Growers love fertilizing their prized plants to promote healthy plant growth. However, many growers don’t know that using the wrong kind of fertilizer can actually harm flowering plants. This is why smart growers use bloom booster fertilizers that are specifically designed for plants in the flowering stage.
Kushteller’s top recommendation for bloom boosters is the Lotus Nutrients Bloom Pro Series.
Best bloom booster fertilizers
Our top choices for bloom booster products are:
- Lotus Nutrients Bloom Pro Series – Best all around bloom booster
- ILGM – Marijuana Fertilizer – Best “total package” fertilizer set for supporting growth from seedling to harvest.
- Fox Farm Tiger Bloom – Best liquid bloom booster
- Lotus Nutrients Boost Pro Series – Best late stage bloom booster
- Advanced Nutrients Bud Ignitor – Runner up bloom booster
- Miracle-Gro Bloom Booster Flower Food – Best low cost bloom booster
Best bloom boosters – full analysis
The Lotus Nutrients Bloom Pro Series is our top choice for growers looking to increase their bud blooms. The Lotus Nutrients group is a team of growers, scientists, and horticulturists based out of North Carolina. Their goal was to create a series of nutrient products geared towards each stage of cannabis plant growth.
The Bloom Pro Series is designed with the plant nutrients required to trigger to rapid onset of bud production during the flowering phase, as well as enhance bud size and density. The Bloom Pro Series uses a proprietary blend of 14 macro and micro nutrients, as well as amino acids.
Looking at reviews on trust pilot confirmed my own experience (currently at 4.5 stars with about 450 reviews), which is that this bloom booster provides a great value and delivers on enhancing flower production.
Lotus nutrients is part of the supercloset.com group, which also owns Gorilla Grow tents as well as Kind LED, two other well regarded companies in the indoor growing space.
Convenience and Usability
The Bloom Pro Series comes as a dry power. It must be mixed with water into a solution, which can then be watered onto soil for traditional grows or applied directly for hydroponic grows. The mixing process is very easy, and the ingredients in this mixture are fully chelated which makes absorption quick and easy.
Some people may prefer a liquid solution that requires no mixing at all, but dry powders are compact and easier to store because they have no water added.
This products has the nutrient combination that I look for in bloom boosters, which is higher levels of phosphorus and potassium and lower levels of nitrogen. They also have a good supporting mix of required micronutrients, as well as kelp extract to feed the beneficial soil microbes in your growth medium. Their exact nutrient breakdown is as follows:
- Nitrogen: 5%
- Phosphate: 10%
- Potassium: 14%
- Calcium: 5%
- Magnesium: 1.5%
- Sulphur: 3%
- Boron: .02%
- Copper: .01%
- Iron: .1%
- Manganese: .04%
- Zinc: .02%
All of the nutrients are sourced organically, so I consider this to be an organic bloom booster. This is desirable because non-organic blends can have additional unwanted minerals or compounds. This is especially good for hydroponic systems where non-organic chemicals can plug watering holes and sprinklers.
Lotus Nutrients smallest 16 oz container currently costs around $24. This brand is a good value because when you buy it, you are paying for dry product rather than a liquid that is 95% water already.
From my experience, I believe this bloom booster delivers on its stated promise of delivering “prolific blooms”. I started feeding my plant this mix right as it began blooming, and I did notice that buds grew big and dense. Overall, I was very satisfied with my trial of this brand and recommend it as our top choice.
ILGM stands for “I Love Growing Marijuana”, and judging by the abundance of growing articles and ebooks on their website, I’m definitely inclined to believe them! This group primarily specializes in selling seed packs and grow kits, but their nutrient package is excellent as well.
The ILGM Marijuana Fertilizer package is actually a full set of fertilizers that can support the plants growth from seed to harvest. This package includes two bloom boosters, one for the start of the flowering stage, and one for later use towards the end of the flowering stage.
Additionally, the set includes fertilizer for seedling and vegetative stage plants. This package is a great choice for growers who want a “total solution” for their plant’s growing needs.
ILGM has a large customer base, and the over 200 reviews for this product give it a 4.9/5.0 stars.
Convenience and Usability
This nutrient package comes as a dry powder. The mixing process is very simple and can be done quickly.
This fertilizer set is user friendly, and has a full cycle feeding chart that explains exactlywhat nutrient amounts should be given to your plant for each week. The chart explains when to switch from one fertilizer to another, and how much should be given to you plant (either in soil or hydroponically).
This type of clear instruction avoids a lot of the guesswork for feeding your plant, and is especially helpful for newer growers.
The ILGM fertilizer set emphasizes the “big three” essential nutrients of nitrogen, phosphorus, and potassium. Known as the N-P-K ratio, plants usually need more N at earlier stages, and and less so at later stages. The ILGM fertilizer set uses that exact progression:
- Seedling Fertilizer N-P-K: 11-40-13
- Growtime Fertilizer N-P-K: 19-5-20
- Flowertime Fertilizer N-P-K: 15-6-30
- Plant booster N-P-K: 0-27-27
Higher potassium levels support photosynthesis throughout the plant’s development, while potassium supports root and flower development for the seedling and flowering stages.
The full ILGM fertilizer package currently costs $49. This is a good value if you’re looking for a complete fertilizer solution for all stages of your plant’s growth.
However, I would not buy this full set if I was only looking for a bloom booster fertilizer. In that case, I would look for an individual bloom booster to get the most value for my money.
This product set was easy to use from start to finish. I used it on a small blue dream autoflower plant that I was growing. The charts were easy to follow, and I was able to time all of my nutrients appropriately. This resulted in a very satisfactory grow with a large yield.
Fox Farm is a well known fertilizer company. They were founded almost 40 years ago in Humboldt in 1984. They are known for emphasizing high quality and organic ingredients. Their products are found all over amazon with hundreds of positive reviews.
The Tiger Bloom booster is a liquid fertilizer, meaning the no mixing is required for this product. It is low salt, with chelated minerals for rapid nutrient uptake. While this is not a fully organic bloom booster, it is formulated with about 80% organic nutrients.
The Tiger Bloom booster is designed to increase bud density, and also create a large flower canopy with abundant flowering for your cannabis plants. The product can be used on flowering plants during any part of the flowering phase.
Convenience and Usability
The Fox Farms Tiger Bloom booster is very convenient to use. It is already in liquid form, but it is a concentrate that must be diluted with additional water before using. Instructions require about 2-3 teaspoons per gallon, so make sure that you have a container that can hold a gallon of fully mixed solution.
Instructions also note that this bloom booster can be used as early a 5-6 weeks during the grow, when buds are first starting to form.
This bloom booster fertilizer emphasized the big three NPK nutrients, but also contains some trace minerals that are required in smaller amounts.
The NPK ratio for this bloom booster is 2-8-4. Like other good flower fertilizers, this fertilizer contains a small amount of nitrogen and higher amounts of potassium and phosphorus.
It also contains the following trace minerals:
- Magnesium: .5%
- Boron: .02%
- Copper: .05%
- Iron: .12%
- Manganese: .06%
- Zinc: .05%
Trace minerals are good for preventing deficiencies, although they will not help a plant bloom by themselves. I would have liked to see calcium included as a trace mineral, but calcium deficiencies are usually not an issue.
Overall this product is a good value. Small containers can be found for as little as $20-$25 on amazon. This is a reasonable value, although it is already in liquid form, meaning that it is a bit diluted compared to the powdered bloom boosters on this list.
Overall I was satisfied with my results when using this fertilizer. This product delivered on its promise for big blooms and enhanced bud production.
The Fox Farms bloom booster is convenient because it can be used at any point in the flowering cycle. However, there are other products further specialized for early stage and late stage flowering plants. These products may be of interest to advanced growers trying to target their nutrients.
The Boost Pro Series is another product in the line of bloom boosters available for Lotus Nutrients. While the Bloom Pro Series is designed for the earlier parts of the flowering phase, the Boost Pro Series is designed to enhance your buds in the final weeks before harvest.
The Lotus Boost Pro series is designed to give a final boost of flower bud size and density, while also maximizing oil production for increased potency and taste. This product can work as a great finisher as your begin prepare it for harvest.
Convenience and Usability
Like the Bloom Pro Series, the Boost Pro Series also comes as a dry power. It must be mixed with water into a solution before feeding to your plants. The mixing process is very easy, and the ingredients in this mixture are fully chelated which helps plants absorb them quickly.
These dry powders are compact and easy to store because they have no water added.
Lotus Nutrients products come with helpful charts for determining how much fertilizer to use, and when to switch between products.
This product is very high in potassium and phosphorus (derived from soft rock phosphate). Plants in the final blooming stages require little nitrogen, so this is kept at very low levels.
This is the final nutrient breakdown for the boost pro series:
- Nitrogen: 1%
- Phospohorus: 15%
- Potassium: 30%
- Sulphur: 8%
Additionally, this pro boost product includes a range of amino acids that work to support bud growth in the final stages of the bloom.
This product is fairly expensive, and currently costs $28 for 18oz. This is a dry powder concentrate, so you get a lot for your money. I would recommend this product for cannabis growers looking to give their bud and flower growth a “final boost” before harvest.
Results with this product were very good. Flower buds tend to grow a lot in their final days and weeks. Supporting their growth in this stage can mean the difference between a mediocre harvest and a great one.
Advanced nutrients is another established company, founded in 1999 by Mike Straumietis. Originally a wholesale distributer for hydroponics companies, Mike’s engineering approach convinced him that he produce better formulas for plant fertilizers.
Bud Ignitor claims that their special formula can significantly increase the density of your bud canopy by up to doubling the number of bud sites on your plant. They also claim that this product can boost the speed that your plant grows flowers, so much so that you can get in one extra harvest per year.
Convenience and Usability
The Bud Ignitor bloom booster comes in a liquid form, and is very convenient to use. It is a concentrate that must be diluted with additional water before using. Instructions require about 2mL per liter. Usually for these, it’s necessary to make a bigger batch that can be used over time, as it’s more work to measure out such small amounts.
This product does not list its exact NPK ratios, however it emphases high levels of potassium and phosphorus. These are the two nutrients found in high levels in most bloom boosters, so this is a good start.
The other ingredient found in this bloom booster is kelp extract. Kelp extract can help plants by feeding beneficial soil microbes, and therefore supporting healthy root growth. This is absolutely a plus, as good nutrient uptake (supported by healthy roots), it very important at this stage.
Bud Ignitor costs around $25 for .25 liter on Amazon. This cost is comparable to many of the other products found on this list. However, the values is somewhat less for this liquid concentrate product, as dry powder concentrates tend to provide more nutrients for the money.
Using these nutrients on my plants, I did notice enhanced blooms compared to not using them. However, I’m not completely convinced that it can speed up your blooms and add an entire harvest per year, as the product claims.
I would also prefer for them to include other micro nutrients in the formula.
Overall, I think this is a good enough option, but would recommend other products on this list.
Miracle Gro is the best known product on this list. They are a big name in fertilizers and have thousands of reviews on amazon and other websites. These products are readily available at nearly every home and garden store, as well as online.
Miracle Gro Bloom Booster Flower Food is their version of a bloom booster product. While this brand is known more as a general gardening fertilizer, it can certainly be used on cannabis plants as well.
This bloom booster is water soluble, and is convenient to both purchase and use.
The Flower Food product’s main ingredients are the standard NPK nutrients. Their NPK ratio is 15-30-15, which means that this product still has a fair amount of nitrogen in it. A product like this would be best used in the early stages of blooming, or pre-bloom. Using this product later in the bloom cycle may lead to nutrient burn.
Reviewing the ingredients in this product, I also see that it includes several trace minerals such as boron, copper, iron, manganese, and zinc. Several of these nutrients are needed for growing cannabis, however I would say this product is not optimized for it as it does not include trace minerals such as magnesium or calcium.
Additionally, I don’t see ingredients that would promote microbial growth such as kelp extract, carbohydrates or other amino acids.
Miracle Gro is certainly the most inexpensive product on this list. It is available for $6 for 1.5 Ibs of product. This makes is a good value for buyers on a budget.
Using this product had good, but not great results. I used this product sparingly at the start of the flowering and bud production cycle, as I was concerned about nitrogen burn using it towards harvest.
Overall I would say that it was helpful, but that I noticed better results from products formulated specifically for growing cannabis.
Why you should use bloom boosters for flowering plants
As your cannabis plant grows from the seedling and vegetative stage and into the flowering stage, its nutrient requirements change. Mainly, the plant will require less nitrogen and more potassium and phosphorous. These nutrients support photosynthesis and the movement of water and carbohydrates within the plant.
Bloom boosters work by providing a nutrient profile that supports flowering plants. Some may even include essential oils, amino acids, or beneficial microbes that can help support your plant’s root growth.
Bloom boosters usually have less nitrogen than other fertilizers. Excess nitrogen supports plants in the vegetative stage, but should be reduced when a plant begins flowering. At this stage excess nitrogen can give your plant nutrient burn, and should be avoided to support healthy blooms.
What else is in bloom boosters?
Beyond the NPK (nitrogen, phosphorus, potassium) macro nutrients, bloom boosters can contain an array of other nutrients designed to help flowering plants. A common one is sugar, which is be quickly absorbed by plants and used as fuel.
Trace minerals are another popular ingredient type. These minerals are required in small amounts by many plant species to prevent nutrient deficiencies. While it’s common to get these nutrients through garden soil or water, trace minerals in fertilizer can be a good insurance that your plant is getting what it needs to grow.
Finally, there are what I call “extras” included in the fertilizer. These could be anything from beneficial microbes, to amino acids, to something like humic acid which can help plant absorb nutrients. These may not be necessary in a fertilizer, but have the potential to boost your plant’s growth.
What happens during the flowering stage of a plant?
When a cannabis plant starts to flower, it will cut off the growth of all its branches, leaves, and roots. At this point, all energy is directed towards growing buds. Leaves or branches will start to yellow or even die towards the end of the grow, as the plant neglects feeding them.
Bud growth generally takes a few weeks, at this point bloom boosters work to provide the exact nutrients needed to support bud growth.
Kushteller recommends the Lotus Nutrients Bloom Pro Series as their number one choice of bloom booster fertilizer.
Yes, they can lead to denser and bigger flowers through specially formulated nutrient profiles.
Kushteller recommends the Lotus Nutrients Bloom Pro Series as their number one choice for blooming flowers.
Bloom boosters can be used as soon as buds begin to form on your plant.