Growing in Coco: Best Practices

Coco coir substrates are a popular choice for cannabis cultivation, are sustainable and renewable, and have numerous benefits.

They come in both loose bags and compressed grow cubes, and are an excellent alternative to rockwool blocks.

Coco coir is a sustainable byproduct of coconuts, and repurposed for garden use instead of being discarded. It can also be reused after harvest following a rinse, repurposed for compost, or as a topdressing to retain moisture.

Managing coco’s moisture and nutrient availability will get your garden in great shape from seed to harvest!

Cannabis Supplements for Moisture Management

To manage substrate moisture and nutrient availability in coco coir for commercial growing, know the key terms:

• Saturation describes the total volume of water that a substrate can hold. It is expressed as a percentage of the substrate’s weight or as the water-holding capacity (WHC).
• Field capacity indicates the amount of water that remains in a substrate after excess water has drained.
• A permanent wilting point is reached when no moisture is left in the substrate for plants to extract.

This also highlights the importance of consistent moisture monitoring and irrigation adjustments based on moisture readings. A soil moisture sensor that measures volumetric water content (VWC, %) is a simple tool that can be placed in the root zone to monitor moisture.

Using the Solus Teros 12 substrate sensor, coco is fully saturated at 40% and needs water near 20%.

• Consistently over-saturated media increases the risk of root diseases and lower crop yields.
• Media that dries to the permanent wilting point may cause irreversible damage to plant roots. Consistent moisture is important to ensure root absorption of nutrients without allowing plants to reach the wilting point.

Precision Matters at Scale

Even the best sensors need to be calibrated regularly. Coco coir’s composition can shift over a cycle, and sensor drift is real.

If your readings are off, your irrigation inputs will be too. Most commercial teams set up a monthly calibration routine, using manufacturer standards or even their own in-house substrate samples.

VWC Thresholds

Some cultivators may push the lower limit of VWC to 18% for late flower, chasing a bit of generative stress for denser buds. Others may keep it closer to 22% for younger plants to avoid any risk. The key is consistency, as big swings in VWC can stress roots and slow growth. At scale, this means lost revenue.

Automation Tips

Integrate your VWC sensors with an irrigation controller to trigger watering events based on moisture data. Set your thresholds and let the system handle the rest.

You might also stagger your irrigation events to create drybacks for cropsteering. Some operations even run short, frequent pulses (e.g., 6-8 times per day) to keep coco in that sweet spot.

Coco Coir for Thriving Cannabis Nutrient Systems

Rx Green Technologies offers three types of coco coir substrates:

Loose Coco Coir (2 Cu Ft)

• Available in 100% coco and 70% coco/30% perlite blends.
• Loose coco coir for cannabis is ideal for filling reusable or disposable pots, or when used as a top dressing for seasonal outdoor pots and beds.

Ready-To-Use Coco Grow Bags

• Our new Ready-To-Use (RTU) Coco Grow Bags deliver an effective cannabis growing medium for cultivations of all sizes.
• Available in 1-gallon and 2-gallon sizes, RTUs come filled with OMRI-listed clean, buffered, pre-hydrated loose coco coir.
• Simply rip open the bag, roll it down a few times, and plant your plants. Watch them grow to their full canopy potential.
• This is an ideal option for large-scale commercial cannabis cultivation facilities with automated irrigation, or for any grower looking to reduce labor spent filling pots and transplanting.

Compressed Clean Coco

• Clean coco cubes are compressed bricks of pure coco coir packaged in a mesh bag that allows oxygen to reach the root zone.
• Once placed, simply hydrate the cubes and place seeds, rooted cuttings, or clones in the expanded bags.

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Nutrient Delivery Best Practices

In commercial cannabis grows, you’re orchestrating an operation where a missed beat can mean reduced quality, maturity, and yield.

Feeding Schedules

• Vegetative stage: During veg, coco’s fast drainage means you’ll want to feed more frequently, but with a lighter hand. Many cultivators stick to a schedule that ramps up EC (electrical conductivity) gradually. Tweak your numbers based on runoff readings and plant response.
• Flowering stage: Flip to flower, and now you’re feeding for bud set and resin production. Phosphorus and potassium are an important part of the base flower feedings. They can also be increased as an added pair in addition to your feeding schedule to enhance flower and resin development, known as a “PK boost.”

Coco’s CEC

Coco coir’s cation exchange capacity (CEC) is like a nutrient magnet. It grabs onto positively charged ions (calcium, magnesium, potassium) and holds them in reserve for your plants.

• Buffering and supplementing: Start with buffered coco. If you’re prepping your own, soak it in a cal-mag solution before planting. Rx Green products are already pre-buffered for you, boasting higher CEC and lower sodium, giving you more consistent results with less work.
• Nutrient tweaks: Because of coco’s CEC, you’ll want to increase your calcium and magnesium inputs. And, coco’s tendency to hold onto potassium means you may need to dial back Potassium, especially if you’re seeing leaf tip burn or strange deficiencies.

Flushing

Regular flushing keeps your root zone clean and your yields on track. It helps give your plants a fresh start.

• Routine flushes: Many large-scale growers flush every 3-4 weeks, running 2-3x the pot volume of pH-balanced water through the medium. Check your runoff EC – if it’s high, keep flushing until it drops to a reasonable level. You might use a light nutrient solution for the final rinse to avoid shocking the roots.
• Runoff management: Aim for 10–20% runoff every feed. This helps prevent salt from building up, making full-on flushes less frequent. It’s also less stressful for your plants. Test runoff regularly with your EC meter.
• After the flush: Resume feeding with a diluted solution and ramp up as the plants bounce back.

Irrigation Strategy

Adopting a proactive approach to irrigation is key. By appropriately timing your irrigation, you can ensure consistent moisture levels and delivery of cannabis nutrients without the risk of overwatering or overfeeding.

Before planning your irrigation, use the sensor test to identify the saturation range to the wilting point. This gives you a clear plan of action.

Irrigation timing and volume largely depend on environmental conditions and irrigation system components.

• A general rule of thumb is to apply 10-15% more water than the container will hold. This allows for some runoff with each irrigation and reduces the potential for salt accumulation.
• The flow rate must be adjusted to allow thorough media saturation but avoid container overflow.
• Clear water flushing of the coir substrate between nutrient feedings reduces and prevents salt buildup.

Irrigation cycles typically start one hour after lights on or sunrise and end one hour before lights off or sunset.

Depending on conditions, irrigations for cannabis plants can be scheduled hourly or more frequently if needed. Excessive dry down between irrigations may increase soluble salt concentration and contribute to the substrate’s hydrophobic properties.

Storage & Disposal

All coco substrate products should be stored in a dry area, off the ground, and protected from the elements. Used loose coco coir for cannabis may be reused, composted, or disposed of in a landfill.

Read more about Clean Coco Storage in our Rx Resources.

Composting Used Coco

Turn your spent coco into a valuable resource with a few organized steps:

1. Gather used coco from all grow rooms. For any chunky leftovers, run them through a shredder to speed up decomposition.
2. Rinse coco to remove excess salts and nutrient residues.
3. Mix coco with green waste (like plant trimmings) and a nitrogen source (like food scraps or manure).
4. Build piles at least four feet high to retain heat. Aerate regularly by turning with a front loader or using forced-air pipes. Keep the oxygen flowing.
5. Monitor temperature and moisture. You want it hot, but not soggy.
6. After 2-3 months, let the compost cure for another 1-2 months. The end result should be a rich, crumbly material ready for outdoor beds or greenhouse use.

Carbon Footprints

If you’re weighing your growing medium options, it helps to know the environmental impact associated with each:

• Coco coir: Made from coconut husks, coco is a renewable byproduct. It’s shipped in compressed blocks, lowering freight emissions. And when composted, it returns organic matter to the soil. Its carbon footprint is generally lower than peat moss and rockwool.
• Rockwool: Manufactured from spun basalt rock, rockwool is inert and recyclable (in some countries), but it’s energy-intensive to produce. Many large-scale grows love it for its consistency and disease resistance. Some regions now offer rockwool recycling programs, which helps offset the initial carbon cost.
• Peat moss: Harvested from bogs, peat moss is prized for its water-holding capacity. But it’s non-renewable on a human timescale. Extraction releases stored carbon, making its footprint higher than coco or rockwool.

Schedule a Product Trial

Want to try our premium commercial cannabis grow supplies and see the results for yourself?

Contact an Rx Green Rep and schedule a product trial to try our top-quality, R&D-tested cultivation supplies in your grow.