Cannabis Indoor Growing Class - Hydroponics 101 - Tools, Nutrients and Grow Tips
Indoor Class 2025 - Purple Runtz Cake - germinated 12.16.24
Welcome to Hydroponics 101: Indoor Cannabis Growing Basics
Welcome to the next lesson in our Cannabis Indoor Growing Class 2025! Today, we’re diving into the fundamentals of hydroponic cannabis cultivation, covering pH levels, nutrients, and PPM (parts per million)—essential knowledge for any grower looking to maximize yields in an indoor hydro setup.
Join Christian and Jackie on their hydroponic cannabis journey, as they navigate the challenges and rewards of growing without soil. Whether you’re new to hydro systems or looking to fine-tune your setup, this guide will help you understand how nutrient solutions, oxygen levels, and root zone management play a crucial role in plant health and high-quality cannabis production.
Let’s get started with the basics of hydroponic cannabis growing!
Hydroponics 101: The Basics of Growing Cannabis Without Soil
Hydroponic cannabis cultivation is a soilless growing method that delivers essential nutrients through water instead of traditional planting media. This technique allows growers to have precise control over nutrient intake, oxygen levels, and pH balance, resulting in faster growth and higher yields compared to soil-grown cannabis.
In hydroponic cannabis systems, plants are either anchored in an inert growing medium (like perlite, rockwool, or lightweight expanded clay aggregate, known as LECA) or held in place by a collar that supports the stem. These systems provide an optimal root zone environment, where plants can absorb nutrients more efficiently.
Why Choose Hydroponic Cannabis Cultivation?
Hydroponics offers several advantages over traditional soil growing:
Faster Growth & Higher Yields – Hydro systems create an ideal nutrient delivery process, allowing plants to focus on bud production rather than root expansion.
Less Labor-Intensive Setup – No heavy soil to move, and smaller containers can be used.
Easier Postharvest Cleanup – No soil means no mess. Cleaning, disinfecting, and replanting are more efficient in hydroponic cannabis gardens.
Better Control Over Nutrients & pH – Maintaining the right pH and nutrient balance is easier, reducing the risk of deficiencies or toxicities.
Prevents Common Soil Issues – Hydroponic systems eliminate problems like root rot, pests, and soil-borne diseases that can plague traditional container gardens.
Choosing the Right Hydroponic Growing Medium
While hydroponic cannabis is grown without soil, most systems still require a growing medium to support plant roots. These substrates can be either inorganic or organic:
Inorganic Hydroponic Mediums – These materials do not break down easily and have no buffering capacity. Common examples include perlite, rockwool, and LECA (clay pebbles).
Organic Hydroponic Mediums – These carbon-based materials, like coconut coir and wood chips, are sometimes used for their water retention properties while still allowing good drainage.
Selecting the right hydroponic substrate depends on your grow system, water retention needs, and nutrient delivery method.
From Christian and Jackie’s Garden: Key Takeaways from Our Hydro Experience
Hydroponic growing has been a fascinating and rewarding journey for us. While the method can be a bit of a challenge at the start, it’s also incredibly rewarding. We’ve made our share of mistakes, but each has taught us something new.
Overall, we’ve learned that staying on top of the basics is key to success. One of the biggest differences compared to outdoor growing is how much more attention we have to pay to the plants, especially during the vegetative (veg) phase.
In soil, there's a natural buffer that helps maintain stability, and we've developed a deeper appreciation for it as a growth medium. But with hydroponics, there’s much less margin for error, and you have to be extra vigilant—especially as beginners.
The Vivosun tent’s three-sided access is incredibly helpful, making regular maintenance much easier. Jackie is using a basic siphon system to refill the containers.
We’ve learned a lot through trial and error, and we're excited to share some key takeaways from our experience so far:
1. Invest in Good Tools: pH and PPM Meters Are Essential
One of the first and most crucial lessons we learned was the importance of accurate pH and PPM (parts per million) meters. When we first started, we underestimated how vital it was to have precise nutrient readings—but we quickly realized that without well-calibrated tools, you’re flying blind.
Why pH & PPM Meters Matter in Hydroponics
pH meters ensure your plants can absorb nutrients efficiently. Even small fluctuations can lock out essential nutrients, leading to deficiencies.
PPM meters help track nutrient concentration in your hydroponic reservoir, preventing overfeeding or underfeeding your plants.
Calibrating and cross-checking multiple meters helped us understand how minor discrepancies affect plant health.
If you plan to grow hydroponic cannabis regularly, investing in quality pH and PPM meters is a game-changer. Reliable equipment makes a world of difference in ensuring a healthy root zone, balanced nutrient uptake, and thriving plants.
We opted for a classic ATC PH meter since it allows for manual adjustments, which is really helpful. We used a Bluelab pH calibration solution to fine-tune it. Tip: Always put the cap back on your pH meter after use to ensure its longevity!
2. Pay Close Attention to Your Plants—Daily Checks Are Crucial
“Use your eyes, and act quickly.”
One of the biggest lessons we've learned in hydroponic cannabis cultivation is that observation is everything. Unlike soil-grown plants, where the medium provides a natural buffer, hydroponic plants react much faster to changes in their environment—both good and bad. That’s why we make it a point to check on our plants at least twice a day, carefully inspecting every detail to catch potential issues before they escalate.
Spotting Deficiencies Early: Our Magnesium Deficiency Lesson
One of our first major challenges was dealing with magnesium deficiency—something we had never encountered in outdoor growing. In soil, nutrients break down slowly, giving plants a steady supply over time. But in hydroponics, nutrient imbalances can show up almost immediately, making daily monitoring essential.
At first, we were stumped by what we saw—yellowing leaves with dark green veins—until we turned to one of our go-to resources, Marijuana Garden Saver, to diagnose the issue. Magnesium deficiency has a distinct pattern, and once we recognized it, we knew exactly how to fix it.
Lesson Learned: Trust Your Eyes, Not Just the Numbers
Even though our PPM readings were within the ideal range, our plants were still showing signs of stress. Following Ed Rosenthal’s advice, we added a Cal-Mag supplement to our nutrient mix, and the problem cleared up almost immediately. This experience reinforced a key hydroponic growing lesson:
Don’t rely solely on numbers—your plants will tell you what they need.
Daily plant inspections are crucial for catching problems early.
React quickly to nutrient deficiencies before they affect overall plant health.
By learning to read the visual cues our plants were giving us, we gained a deeper understanding of hydroponic cannabis cultivation—and saved our grow in the process.
A pale green or yellow tint will start to appear along the veins and edges of the lower, older leaves—one of the classic indicators of magnesium deficiency in cannabis. In some cases, you may also notice reddening of the stems. The yellowing leaves really worried us, but after adding Cal-Mag to the nutrient mix, we saw healthy new growth within just four days!
Ed stopped by a couple of times to check in and make sure the plants were recovering well. His experience and advice were invaluable, helping us fine-tune the nutrient balance and ensure they were back on track.
3. Quality Nutrients Are Key for Hydroponic Cannabis Success
One of the biggest lessons we’ve learned in hydroponic cannabis cultivation is that not all nutrients are created equal. In the beginning, we didn’t realize how much the quality and balance of nutrients would impact our plants. But we quickly discovered that using cheap or poorly formulated nutrients can lead to imbalances, deficiencies, and stunted growth.
The Right Nutrients for a Strong Grow
Now, we always keep a basic but essential nutrient lineup on hand, including:
A/B Nutrient Mix – The foundation for hydroponic feeding, providing balanced macronutrients.
Cal-Mag Supplement – Crucial for preventing calcium and magnesium deficiencies, which are common in hydro systems.
Bloom Enhancers – Boost flower production and resin development for higher yields and better potency.
Having high-quality nutrients ensures that our plants absorb everything they need efficiently, reducing the risk of deficiencies or toxicities.
Tracking pH, PPM, and Feedings: Why Documentation Matters
One of the best habits we’ve developed is keeping a detailed grow log. This includes:
Recording pH and PPM levels – Helps us spot trends and maintain nutrient stability.
Logging feed schedules – Tracks when and what we feed our plants, making adjustments easier.
Identifying patterns – Allows us to troubleshoot problems faster and fine-tune our approach for future grows.
Hydroponic cannabis growing is a learning process, and we’ve found that consistency and documentation are key to optimizing plant health and maximizing yields. The more data we track, the better we understand what works—and what doesn’t.
Different products are being used for this grow.
Vivosun Base A and B—for the base nutrients. Although the instructions recommend a 1:1 ratio, we adjusted it to 6:4 (A/B) during the veg phase since Base A contains more nitrogen, which plants need more of at this stage.
Vivosun Cal/Mag to prevent deficiencies,
DYNOMYCO mycorrhizae to support root health, and
Si-Tech from Agromagen, a sprayable nutrient solution that enhances plant resilience and overall growth.
4. pH Levels Are a Constant Focus in Hydroponic Cannabis Growing
In outdoor cannabis cultivation, we usually check the soil pH once in the spring, adjust it if necessary, and then let nature take its course. But in hydroponics, it’s a completely different story—pH levels must be monitored and adjusted regularly to ensure optimal nutrient uptake.
Why pH Management is Critical in Hydroponic Cannabis
Unlike soil, which has a natural buffering capacity, hydroponic systems are highly sensitive to pH fluctuations. Even small shifts can lead to nutrient lockout, where plants are unable to absorb essential minerals. The ideal pH range for hydroponic cannabis is:
5.8 – 6.3ph – The sweet spot for optimal nutrient absorption and overall plant health.
If pH drifts too high or too low, plants can develop deficiencies even if the correct nutrients are present in the reservoir. This is why daily pH checks are a crucial part of our routine.
How We Keep pH Levels Stable
Daily Monitoring – We check pH at least once a day to prevent sudden swings.
pH Adjusters – Using pH Up and pH Down solutions to maintain the ideal range.
Stable Water Source – We use filtered or dechlorinated water to prevent unexpected pH fluctuations.
Gradual Adjustments – Making small pH corrections rather than drastic changes to avoid shocking the plants.
By keeping pH levels consistent and within range, we ensure that our hydroponic cannabis plants receive all the nutrients they need for strong, healthy growth.
We quickly learned that pH can fluctuate more easily in hydroponic systems, especially when you change nutrient mixes or add supplements. A slight shift outside the ideal range can lead to nutrient lockout or other problems. To keep the pH in check, we always have pH-up and pH-down solutions on hand.
The Vivosun Shop has all the products needed for this grow. If you're interested in any Vivosun products, they’re running some fantastic sales, and with the promo code Ed420, you’ll get an exclusive 15% discount across all their products!
Overall, this has been a truly gratifying experience. The plants are starting to flower, and we’re excited to continue this journey, learning and improving along the way!
Next time, we'll dive into Integrated Pest Management (IPM)—covering some common insects and diseases you might encounter and the best ways to tackle them. Remember, the most effective way to deal with these issues is to prevent them from happening in the first place. Prevention is key! Stay tuned.