Now my 'Cedrico' tomato plants are up to size and have a good root system showing out the bottom of the block is time to set up my high pressure drip system where I'll be growing the plants on 1m rockwool slabs. I have 20 healthy 'Cedrico' plants all of which I'll be choosing the best 14 for the system.
To start with I have placed the 1m grodan 'expert' slabs in their plastic trays (know as aqua trays). I insert the slabs upside down and place the trays on top of the catchment tank which is just over 2m in length. I have also made a support bar which is 2.3m in length which you can see behind the tank. I also turn the drainage tubes at the end of the tray to face up so any excess solution stays in the tray.
Now the slabs are on a flat surface I cut a slit at the drainage end of the tray and fill a 100L tank with nutrient solution at a strength similar to what the plants have been getting feed over the last few days, EC 2.2 with a pH of 5.5 using the Vita-Link 'Easy grow' 1 part nutrient . I also add in to the solution some Beneficial Bio-Link plus which will help establish a good root system. From the storage tank I fill a watering can and pour the nutrient solution into the slabs through the slit until the slab is fully saturated throughout. The slabs are then left to pre-soak for around 12 hours.
While the slabs are soaking I get the pipe work ready. For high pressure drip systems I use 3/4" supply tube with 3/4" compression fittings. For this system I need 4m of supply tube, 1 compression 'stop end' and 4 compression elbows. The tubing will be attached to the support bar at the top end of the slabs running up the the blue 220L nutrient reservoir.
In the reservoir I have a 4000lph WGP55 little giant pump attached by 3/4" tricoflex hose to a high pressure filter set. The filter will help the drippers from clogging and also can be used to regulate flow and mix the solution in the reservoir.
This picture show the fittings needed to join the pipe work together. Cable ties come in handy to attach the pipe work to the support bar keeping it off the floor.
The drippers I will be using are called know as high pressure self compensating drippers. These drippers have a small brow compensator that plugs into the supply tube and is held with a barb to stop any leaks. These compensator's have a small diaphragm inside which makes them only open under pressure when the pump is on. When the pump goes off the pressure drops in the supply tube and the diaphragm closes. This means that each dripper acts like an anti-siphon valve stopping any through flow of water. The green tool is a hole cutter to make a hole in the supply tube to insert the compensator into.
Now the slabs have been soaked for over 12 hours i turn the drainage tubes down and position the slabs so one end is on the support while the other end is draining into the catchment tank. The catchment tank is weighted with bricks to stop it from turning up under the weight of the slab.
Once the slab stops dripping I remove them from the stand and turn up the drains up again so the trays can be placed on the floor so I can start attaching the pipe work. The support bar is about 1.5cm higher than the catchment tank to give around a 1:100 gradient to the slab to allow the solution to drain out. Some slab trays come with an inbuilt gradient, like the 1.3m aqua tray. This drainage gradient is important as too steep will give a wet end and a dry top while too shallow will keep the whole slab too wet.
This hydroponic system is a low pressure recirculating drip system and is named the 'Wilma'. This is made my Nutriculture and comes in 5 sizes from 4 pots to 20 pots. This one is the most popular amongst growers, the Wilma 8 pots system. This system has a reservoir as the base on which the tray is placed to support the 8 pots. A submersible pump (maxijet 1000) sits in the reservoir which is attached to a supply pipe with one dripper branching off to each pot. The nutrient solution is pumped from the reservoir, through the drippers and through growing medium in the pot finally returning back to the reservoir. I have previously used this recirculating drip system to grow herbs, potatoes, tomatoes and chillies but this time I'm using if for a variety of cabbage called 'Green Chancellor'.
This system is extremely easy to set up, all you do is place the tray on the reservoir, position the square pots in place and connect the drippers to the supply line, this only takes few minutes. With the Wilma system you have a choice of growing mediums, i am going to use coco coir and perlite mixed at 80% coco to 20% perlite.
The square pots for the 8 pots system hold 11L of growing medium. I place 2 strips of spreader mat in the bottom of the pot to cover the large holes to stop the growing media from falling into the tank while still allowing water to flow freely. I then add around an inch of clay pebbles in the bottom to help get good drainage and top up the rest of the pot with my mix of coco and perlite.
As with every hydroponic system i always ensure the my plants are very well established before transplanting them. You can see the roots of this cabbage plant are abundant and healthy. After the plants are potted into their larger pots i water them in by hand using Canna's Coco 2 part A+B nutrient at an EC of 1.6 with a pH of 5.8, i also add Vita-Link 'Bio-Plus' which is a fantastic rooting stimulator. Coco coir and perlite are both inert growing mediums so need to be watered with nutrient solution straight away.
Now they are watered in i will water again in 3 or 4 days by hand. I always water enough so a little run-off leaves the pot into the tank. I'll hand water the plants for 2-3 weeks until they need to be watered everyday at which point I'll fill up the reservoir beneath and used the pump to irrigate the plants once a day using a timer. Too much water straight after transplanting can get them off t a poor start so i make sure they are well established in their pots before feeding everyday. This variety of cabbage can get quite big, only time will tell.
