Rockwool is a nice clean media which has a perfect Air:Water ratio and comes in a ready to use cube format.
Rockwool is a natural media made from a volcanic rock (basalt). The rock is liquefied under extreme heat in special furnaces and then spun into threads and re-solidified into cube format. The production process guarantees sterility in the final product.
When hydrated, each cube has a consistent 80% Water 20% Air ratio which makes it an ideal media for hydroponics as it is difficult to overwater the cubes. This prevents seedling problems such as damping off.
The rockwool comes in sheets of 100 cubes – 6000 cubes per box.
To use this media simply unpack however many sheets of cubes you need from the box, fully submerse the cubes and then drain them off, place the cubes into your propagating carry trays, place the seed in the pre-punched hole provided on top of the cube, gently spray the cubes with a fine shower of water to wet the seeds and cover them and put in a cool, dark area. Lettuce seeds normally germinate overnight.
Then uncover the carry trays and transfer them onto your Ebb and Flow propagation tables and leave the system to irrigate by automated controller. Once the seedlings are at a reasonable size for transplanting (usually at the third true leaf stage) simply separate the cubes and place them in the main growing system.
The cubes can also be pre-separated at the time of seeding and put into the individual cells on cell trays if required. This prevents any root entanglement if the seedlings are grown to a larger size.
25x25x40mm Cubes
Rockwool is a very popular media in NFT lettuce and herb systems.
Lettuce and herb growers use a single 25x25x40mm cube which is sufficient to sustain the root zone of the plant from the seedling stage until maturity.
A large quantity of cubes can be placed on Ebb and Flow propagating tables without using up much space. The cubes are perfect for NFT systems because they do not release any biofilm or grit which is common for other organic based or free flowing medias. It is therefore very easy to keep an NFT system clean when using rockwool.
The 25x25x40mm cubes have a flat base so they are free standing when placed into an NFT gully. This eliminates the need to use a growpot for support, which saves a grower a lot of time and expense because growpots need to be cleaned and sterilised before reuse.
Rockwool prices are very competitive, and even though the price may be slightly higher than other loose medias, which growers use to manually fill pots, the ready to use low volume cube format of Rockwool saves a lot of time and labour and shipping costs which easily recovers any additional cost. The guaranteed sterility of the media also makes it a wise choice for hydroponics. Should there be any issues with root disease a grower can immediately rule out the growing media as being a source of contamination.
The key to using rockwool is to prevent root entanglement prior to transplanting and to avoid damaging the roots when transplanting. Therefore, don’t let the seedling grow too large. Plant it out a bit earlier into the main growing system. If a larger seedling is required, then separate the cubes into cell trays when seeding, or transplant the cubes from the Ebb and Flow system into an intermediary NFT system (with close hole spacing) for several days before transferring into the main NFT system.
75x75x65mm Cubes
Tomato and other vine crop growers (e.g capsicums & cucumbers) typically propagate their seedlings in a 75×75 x 60mm cube on and Ebb and Flow table. Once the seedling has outgrown the cube you simply place it on top of a larger media filled slab, bag or pot and within a day the seedling has anchored itself on top as it expands its root system into the new host media.
150x150mm Blocks
Ideal for larger plants such as medicinal cannabis. These large blocks can act as a stand-alone media so the grower can grow a full-term crop in them without needing to transplant the block onto the top of another media. Or, keep the seedlings longer in these large blocks before transplanting them onto a larger body of media. Any roots that emerge will become air pruned. As with all growing systems the grower must ensure they time their irrigations to match the transpiration requirements of the plant to prevent drying out of the media and wilting.
200x200mm Blocks (The largest available in New Zealand)
These jumbo-sized blocks are the largest available in New Zealand. Perfect for containing an extensive root system in medicinal cannabis. These large blocks can act as a stand-alone media for a full-term crop or as a transitional media before it is transplanted onto a larger body of media.
Rockwool Drip Caps
The drip caps are available for the 150x150mm or 200x200mm Blocks
They anchor themselves to the top of the block with spikes and a separate clip attaches to the edge of the Drip Cap to hold the microtube feeder.
The Drip Cap allows for an even distribution of nutrient solution over the larger surface area of the block.
Important note – All rockwool cubes must be fully soaked and drained to waste prior to seeding. The cubes will never fully hydrate later on if they are not 100% soaked right through the first time. Full submersion prior to seeding is recommended.
A range of trays are also available from Pure Hydroponics for holding the rockwool cubes when they are in the nursery Ebb and Flow system.
Sizes and Quantities
The Rockwool cube sizes available from Pure Hydroponics are as follows:
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- 25x25x40mm Cubes – Slab of 100 Cubes (Pure Hydroponics Brand)
- 25x25x40mm Cubes – Box of 6000 Cubes (60 x Slabs of 100 Cubes) – 12 Boxes per Pallet (Pure Hydroponics Brand or Grodan Brand)
- 75x75x65mm Cubes – Sold Individually (Grodan or Cultilene)
- 75x75x65mm Cubes – Box of 384 Cubes – 12 Boxes per Pallet – 27/35 hole (Grodan)
- 75x75x65mm Cubes – Box of 480 Cubes – 12 Boxes per Pallet – 20/15 or 28/35 hole (Cultilene)
- 100x100x100mm Cubes (Pure Hydroponics Brand)
- 150x150x150mm Blocks (Pure Hydroponics Brand)
- 200x200x200mm Blocks (Pure Hydroponics Brand)
- Rockwool Growing Slabs – 900x300x75mm (Cultilene)
- Rockwool Growing Slabs – 1000x195x75mm (Cultilene)
- Grodan Kiemplug 20x20mm (2,880 plugs per carton)
- Other cube sizes are able to be ordered in if required.
Full 20′ or 40′ container load options delivered directly from Europe are available.
Please contact Pure Hydroponics to discuss which cubes are the best for your situation.
