How to Use Coconut Coir for Your Raised Beds

Coco Coir, a derivative of coconut husk processing, is used to make brooms, animal bedding, rooting mats, hanging grow baskets, doormats, and thick ropes. It also offers many unique agricultural benefits. If you’re looking for an eco-friendly way to maximize healthy soil and grow big in raised beds, coco coir may be the amendment you’ve been looking for. 

Growers can mix coco coir into their existing soil of raised beds or garden beds to assist with soil structure, compaction issues, maintaining nutrients, and improving drainage for better crop health. It’s pH neutral, inert by nature, light to ship, and reusable up to three times, making it an eco-friendly soil additive. While there are benefits and pitfalls, incorporating coco coir into your farm business and backyard homestead operation is easy. 

Understanding Coconut Coir

Coconut coir, or coco coir, is a naturally antifungal and pH-neutral alternative to peat moss made from previously unused coconut waste products. Producers use the husk material surrounding the nut and flesh of the coconut (Cocos nucifera) to produce various coco coir substrates. The farming community adopted this exciting product for its remarkable water retention, ability to improve drainage, and environmental sustainability. The dense coconut coir bricks are easy to rehydrate and mix into existing soils, they can also be used in hydroponic growing as a substrate. When incorporated correctly, coco coir provides a perfectly stable and nutritious environment for seedlings' early growth and maturity stages.

Three different coconut products come from coconuts for use in traditional growing systems, raised beds, or hydroponically:

Coconut pith, peat, or coco dust has a thin, granular consistency when dry. When you add water, it plumps up and has a solid ability to hold onto moisture. Avoid using coco peat alone, as your plants’ roots may drown from all the moisture they hold onto. This product has a fine consistency because of its sifting process, and its water retention abilities are perfect for indoor seed-starting in Cell Trays or 1020 trays. It also may perform well when starting tiny seeds that require consistent moisture for proper germination. Coco fibers are long, stringy, and durable. They are often used to mulch around crops, trees, and houseplants. When mixed with other growing media, they provide air pockets, but note that since they break down quickly, the air pockets will also diminish with time.  Coco chips combine peat and fibers, which creates a consistency and look similar to woodchips used as mulch, pathways, and landscaping. 

These three combined by-products make a rich, deep brown product called coconut coir. Coco coir dates back to the 1940s when a soil scientist noticed that the properties of the byproduct of processing coconut husks were similar to peat moss. However, it didn’t gain popularity in the farming and hydroponics communities until the 1990s, when Dutch farmers realized they could produce it quicker and more sustainably.

After the coconut flesh harvest, coir producers soak leftover husks in fresh or tidal (ocean) water, which affects salt levels. If they use tidal water, they must take additional steps to remove the salts. The husks are removed from the water bath, dried for at least one year, processed into various growing substrate types, and then baled or bagged for sale. 

Related: Top Five Best Growing Mediums For Microgreens

Benefits of Coconut Coir

• pH balanced: Coir pH is naturally 5.2 to 6.8, giving growers flexibility and the ability to adjust based on what they’re growing. Balance out acidic or alkaline soil by consistently adding coir. 
• Coco coir retains water and improves drainage, which is especially vital in sandy soils. Water retention capabilities allow it to hold up to ten times its weight in water! 
• Anti-fungal properties for healthy roots
• Deters pests with natural properties, including bacteria and fungi.
• Rot-resistant
• Its lightweight nature makes it easy to manage, move, and store.
• Improved aeration for good root development and prevents root rot.
• Enhances soil structure.
• Sustainable alternative to diminishing endangered peat moss bogs. 
• It is easy for growers to adjust since it has a soil-like look and feel.
• It contains significant levels of potassium and phosphorus, which is ideal for the early stage of growth, making it an excellent option for microgreen growers. 

Coconut processors used to burn the by-products, adding to our atmosphere's carbon, but choosing coco coir helps offset these harmful effects while growers reap the benefits. In an exciting study, Coconut Waste: Discovering Sustainable Approaches to Advance a Circular Economy (Vieira et al., 2024), researchers pinpoint new ways to repurpose coconut waste to promote responsible consumption and clean energy sources. 

Disadvantages of Coconut Coir 

• Growers must amend the coir before using it because of its low NPK levels. Mixes are available, but they are cost-inhibitive for some. 
• It may contain high salt levels if not rinsed and processed correctly. Research and trust your distributor has rinsed it in fresh water to avoid this issue. 
• Un-boosted coir is naturally low in nutrients, with an NPK level of 2:1:2, depending on the brand and rinsing process. 
• Some may have difficulty finding it locally. 
• Growers may find it tedious to soak to rehydrate and break apart. 

It’s essential to secure high-quality coconut coir from diligent producers. Some producers mass-produce coir and pile it up for extended periods, leaving it vulnerable to pathogens. Sterilization requires chemicals before the product can be packed and sold to growers. To avoid chemically treated products, find a producer that is transparent with their processing systems, rinse husks in fresh water, and create blends conducive to your growing practices. 

Cation Exchange Capacity (CEC)

CEC measures soil’s ability to hold and release nutrients when plants need them. You’ll see this number on most soil tests, and it’s an important measurement to be familiar with as the potential of nutrients for your plants. Let’s first discuss the basics of an atom’s makeup and charge. 

Recall from intro chemistry: the nucleus of atoms has positively charged protons and negatively charged electrons, and they’re most often off-balanced. When an atom loses electrons, it’s positively charged because protons outweigh the electrons; we call this a cation, which can be acidic or basic. Soil cations vital to growing high-quality, healthy fruits and veggies are calcium, magnesium, potassium, and sodium. We’ll call these nutrient cations. Think of soil as the warehouse where all the necessary nutrients are stored, but we must ensure our plants can access them. 

Healthy soil must be able to adsorb, or hold onto, these nutrient cations because they are food for the food we’re growing. Without cations in the soil to help adsorb nutrients, they’d wash away during wind and rain storms, and our crop production would severely decrease. Soil’s negatively charged sites attract the positively charged cations because, as the introductory chemistry class taught us, opposites attract. 

So now, back to the CEC, which refers to the number of sites not tied up with other electrons and protons, making the sites exchangeable. When the positively charged hydrogen ions produced by plant roots and microorganisms surround nutrient cations and get close enough to the negatively charged exchange sites, the hydrogen ions will fill the exchange sites (taking over the potassium and phosphorus) and neutralize the charge. The static bond breaks, leaving phosphorus and potassium in coco coir available for plant uptake! 

Growers can increase their soil CEC by promoting healthy microbial activity, which coco coir promotes. Clay soils and soils high in organic matter naturally have higher CEC than sandy soils. The table below indicates that clayey and organic soils are typically higher in CEC, according to the Ohio State University Extension the relationship between soil texture and CEC is as follows:

pH Buffering of Coco Coir 

You might have stumbled across this term if you've read about using coco coir. Coconut coir has naturally high chloride salts, potassium, and sodium levels, which must be tested and adjusted before agricultural use. Coconuts grown in coastal regions have higher salt levels. “Buffering” is the introduction of calcium and magnesium that offsets the salt and potassium levels using the exchange process, which was just detailed. 

While some companies buffer the coir before packaging it, this is not standard practice before making coir bricks and is usually up to the customer to do before using it. Most bricks have yet to be processed, but read the packaging to confirm. Don’t let this extra step deter you from using coco coir! If you understand how critical healthy CEC is, you’ll realize that buffering is a crucial step. 

To buffer, soak the coco coir in fortified water. A general rule is for every 100 grams of coir, add two grams of calcium and ½ grams of magnesium to water, allow the rehydrated coir to soak for up to 12 hours, and then drain it. Your coir is now in equilibrium and will not compete with your plants for nutrients. 

Pro tip: Growers can account for the nutrient lag after buffering by adding fertilizer high in calcium and magnesium when prepping their raised beds so their crops aren’t deficient. 

If you’ve been growing for some time, you’re likely familiar with seed packets indicating the pH needs of various crops. pH is a crucial piece of the puzzle when growing high-quality products. Ensure additives and garden amendments complement, align with, and balance your garden’s pH needs. Use lime to adjust up to a year before planting pH-sensitive crops like blueberries, then soil test. 

Preparing Coconut Coir for Raised Beds

Coconut coir is condensed into tightly packed bricks before selling. It’s lightweight when shipped and easy to store. To rehydrate bricks: 

• Place the coir brick into a plastic tub or bucket. 
• Measure warm water according to the grams of water-to-coir ratio listed on the packaging. If your packaging doesn’t contain this information, weigh your water and record how much worked for you so you’ll have it the next time you need it. Alternatively, just slowly add warm water until you like the consistency of the substrate. If you don’t want to rehydrate the entire brick, slowly add water, scraping off what you need, then remove the brick and store it. 

Pro tip: Warm water is not required but will allow the coir to expand more quickly. 

• Use your hands to help break apart the clumps and mix them into the water until fully incorporated. 
• When the water is absorbed, the consistency should be soft and fluffy. Depending on the brick size, the process may take up to an hour. 
• Store for future use or mix in soil amendments and use immediately.

Pro tip: Vent your storage container to reduce the substrate's mold risk. 

VIDEO: The Magic of Coco Coir Bricks: Filling 3 Bootstrap Farmer Trays Effortlessly!

Mixing Coco Coir

When mixing coco coir into existing raised bed soil, use a 1:1 ratio, adding horticultural sand, compost, or perlite to adjust the soil consistency. Test the soil first to avoid over-applying nutrients that can damage plant growth. 

Always incorporate perlite, vermiculite, pumice, or coconut fibers with coco peat before using it as a standalone grow media to create vital air pockets. Mix them a little at a time and thoroughly to ensure uniformity and avoid pockets of unmixed material. Here are a few ratios to try:

• Use a 3:1 ratio of coir to perlite to prevent your roots from drowning.
• Mix four parts coir with one part perlite and one part worm castings for an additional seed-starting boost. 
• Four parts soil, three parts compost, two parts coconut coir, and one part worm castings.
• Experiment with the ratio, which will differ slightly for each grower’s specific soil type.  
• Mel’s Mix from Mel Bartholomew’s Square Foot Gardening includes equal parts peat moss, vermiculite, and compost. Replace the peat moss here with coconut coir and give it a whirl. 

Add fish fertilizer or bat guano additives to your coco coir to make a nourishing grow media. Many tried-and-true blends are available online and in gardening books, but the best one is the one that works for you in your setup.

Related: 1020 Trays & Flats

Planting in Coconut Coir-Amended Raised Beds

Growing in coconut coir-amended raised beds will feel no different than you’re used to once it’s well incorporated, except you’ll need to water differently. The differences will come once you see the growth difference between young seedlings and crop yield increases. 

Choosing the Right Plants

Coco coir affects soil pH, nutrients, and salt levels, so growers should choose crops wisely when starting. Select plants based on their nutrient requirements and moisture needs. Here are a few crop families that do well in coconut coir-amended garden beds. 

Vegetables: 

• Cherry and Roma-style tomatoes need lots of water as they develop and mature, but too much increases the risk of fungal diseases, root damage, fruit cracking, and plant stress. Coco-coir serves as a reliable moisture manager, which reduces these risks. 
• Coco coir helps your soil retain nutrients, crucial for successful pepper growing. Read Pepper Geek’s Basic Potting Soil Recipe for Peppers in Raised Beds or Containers. 
• Eggplants thrive in consistently moist soil. Incorporate high-quality coco coir into your raised bed to help the grow media retain irrigation water and rainfall.
• Cucumbers are mostly water, so adding coco coir will help keep the soil moist and balanced, helping the plants produce juicy and delicious fruits. Coir provides the support necessary for vining plants.

Fruits: 

• Strawberries have shallow roots and don’t like sitting water, which attracts pests. Add plenty of perlite before planting strawberries in coco-amended raised beds for good drainage. 
• Melons will need additional fertilizer and nutrient monitoring as they are heavy feeders and remain in the ground for a long time. Coco coir will provide the aeration their roots need for development and help reduce root rot. Melons prefer slightly acidic soil. 
• Select bush, dwarf, or half-high bush blueberry cultivars for best success in raised beds so they are well-supported. Water them lightly with drip irrigation but more often than you would normally. Closely monitor your pH levels to ensure they’re between 4.5 and 4.8. A Colorado State University study states their coir, peat, and perlite blend provided the perfect pH for blueberry growing. 

Herbs: 

• Don’t leave basil in soggy water. Ensure your coconut coir-amended raised beds are thoroughly blended and well-draining for best results. 
• Cilantro likes the consistently moist soil coco coir provides and the added aeration. 
• Mint is carefree but will appreciate coco coir’s moisture consistency. 

Ornamentals: 

• Geraniums require a consistent and well-balanced moisture level, which coir offers. 
• Mix coir in a 1:1 ratio with potting mix for orchids. Add a slow-release fertilizer to boost nutrients lacking from the coir. 
• Roses will thrive in the disease-resistant environment coir provides. 
• Petunias will bloom abundantly and grow well if the soil is adequately aerated, allowing the plant to develop healthy roots. 
• Begonias prefer loose, lightweight soil, so they’ll appreciate a softer, more porous coconut product.

Raised beds amended with coconut coir products will allow many different plants to perform well. Experimenting and adjusting ratios of compost, perlite, native soil, and coco coir and keeping detailed data records will help your garden thrive. 

Pro tip: Put houseplant cuttings like pothos, snake plants, and philodendrons in coco coir discs; the moisture retention capabilities and increased aeration are perfect for all grower levels, but especially beginners who may struggle with finding the best watering schedule. 

Related: 10 Must-Have Indoor House Plants for Gardeners and Plant Lovers

Seed-Starting with Coco Coir

For seed-starting, incorporate vermiculite with your coir and soil mix, or sprinkle it on top to keep the soil from waterlogging. Use a balanced product with the Goldilocks amount of seed pockets and fibrous material to ensure your seedlings don’t dry out and produce strong, healthy roots. Use bottom watering methods when using more porous coir products, and avoid shifting the seeds around. The consistency of products will differ slightly depending on the company. Mist or lightly water seed trays from above when using a finer coco coir product like coco peat that holds more moisture. 

Many coir producers make coco peat pellets, coins, and discs, which are blended and explicitly packed for seed-starting in various shaped and sized containers. The spongey texture is the best mixture for robust root development, nutrient uptake, and moisture retention. 

Consider coir plugs or pellets for easy and quick seed germination. As the name implies, these products are round plugs into which growers put their seeds directly. The environment provides balanced moisture and space for healthy roots to form. They’re individually wrapped for easy sowing and reliable germination. Set them in a 1020 tray in a warm area with access to sunlight. 

Ongoing Care

Coconut coir naturally contains high levels of potassium and phosphorus but lacks calcium and magnesium, which growers should closely monitor before transplanting crops to the raised beds. Well-balanced and slow-release fertilizers are not ideal when using coconut coir, and doing so could result in over-fertilization and burned plants. Filter for or ask for options that align with coco coir use. If using these you will need to supplement with a CalMag specific liquid feed during the flowering and fruiting phase. 

Soil test after each round of crops or biannually, especially if you are reusing coco coir, to ensure your raised beds continue to provide the nutrients plants require. Use one of our DIY Portable Low Tunnel Kits over your raised beds for extended, ergonomic growing. The coverage will protect plants from the elements, allow you to control the precipitation received and temperature, and possibly slow the breaking down of the coco coir. 

Growers should adjust their watering schedules and techniques when using coco coir. It will respond more like hydroponic grow media, so you’ll likely need to water less frequently but more in volume. Drip irrigation will work best. Remember that coconut coir has strong water retention capabilities, so water less at first and add as needed after allowing water to absorb. Use a moisture meter for quick, easy readings. 

Maintenance and Troubleshooting

If you’ve used the finger soil test in the past, the results may vary with adding this water-retaining material. Place your first two fingers several inches down in the soil. When soil is on your fingers when you pull them out, the moisture levels are sufficient, but if they’re dry, it’s time to water. Check more often than not to ensure you grasp the new normal and adjust your schedule. To increase aeration, regularly fluff your raised bed mix. 

Related: The Best Drip Irrigation for Container Gardening in Small-Scale Gardens

Pests are attracted to decaying matter, and since coco coir is slow to break down, few pests flock to it. Mulch coco fibers help dry soil surfaces, reducing algae growth and deterring pesky fungus gnats and fruit flies. Since pest pressure is always possible in agricultural settings, scout and monitor as usual. If pests become a concern, rinse the coir with boiling water before reusing, add a higher level of perlite or fibers, or use sticky traps. 

Common Issues And Solutions When Working with Coco Coir

As magical as coconut coir products sound, they, of course, have their issues. Here are a few. 

Compostability

As mentioned, coconut coir is reusable and 100% compostable, so it will break down during its last few uses, which may slightly affect your crops. However, the naturally high levels of lignin attract beneficial microorganisms, slowing decomposition. Our article Reusing Spent Trays of Cut Microgreens dives into unique ways to reuse various types of grow media in spent trays. 

Managing Nutrient Levels 

Closely monitor the nutrient levels after each growing season because of coconut coir’s inert properties, pH neutrality, and compostability after a few grows. The results of soil tests will help guide how to amend, if you’re watering enough, and most importantly, if your crops have what they need for healthy growth and increased yields.

Cost

The cost of coco coir turns some growers off, so let’s flip this thought process to make the fact that it breaks down into a positive aspect. Like straw mulch, woodchips, or leaves, coco coir will break down and become part of your raised bed's soil composition. The breaking down coir adds organic matter and helps attract beneficial microorganisms, boosting fertility to support future garden crops!

Remember, you get what you pay for. The source and preparation process matters greatly, so if you see ten bricks for $30, there’s a reason for that low cost. Low-grade products will likely test high for salt and may contain harmful oils due to the lack of or poor leaching process. If you find a company you love, ask if they offer a discount when purchasing in bulk. 

FAQs

How do I prepare coconut coir blocks for use in raised beds?

Rehydrate your coco coir brick by adding warm water, which I detailed more thoroughly earlier. If you only need to rehydrate a portion of the brick, slowly pour warm water onto it, scraping away as it softens and expands, leaving the rest solid. Measure out the coir after deciding what ratio of soil additives you’ll mix into your native or bagged raised bed soil. Mix all the ingredients thoroughly for the best results. Store the remaining brick in an airtight container away from critters. 

Can coconut coir be reused, and if so, how?

Before reusing coir, growers must recondition it and break down the old root systems so the new plant’s roots don’t have to battle with them for space as they develop. After removing old roots and washing the coir in distilled water, soak it in specialized enzymes to break down roots into sugar. Then, beneficial microbes will feed on the sugars and convert them into food for the next round of crops. Growers can reuse coir up to three times before it’s no longer stable enough to use as a stable growing environment. It’s much less capable of retaining moisture and nutrients as it breaks down. Utilize a pH meter and EC conductivity probe to test levels before using it again. 

What vegetables thrive best in coconut coir-enhanced soil?

Many vegetables thrive from the drainage, aeration, water retention, and neutral properties coco coir offers. Bok choi, onions, leafy greens, cauliflower, peppers, and herbs are a few crops that will perform well in coir. Houseplants and ornamentals will also thrive in the right conditions.  

How does coconut coir compare to peat moss regarding performance and sustainability?

Unlike the peat bogs from which we harvest peat moss, coconut coir is renewable and environmentally friendly. Covering less than 3% of Earth's land, peat bogs contain the largest store of natural carbon and help improve water quality, so we should do everything we can to keep them intact. 

Using coconut coir and fibers creates a no-waste product. Since coconut coir retains moisture better than peat, growers can conserve water. When coconut coir has served its purpose, it is fully compostable. Unscathed peat bogs are a finite phenomenon that is quickly diminishing, so adjusting to this alternative and reusable product benefits the planet and growers. 

Are there any plants that should not be grown in coconut coir?

High salt levels can adversely affect crops, so growers should avoid growing those sensitive to salt levels. When growing cucumbers, celery, beans, and radishes, ensure you choose a product properly rinsed of tidal water salts. Alternatively, look for products rinsed in fresh water to avoid this issue. 

Does coco coir change the pH of the soil?

Coco coir is pH-neutral, and since most vegetables require a balanced pH between 5.0 and 7.0, it is an excellent addition to your growing medium. Consistently using it can help balance acidic or alkaline soil levels.