Grow Journal: Aug - Nov 2024

Posted Sep 19, 2024 Updated Oct 4, 2024

By JD Henson , Ethan Cochran

9 min read

Batch AU24 is a 6-plant group of autoflowering cannabis being grown in a 50 gallon recirculating deep water culture system. The group germinated between August 18th and 19th, and is expected to be harvest around November 11th.

This is our first run using a RDWC system, so while we are using relatively fresh genetics, we are mostly sticking to a known and trusted breeder for our seeds.
Our nutrition/supplement needs are covered with a custom regimen combining products from General Hydroponics and Botanicare.
Light is provided by 2x ROI-E720 LED fixtures, with an exceptional PAR output of 1850 umol ppf, these fixtures are more than sufficient for our grow space.

Germination

On the 18th of August, 4 out of 6 seedlings have popped out of their shells, and by the 19th all plants have presumably begun photosynthesis. The two labels obscured in the below image are Lemon Pie and Forbidden Runtz, both bred by Fast Buds. Gorilla Cookies is another autoflower bred by Fast Buds. Bourbon Berry, the odd one out, is an autoflower bred by Twenty20.

Veg Begins

Between August 21st – 23rd all plants have properly began vegetative growth, and are now transferred into the RDWC system. A layout diagram has been made for easy reference throughout this article.

Veg Day 11

Having long outgrown their starter cubes, all the plants have transitioned well into into their reservoirs. While there is no obvious signs of a leader(s) yet, there is a probable calcium deficiency noticeable on one of the Gorilla Cookies (back row, farthest right).

Veg Day 15

With the plants now fully acclimated to the RDWC system, and the probable calcium deficiency taken care of, the plants are beginning to really fill out. The three Gorilla Cookies (whole back row) are pulling ahead, with Bourbon Berry (front row, farthest left) not far behind.

The Forbidden Runtz (front row, farthest right) is the smallest of the pack so far, but is otherwise healthy and shows no signs of nutrient deficiency or burn.

Flower Begins

At this point it’s important for us to talk about the difference between autoflower and photo-period cannabis. At it’s most simple, autoflowers have a genetic hard-coded lifespan, while photos have a life cycle that adapts to light. Photos give you more control, and room for error, however they require strict isolation from light during their off-period, and often require more training. Autos in contrast with their fixed lifespan, have little room for error, but often flower faster and may require less training for an optimal canopy.

People have lots of strong opinions about the photo vs auto debate, so just know that both are great and have their places in different situations. In recent years fast-flowering photos have become more and more popular, and we may experiment with them in the near future.

On September 9th, the AU24 batch began it’s transitional period from veg into flower. With the plants being autoflowers, this happened on it’s own according to their genetic clock, rather than being triggered by a change in their light schedule. Despite having a mix of different genetics in the batch, with both indica and sativa presenting plants, they all still transitioned at roughly the same time due largely in part to intentional strain selection, and receiving identical nutrients from a shared reservoir system.

Flower Day 5

Just under one week into flower, the plants are transitioning nicely and beginning to put on lots of bud sites.

Flower Day 9

Despite some minor issues with nutrient concentration due to faulty measuring equipment, the crop is looking fantastic. While the Forbidden Runtz is still the smallest of the pack, you can see it has very tight internodal spacing, and has a pretty high density of bud sites. It’s larger sisters are similarly healthy.

Flower Day 12

On day F9 (after taking the above photo) the entire crop was lollipopped. Lollipopping is a very popular technique used by many growers alike, but the question of why you do it is an important one. Lollipopping’s definition as I see it, is removing unnecessary leaf and branches that will just flat out not make to the surface of the canopy. This will not only make the plant focus more on its productive branches, but will also help the plant breathe.

Removing this extra material will allow a better exchange of airflow, allowing the removal of stagnant O2 left over from photosynthesis, and providing a better supply of fresh CO2 (i.e. “Breathing”). In a more traditional soil or semi-soil system, this may also help with pests, but will have little effect in that regard with our medium.

As you can see, we go for a much less aggressive approach than some growers. Our goal is to only remove branches that would essentially feel like a waste of time to even bother processing once harvested. Good quality LED lights tend to provide great light penetration, so in our case, it is really only the bottom couple of nodes on each plant that get removed.

Overall with the group firmly in their transitional period, upward growth has slowed somewhat. However, all of the plants continue stacking new nodes, and have begun the formation of future colas. Even our outlier, Forbidden Runtz, is looking very promising at this stage.

Flower Day 15

Having mostly finished their transitional period, this is when we consider the plants to have truly started flower/bloom. For the past 2 weeks or so, they have been getting a blend of nutrients that focuses both on root/leaf/stem development, as well as nutrients for flower production. There is a whole lot going on under the hood at this time, so they’re getting about the most diverse range of nutes and supplements they will their whole lives.

From this point on though, it’s all about flower production. Their nutrition regimen will narrow in scope, their growth will change dramatically, and the plants have already begun to show it.

Aside from differences in size alone, you can really begin to see the difference in strains and phenotypes coming out of the transition period. Note the significant difference in cola formation between the Lemon Pie and any of the other plants. Lemon Pie is very showing in its historically Sativa genetics, in stark contrast Forbidden Runts which is an indica-dominant hybrid (of which we got a particularly indica-dominant pheno) sits much lower, and is stacking tighter.

The Gorilla Cookies fall somewhere in between, with their lineage being closer to a truly balanced hybrid. The far left (according to the diagram above) Gorilla Cookies is the most indica-presenting (despite its very large size, it has tighter internodal spacing & more indica-presenting leaves), with the far right Gorilla Cookies the most sativa-presenting.

Overall, all the plants in the batch are coming into full flower with very strong and tight stacking across the board, and noticeable trichome production beginning on the middlemost Gorilla Cookies.

Flower Day 22

Coming up on the halfway point of flower, it’s become very apparent that these plants will need to be supported in one way or another. After a fall-over that fortunately didn’t result in any long term damage, we designed and are in the process of implementing a trellis system for each plant, to provide support as they continue to put on more weight.

Due to space constraints, the largest of the plants have needed cut back several times. While it never feels good to trim what is likely viable future bud, if the plant is allowed to grow outward into the walls, it will reduce airflow and could result in mold/bud rot. If they are allowed to grow upwards into/near the light fixtures, it will result in light burn and will block neighbors from getting sufficient light.

Controlling plant size is a fine balancing act for indoor growers, and you have more limited options to tackle this challenge when running autoflowers. If you keep your plants too small, you end up paying more gram per gram in nutrients and electricity by leaving space on the table. (Plus, who doesn’t want to grow bigger plants right?) However, with the risk of stunting other plants in your batch, or worse yet developing mold, it’s better to err on the side of caution.

You can see from the canopy shot below, the vegetation is very thick, so maintaining adequate airflow and humidity is absolutely critical in the coming weeks. While it’s been very rainy recently in Ohio, with cooler weather around the corner, we have the environment on our side. Ohio tends to be very humid in warmer months though, so when growing in Spring through Summer, we typically end up using a dehumidifier at one point or another.

With proper airflow, up to 60% RH is acceptable during the vegetative stage and can even help with growth. However from here on out, we try to keep them in an environment between 40% to 50% RH. Any higher and the risk of mold and rot increases, and any lower may result in the degradation of terpenes, cannabinoids, and other biochemicals.

Growing

This post is licensed under CC BY 4.0 by the author.