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Pro step by step guide to cuttings in rockwool
 YOU ARE HERE : Advice Home / Growers Guide / NFT and ROCKWOOL / Pro step by step guide to cuttings in rockwool 

This following tutorial has been donated by 'Tony', and  is one of the most detailed and professional step by steps that we have seen.

A big shout to Tony at Hydrotops, who not only makes top feeds for your ladies, but believes, as we do, that knowledge should be shared as freely as possible.  

Taking stem cuttings


·     Thermostatically controlled propagator ( ideally, if can't get one, just  get a standard heated one instead)

·     Sterile scalpel

·     Rooting Compound/gel

·     Nutrient concentrate additives for cuttings / young plants

•  Root Stimulator ( and Bactivator if wanting to use hydrotops range, see shop)

·   Rockwool rooting cubes / Rockwool growing blocks

·   Perlite or Seramis

·   Propagation lighting


Carefully wash your propagator inside and out in a hot bleach and soap solution and rinse thoroughly in fresh cold water. Dry the propagator and cover the base to a depth of 25mm with moistened perlite or seramis. Set the thermostat to 25 degrees Celsius.


Prepare the Rockwool rooting cubes by soaking in a nutrient solution designed for cuttings and newly formed plants.  Root Stimulators and( Bactivator) should be added to the soak­ing solution for the best results. It is essential to set the solution used at the correct EC. If your solution EC is too high it will inhibit the quick formation of roots. If too low nutrient problems may occur once roots are formed and the young plants’ demand for nutrients significantly increases. A good guide to the correct EC is outlined below:0.8 to 1.2 in soft water areas (Background EC 0.1 to 0.4) 1.0 to 1.4 in hard water areas (Background EC 0.5 to 0.8).The pH of the solution should be between 5.8 to 6.5. Ensure that the cubes are fully immersed and allowed to soak for at least three hours, preferably overnight.


Take all of the cuttings from the mother plant at the same time. Only young, vigourous growing shoots should be selected for cuttings. Cut the stem between two nodes at an angle of 45 degrees and immediately place the cut end of the cutting (basal end) into a container of water.

The cuttings may be kept in low light levels at this stage for up to 12 hours.


Remove the rooting cubes from the soaking solution and place on a sheet of clean absorbent paper or dry perlite, to draw out the excess moisture.

The rooting cubes should be moist but not over-wet.If insufficient water has been drawn out, the cubes may be squeezed gently to remove any excess nutrient solu­tion until dry to the touch.


Most rooting cubes have a hole in the centre for the cutting stem. Do not use this hole for rooting the cutting. The diameter of the hole is often larger than the cutting stem. It is essential that the stem of the cutting fits snugly in the rockwool to ensure rapid rooting.

Make a small hole in one corner of the rooting cube the same diameter as the cutting stem with a cocktail stick approx.5mm in from the edge.The hole should be deep enough to cover at least one, preferably two nodal points.

There is a greater ratio of air to water at the edge of therooting cube,which will encourage quicker root production.


Choose a cutting from those taken and remove leaves from the two lowest nodes.

Trim the cut end back to a position just below the bot­tom nodal point at 45 degrees.

Dip the stem in liquid rooting hormone for approx. 5 seconds ensuring the trimmed nodes are immersed. Insert the cutting immediately into the prepared rooting cube. The top trimmed node should be just below the surface of the rockwool.


The surface area of the remaining leaves on the cutting needs to be reduced by approx. 50%.To do this cut the large leaf blades in two with a pair of clean, sharp scissors.

This allows the young plant to reduce its rate of tran­spiration and divert energy into producing roots.


Immediately place the cutting into the propagator.The humidity in the propagator should be maintained at 78 to 85% RH during the complete rooting period.This can easily be maintained by moistening the perlite cover­ing the base.

Repeat stages five to eight for each cutting you require.


Once all the cuttings are planted up mist them with warm water. Place the cuttings in moderate light or under fluorescent propagation lights. A photo period of 16 to 18 hours should be used.

Mist the cuttings daily in warm water for the first three days.On the fourth day,the cuttings can be misted with a solution of root stim and nutrient for young plants at the same EC used for soaking the rooting blocks

Check the rooting cubes daily for signs of rooting from this point. Using this method roots will usually appear within 4 to 5 days. Do not let the cubes dry out.If required water the cubes by dipping the base into a shallow con­tainer of nutrient solution and allow it to rise halfway up the cube by capillary action.

Rockwool rooting cubes should always be watered from the base and the upper surface of the cube kept reasonably dr


Once roots are clearly seen growing from the bottom and sides of the rooting cube, the cuttings can be transplanted into a growing block. Prepare the rockwool growing blocks by soaking in a solution of a ypung plant nutrient, Root Stimulator and Bactivator.

Set the EC of the solution to 1.0 to 1.2 in soft water areas (background EC 0.1 to 0.4) 1.2 to 1.4 in hard water areas (background EC 0.5 to 0.8).The pH of the solution should be between 5.5 to 6.0. Ensure that the blocks are fully immersed and allowed to soak for at least three hours, preferably overnight.


Remove the growing blocks from the soaking solution and place on a sheet of absorbent paper or dry perlite to draw out the excess moisture.The growing blocks should be moist but not over wet.If insufficient water has been drawn out on the paper or perlite they may be squeezed gently to remove any excess nutrient solution.


Carefully place the rooting cube containing the rooted cutting into the growing block and return to the propa­gator.

Over the next few days gradually lower the humidity around the cutting to around 70% RH. Water the rooted cuttings at 12-hour intervals with 50 to 75ml of nutrient solution made up as directed in step ten.

As the cuttings develop, the strength of the nutrient solution can be increased by EC 0.1 to 0.2. Maintain the photo period at 16 to 18 hours. The propagator lid can be opened for a few hours each day to harden off the cuttings.Once a good root system is clearly seen beneath the growing block, the cutting is ready to be transferred to the growing system. Remove plastic sleeve from the growing blocks when place in in NFT systems to avoid creating a breeding ground for fungal infections. This method of taking cuttings is well tried and tested and when these instructions are followed success rates of 100% will be easily achieved. Attention to detail, clean­liness and good practices at this critical stage of the hydroponic growing cycle will pay dividends in terms of plant health, vigour and crop yield later in the cycle.


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