5 – 6.5
- alternate watering with regular water
- add extra calcium and magnesium
Even the healthiest plant might suffer from calcium and magnesium deficiencies if grown in coco coir. Save yourself some trouble by making sure you use something with a little extra Calcium and Magnesium.
It doesn’t matter which calcium and magnesium supplement you get. Most are fairly inexpensive and will work perfectly. General Hydroponics has a supplement by the name of “CaliMagic,” or you can try the one by Botanicare called “Cal-Mag.”
Canna Coco A + B and Cal-Mag
Both of these options are very popular with people who prefer coco coir growing. Canna is one of the first marijuana specialized nutrient suppliers from Amsterdam. Products are available worldwide , check this link at Amazon for all Canna products
Fox Farms Nutrient Trio for Hydroponics
You don’t have to get a Coco Coir fertilizer, however. Fox Farm’s system is excellent for preventing calcium and magnesium deficiencies, but it never hurts to have some Cal-Mag around just in case.
As mentioned earlier in this article, the “Grow Big,” “Tiger Bloom” and “Big Bloom” is all you really need. Just don’t overdo it in terms of dosage because the trio is already quite strong. Be sure to follow the feeding schedule provided by Fox Farms, and you will be good to go.
If you want to purchase one of their supplements, the FF trio comes highly recommended. Fox Farm Trio for hydroponics is available at this link.
Fertilizers are not the only way to improve the health of your plant. You can also focus on the air.
Vinegar-baking soda CO2 generator
Plants breathe in carbon dioxide and exhale oxygen, so naturally, marijuana flourishes in surroundings that are high in carbon dioxide (CO2).
Did you know?
White vinegar is an excellent source for creating carbon dioxide.
Here’s how you create more CO2 for your plants:
- Place baking soda in a 1-liter bowl
- Slowly add white vinegar to the bowl
You don’t need to add much. One drop of white vinegar every two minutes will suffice.
When the vinegar mixes with the baking soda, a chemical response occurs that makes the two substances inactive, creating ample carbon dioxide. This takes place until either the baking soda is expended, or the vinegar is completely gone.
An indoor grower can use vinegar generators the same way IV drips are used in the hospital. The easiest way to do this is with a bottle filled with vinegar. Duct-tape the bottle and hang it over some sort of open bowl or container that is filled halfway with baking soda. Poke a hole in the vinegar bottle cap with a small finishing nail to let it drip its contents from the hole and mix into the baking soda in the bowl underneath it.
However, the drip method may not be ideal for your grow.
The best environment for a vinegar/baking soda drip generator is in a small confined space where no air will blow away any of the CO2. You also definitely do not want the smell of vinegar to bring unwanted attention to your marijuana growing operation.
A vinegar-soda drip generator also doesn’t work well in the outdoors, where open breezes quickly carry off any CO2 that is generated. This in addition to a steady and unmistakable odor of vinegar that could, if the breeze was favorable, lead thieves or authorities directly to you.
There is a better way. Make a mini bomb.
For the CO2 process to be effective, you want to create a carbon dioxide filled environment that totally stops any of the CO2 from going out of the space. There are many ways to do this. To keep it simple, you can completely cover your plant with a huge plastic bag draped over the top. It needs to be long enough to touch the ground while also not touching the tops of the plant either.
Here is a CO2 generator using a different method:
Video by Sensi Weed
Once you’ve created your cover, put some sort of open plastic bottle or container with 1-quarter baking soda standing up right underneath it. It should be under the dome you’ve created. Now, from underneath the cover, pour a tablespoon of vinegar into the open bottle. Pour just enough that it starts to foam as it creates CO2. Then go ahead and leave it under the dome, closing the cover behind you.
Give it about 15 minutes before adding more vinegar to the rest of the baking soda. Blend everything well.
Tip: make sure to download my free Grow Bible for more information
Your CO2 bag needs to remain on the plant for at least four hours so that everything is completely submerged in the tissues. You can repeat these steps as often as you feel it needs to be done.
There is no such thing as giving your marijuana plant too much CO2. When using these bombs, some growers prefer to do it at night time due to the smell it creates.
The best scenario is not needing to use fertilizer at all. You can do this by paying attention to your roots.
How do you do that?
You check the pH.
Effectively managing the pH of your root is vital to protecting your plant from nutrient problems. Before you water your marijuana plants check the pH of the water. For your marijuana to properly absorb the nutrients it receives, the pH has to be right.
Measuring the pH is easy.
There are pH test kits available at a decent price that do the work for you. Some of the nutrient systems on the market even provide these kits.
Best of all, the process gets easier.
After you have done it a few times, it will only take you about 5 minutes, and it can be done when you water your plants. Trust me: you want to make a habit of checking the pH if you want to ensure your plant is in its best health at all times.
Don’t worry about always getting the pH right. It is far more important to monitor it and see that is remains in the proper ranges.
Below are the proper pH ranges for soil and hydroponic growing.
Soil pH: 5.8 – 6.5
Hydroponics pH: 5.5 – 6.5
When to stop fertilizing
Honestly, there isn’t a definitive answer to when you should stop fertilizing. It really depends on the grower as everyone has a preferred way of doing things. You may choose to fertilize until harvest, or you can refrain from fertilizing days or even weeks prior to the end.
Generally, you should stop giving nutrients to soil-grown plants earlier than plants grown in hydroponics. A 1-14 days or more flush is common for hydroponic growers.
It’s a good idea to continue using flowering and blooming formulas for the first few weeks of the flowering stage. You can choose to start flushing your plants about two weeks before harvest. You’ll have to use your own good judgment of when you think your plants are ready to be flushed.
Here’s the deal, however:
You may not have to use nutrients in the first place.
Unless there are deficiencies such as the yellowing of leaves around the base of the plant, then you really do not need to give your plant a ton of nutrients. The way the plant tastes is affected by how much nutrients are added to it, so overdoing it could cause the taste to be off.
Don’t mistake the normal process as a problem.
At the end of the flowering period, bottom leaves will turn yellow. This is normal – not a lack of nutrients!
Whatever the suggested amount of nutrients are, it is best to cut that amount in half when you first begin. You will want to increase the dosage as soon as you detect the first sign of malnourishment.
Remember that a small amount really does go quite far!
Seeing yellow leaves near the base of the plant is fine so long as it is closer towards the end of the flowering stage. Yellow leaves only need to be addressed in the early stages of the marijuana plants life cycle. Just be certain to make sure there are enough leaves to make it to harvest time.
Overfeeding your plant can cause nutrient burns which will never go away. Once the damage is done there is nothing you can do about it. Literally, all the leaves will be burned forever.
Nutrient burn is a sure sign you have done too much. If in fact, the buds are already developing, overfeeding may lead to burns on the sugar leaves on the plant buds. Although the actual buds may be fine, this results in the harvested buds looking very rough.
As soon as the leaf tips turn brown, you have to slow down on the nutrients.
Again, starting your dosage at half strength is best unless deficiencies are present. All strands are created different, and you just may have a strand that can easily be affected by nutrient burn. Usually, the only people who have to increase their nutrients are the ones with fast-growing plants that use very bright lights.
If you choose to water your plant by hand, then monitor the PPM of the run-off water at the bottom as well as the water you are pouring into it. By observing the run-off water after you pour your nutrients in, it is easier to notice if there is a difference in the PPM.
Let’s say you notice the PPM increases – then it is an indicator that you may be providing more than enough nutrients. However, if the PPM decreases, then you should give your plant more food since your plant is absorbing the nutrients to the point that it is not leaving any left over.
When you need to use fertilizer for your marijuana plants, it is important that you choose the right one. That’s why learning how to pick nutrients is the first step to growing the best marijuana you can possibly grow. If your growing in soil, you’re going to have different needs than if you are growing hydroponically. You also may be able to improve your plant’s growth by simply adding more CO2.
While it is important to remember that fertilizer should not always be your first solution, especially if you don’t know how to, you shouldn’t be afraid to add nutrients with confidence.
Thanks for reading. Please leave comments or questions below and don’t forget to download my free grow bible
Frequently asked questions
Are there other options for natural fertilizers? Yes! Nature provides many options for both nutrients and pesticides when growing marijuana. I’ve only mentioned some of my favorites. Learn more natural alternatives in this article.
How do worm castings work? Worm castings are like chicken manure and urine except they come from earthworms. In addition to adding nutrients, the earthworms help aerate the soil. Learn more in this article.
Is there a difference between liquid and dry fertilizers? There is not! Powdered fertilizers are the same except they do not have the added water. If you don’t mind doing some mixing, there is nothing wrong with staying dry.
How do you know
Looking to grab some nutrients? Read some of our happy customer experiences!
The founder of I Love Growing Marijuana, Robert Bergman is a marijuana growing expert that enjoys sharing his knowledge with the world. He combines years of experience, ranging from small-scale grows to massive operations, with a passion for growing. His articles include tutorials on growing... [read more]