rockwool for hydroponics
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4 Best 1.5 Inch Hydroponic Rockwool from Amazon

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Are you looking for the best Rockwool for your hydroponic garden?

If so, you’ve come to the right place.

This blog post will look at four of the top Rockwools on Amazon.

What Do You Know About Rockwool First?

Rockwool is a popular choice among hydroponic gardeners because it is an inert substrate that doesn’t contain any nutrients. This makes it ideal for growing plants in a hydroponic system.

Rockwool is made from basaltic rock and chalk, super-heated, and spun into a cotton candy-like consistency.

It is sterile, pH neutral, odorless, and does not support the growth of algae, fungi, or bacteria.

Additionally, it comes in many different forms, such as cubes, plugs, loose fiber, and starter sheets. You can use it to start your seeds or cuttings directly in it or as a rooting medium when transplanting to another growing medium.

Let’s take a closer look at some of the best Rockwool on Amazon!

#1. Grodan Mini Blocks Grow Media Rockwool Stonewool Cube Propagation

Brand & Manufacturer: Grodan

This product is designed for starting seeds and cuttings and can be used with any loose media such as grow cubes or grow chunks. Once the seedlings have germinated, you can transplant them into any larger container. The Mini-Blocks can also be placed on a larger Gro-Block for added support.

They are easy to use and can be placed in various settings. The good news is that they are very affordable and work well for both cuttings and seeds. This comes with Twin Canaries Chart.

List the pros and cons of Starter Mini-Blocks.


  • Affordable
  • Easy to use for cuttings & seeds
  • It can be used in a variety of different settings
  • Come with wrappers that help prevent algae growth


  • It can be challenging to remove the wrapper around the individual cube
  • They can be a bit high in pH, so you may need to soak them in freshwater for a few hours before using them

Overall, this is a great product. I would recommend this Grodan Mini Block Rockwool to anyone starting in hydroponics and this is cost only around $8.


#2. Grodan A-OK 36/40 1.5 Inch Starter Plugs, Sheet of 98

Brand & Manufacturer: Grodan

Stonewool (Rockwool) is a form of compressed rock wool made from molten rock spun into cotton candy-like fibers and compacted. Grodan is different from other Rockwool brand manufacturers in that it produces various types of fibers.

This Rockwool is ideal for germinating seeds and propagating cuttings. With a humidity dome and heat mat, these sprout seeds rapidly in early spring to have mature plants ready for spring planting. They are made of spun rock wool, which is lightweight and easy to cut with scissors.


  • Great quality
  • Lightweight and easy to cut
  • Ideal for germinating seeds and propagating cuttings
  • Seedlings or cuttings started in these Grodan cubes can also be transplanted into traditional planters and growing mediums.
  • Suitable for the plant in meeting various phases of its life cycle.
  • The plug’s V-shape form deters root tangling.
  • They absorb nutrient solutions well.
  • Retaining plenty of oxygen to allow rapid plant growth


  • Sometimes, if you reuse the Rockwool, it may rot and cause the fresh seed to decay.
  • Using this Rockwool without safety precautions will cause Respiratory diseases. Recommended using safety tools.

This Rockwool fits the Grodan Smart Tray Insert, which holds the rockwools above the waterline and allows the roots to grow into the water.

This Grodan starter plugs cost around $23.

#3. Grodan Rockwool Mini Blocks Pack of 45

Brand & Manufacturer: Grodan

Rockwool cubes are an easy and convenient way to start seeds and cuttings. The cubes can sit in a tray without support, making it easy to get started. For best results, put the cubes on the flat side of the tray so that good airflow is around the cubes. Remove the wrapping and transplant it into any loose media, such as grow cubes or chunks.

These cubes are famous for the production of aquatic plants. The advantage mini-blocks have over A-OK starter plugs, and macro plugs are that they can sit in a tray without support.


  • Suit for hydroponic gardening
  • No pollutants
  • Affordable
  • It does an excellent job at holding moisture
  • Easy to work with and lightweight
  • They are more stable and hold water longer. Perfect for cloning


I recommend this Grodan mini block Rockools as they are easy to use and ideal for starting your plants with the cost of around $16.

#4 . Rockwool/Stonewool Grow Cubes Starter Sheets 

Brand: NREOY

Manufacturer: DECO2PRO LLC

This Rockwool Cubes Starter Plug-Pack of 28 comes with a pre-made planting hole. The cubes are ideal for planting cuttings, seeds, and other items directly in the cube: place cuttings, seeds, or other objects into the cubes for rapid, easy rooting and sprouting. You can easily transplant once roots have formed by whatever method you choose.

Rockwool starter plugs are utilized in hydroponics, seed starting, cuttings, plant propagation, Cloning, Plant Propagation, and Vigorous Plant Growth.

With or without soil or water-based substrates, they give your plants an excellent early root system because their open structure provides 20% air space when saturated, which helps keep roots weightless – though still moist!

Each cube is 1.5×1.5×1.5 inches for most plants without being too big and taking up space in your grow room.

Let’s look at the pros and cons of this Rockwool to help us make a comparison.


  • Encourages Faster Initial Rooting
  • Its Firmness Is Guaranteed
  • Provides 20% Air Space When Saturated
  • It takes advantage of an ample oxygen supply to the root zone and swiftly absorbs nutrients.
  • It holds moisture for a long time
  • Easy to transplant – It’s an advantage over soil gardening: You can plant the cubes directly into potting mix, which is more straightforward than beginning in the dirt! Planting holes that are predrilled make seeding and plant propagation a lot easier. It’s ideal for both hobby and commercial growers. You may easily separate the cubes after the roots have developed and transplant them.
  • The great thing about this is that it fits any standard flat growing tray with the net pot that’s at least as big as the Rockwool cube with 1.5×1.5×1.5 Inches.
  • Wide application -These Rockwool starter plugs are widely used in hydroponic, seed starting, cuttings, plant propagation, and more.
  • Good for hydroponic beginners
  • Unlike a peat pot, the Rubi cube does not disintegrate.


  • Aware of how to use Rockwool safely?- The cubes do break down over time.
  • If you pick up wet rock wool, be careful not to stuff it too hard. If you do, the fibers will stick to your gloves and wound your hands/fingers.

Overall, the Rockwool Cubes Starter Plug-Pack of 28 is an excellent product for those looking for an easy and efficient way to start their plants. The plugs are easy to use and provide a perfect root system for your plants. 

I would recommend this Rockwool grow cube to anyone looking for an easy and efficient way to start their plants.

Comparison of All Four Rockwools Based on Amazon Rating by Feature

Rockwool number mentioned aboveValue for moneyEasy to useCustomer review
Grodan Mini Blocks Rockwool Cube4.54.74.5
Grodan A-OK 36/40 1.5 Inch Starter Plugs4.34.74.6
Grodan Rockwool Mini Blocks Pack of 454.14.64.6
NREOY Rockwool Cubes Starter Sheets4.24.24.3
Comparison of All Four Rockwools Based on Amazon Rating by Feature

In Summary

Rockwool cubes are a standard for hydro-gardening, and these individual cubes seem to work okay. They’re made of a material that can irritate lungs, eyes, and skin. So be safe while using. 

It’s essential to pH adjust them before use. Algae also seem to thrive in this stuff more than any alternates. 

Rockwool is a growing medium that replaces soil and holds moisture more efficiently. Rule of thumb when starting seeds, don’t use fertilizer or hormone solution until the roots have sprouted through the net cup containing the rock wool. 

Despite those cons, the cubes are a perfect fit for our hydroponic setup, and they keep the seeds pretty clear of pollutants. Overall, they’re an okay product, but there are definitely better options.

Overall, the Rockwool is an excellent product for propagating, and I would recommend Rockwool to anyone starting plants from seed or clones. Overall, Rockwools are an excellent product and well worth the price.

Thank you for taking the time to read my review.

Also, read:
Cheap Grow Lights Alternatives Used in Indoor Hydroponics
Coco Peat vs Coco Coir: What’s the Difference?

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