Best Coco Coir for Growing Cannabis — How to Choose
The one thing to check before you buy
Buy buffered, low-starting-EC coco from a reputable brand — not a cheap unwashed brick. Natural coco fibre contains salts that can throw off the pH and EC of your feed; buffered, rinsed coco is meant to remove that problem before you start.
We do not link an Amazon.com listing for this coco. Look for the label instead: RHP-certified, pre-buffered, and a low starting EC published by the maker.Listen to the summary
The Short Version
Coco looks simple, ground coconut fiber, but brands differ in what they do to it and what they publish about it. We compared the three big European brands, Canna, Plagron and Atami, on what each maker states on its own product pages. The pick for beginners: Canna Coco Professional Plus+, which Canna describes as buffered and rinsed, with the RHP quality mark. Plagron publishes a starting EC below 0.2 for its unfertilised Cocos Premium. Atami sells a lightly pre-fertilised coco and an unfertilised one. We have not tested any of them ourselves.
Buying in the Netherlands? Jump to the Canna and Plagron picks with Bol.com links →
Why coco quality matters
Coco is not a "neutral" substrate — natural coconut fiber contains salts (potassium, sodium) that can throw off the pH and EC of your nutrient solution. Makers rinse their coco to strip those salts and then buffer it; Canna, Plagron and Atami all say so on their product pages.
Second factor: structure. Fine, consistent coco drains more evenly than coarse material with long fibers, with fewer spots that stay too wet or go too dry.
Third factor: pre-fertilisation. Some coco already contains a little feed (Atami's Cocos Substrate, enough for the first week according to Atami); some contains none (Plagron Cocos Premium, Atami Washed & Buffered). That decides when you start feeding.
Before you buy — watch this
Official General Hydroponics how-to
Video: “General Hydroponics How-To: Mixing Flora Series”, from General Hydroponics' own channel. It is about mixing GH's Flora nutrients, not about choosing coco.
1. Canna Coco Professional Plus+ — our pick for beginners
Canna Coco Professional Plus+
RHP quality mark · buffered and rinsed · starting EC not published
Per Canna's product page (checked 17 October 2026): 100% coir from Indian coconuts, buffered and rinsed with a special process, and soaked in fresh water only so no salts are added. It carries the RHP quality mark and, according to Canna, can be reused several times. Canna does not publish a starting EC on the product page, so we don't quote one. If you're new to coco, it pairs with Canna's own coco nutrients and instructions.
View on Bol.com (Netherlands) → Checked 29 October 2026: in stock at a Bol seller. The Amazon.nl listing showed “Currently unavailable” that day, so we no longer link it. We do not link an Amazon.com listing for this coco. Look for the label instead: RHP-certified, pre-buffered, and a low starting EC published by the maker.2. Plagron Cocos Premium — our pick if you run your own feed
Plagron Cocos Premium
RHP certified · unfertilised · EC below 0.2 mS/cm (Plagron)
Per Plagron's product page (checked 17 October 2026): fully buffered and rinsed, RHP certified, no fertilisers, EC below 0.2 mS/cm and pH 5.8–6.8 (both measured 1:1.5), and ready to pot straight away. If you already run Plagron's nutrient line (Cocos A+B), this is the matched choice.
View on Bol.com (Netherlands) → No Amazon.com listing for Cocos Premium that we could verify (checked 19 October 2026).3. Atami Coco — check which version
Atami Coco Substrate
Two versions: lightly pre-fertilised (EC 0.80–1.00) or unfertilised (EC below 0.3)
Check which version you buy. Atami's Cocos Substrate (checked 17 October 2026) is lightly fertilised, aged, washed and buffered, with enough feed for the first week and an EC of 0.80–1.00. The Washed & Buffered Cocos is unfertilised, with an EC below 0.3. We found no RHP mention on the Atami product pages.
We publish no price for Atami (no checked source), so we don't call it cheaper. A workable choice as long as you know which version you have.
Head-to-head comparison
Source: the Canna, Plagron and Atami product pages, checked 17 October 2026.
| Coco | EC (maker) | Pre-fertilised | RHP mentioned |
|---|---|---|---|
| Canna Professional Plus+ ★ | Not published | Not stated | Yes |
| Plagron Cocos Premium | <0.2 mS/cm | No | Yes |
| Atami Cocos Substrate | 0.80–1.00 | Lightly (first week) | Not stated |
| Atami Washed & Buffered | <0.3 | No | Not stated |
How to choose
You're a beginner (first 1–2 cycles): Canna Coco Professional Plus+. Buffered and rinsed per Canna, and with Canna's own coco nutrients and instructions you have one matched system, so you can focus on the basic rhythm (watering + feed schedule).
You run Plagron nutrients or want a published low EC: Plagron Cocos Premium. Unfertilised and below 0.2 mS/cm per Plagron, so the EC in your pot comes almost entirely from what you feed.
You choose Atami: it works, as long as you know whether you have the pre-fertilised Cocos Substrate (EC 0.80–1.00) or the unfertilised Washed & Buffered (EC below 0.3).
FAQ
Canna Coco vs Plagron Cocos — which is better? Both makers describe their coco as buffered and rinsed and RHP certified. Plagron publishes a starting EC below 0.2 mS/cm and no fertilisers for Cocos Premium; Canna publishes no starting EC on its product page. Choose mainly on the nutrient line you already use.
What is the RHP mark and does it matter? RHP is a Dutch quality mark for potting soils and substrates. Canna and Plagron both mention it on their product pages; Plagron links it to quality requirements and a sustainable origin of the substrate. We found no RHP mention on the Atami product pages we checked.
Is expensive coco really better than budget coco for yield? We have not measured it, and we know of no independent comparison of these three brands. What the makers publish differs mainly in pre-fertilisation and EC: Plagron Cocos Premium and Atami Washed & Buffered are unfertilised with a low EC, Atami Cocos Substrate is lightly pre-fertilised (EC 0.80-1.00), and Canna publishes no EC. Choose the type that fits your feeding.
Can I reuse coco between cycles? Canna says Coco Professional Plus+ can be reused several times and makes a good potting-soil improver afterwards; Plagron says Cocos Premium can be reused as a soil improver. How many cycles exactly, and whether you need to re-buffer, is not on their product pages. Don't reuse coco from a plant that had a pest issue (especially fungus gnats or root aphids).
How often should I water in coco vs soil? Coco is usually watered more often and in smaller amounts than soil. How often depends on pot size, plant size and climate, so we don't give a fixed schedule. Water until some runoff comes out of the bottom of the pot.
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