When to use PK boost?

Before you start, understand that PK Nutrients, Boosters and PK Boosters all exist, and are different things.

When to use PK / Boost?

PK Nutrients should be used from the first week of flowering, right up to flushing as they provide plants with the right nutrients to focus on forming new bud sights.

Boosters or ‘sugar stimulants’ should be used 7 – 10 days after introducing PK nutrients because you want to focus on providing PK nutrients to develop new bud sights, then introduce Boosters to pack the weight on them buds.

What are PK Nutrients?

Simply put, PK nutrients are specially formulated to contain a higher concentration of potassium and phosphorus. It helps to stimulate the natural chemical change that cannabis plants undergo when transitioning into the flowering stage, you will notice that on the bottles of PK nutrients they will mention a ratio of either 8/9 or 13/14, whereas PK boosters don’t usually mention the potassium and phosphorus ratios.

PK Nutrients work by providing your plants with a high reserve of Potassium(P) and Phosphorous(K), tricking the plant into thinking it’s ready to begin flowering and thus will begin to focus energy into the growth of new bud sights.

By providing PK nutrients you are giving your plant an early-start to begin bud sight and bud development, allowing a longer time to fully flourish and provide denser buds.

You will notice that most brands stick to the PK ratio of 13-14, although you may think it’s the same product amongst brands, it’s not – it’s important to remember that different brands have researched and perfected techniques using the different compounds, ingredients and technologies.

What are Boosters?

Boosters or ‘sugar stimulants’ can help trigger chemical changes in your plants and increase the rates of which chemicals react, this is known as the metabolic rate.

Some boosters use synthetic plant growth regulators which have been specially developed to stop vertical growth in plants and help encourage the plant to focus on producing more buds, most boosters are made from plant extracts to amplify chemical signals and help trigger hormones that encourage the plant to produce more buds.

Unlike PK nutrients, a formal definition doesn’t exist for boosters and thus a wide range of products are often labelled as a booster. Most boosters on the market are derived from plant extracts which don’t need to be listed on the label unlike NPK values so it can be hard to know what is inside a bottle of a booster.

Must Have Boosters

Take a look at our top 5 must have Boosters, this isn’t just a personal preference, we’ve done our research and this is what sells the best, and is best rated by amateurs and professionals.

Starting with the highest rated booster, Golden Tree by Humboldts’ Secret at number 1


This expert blend of nutrients from Humbolts Secrets can not only be used during flowering – when used during veg it can reduce the veg time by up to 50%! Used for flowering, HS Golden Tree increases the yields and quality of harvests.

Golden Tree is a proprietary blend of kelp, amino acids, carbs, and other good stuff, suitable for use with coco-coir, soil or hydroponics. It can be used as a foliar or a root spray and even contains essential nutrients to recover sick plants! – A true must-have for any grower and that’s why it’s our #1 alternative to Bud Candy!

Humboldts Secret Golden Tree
1300+ Reviews
Humboldts Secret Golden Tree
  • Vastly decreases vegetative time by up to 50% whilst increasing yields by up to 20%.
  • A Powerful Root Stimulator, Growth Accelerator, Carbohydrate Loader, Bloom Enhancer, Plant Strengthener, and More – all in a single bottle.


Another great option is Botanicare Sweet Raw, enhancing your cannabis plant’s flavours and odor, Sweet Raw is specially formulated with carbs, organic acids, vitamins as well as vital amino acids. This specialized blend of nutrients ensures a stress-free transition into the flowering stage with hearty, fruitful crops.

Sweet Raw is ideal for organic soil growers due to the high levels of organic matter used, or for use in hydroponic systems as this formula is clog-free!

Botanicare Sweet Carbo Raw
1300+ Reviews
Botanicare Sweet Carbo Raw
  • Develops hardy plants with compact internodes.
  • Improves balance between respiration and photosynthesis.
  • Maintains balanced metabolism for plants grown with C02 and HID lighting.
  • Will not clog systems.


Rock Resinator is a revolutionary bloom booster that will drastically improve as well as increase essential oil production and bud density. Resinator provides the highest quality soluble phosphorus and potassium for transition into the flowering stage.

An increased yield of up to 45% has been observed in studies by using Rock Resinator.

Rock Resinator Heavy Yields
  • Bulk out your yield with Rock Resinator Heavy Yields.
  • Expect size, taste, smell, colour & essential oil production to improve.
  • Naturally brewed, decomposed plant materials that can’t be synthetically manufactured.


CANNABOOST Accelerator boosts the metabolism of your plants. This is important because the rate of which your plant will uptake nutrients depends on the plant’s health and metabolism rate. CANNABOOST is specially developed for short cycle plant varieties and works wonders on autoflowers!

CANNA Boost Accelerator
  • Can be used with any growing system and in combination with any feeding with no exceptions.
  • Increases the speed of photosynthesis which greatly increases the sugar production in the fruits.
  • Stimulates the development of new flowers.


Explode is a flowering booster, helping to give your plants in flowering all the nutrients it needs in this phase. This flowering booster consists of several micronutrients, vitamins and acids, giving the plant an explosive bloom.

Suitable for every irrigation system with no residue left behind!

Dutchpro Explode
  • Explode is a brilliant bloom stimulator that delivers precious nutrients and minerals to your plants throughout the flowering stage.
  • Used by commercial growers worldwide to achieve amazing yields and plant vigor!
  • Explode is THE bloom stimulator that’s taking the market by storm!

What are PK Boosters?

Some products combine a booster ingredient with PK nutrients to help increase yield, people often refer to these as PK boosters as well as confusingly calling stand-alone PK nutrients ‘PK boosters’.

You need to take care to not use two products that do the same thing as you will nute burn your plants, as a general rule of thumb you should try and avoid using two products at the same time if they both contain high PK levels, however it is possible to use a booster alongside PK nutrients if the P and K levels on the booster are fairly low, (less than 1.5%)

PK 13/14 ratio explained

When you see PK 13/14 on a bottle of nutrients, this means that there is 130g of phosphorus and 140g of potassium per litre of the nutrient solution when dissolved in water, universally this is accepted to be a 1:1 of P to K. When using this formulation we can be confident that you are applying as much extra phosphorus as potassium in addition to your base nutrients

PK 9/18 ratio explained

PK 9/18 means that there is 90 g of phosphorus and 180g of potassium per litre of the solution when dissolved in water, this is accepted to be a ratio of 1:2. At this concentration, the recommended dosage is 0. 5 ml/litre.

What about PK 13/14 for auto-flowers?

We’ve covered that too, check it out.

Author: tgallone

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