a few light squeezes under the water then let them soak for half an hour. Discard this water.
The third flush is done with lukewarm water adjusted to pH 5.5 in which they’re left to soak for half an hour. Discard this solution and squeeze most of the liquid out of your cubes. Now your rockwool is ready to receive nutrients & plants!
Because our babies have already got roots peeking out from the peat pellet, we can now prepare a very light solution of NPK veg nutrients, root booster, seaweed extract and trichoderma for the rockwool – at this stage we only take the mix to 1.1 EC from seed (1.2 EC if from cuttings) and bring the solution to pH 5.5. Soak your rockwool cubes in this solution for an hour. Carefully drop your plants into the rockwool, gently close up any gaps between the peat pellet and rockwool, then sit back and feel pleased with yourself.
Make your rootin’ tootin’ root boostin’ hydroponic kindergarten!
Now it’s time to assemble our incredible Ultimate Rooting hydroponic system. We will only keep the plants in this system for a week to ten days, but it gives them the best start possible before you install them in their final home. Nutrient solution is pumped through the rockwool, dripping out from underneath into the tray to create a recirculating active system.
The magic comes with the screen – as the roots grow through, they hit air and the tips die off triggering an explosion of new root growth from within. We time the feed schedule and adjust the nutrient composition to encourage the most extreme roots possible before we transplant to their final site.
Sterilise your trays, pump and screen. Diluted Hydrogen Peroxide or isopropyl alcohol works well and doesn’t leave any residue that’s unfriendly to plants. Put your small tray down on the bench and attach your pump to the base, towards the back end of the tray and away from the centre. Lay your screen over the tray. Next fit your inline filter to your pump, then your dripper manifold and tubing.
The pump filter and manifold should be sticking up through the hard screen.
It is useful to use the smaller plant tray at this early stage, as you won’t need to make up such large quantities of feed just to get the depth high enough for the pump to work efficiently. Using less nutrients is also more economical for you and better for the environment too with less waste solution. As the plants grow too large for the small tray you can simply lift the screen, pump, plants and dripper in one convenient movement and swap the bottom tray to a larger one.
If your screen is unsupported anywhere you can place a couple of metal rods laying across the top of the tray under the screen, supporting the weight of your wet rockwool. Alternative methods are to fold the screen edges carefully up to give some rigidity or better yet just get a larger screen and cut it to fit, leaving an inch or so of overlap all around the large tray.
Think about your plant spacing and cut your dripper delivery tubing to reach each plant easily, but avoid leaving masses of excess to get in the way when they are tiny and bunched closer together. Depending on what you are growing, you may need to allow for up to a 12 inch circumference of space per plant by the time you are ready to transplant again in about 10 days.
Now it’s time to install the plants. Place them directly onto the screen and push a dripper stake into each rockwool cube. It’s easiest to work from the closest to the pump outwards. If you’re working with seedlings they are still absolutely tiny at this stage so you can bunch up the cubes to make the best use of your light coverage. Space them out as they grow, so none of the plants ever touch each other at this early stage. If young plants feel restricted they won’t develop such good lateral branching.
Optimising your feed schedule strength and timing
Make a full spectrum vegetative nutrient solution with NPK+micro nutrients+root booster. We still keep the solution light at this stage, so we mix until we measure 1.1 EC for seedlings, 1.2 EC for cuttings. Tip this into your tray, which conveniently acts as your tank too. Test the pump & dripper are working as expected, with even flow from all the dripper stakes.
The nutrient solution should fill each cube and drip through back into the reservoir from multiple points on the base of the cube. Ensure that the dripper tubing isn’t pulling the stake back into the plastic wrapper on the rockwool, or you risk some nutrient running down the outside and missing the young plant altogether.
If growing from seed, increase nutrient strength to an EC of 1.2 after they’ve been in the rockwool for 3 days, and keep it there until transplanting next week.
Often when people use dripper systems, they use a very fast timer to only replace a small amount of nutrient per feed.