All about early flower

Genetics are your ceiling

The first few weeks of flower are a crucial period of the cannabis plant life cycle in which they are still putting on a substantial amount of biomass and setting the flower sites that will exponentially increase in size during mid-flower.

So you’ll want to consider what kind of genetics you will be running, as not every variety will perform the same under the same conditions.

The potential for how each variety of cannabis expresses itself is woven into its DNA.

Most varieties grown today will double or triple in height during the first few weeks of flower, which is huge to consider.

This means that some varieties will always have a tendency to stretch hard or grow very tall regardless of conditions, while others will remain smaller. Other hybrids of today have malleability when it comes to stretching.

That means that plant height can be as short or tall as you desire, depending on how you control the environment, irrigation, and your plant training

But what is really going on during these first few weeks?

Stretch Begins

Photoperiod seeds will begin to flower as the light cycles shorten, whether naturally as the day length decreases or artificially as the grower changes the light schedule.

Autoflowering seeds will begin flowering after a given period of time regardless of the photoperiod, similar to how a determinant tomato sets flowers after a given period.

During this time, your plants will undergo several hormonal changes:

Auxins: This hormone typically supports cell elongation in vegetative growth but begins to decrease as flowering begins.
Cytokinins: This hormone favors flower development and begins to increase as your light cycle decreases
Gibberellins: This hormone stimulates stem elongation, which ultimately supports flowers and increases in concentration as flower begins.

With these hormonal changes occurring, your plants will begin what's known in traditional agriculture/horticulture as “bolting” but commonly known in the cannabis industry as stretching or the stretch period.

During stretch, it’s ideal to alter your environment, fertigation solution, and fertigation frequency and implement various plant training techniques to get the most out of your plants on harvest day.

Plant Training During Stretch

Implementing a number of plant training techniques during stretch can help you control plant height as desired and exponentially increase your flower yield and quality.

Use Trellis Netting

One of the most underutilized and underrated tools in the facility is your trellis netting.

Not only can this netting support the weight of your plants as they gain weight, but it can act as a canvas in which each gardener can control the direction of plant growth.

Bending branches underneath the netting itself will stimulate lateral growth nodes to bolt upward, effectively increasing the yield potential of your plant.

If utilizing trellis netting in your facility, it’s ideal to implement the first layer during the first day of flower, but no later than the first week of flower. This ensures that you can begin to work your branching outward in an effort to promote yield from the start.

Home growers or those with limited overhead space will make their second layer the last layer used. This layer is primarily to control spacing and the weight of the developing flowers.

Most greenhouse and indoor commercial growers and those without limitations on ceiling height at home will look to finish after the third layer is applied. Similar to the second layer, this third layer can be utilized to promote further airflow and spacing, as well as support the swelling flowers.

Its best practice for most varieties to have no more than 6” of flower above the final layer of trellis netting to avoid branches lacking support and snapping due to flower weight.

Low-Stress Training

This is the first method I recommend and involves gently bending the branches in between nodes in an effort to redirect the main branch’s growth, encourage lateral shoot growth upward, and control plant height.

No branches need to be broken to accomplish this, just take your time and work the branch very slowly. Each variety of cannabis will be different: some are prone to becoming stiff, while others are much more malleable.

Lollipopping

This is an intensive defoliation strategy in which the grower removes fan leaves from the lower to middle canopy in an effort to increase light intensity, improve airflow and redirect energy and nutrients to flower sites.

To get the most out of this technique, its ideal to wait until each variety has completed their stretch to prevent stunting plant height early. For most 9 week varieties, between day 18 and 22 are ideal to execute this strategy.

Supercropping

This is a high-stress method of plant training that involves damaging the soft tissue of stems, typically by pinching and/or bending without causing the branch to break in a harmful manner.

Ideally, this method is not utilized unless absolutely necessary, such as when your branches are getting too close to the light fixture. Branches can slightly break during this process and fully recover, but it's not ideal as it becomes an invitation for harmful pests and pathogens.

Altering Your Environment

To complete your visibility over pH during the process of irrigation, it’s also important to look at your runoff or leachate pH values.

You won’t be steering your entire crop off of runoff pH data alone, but recording runoff pH completes the puzzle with an additional data point that lets growers know how their plants are uptaking the nutrients in the media.

When growers consider this data point in tandem with feed pH and media pH, an educated decision can be made about how to alter the fertigation solution or schedule for better nutrient uptake.

If your runoff pH is lower than your inflow or feed solution, it could mean a few things:

A. Your plants could be happy with the feed concentration, but have an imbalance of negative and positively charged ions due to consuming negatively charged ions like sulfates and phosphates. With a higher concentration of positively charged ions, the pH of the solution decreases.

B. You are feeding too high of a feed concentration to your plants, leading to nutrient lockout and pH drop.

C. A hard dryback can lead to a decrease in pH due to the accumulation of acidic ions in the solution.

A higher runoff pH than your feed solution suggests that your plants aren’t taking up certain nutrients efficiently potentially due to high feed concentrations.

You’ll notice your plants struggle to uptake negatively charged ions like phosphate and iron.

It’s also crucial to take your runoff samples simultaneously concerning your irrigation.

Meaning, take your samples at the same time each day. Otherwise, you will likely skew the data due to evaporation, rising EC and ionic concentration.

Fertigation During Stretch

How you feed and water your plants also plays a role in plant growth during the first few weeks of flowering.

If you have a variety you’d like to stretch a bit more, it’s ideal to keep your irrigation strategy similar to vegetative growth by offering frequent but small shot sizes.

1%-3% of your total substrate volume should be applied every 30-45 minutes.

Your total time irrigating should be over a long period of time as opposed to reaching your target quickly and pushing runoff too early.

For varieties that you’d like to control stretch on, it's ideal to switch to a more generative irrigation strategy when you begin flowering.

This means applying larger shot sizes at each irrigation event, somewhere between 4%-6%, and finishing all irrigation events within a quick period of time.

Regardless of variety or the strategy you choose during these first few weeks, it's ideal to allow 1-2 hours to pass after the sun comes up or your lights come before your first irrigation event of the day to allow your plants to “wake up,” begin transpiring and drying back.

As the days pass and plants respond well to the irrigation schedule you chose, you’ll notice your plants demanding a higher volume of water at each irrigation event.

Listen to your plants and give them what they need while staying within the confines of your irrigation strategy.