I have chosen to grow a variety of beetroot called Pablo for its uniform shape, smooth skin, great taste and high yield. As you can see i have germinated the seeds in jiffy peat pellets. I like these because they retain moisture well and contain slow releasing nutrients that are vital for early growth. I have brought them on until they are well established and about 10 - 15cm in height. Their leaves are weighty so i have used sandwich bag ties to hold them up by tying a loop around the stem and sticking the other end in the peat pellet.
Sit the 45 litre nutrient reservoir on a level surface and place the flood tray on top so that it sits in the grooves. position the tank so the gap faces the front. This is where you check and fill the nutrient solution. There are two tubes that stick upright from the flood tray. The smaller of the two nearest the front is attatched to a microjet mc 450 pump and allows for the nutrient solution to flood the medium in the tray.
The second larger upright tube is an overflow drain so that the flood tray can never overspill into the grow room. Handy when theres electrics about. There are also small holes in the grooves of the tray which are for drainage too.
I have added a thin layer of large 8-12mm clay pebbles to allow for better drainage.
I have filled the rest of the tank with seramis that are smaller than the clay pebbles i have used and they also hold onto more water to prevent drying out between floods.
I dug a space in the seramis to fit the peat pellet, in a staggered arrangement for maximum growth space and covered it back up with the seramis.
After transplanting the plants look lifeless and limp. This can be normal as there are stress factors such as a sudden drop in humidity and temperature from coming out of the propagator. Also because the seramis was dry when i transplanted i felt that it sucked some of the moisture out of the roots and peat pellet by process of osmosis.
I took a jug and scooped the nutrient solution i pre-mixed from the nutrient reservoir and poured it over the medium. I then made a black and white cover to prevent loss of moisture from the medium, i cut holes in the right place and pulled the plants through.
After a few days when the plants had rooted in and become established i began to flood the table once a day using a grasslin segmental timer set to 15mins on at mid day.
After nearly two weeks the beets are showing rapid signs of growth.
Here's an overview of the greenhouse with most of the plants just gone into the different systems. The humidifiers are going to play an important role in the early establishment stages as there will be less demand for water to be uptaken by the roots and will allow the plant to spend energy in root growth. A young plant with a healthy mass of roots will be more hardy and have a much higher yield potential.
Another way to maintain high humidity levels in the establishment stages is to use something like these propagation domes. I've used them on the IWS flood and drain and the IWS dripper systems because they are a perfect fit. They create a micro-climate where moisture generated from the pot and the plants leaves can't escape and so elevates the humidity levels inside. The vent on the top can be opened gradually to control the humidity levels, gently easing the plant into the surrounding environment. This ensures that the plant can withstand the humidity levels of the main room with minimum of stress.
On the left hand-side of this picture you can see the tomato plants in the autopot system. I've got coco fibre mixed with perlite as the growing medium but you can use rockwool cubes, mapito, serramis, fytocell or soil (anything with a good capillary action but has a good air content). At the minute the pots aren't connected to the water butt. Even though it is a self-watering system i choose to hand water for the first couple of weeks. This is because i do not want the plants to be overwatered at such an early stage. By hand watering i can allow the pot to dry out slightly before the next watering. This will increase the air content within the pot and lower the water saturation level creating a perfect environment for a young root system to grow in.
Everyone has their own ideas and methods for rooting plants in NFT systems. Working at a Aquaculture i get to hear them all and i'd say there's no set practice that will work the best everytime. What will work best everytime for one person doesn't mean it will definately work best for another. There are many irrigation patterns that people go through like 15mins on every hour and will increase the frequency as they get bigger. There are generally two types of people, people who overwater plants by either putting a plant on the system before its had chance to root properly and/or having their pump on too high a setting where it floods the tray and drowns the young roots. On the other hand you get people that try that hard to get as much air as possible to the roots by having a massive ammount of time between irrigations for a prolonged period despite having a good ammount of root mass in the block to begin with. Even though the block may feel wet still the pioneer roots that are on the tray will dry up and the demand on the plant may outweigh what is supplied to it thus stressing it and not allowing its roots to develop properly.
I've said it before that every plant has a different root system and every growroom environment is different therefore each time needs its own tweaking. I will only start with a plant that has an abundant ammount of roots in the block, that way it will cope better the environment change and ammount of water you throw at it. I've personnaly not had any problems with putting a well rooted plant on the system with a constant flow on a slight trickle. This is the way commercial greenhouses have done it for years to great success.
Aubergines in the amazon were a doddle because i didn't need to alter irrigation settings as the aeroponic method delivers an ideal ammount of water and air to the roots so i just left it sprinkling 24hrs.
Both the tomatoes on the high and low pressure drip feed systems were left to sit in pre-soaked rockwool and coco slabs. They didn't need an irrigation for a number of days. The slabs remained damp enough for up to 5 days before needing a watering, and that was only to prevent a ph or ec change. They weren't regularly irrigated till up to 2 weeks after hand or manually irrigating them. This let the root system develop so it can cope with the frequency of timed irrigations daily.
