Best Fertilizer for Weed-Top 6

best fertilizer for weed

Have you been looking for the right fertilizer to nourish your weed cultivation? When it comes to cannabis or weed plants, there are many fertilizers designed to keep them healthy. The perfect fertilizer will vary depending on the strain you are growing.

 It will also depend on the growing method and the current growth phase of the plant. The right amount of nitrogen, phosphorous, and potassium is necessary during each stage. Read ahead as we guide you through the process of fertilizing weed.

We also review some of the best fertilizer for weed options on the market.

A Few Basic Facts About Weed

Before we get to the conditions required to fertilize weed, here are a few basic facts about the plant. These will help you understand your plants better so that you can begin cultivating and fertilizing them for the best yield.

The first thing you should know about growing weed is that it is best learned through experience. You can read about the best method, light, and space for growing. However, all the knowledge will mean nothing until you go ahead and get your hands dirty.

Start growing it now, and you will only get better with time. We are here to help you with the research so that you can begin cultivating as soon as possible.

Take Notes and Pictures

Have you just used a new fertilizer on your cannabis plants? You want to know that it is working. The best way to test your growing and nutrition methods is to compare. Keep a notebook dedicated to weed cultivation.

Take notes about the growing process, conditions, and fertilizers you use. Supplement this with pictures. Over time, you will have a clear picture of what works for your plants and soil.

Weed Cultivation and Timelines

In general, your weed plants may take about 3 to 5 months to grow from seeds into plants that you can harvest. To enjoy them at their full potency, the buds have to be cured and dried for about 3 weeks following this.

Pay attention to this timeline so that you can plan any vacations or trips accordingly. It is important for you to be present at the harvesting stage so that you can make the best of your weed plants.

Fertilizers Are Not Food

With cannabis, fertilizers and nutrients should be treated more like multivitamins and less like food. It means that less is more and that your plants should be fed just the recommended amount.

You may end up burning your plants if you add more. Begin with half the recommended strength of the fertilizer and test to see how your plants do. Add more only if necessary, and always stop a little below the recommended amount to prevent burning.

The Strain of Cannabis

Your method of growing has to be tailored to the strain that you are planting. It will affect everything from the height of your plant to the length of growth stages. The size of the buds will also depend on this.

The THC and CBD levels will also differ depending on this. Pick your plant from a trusted breeder who can give you an idea of the genetics of the mother plant. This will make feeding and caring for your plant much easier.

General Care for Weed Plants

Caring for your weed plants well is crucial to get the nutrients to reach them just right. As a general rule, cannabis plants grow easily, and you won’t have to fuss over them too much. However, growing a healthy plant will take some effort on your part.

Check for the Right Humidity and Temperature

Healthy cannabis plants are grown in conditions that have the right humidity and temperature. It is especially true during the germination stage when you require a stable and gentle heat.

At this point, a temperature between 68 and 78 degrees Fahrenheit is ideal. If it is too hot, the plants tend to lose moisture, stressing them in turn. This does not mean that low temperatures are ideal either.

If the temperatures are too low, the plants will be unable to absorb any essential nutrients. By paying keen attention to the temperature and humidity levels, you will be treated to healthy, thriving plants.

If you are a beginner, pick out some resistant strains that can adjust to different weathers. You won’t have to worry too much about these as they tend to adjust to their environments with ease.

If you are growing your weed plants in an area that experiences hot climates, pick out strains that are suitable for hot temperatures.

Soil Conditions for Weed Plants

If you want to avoid weak and sick weed plants, pay attention to the soil you are growing them in. When you pick potting soil for your weed plants, you should look for the following things.

Well-Drained Soil

If there is too much water in the soil, the roots of your weed plants will find it difficult to absorb the nutrients you feed them. You will also have to ensure that the soils are not too loose. This will prevent any moisture absorption.

Look for a potting mix that has perlite in it. This can ensure proper drainage. It is better to avoid sand-based and clay-based soils.

The PH Level of the Soil

When you grow your weed plants, the right pH level is also crucial. If the pH level of the soil is appropriate, the roots of the plant will be able to absorb nutrients better. For your weed plants, a pH level of 7 leads to a good acid-basic balance.

Do note that it is necessary that the soil is not overcrowded with nutrients. Hence, make sure to check the pH levels of the soil regularly. It helps ensure that the soil is great for the roots of the plant.

The Perfect Amount of Light for Marijuana

If you are cultivating weed, you know that it is a rather self-sufficient plant. To prepare their own food, the plants, however, require optimum light exposure. This helps the conversion of carbon-di-oxide to sugar.

Not having enough light can tamper with the growth of the weed plant. If there isn’t enough light, you also risk your weed plants getting thinner. It is because they stretch to move closer to the light source, hence getting thinner.

Such plants will also not have as many leaves. To avoid this, you just have to adjust your light source if the plant is growing indoors. If it is outdoors, ensure that you receive direct sunlight. Do note that overexposure to light can also be harmful.

It can result in weakened and burnt leaves. For indoor growers, there are many types of lights that can make the plant grow well. From High-Intensity Discharge (HID) lights to LED lights, the choices are many.

Ventilation for the Weed Plants

If your weed plants are growing outdoors, the airflow is not as important. However, this is an important aspect that indoor growers need to take care of. Well-ventilated growing areas ensure that the buds are healthy and well-sized.

They also minimize any excess smell that the weed plants produce. It is important to monitor the carbon-di-oxide levels in the air as well. If you want to produce cannabis to sell, you can benefit a lot from CO2 generators.

Place these in the growing area, and the carbon-di-oxide will be converted to sugar. The plants then convert this into energy. Too much heat in the room without enough CO2 can result in a host of problems.

It may result in heat stress where the leaves on the weed plant become spotted and brown. It may also cause nutrient burn as plants tend to drink more water in the heat. The lack of moving air can also lead to white powdery mildew on the leaves.

The buds may not develop, and the roots may also rot. In many cases, the potency, aroma, and taste of the cannabis will be lost. As a solution, simply ensure that the indoor weed plants are not enclosed.

It is especially necessary if the lighting system in your space crosses 400W.

How to Water Your Weed Plants?

To nourish your weed plants, you will have to water them regularly. Water enhances the flexibility and vigor of your weed plant. The internal temperature of the plant is also regulated by the water that you add to it.

Don’t water the plants too much, or the roots can get choked. In this case, they will have very little access to oxygen. To know when to water a cannabis plant, pay attention to the color on the leaves to see if they are yellowing or green.

See if the plants are rigid and strong as well. Note that an overwatered plant can look tired and lifeless. In this case, the leaves remain dark green. However, you will notice that the tips of the leaves will curl.

In case the plants are not watered enough, you will see brown or yellow leaves. These will be lifeless as well. Whatever you identify, alter the water levels to suit the needs of your plant. Feel the soil as well to get an idea of how much water you will have to add.

How Often Should I Water My Weed Plants?

It is a good idea to water the weed plants once every two to three days. You can create a watering schedule for the same. Each time you water, see that the water pools on top of the soil in the pot.

However, the water should fully seep through in a few seconds as you move on to the next plant. If your weed plant’s soil is extremely dry, water twice. The first time around, the water will quickly seep through the soil and drain out.

You will have to water it again so that the soil absorbs the moisture.

Materials to Ensure Moisture

To make the watering process easier for your plants, the following materials come in handy. Keep these in sight so that you can use them as necessary.


This material is light and airy and ensures that the soil gets a good flow of oxygen. Adding perlite to your soil will keep away clumps. Hence, you can water it easily.

Drip Irrigation Lines

Drip irrigation lines are a great option for your cannabis plants. It will help you in watering your weed plants evenly. It also prevents flooding in your pot. If there is flooding, perlite will come to the surface of the pot. In this position, it does not serve any purpose.

Using Smart Pots

Canvas smart pots are a great option for your weed plants. It is because they help heat to escape and the water to drain. In addition to this, it also assists the roots in breathing just right. Hence, the quality of the plant roots is improved.

They will also be able to handle being watered very well.

You may also be using a completely different system like hydroponics. In this case, you will have to add nutrient-rich solutions to a pot that may have inert soil. Many fertilizers are compatible with hydroponics.

This method is preferred by many growers as it is easier to control the pH and nutrient ratio of the soil. It is also easier to keep pests away.

How to Feed Your Weed Plants?

With weed plants, it is important not to overfeed them. They are sensitive to nutrients, and too much can burn them. Read ahead as we discuss how you can feed your weed plants right.

Nutrients Required by Weed Plants

There are three nutrients that a cannabis plant can benefit from in larger quantities. These are macronutrients and include Nitrogen (N), Phosphorous (P), and Potassium (K). These nutrients differ for each of the growing stages of the plant.

In addition to these, other nutrients like calcium, magnesium, and sulfur can also aid in plant growth. Important micronutrients also include chlorine, boron, copper, manganese, iron, zinc, and molybdenum.

All of them contribute in specific ways to your weed plant’s overall health.

When to Fertilize Your Weed Plants?

Your weed plants have to be fertilized in stages. The process begins during the seedling stage when the plant begins to grow 3 to 4 sets of true leaves. At each stage following this, you will have to use a specific N-P-K ratio through the vegetative and flowering stages.

What Kind of Fertilizer (N-P-K) Should I Use of Each Stage?

Your weed plants will require nutrients in different ratios depending on their growth stages.  For cannabis seedlings, you will have to begin feeding them when they are 3 to 4 weeks old. At this point, a Nitrogen-Phosphorous-Potassium (N-P-K) ratio of 2:1:2 is required.

You can continue with this ratio even one week into the vegetative growth phase. You can gradually move to 4:2:3 fertilizers. During the mid-vegetative phase, the number of nutrients needs to be high in order to promote healthy and strong foliage.

At this stage, 10:5:7 fertilizers are a good option for optimal growth. In the final stage, a bloom booster is a good option. At this point, you can lower the nitrogen levels. A 7:7:7 fertilizer is a great option during this stage.

Following this is the flowering stage for the plant. At this point, your weed plants will need more potassium and lesser nitrogen. Look for a 5:7:10 fertilizer at this stage. You can then increase the nutrients. You will, however, have to ensure that that potassium is the highest.

During mid-flowering, you can use 6:10:15 as the ratio. Finally, before harvest, a fertilizer with an N-P-K ratio of 4:7:10 is preferred.

How to Fertilize Weed Plants?

The fertilizer that you pick will have specific instructions that will guide you through the fertilization process. However, most fertilizers are water-soluble, and you can follow a general method to fertilize your weed plants.

For your weed plants, heated water at about 22°C is necessary. You can add the nutrients to the water and stir it well. Add just the recommended amount and do not exceed it. It is better to err on the side of less than more.

You can adjust the pH of your fertilizer if you like. Nitric or phosphoric acid pH down supplements are a great option. Your plants are now good to go. During the last week before harvesting, you will have to water the leaves of the plant down with water.

This is the flushing process. It ensures that no nutrients are left on the surface of the plants that are harvested.


Best Fertilizer for Weed Reviews

Read ahead as we review some of the best fertilizer for weed options on the market.

1.     Osmocote Smart-Release Plant Food Flower & Vegetable

N-P-K Ratio: 14-14-14

For full blooms and healthy weeds, this fertilizer is a great option. It has been formulated to promote vigorous top-growth for higher yield. It also ensures that the roots on the plant develop strongly.

The fertilizer is also a great option for anyone growing perennials. It is also an excellent source of nutrition for the vegetables in your garden. When you use it in your garden, expect some colorful blooms and flavorful vegetables.

You will also be able to watch your weed flourish. It can feed your plants for up to 4 whole months. It is a smart-release fertilizer that comes in the form of granules. Each granule is coated with semi-permeable resin. The granule contains the nutrients for plants.

The coating on the granule enables water to enter it. Hence, the ingredients inside the capsule are dissolved to just the right amount. With changes in temperature, these nutrients are released, and your weed will receive the right nourishment.

During the active growing periods, more nutrients are released. It is because the temperature tends to be warmer then. You will be left with an empty shell once the fertilizing process is completed.

Ensure that you sprinkle just 1 scoopful of plant food for 2 gallons of water or 4-square feet. You then mix it into 1 to 3 inches of topsoil. You can then water your weed regularly. Do note that you can add the next supply of fertilizer after 4 months.


  • Easy to use granules
  • Good root development
  • Excellent top-growth
  • It brings color back to plants


  • Leaves empty granules in garden soil

2. Fox Farm FX14049 Liquid Nutrient Trio Soil Formula Pack of 3

N-P-K Ratio: 2-8-4 (Extra Strength), 6-4-4 (Grow Big), 0.01-0.3-0.1 (Big Bloom Concentrate)

Outlined above are the N-P-K ratios for the 3-pack fertilizers that have some of the favorite fertilizer options from FoxFarm. Together, they contribute to the nutrition levels of your weed plants. It will give you the right boost of nutrients for the perfect bloom.

For abundant and good growth on your weed, begin by using the Grow Big Hydro. As soon as you notice the first sign of flowering or buds set in, promptly switch to Tiger Bloom. You can use Big Bloom to increase nutrient cycling.

You can also use it to heal the root systems of your plants. Since it has rejuvenating properties, you can go ahead and use it through all of the growing cycles. Hence, it is a good option for late-season blooms and mature plants as well.

You can expect some compact and lush growth from using Grow Big. It promotes vegetative growth for healthier plants. On the other hand, Tiger Bloom acts very fast and is high in phosphorous. It is very potent, as well.

You can use big bloom on all of the fruiting and flowering plants in your garden, in addition to weed. For the best results, use the three in a sequence, and you will see your weed stand healthy and tall in your garden.

In the case of cannabis, it gives your plants big buds and a high THC content as well. You can also use it periodically for indoor and outdoor growth.


  • 3-pack fertilizer for complete nourishment
  • Great for weed
  • Results in juicy buds
  • No strong smell


  • The high dosage will burn plants

3. Advanced Nutrients GL525050-12 Big Bud Liquid Fertilizer

N-P-K Ratio: 0-1-3

This Advanced Nutrients fertilizer is an excellent option to help flowers grow larger and heavier. You will also find that they are denser on applying this fertilizer. You will see that they have an increased amount of essential oils in them.

Healthier flowers also have more aromatics and phenols. Terpenoids and other potency factors will also be increased substantially. Your weed harvest is also likely to do much better in the market with this fertilizer on your side.

It results in significant and measurable increases in total harvest weight. The market value of your harvest hence increases as well. All of this is accompanied by ease of use. You won’t have to assemble the fertilizer and can simply go ahead and apply it to your weed.

The booster contains L-amino acids along with potassium and phosphorous of the right kind. Together, these essential nutrients and will contribute to high-yielding blooms. It does so during the blooming phase for better and bigger results.

For the best results, you can use about 2 ml per liter of water. Use this through weeks 2 to 4 of the flowering phase for your plant. If you are mixing it with any organic fertilizers, use just half the recommended amount.

 It can also be used for hydroponics. You can also use it in aeroponic and drip irrigation methods of growing, among others. You may also notice that it balances the pH of our soil and keeps the leaves green and stems very strong.

You can also go ahead and use it on your vegetables for better-tasting yield.


  • Very high yield
  • Bigger and better bloom
  • Can be used in most growing methods
  • Great-tasting yields


  • On the expensive side

4. General Hydroponics Flora Grow, Bloom, Micro Combo Fertilizer

N-P-K Ratio: 2-1-6 (FloraGro), 5-0-1 (FloraMicro), 0-5-4 (FloraBloom)

This is the original Building Block Nutrient System that will supply your weed with the right primary, secondary, and micronutrients. You will see that the crop quality once you use this fertilizer is better. The nutrients are perfect for enhanced yields.

Depending on the plant you are growing, you can mix and adjust the three fertilizers that come in this pack. These are the FloraGro, FloraMicro, and FloraBloom, who come in different N-P-K ratios. Hence, each of these serves a specific purpose for your weed.

The right mixture will enhance the nutrition and aroma of your plants. You will also find that the flavor and essential oils on your plant are also boosted. You can use it for plants cultivated in soil or using hydroponics.

The pH of the soil is also balanced to allow for ease of use. The fertilizer 3-pack is also a choice of Antarctic research scientists and those from NASA. This is due to its reliability and superior formulation and leaves plants thriving.

Good solubility is necessary for a fertilizer. This 3-pack contains fertilizers that have highly purified concentrates that allow for maximum solubility. The FloraGro fertilizer works to promote vegetative and structural growth on your plants.

It also helps to build strong roots. FloraBloom fertilizer helps develop fruits and flowers. It stimulates them to result in plants with enhanced aroma, flavor, and essential oils. With the right amount of magnesium, sulfur, and potassium, your weed will stay healthy.

The FloraMicro is considered the building block of this system. It provides plants with the necessary nitrogen, calcium, potassium, and trace elements.


  • Enhanced aroma and flavor
  • A good supply of nutrients
  • Good structural growth
  • Maximum solubility


  • Strong odor

5. Flower Fuel 1-34-32 Bloom Booster

N-P-K Ratio: 1-34-32

If you are looking for a super-premium booster for your weed, this is the right choice. It has the right nutrients, amino acids, organics, and Vitamins to keep your plants healthy. Apply this fertilizer, and you can expect larger and denser harvests than before.

It also promotes better resin and essential oil content. You will be treated to valuable crops that will look much better as well. Every jar of Flower Fuel is made of more than 40 proprietary ingredients.

These include amino acids, hormones, and essential organic components. All of the micro and trace elements that your weed plants need will also be available in this fertilizer. So go ahead and use it in the right amount to get the best weed harvests.

It is a soluble bloom fertilizer that is 100% hydroponic grade as well. You can use it with any base nutrient. It works especially well with 2 and 3-part nutrients that are popularly used. Go ahead and use it in soil or an aeroponic system as well. You can even use it in coco.

The 250g pack will last you for 200 gallons of water. You can hence expect bigger and better harvests for a long time. Flower Fuel is recommended because it is an easy way to get fuel to your weed.

 Hence, you will be left with enough time to attend to pests and keep up watering routines. For any professional grower, you can expect bigger yields with good market value by expending minimal effort. Hence, hobbyists and pros will benefit from this fertilizer.


  • Full of essential nutrients
  • Easy to use
  • Dissolves quickly
  • Leads to large harvests


  • May cause pH spikes

6. Humboldts Secret Base A & B Bundle Liquid Fertilizer

N-P-K Ratio: 4-0-1 (Base A), 1-4-2 (Base B)

This fertilizer comes with the right macronutrient profile to enable good plant nutrition. It comes in 2 variants of Base A and Base B with different N-P-K ratios. It is hence a great nutrient fertilizer for your weed.

It is a holistic and complete feed for nourishing these plants. It is great for indoor plants as well. The fertilizer comes in a signature blend that contains Phosphorous, Nitrogen, Calcium, Potassium, Fulvic Acid, and magnesium.

The two-part system is also very easy to use. They work at equal rates and can be used throughout the growing cycle. You can begin using it when the vegetative stage commences. You can then continue using it till the end of the flowering stage.

Use it each time you water your plants for the best results. It is also a versatile fertilizer that is compatible with all growing mediums. Whether you are using potting soil for indoor plants or aquaponics, you can go ahead and use this fertilizer.

You can also use it for coco coir and aquaponics. It is a commercial-grade fertilizer that is also garden safe. Hence, your flowers and plants will remain healthy. The ingredients are 100% water-soluble and balanced for pH as well.

Both home and commercial growers make use of this fertilizer pair for thriving weed cultivation. It also works very well across lawns, plants, bushes, flowers, and trees.

Ensure that you don’t mix the two bases in their concentrated form. This can lead to unwanted chemical reactions. For the best practice, mix them into a reservoir of water.


  • Apt for all growing stages
  • It can be used in many growing methods
  • Garden-safe fertilizer
  • pH balanced


  • Less quantity for money

Frequently Asked Questions (FAQs)

Here are some popular questions about growing and fertilizing weed plants answered for you.

1. What Soil Should I Use to Grow Weed Plants?

Any good quality organic soil will help your weed plants grow and flourish. It is not a good idea to mix time-release nutrients with the soil for weed. Mix your soil with about 20% perlite and some good fertilizer, and it should be ready to grow.

2. What Kind of Container is Apt for Weed Plants?

Weed plants are not very picky, and any plant container will do the job. However, many people opt for smart pots that are made of fabric. This helps deliver oxygen to the roots of cannabis. Hence, you can prevent instances of overwatering.

3. Can I Use Tap Water to Grow My Cannabis?

Yes, you can go ahead and use tap water. Cannabis is not a very picky plant, and adding nutrients to the soil along with water from the tap can keep you healthy. If you have noticed that the water in your tap is toxic, use Reverse Osmosis (RO) water instead.

4. Which Nutrients Will Lead to the Biggest Buds on My Weed Plants?

Nutrients for weed plants are essential supplements, but light exposure is the necessary element for big buds. Add your fertilizers, and make sure to expose all parts of your plant to sufficient light. The plants will be able to boost their nutrition and grow bigger buds as a result.


Weed plants have been known to survive in many environments and harsh conditions. However, the healthiest plants with good harvests owe it to good care. You will have to pick the right soil and water your plants regularly. You can also feed the plant by taking your pick from the best fertilizer for weed options we have reviewed above. Go through our extensive guide and begin growing your weeds now. With practice, your plants will only get better.