The Ultimate Guide To Feeding Flowering Cannabis Plants

Sep 27, 2024

Whether you are planting cannabis for personal or commercial purposes, it is essential to understand the proper nutrients for high-quality buds with the best smell and taste. Cannabis plants are sensitive to nutrients, and you should ensure you don’t cross the line between underfeeding your plants and using too many chemicals.

While every cannabis growth stage is essential for high-quality yields, you should pay the most attention to the flowering stage. This is when they start to produce flowers, meaning you must provide the plants with the proper blooming nutrients.

One advantage I experienced when growing my cannabis plants indoors is that I can control when they start flowering. The flowering stage begins immediately after you reduce the amount of light your plants get. This means you should switch the schedule to 12 hours of light and 12 hours of darkness.

Proper Nutrients For The Flowering Phase

The cannabis flowering phase is usually divided into weeks or stages. Different strains have different flowering durations, lasting between 8 and 11 weeks. Flowering cannabis plants require more potassium and phosphorus and less nitrogen to promote the development of big, resinous flowers. This makes NPK the best bloom fertilizer because you only need to change the ratios for different requirements.

NPK fertilizer ratios for early, mid, and late flowering stages of cannabis growth.

Early bloom stage: Week 1-3

Usually referred to as the transition stage, this is the time when the cannabis plants prepare themselves for blooming. When caring for my first cannabis plants, I thought that once I stopped exposing them to too much light, they would stop growing and begin developing buds.

I was, however, shocked because, during the first week, my plants experienced accelerated growth and stretching. This is known as the flowering stretch, and the cannabis plants usually want to outgrow surrounding plants for better light penetration and to get more inter-nodal distance for more flower clusters.

The second week is when you can distinctly tell between male and female plants. Females begin developing long and white pistils on their bud sites, while males grow round pollen sacs.

By the third week, the plants will stop stretching and focus their energy on developing buds. While the buds might still be tiny, you will see bigger calyxes and trichomes. When shifting the ratios of your fertilizer, it is best to do it gradually to ensure your plants adapt well. During the first three weeks, it is best to use an NPK fertilizer with ratios of 5:10:7.

Mid-bloom stage: Week 4-5

Cannabis plants stop growing and focus primarily on bud development. You will notice bigger flowers daily, thicker calyxes, a more defined trichomes layer, and more pistils.

The plants will also start producing more complex and noticeable aromas. The best NPK formula in this stage is 6:15:10, but monitor how your plants respond first.

Mid-late bloom stage: Week 6-8

You will have thick and big buds with more white pistils at this stage. They will also have a thick trichomes coat, giving off more potent and intense aromas. The buds will be heavier and denser, and the calyxes will be notably bigger.

If you have fast-flowering strains, they might be ready for harvest with more mature buds, darker-colored pistils, and more trichomes. Because of the heavy buds, it is essential to support your plants.

The plants at this stage will require minimal to no nitrogen. Therefore, you can use an NPK formula of 4:7:10 or bloom boost with a 0:50:30 ratio.

Late bloom stage: Week 8 to harvest

This is the final stage of the flowering phase, where you will see denser and firmer buds coated with thicker layers of trichomes. The trichomes should change into a milky white color from clear, with some becoming amber and the pistils becoming darker.

Ensure to keep the phosphorus and potassium levels high, but flash the plants with clean pH-balanced water two weeks before harvest. This ensures that the plants use all the remaining nutrients while preserving the bud’s natural flavor.

After flushing, it is normal for the plants to have some yellow leaves because they don’t have as many nutrients as before. The reduced blooming nutrients from the growing medium force the plants to move the remaining nutrients from the older leaves to the buds.

Organic Vs. Synthetic Fertilizers

Using an organic or synthetic cannabis bloom fertilizer depends on your budget and personal preferences. Organic fertilizers are usually made from organic sources like vegetable and animal waste.

They usually come in powder form, unlike synthetic fertilizers that you can also buy in liquid form. Before deciding which one to use, it is essential to understand the pros and cons of each.

Synthetic fertilizers pros

 

  • They are absorbed faster, making them better for situations like treating nutrient deficiency
  • They give you more control over the nutrients you introduce to the plants because manufacturers use specific ratios

Cons

 

  • They are harmful to the environment
  • It is easy to overfeed the plants with synthetic fertilizes

Organic fertilizers pros

 

  • They are environmentally friendly and eventually enrich the soil
  • They protect the plants from too many nutrients because of their slow-release nature
  • They help with water retention and improved airflow

Cons

 

  • It takes longer for plants to absorb them
  • They can introduce pests and insects to the plant
  • They need microorganisms to break down the nutrients

Common Nutrient-Related Problems

While you might follow all the blooming nutrients requirements, you might run into issues depending on how often you feed your plants and the blooming fertilizer you use. Here are the most common problems and how to recognize and treat them.

Comparison image showing signs of nutrient burn and nutrient deficiency in cannabis plants

Nutrient burn

This happens when you overfeed your cannabis plants or when there is nutrient buildup in the growing medium. You will notice dark green leaves with nearly neon green tips that usually bend almost 90 degrees upwards.

The plants will also have a deep red, purple, or magenta branches and stems. You might also notice yellow calyxes in your flowering plants, followed by rapid dying.

You can quickly treat this by flushing the growing medium with clean pH-balanced water for a week before introducing fertilizer again.

Measuring EC and PPM is also essential in preventing nutrient burns. EC (electrical conductivity) is the amount of total dissolved salts in the growing medium. PPM (parts per million), on the other hand, is a measure to indicate how much nutrients are present in the growing medium.

Nutrient deficiency

This happens as a result of nutrient lockout or underfeeding. Nutrient lockout happens when nutrients build up around the roots or when there is a pH imbalance, preventing the plant from absorbing the available blooming nutrients.

Plants with nutrient deficiency might have brown or yellow leaves, dry foliage, and discolored stems. You can treat this by introducing more nutrients or treating nutrient lockout first.

pH imbalance

This might result from imbalances in your water, medium, or the blooming fertilizer you use. If not treated immediately, pH imbalances will heavily affect the quality and quantity of your yield.

If the imbalance comes from your fertilizer, you should try Advanced Nutrients pH Perfect Sensi Bloom. This fertilizer automatically balances the pH in your growing medium, introduces unique ingredients for better floral structure, and promotes earlier blooming with increased budding sites.

Chart showing optimal pH and electrical conductivity (EC) levels for cannabis plants during the flowering stage

Other Requirements The Blooming Stage

In addition to nutrients, cannabis plants require the proper temperature, humidity, water, and ventilation for high yields.

Lighting

Light is essential in the early stages of cannabis growth. However, in the flowering phase, cut it short to 12 hours of light and 12 hours of darkness. This ensures your plants stop concentrating on producing more leaves and instead focus on developing buds.

Refrain from interacting the periods of darkness, even for short periods, because that will interrupt the budding process. You can increase the dark periods as you progress into the flowering phase.

Temperature

The best temperature for flowering cannabis plants is between 18 and 26 degrees C. Very low temperatures will slow the plant’s growth, while very high temperatures will cause excessive dryness, burnt leaves, and stunted growth.

You should maintain daytime temperatures around 26 degrees C and night temperatures between 16 and 18 degrees C during the first three weeks.

Humidity

The best humidity for flowering cannabis plants is between 40 and 60%. Too little humidity will cause excessive dryness, while high humidity can result in mold and fungi growth.

Humidity for the first three weeks should be between 50 and 60 %. In weeks four and five, it should be around 50% and 30-40% from week six to harvest time. You can regulate the humidity using a dehumidifier or exhaust fan.

Table showing optimal humidity levels during cannabis flowering stages

Water

Ensure you water your cannabis plants with clean and chlorine-free water and ensure they have proper drainage. To ensure you don’t overwater them, stick a finger into the soil and water when the first few cms are dry.

Ventilation

Ventilation during flowering is essential to prevent fungi, rot, and mold development. Invest in a good fan to circulate air around the growing area and an exhaust fan to pump out the musky air.

pH levels

The best pH levels for blooming cannabis plants are between six and seven. Therefore, ensure you keep the fertilizer levels healthy to avoid imbalances. You can also use Sensi Bloom, an Advanced Nutrients pH perfect fertilizer throughout the flowering phase.

FAQs

 

What secondary nutrients do flowering cannabis plants need?

In addition to potassium and phosphorous, you should provide your plant with calcium, magnesium, sulfur, manganese, zinc, chlorine, iron, boron, copper, cobalt, silicon, and molybdenum.

Must I use a bloom boost?

A bloom boost is essential because it helps stimulate flower growth. Bloom boosters are complete fertilizers with potassium, phosphorus, and nitrogen geared toward increasing the phosphorus supply.

It would be best if you introduced them in the fifth or sixth flowering week, but they are unnecessary unless a soil analysis shows a phosphorus deficiency.

Does feeding remain the same even after changing lighting hours?

As your cannabis goes deeper into the flowering stage, you should continue reducing the light you expose to encourage more budding. Cannabis plants put on more mass during the low light periods, produce fan leaves, and later grow inflorescences.

They produce most of their CBD and THC on small leaves and bracts amidst the inflorescences. The leafy nature of the bracts means they need similar nutrition to leaves, so you don’t need to change the nutrient formula.

Can certain nutrients increase cannabinoid percentages?

Every cannabis grower wants their yield to have high cannabinoid levels. However, no research has indicated a direct link between specific nutrients and cannabinoid levels.

Some people, however, use nutrient stress to increase cannabinoid levels, but this is a complex subject. Nutrient stress can change the profile of up to 100 cannabinoids in over ten ways and might suppress growth.

A better strategy to increase cannabinoid levels is to produce bigger flower masses or heavier buds.

Conclusion

Feeding your cannabis plants during the flowering stage determines the quality and quantity of yields you get. It is essential to watch the frequency you provide our plants and the quality of the blooming fertilizer you use.

Ensure you buy from a reputable store and compare different brands. Some brands usually have pre-measured kits for every stage of the flowering phase, making it easier to monitor the effects.

Grinding cannabis with hands

Razor

Like weed is ground with a knife, so is weed ground with a razor. Your bud should be placed on a plastic cutting board or another spotlessly level surface. Use a razor to cut it apart carefully. A razor will work if you’re extremely careful about cutting your fingers.

Blender

A blender is my best friend when dealing with more significant volumes of marijuana. Clean your blender and throw it in your stash. Switch it to the pulse setting so you may manage the timing of the blending to ensure you don’t waste your weed since the blender is a bit powerful. Shorten the intervals as necessary to achieve the desired texture. A blender, though, should be your last resort, especially if the amount of weed is small.
Point to note:

  • Before blending, remove any stems and seeds because they will harm the blender’s blades.
  • Since the blender could be a bit strong, try to keep mixing for no more than 10 seconds.

Reasons why you should grind your weed

Grinding up your weed allows air to flow easily through your bong, bowl, or joint, which means a cleaner burn and a more even pull throughout. Below are the benefits of grinding, whether with a grinder or not.

  • Better portability. After grinding the weed, you can call in small containers or sachets.
  • It tastes better. Smoking ground marijuana helps remove the terpene profile’s inherent flavors. Cannabis has a better flavor and taste; many report an improved smoking experience.
  • Provision of slower burning joints.

Disadvantages of not using grinders

 

  • It takes a lot of time to prepare the weed.
  • Breaking down the weed with your fingers can leave them extremely sticky, which is annoying.
  • It is difficult for you to roll the joint conveniently. It is hard to get a fine product compared to using a grinder.
  • The marijuana smell is also left on your fingertips and other home appliances.

Conclusion

Getting to grind your weed helps it taste better, and you don’t have to worry whether you have a grinder. A coffee grinder may just be the best tool for breaking down a huge quantity of cannabis into a uniform, finely ground finished product. It can quickly grind a lot of material with relatively little effort.