In this report, we’ll detail our time with C4 Automatic. These plants are incredibly compact and boast a remarkably fast flowering time, making them ideal for indoor growers worried about space or privacy. While the yields might not blow anyone away, the strain’s ease and reliability make it a great pick for novice growers or those with limited headroom.
Total growing time: 81 days
Flowering time: 61 days
Final height: 43 cm
Final yield: 42 grams
THC content: 18.24%
C4 Automatic is a 60/40 indica/sativa hybrid developed for the Sensi Seeds Breeding Grounds project alongside the team at Serge Cannabis. The original C4 blends Triangle Kush with Strawnana, and this new, autoflowering version crosses that long-time favourite with Sensi Seeds’ Ruderalis Indica, the very first autoflowering strain created by Nevil Schoenmakers in the 1980s.
We grew our C4 Automatic cannabis plant under a 1000 W lamp set to an 18/6 schedule, in an 8-litre plastic pot filled with BAC Lava mix. Throughout the grow, we kept the space at a consistent 23°C during daytime hours, with nighttime temperatures dropping slightly to 21°C. In the early vegetative phase, we kept the relative humidity at 65% before gradually lowering it as the plant approached harvest.
Germination & seedling
To germinate our C4 Automatic cannabis seed, we placed it on top of a couple of damp (but not dripping) paper towels, covered it with another damp paper towel, and set everything on a plate. This was then all placed into an open plastic bag, which was left in a warm place out of direct sunlight. After a day or two, the seed had split open to expose a small white taproot, indicating it was time to plant.
Next, we planted our seed with the taproot pointing down in a pre-soaked Rockwool cube and put it under a 600 W LED lamp. At this stage, seeds are extremely fragile, so it’s best to avoid excess light, water, or heat that could cause long-term damage to the plant.
After three days, we began daily feedings with 100 ml of pH-balanced water (pH 6.2; EC 0.8) mixed with a small dose of rooting hormone. By the end of the first week, our C4 Automatic cannabis plant had grown to 7 cm tall with a set of healthy pre-leaves.
Vegetation
Entering the second week, our C4 Automatic plant had grown slightly to 10 cm and sprouted its second set of leaves. At this point, the roots were growing out of the Rockwool cube, signalling that it was time to move the seedling to an 8-litre plastic pot. Additionally, we doubled the daily water to 200 ml (pH 6.2; EC 1.4) to help our plant get everything that it needed.
In the third week, our plant continued at a steady pace, reaching a new height of 15 cm and sprouting a new set of leaves, though no signs of lateral branches yet. This new vegetation was a vibrant, healthy green, and the main stem was thickening nicely. To keep up with this growth, we again doubled the water to 400 ml per feeding.
Before flowering kicked off, we added small satchels of Neoseiulus californicus and Amblyseius swirskii to the plant’s pot. These beneficial critters have a symbiotic relationship with cannabis, meaning that they prey on pests like spider mites or thrips without causing any damage to the plant. We replace these every four weeks to maintain a regular supply.
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Flowering
As the fourth week came and went, our C4 Automatic plant sped up considerably, growing to a height of 25 cm. This growth was accompanied by a few new sets of leaves and significant growth of existing leaves, which were moderately broad. With flowering expected to kick off any time now, we upped the water to 800 ml (pH 6.2; EC 1.8) per feeding and switched to Bio Flower liquid nutrients.
As this is an autoflowering strain, we didn’t need to switch the lighting schedule. However, we were growing photoperiod strains in the same place, so we had to flip the light to a 12/12 schedule. Even if you’re only growing autoflowers, it’s important to give them several hours of darkness each day, but they can and will flower on an 18/6 schedule.
Week five saw a massive slowdown of vertical growth, as our plant only gained 3 cm to finish the week standing 28 cm tall. However, this was offset by the rapid growth of existing vegetation, with every leaf growing considerably in size, as well as significant development of the lateral branches. Internodal spacing was still rather tight, though slowly beginning to enter the pre-flowering stretch. To help our plant stay healthy, we again increased the volume of water to 1000 ml per day, and we lowered the humidity to 60% to prevent mould.
In the sixth week, our plant continued its steady growth and was now standing 32 cm tall as the inner nodes stretched considerably, creating a rather open, airy frame. The lateral branches saw a major round of growth and were growing rather far out from the main stem. Over the week, our plant began to show the first signs of flowering, as clusters of small white pistils began to grow at the tips of every branch. To make sure our plant had everything it needed for flowering, we increased the water to 1,500 ml each day. This would not change for the rest of the grow.
Week seven saw nearly no vertical growth, with our plant gaining only 2 cm, finishing at a height of 34 cm. However, we did see a rapid burst of flower growth with buds popping up all over the plant. The buds at the top of the plant were already growing together to form the cola, and the lateral branches were developing healthy flowers throughout.
Over the eighth week, our plant continued its remarkably slow growth, ending the week at only 36 cm tall. By now, the plant was in full bloom, and the main cola had grown to run nearly the entire length of the stem, while the fairly short lower branches continued to grow outwards. By now, our plant was starting to give off a fruity, tropical smell that was certainly noticeable, but not overpowering.
As week nine came and went, our C4 Automatic cannabis plant grew to 38 cm, and flower development continued to accelerate. By now, the main stem was a single, dense cola, while the lower branches were each supporting smaller, though equally dense buds. Despite the relatively long internodal spacing, the plant’s vegetation was fairly dense, and the lower section was a tangle of leaves, which made ensuring proper airflow a top priority.
In week ten, our C4 Automatic plant reached a new height of 43 cm, with the main cola now fully formed and growing thicker with each passing day. The lower branches were doing an admirable job of supporting their new flowers, and the first pistils were gradually turning orange, signalling that harvest was approaching.
Week eleven saw no vertical growth, though the buds continued to grow larger and denser. The lateral branches were now sporting impressive secondary colas, and the plant was almost entirely a single, massive flower. During this time, we lowered the humidity to 55% to help keep the plant free from mould.
In week twelve, we harvested our C4 Automatic cannabis plant.
Harvest
Once it was time to harvest our C4 Automatic cannabis plant, we started by cutting it down at the base and trimming away all of the large fan leaves. Next, we left the plant hanging upside-down in a climate-controlled room kept at 15.5°C with a relative humidity of 50%. Once the smaller branches were dry enough to snap when bent (typically 10-20 days), it was time to move on.
After the plant was dry, we removed the flowers and trimmed off the remaining leaves. The plant’s compact frame only allowed for a fairly small number of flowers, but each one was quite large, moderately dense, and moderately leafy, making trimming a fairly quick, hassle-free task.
When everything had been trimmed up, the buds were placed into glass jars for curing. For the first 24 hours, we left the jars open so that much of the remaining moisture could evaporate. Then we sealed the jars and “burped” them several times per day. And gradually reduced the frequency to once per day over the next several weeks until the buds had finished curing. The process typically requires 4-6 weeks and cannot be rushed.
All in all, we harvested a modest 42 g of dried flowers with a THC content of 18.24%.
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Terpene profile
As our C4 Automatic plant entered the flowering stage, it began to give off a subtle, rich aroma that combined the fresh sweetness of a strawberry smoothie and tropical banana notes from the Strawnana parent, while inheriting warmer Kush undertones from the Triangle Kush line. The scent was definitely noticeable, though the plants’ relatively compact size kept things from getting out of hand.
After drying and curing, the buds took on a deeper fruit-forward scent with clear notes of strawberry purée, creamy banana, and fresh berries layered over hints of gassy Kush and light, earthy doughiness. The flavour followed suit with the taste of a creamy strawberry milkshake and ripe banana on the inhale, followed by warmer, earthy Kush notes through the middle before finishing with a smooth, slightly gassy exhale that left a sweet, lingering aftertaste.
The effects of C4 Automatic were largely balanced from start to finish. Things started off with a cerebral headrush and mild introspection while still remaining calm, euphoric, and physically relaxing without locking us to the couch. This strain is a great pick for any time of day, thanks to its mellow, clear-headed high and steady mood-boosting body buzz that really takes the edge off without dragging you down.
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The outcome
While C4 Automatic won’t blow anyone away with its yields or potency, the strain’s extremely compact size, reliable output, and lightning-fast flowering cycle make this an ideal pick for a sea of green (SOG) grow, or for anyone who values speed over size. Likewise, discreet growers with limited room will love C4 Automatic’s low profile and minimal odour. Additionally, these plants are an amazing addition to fill out any unused space in a grow room, as they won’t compete with any neighbouring plants.
- Disclaimer:Laws and regulations regarding cannabis cultivation differ from country to country. Sensi Seeds therefore strongly advises you to check your local laws and regulations. Do not act in conflict with the law.
