Coco coir, also known as coco peat, is a natural growing medium made from the fibrous husks of coconuts. It is an extremely useful and environmentally friendly substrate for container gardening, hydroponics, and indoor gardening applications.
However, coco coir tends to decompose and break down over time. So a common question many gardeners have is whether or not old, previously used coco coir can be reused.
The quick answer is yes, you can reuse old coco coir under the right conditions. However, there are some important factors to consider when reusing old coco coir to ensure you get the best results.
In this detailed article, we will cover everything you need to know about reusing coco coir, including:
- How to tell if coco coir is still usable
- Steps for refreshing and revitalizing old coco coir
- Tips to maximize reuse of coco coir
- Potential risks and downsides of reusing old coco peat
- Alternative options if coco coir is too far gone
By the end, you’ll have a thorough understanding of how to get the most out of this versatile growing medium during multiple cycles.
How to Tell If Coco Coir is Still Usable
When deciding if your old coco coir can be reused, the first step is to examine its condition. Here are some telltale signs that coco peat should be replaced instead of reused:
Severe Decomposition
If the coco fibers are breaking down into fine particles that resemble peat moss or soil, the coir is too far gone. Healthy coco coir should retain some fiber length and fluffy texture. Extreme decomposition indicates it won’t rehydrate well or provide enough aeration.
Salt Buildup
Used coco coir often accumulates excess mineral salts, either from tap water or liquid fertilizer. Excessive salt content can be harmful for sensitive plants. Check electrical conductivity (EC) with a meter to assess salt levels. An EC reading over 2.0 indicates salts should be flushed before reusing.
Water Repellency
Over time, coco coir can become hydrophobic (water repellent) if allowed to completely dry out between uses. Test a sample by wetting it. If water beads up and doesn’t absorb, the coir won’t rewet easily for reuse.
Fungal Growth
While harmless fungus often appears on old coco, extensive growth can indicate disease pathogens that should not be reused around plants. Visible mold or mushrooms growing on more than 10-20% of the coco means it should be discarded.
Foul Odor
A strong, unpleasant rotten or stagnant odor usually means the coco fibers have already broken down anaerobically. This creates phytotoxic compounds unsafe for plants, meaning the material should be replaced.
If your coco coir doesn’t show these extreme signs of degradation, revitalization is likely possible.
Steps to Refresh and Reuse Old Coco Coir
If your coco peat seems potentially reusable, here are some tips for revitalizing and refreshing it before putting it back to work:
1. Rinse Away Salt Buildup
Use pH balanced water to thoroughly rinse salts from the coco fiber. Drain and repeat several times until runoff EC drops below 1.0. Allow to fully dry before reuse so salts don’t concentrate again.
2. Re-Buffer pH
Once salts are rinsed away, old coco coir often needs pH adjustment. Test runoff pH after a thorough rinsing. If below 5.5 or above 6.5, mix in 0.5-1 tsp. dolomite lime per gallon of coir to safely rebuffer pH.
3. Rehydrate Thoroughly Before Use
Never use old coco coir dry. Presoak it for at least 24 hours before use so it fully rehydrates. Weight it down to submerge all material and allow air pockets to fill. This restores moisture retention ability.
4. Leach Out Accumulated Fertilizer Residue
Frequently fertilized coco coir can accumulate excess nutrients over time. Do several rinses with clean, pH balanced water to remove built up salts from liquid fertilizers before reuse.
5. Add Beneficial Microbes
Reintroduce healthy microorganisms by watering old coco with compost tea or organic inoculants like mycorrhizae. This renews microbial activity to support plant roots.
Following these revitalizing steps will restore used coco coir to near-new condition.
Tips to Maximize Coco Coir Reuse
To get the most cycles of use out of your coco peat, integrate these tips into your gardening practices:
Allow it to Fully Dry Between Uses
Don’t leave coco coir continuously wet. Allow it to fully dry out before compacting for storage. This prevents premature decomposition and anaerobic conditions.
Rinse Salts After Each Use
Giving used coco a quick rinse with pH balanced water after each grow cycle prevents excessive salt accumulation.
Inspect and Remove Any Decomposed Sections
If small portions of the coco start to break down, simply remove those degraded areas before reusing the rest.
Mix With Fresh Coco Coir
Blending reused coco with 10-30% fresh fibers helps rejuvenate its structure and consistency.
Use Loose Media Bags
Avoid compressing coco in tight bags or blocks. Store in loose media bags that allow airflow to prevent decomposition.
Potential Downsides of Reusing Coco Coir
While revitalizing and reusing coco coir can certainly save money, there are some potential downsides to consider:
Decreased Aeration
Over time, reused coco coir tends to compress and lose some of its airy structure. This can reduce oxygen to plant roots.
Reduced Nutrient Buffering
The cation exchange capacity of coco fiber diminishes with reuse, providing less buffering of pH and nutrients.
Unknown Pathogen Risk
Reusing coco raises the small risk of transmitting root diseases like fusarium, pythium, or rhizoctonia. This is quite rare with healthy plants.
Weaker Root Support
As fibers decompose, they provide less physical support for developing root systems.
Fewer Microorganisms
Helpful microbiology like bacteria and mycorrhizal fungi decrease in reused coco coir.
The potential downsides are relatively minor. With proper treatment between uses, reused coco peat can still perform nearly as well as new for several grow cycles.
When to Replace Coco Coir Entirely
Under certain conditions, it’s best to bite the bullet and start fresh with new coco:
– If the coco is more than 50% broken down into peat-like particles, replace it. Extreme decomposition indicates a largely dead medium.
– If salt levels exceed an EC of 2.0, it’s often easier to start over than trying to rinse away excessive salts.
– If you experience unidentified root diseases, replace the coco to eliminate pathogen risks.
– When transitioning between growing cannabis and other plants, replace the coir to prevent residual chemicals transferring.
– For seed starting mixes, always use fresh coco coir to prevent damping off disease.
– If yields, growth rates, or plant health decline over repeated uses, the coco likely requires replacing.
Ultimately, the goal of reusing coco coir is to maximize the value you get from this versatile growing media during its usable lifespan. With proper treatment and storage, good quality coco coir often lasts for 3-5 grow cycles before requiring replacement.
Alternative Options if Coco Coir is Unusable
If your coco peat has simply reached the end of its lifespan, here are some alternative growing media options to consider:
Perlite
This volcanic rock provides aeration, drainage and root support when mixed into other media. Use perlite to amend old coco coir too far gone to use alone.
Peat or Sphagnum Moss
These natural peat mosses offer moisture retention similar to coco coir. However, they provide less aeration and have some environmental drawbacks.
Compost
Homemade or commercial compost offers an organic soil replacement. Compost provides nutrients but may hold more moisture than ideal for some plants.
Commercial Soilless Mixes
These premade blends combine peat, perlite, vermiculite and other amendments to replace coco coir as a soilless medium.
Rockwool
Made from spun volcanic rock, rockwool provides an extremely porous and forgiving medium for hydroponic systems.
Expanded Clay Pellets
These baked clay pebbles, also called grow rocks or hydroton, are reused easily for years in hydro and aquaponic gardens.
With some adjustments, you can switch to any of these alternative growing media if your coco coir has outlived its usefulness.
Conclusion
While new coco coir offers maximum performance, reused coco peat can still be an effective growing medium for several cycles if properly refreshed and revitalized between uses. Learn how to check its condition, treat salt buildup, restore pH, and encourage beneficial microbiology. With the right precautions, you can stretch your coco coir investment substantially. If it becomes overly decomposed or unhealthy, be ready to replace it entirely rather than trying to overextend its lifespan. With the techniques covered here, you’ll be able to confidently reuse or replace your coco coir to support optimal growth.
Summary of Key Points:
- Inspect old coco coir carefully for extreme decomposition, salt buildup, water repellency, fungal growth or foul odors.
- Refresh reusable coco by rinsing salts, adjusting pH, rehydrating, removing fertilizer residue, and inoculating with beneficial microbes.
- Maximize reuse by allowing it to dry fully between uses, rinsing after each cycle, and blending with fresh coco.
- Downsides of reusing coco include reduced aeration, decreased buffering, and lower microbe levels over time.
- Entirely replace coco coir if more than 50% has decomposed or unidentified root disease appears.
- Switch to alternative media like perlite, peat, compost or clay pellets once coco is fully spent.
Frequently Asked Questions
Can I use coco coir after 3 years?
It depends on storage conditions. If kept loose and allowed to fully dry between uses, good quality coco coir can often be reused even after 3 years. But coco stored wet and compressed may decompose too much within 1-2 years to be usable.
Does reused coco coir need more frequent watering?
Yes, reused coco tends to dry out faster between waterings. The decomposition process reduces its water retention abilities over time. Expect to water reused coco peat about 25% more frequently.
Can I mix used coco coir with soil?
Yes, blending reused coco with 30-50% organic soil creates an excellent growing medium. The soil provides some buffering while the coco fibers maintain drainage and aeration.
How do I restore nutrients to reused coco coir?
Add worm castings, organic compost, or slow-release organic fertilizer when rehydrating old coco coir. This will remineralize it with essential nutrients for your next growing cycle.
Why does my reused coco coir grow algae?
Excessive moisture between uses can lead to algal growth on old coco. Ensure it dries fully before compacting for storage. Scrub off any visible algae before reusing.
References
- Disease Control in Coco Coir – https://www.researchgate.net/publication/271466034_Disease_control_in_coco_coir
- Reusing Coco Coir in Hydroponics – https://www.maximumyield.com/reusing-coco-coir-in-hydroponics/2/1275
- Coco Coir Water Repellency Issues – https://www.rxgreentechnologies.com/rxgt_papers/coco_coir_water_repellency.pdf
- Managing Salt Buildup in Coco Coir – https://www.sciencedirect.com/science/article/pii/S1618866717300241
- Coco Coir Decomposition – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4531691/
- Coco Coir Recharging with Microbes – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5315683/
