--- title: "Should You Add Perlite to Coco? Why Growers Do It, and When You Shouldn’t" url: "https://growingexposed.com/should-you-add-perlite-to-coco-why-growers-do-it-and-when-you-shouldnt/" markdown_url: "https://growingexposed.com/should-you-add-perlite-to-coco-why-growers-do-it-and-when-you-shouldnt.md" llm_canonical: "https://growingexposed.com/should-you-add-perlite-to-coco-why-growers-do-it-and-when-you-shouldnt.md" canonical_for_llm: true entity_type: "Article" primary_entity: "Should You Add Perlite to Coco? Why Growers Do It, and When You Shouldn’t" citation_value: "Published on Growing Exposed; canonical URL https://growingexposed.com/should-you-add-perlite-to-coco-why-growers-do-it-and-when-you-shouldnt/." last_updated: "2026-10-28T19:19:52+00:00" --- # Should You Add Perlite to Coco? Why Growers Do It, and When You Shouldn’t Walk into most hydro stores and you’ll find two bags of coco side by side, one plain and one with white flecks through it. The white flecks are perlite, and they change how often you need to water. Perlite makes coco drain faster and hold less water, so the pot dries back sooner and you can feed more often. That suits a grower on an automated drip system. A grower who hand-waters once a day, or grows in serious heat, is often better off with straight coco. Brett, who has run South Pacific Hydro in Canberra, Australia, with his partner Darren since 1993, explained the difference when we visited with Justin Cooper of GreenPlanet Nutrients. The owners say coco and coco perlite are the growing trend in Canberra. GreenPlanet makes a ready-to-use version, Professional Coco Perlite 70:30. ## What is perlite? Perlite is volcanic glass that has been heated to about 1,600°F until it pops, like popcorn, and expands up to 20 times its size. What comes out is the light white grit you see in potting mixes. It’s inert. It has a neutral pH, it carries no nutrients, and it doesn’t hold on to the nutrients you feed. Water clings to its surface and sits in its pores, but it holds much less than coco does. Its job in a mix is to make air space. ## Why do growers add perlite to coco? To get more air to the roots and to water more often. Coco holds a lot of water. Mixing in perlite opens up the medium, so it drains faster and the roots get more oxygen between feeds. > “I like the addition of the perlite in the, in the coco mix. Um, it just elevates it a bit more. It doesn’t hold as much water, but has a good capillary reaction. Um, and it works really well. And you get more drybacks, so you’ll actually get more feeds.” > > > > — Brett, co-owner, South Pacific Hydro Capillary action is how water wicks through a medium, spreading sideways and up through the pot from where it lands. Brett’s point is that perlite cuts how much water the mix holds without stopping the mix from spreading water evenly. ## What is a dryback? A dryback is how much moisture the pot loses between one watering and the next. The plant drinks, water evaporates, and the medium dries down. A mix that dries back faster can be watered again sooner. More waterings in a day means smaller, more frequent feeds, and the roots get fresh air each time the pot dries down. That is what Brett means by more drybacks and more feeds. ## Is straight coco better than coco perlite? Neither is better. They suit different growers. Straight coco holds more water, so it gives you more room for error. Brett says that matters in an Australian summer. > “It’s, uh, more forgiving. Especially in the summertime. We get quite hot summers in Australia. Um, and it’ll hold a bit more water. Far more water than clay, of course. Um, so if something happens, um, you know, you got more chance of your plants surviving.” > > > > — Brett, co-owner, South Pacific Hydro “If something happens” means a pump fails, a timer gets knocked, or you’re away for a day in a heat wave. A pot that holds more water keeps the plant going longer. The catch with straight coco is that it’s easy to overwater, especially the first time. Brett says a couple of waterings a day is usually enough. With coco perlite, you can water a little more often. ## When should you use coco perlite? - **You’re on an automated system.** Drip lines on a timer can feed several times a day. Digital timers now go down to seconds, so you can give each plant a short shot of feed many times a day. Coco perlite is built for that. - **You want to feed more often.** Smaller, more frequent feeds keep the root zone steadier than one big watering. - **You tend to overwater.** Perlite drains faster, so a heavy hand does less damage. - **You run to waste.** Growers who’ve moved from recirculating systems to coco usually feed fresh solution each time and let the runoff go. Coco perlite drains cleanly, which suits that. ## When should you stick with straight coco? - **You hand-water once or twice a day.** Straight coco holds enough to carry the plant between waterings. - **Your room runs hot or dry.** Plants drink faster in heat, and coco perlite can dry out before you get back to it. - **You’re away from the room for long stretches.** More water held in the pot means more time before the plant runs short. ## What are the downsides of perlite? - **Dust.** Dry perlite is dusty and can irritate your lungs and eyes. Wear a mask when you mix it, and wet it down first. - **It floats.** When you water heavily, some perlite rises to the top of the pot. - **It holds no nutrients.** Everything the plant gets comes from your feed. - **It dries out faster.** That’s the point of it, but it also means less margin if irrigation stops. - **It’s mined.** Unlike coco, which comes from coconut husk, perlite isn’t renewable. ## What is the best coco to perlite ratio? The usual mix is 70 percent coco to 30 percent perlite. GreenPlanet calls it a trusted standard among indoor and hydroponic growers. It keeps most of coco’s water holding while adding enough air to water more often. Some growers go heavier on perlite to water even more often. You can mix it yourself, but you’ll be handling dusty perlite and you need to start with coco that has already been washed and buffered. A pre-mixed bag skips both. ## Where to get coco perlite GreenPlanet Professional Coco Perlite 70:30 is RHP-certified, fully buffered coco blended with perlite. It’s ready to use straight from the bag, for automated systems or hand watering. RHP is a Dutch quality mark for growing media that tests for things like pests, pathogens, pH and salt content. At South Pacific Hydro, Darren says customers come back asking for GreenPlanet Coco by name. Growing Exposed does not sell nutrients or growing media, but GreenPlanet Nutrients does. Contact them directly, or use the links below to learn more. In Australia, learn more and find a store at [GreenPlanet Professional Coco Perlite 70:30](https://greenplanetnutrients.com.au/products/professional-coco-perlite/). In North America, contact [GreenPlanet Nutrients](https://greenplanetnutrients.ca/contact-us/) to find out where to buy GreenPlanet coco near you. **Commercial grower? Find your GreenPlanet rep.** Call GreenPlanet toll free at 1-866-913-4769 or email info@mygreenplanet.com and ask who your sales rep or distributor is. GreenPlanet has reps and distributors in Canada, the United States, Australia and Europe. [Contact GreenPlanet Nutrients](https://greenplanetnutrients.ca/contact-us/) ## Common questions ### Does perlite change the pH of coco? No. Perlite has a neutral pH and doesn’t react with your nutrient solution. The pH of the mix comes from the coco and your feed. ### Does perlite hold nutrients? No. Perlite has no nutrients of its own and doesn’t bind the nutrients you feed. Coco does bind some calcium and magnesium, which is why buffered coco matters. ### Is perlite the same as vermiculite? No. Both are expanded minerals, but they do opposite jobs. Perlite adds air and drainage and holds little water. Vermiculite soaks up water like a sponge and is used to hold moisture. ### Why is perlite floating on top of my pot? Perlite is light, so heavy watering can lift some of it to the surface. It’s harmless. Watering more slowly, or using a pre-mixed bag where the perlite is blended through the coco, helps. ### Is perlite dust dangerous? Perlite dust can irritate your lungs and eyes. Wear a mask when you handle dry perlite, and dampen it before mixing. ### Do I still need to buffer coco perlite? The coco part does need to be buffered, or it will bind calcium and magnesium from your feed. GreenPlanet Professional Coco Perlite is fully buffered, so it’s ready straight from the bag. ### How often should I water coco perlite? More often than straight coco, because it dries back faster. Growers on automated drip systems often water several times a day in small shots. Watch how fast your pots dry and adjust from there. ## Watch the full visit Justin Cooper of GreenPlanet Nutrients with Brett, Darren, Nick and Jim at South Pacific Hydro in Canberra. About 15 minutes. Read the full story in [You Can Grow Four Plants in Canberra, But You Can’t Buy the Seeds](https://uc5a1b9bcddbfdcf24f27aa76912.previews.dropboxusercontent.com/p/orig/ADL2fPzBudm2zkffT9jkCAUKP3jPUKzM_QlEUvVnNLc2iNdTtXks5vf2O787crdRPQzI4cdAnt3bDuyH7u-t2hqOM6qDtNvWZo8X8t3f8jnmQ7kCrvumLUf5pBYvQXwurvGfk708Pf0RF6DAIHtYkaChbOxwIxaEQlkvjqEHgri9DIj4yqbNVlhbFA56Cgn_koye3A246T4QcWteQUGCptjww184qMPq13dHPx8yRfSVpNbUIPp6LHZgGQ9_yg679NMxjkghRjyafaw7cSYGJZ5z27xhbVzmeqZdOh8KCJ15VaHiVosC4SK_fg0cjUPv-wUCgqUX1RaiJw3cfmwQ70JN/ARTICLE%20URL%20GOES%20HERE).