Thứ Sáu, 20 tháng 7, 2018

There are several different systems used in hydroponic gardening and all of them are meant to improve the growers control over nutrient, water and oxygen supplies to the roots of the plant. In a hydroponics system the medium used in place of soil contains no nutrients of its own and these are supplied by the nutrient solution. The nutrient solution is circulated around the roots by any one of a number of methods and then is allowed to drain off. The extra oxygen around the roots allows the plants to take up nutrients faster and thus grow faster. It is a misconception that plant roots only require water and fertilizer, if this was all the plant roots received it would grow poorly and probably eventually die. 

The power of hydroponics is the ability to create a continuous cycle of watering, draining and aerating. The plants uptake of nutrients is increased and it grows in a more prolific manner. We can really consider there to be two types of hydroponic systems, passive and active. Passive hydroponics works by the capillary action of the wick and growing medium. Active hydroponics actively moves the nutrient over the roots and growing medium by way of a pump or similar device. There are four methods of hydroponics that I would consider suitable for beginners to attempt. Hydroponics is much more exact than soil gardening and we would suggest that you start small until you have learned your way a little bit before concreting your back yard and filling it full of hydroponic trays. 

Wick Feed

Wick Feed hydroponic methodThe Wick Feed pot is in my opinion the best way to learn the basics of hydroponics. They are readily available in many guises, cheap to purchase and economical to run. I have had excellent results with a 90/10 perlite/vermiculite mix in a wick feed pot purchased for a few dollars from my local K-Mart. 

The Media is placed in the wick feed pot, which resembles a normal plant pot with a reservoir underneath. The plant of course is also placed in the the pot in the media when it is a seedling. As the plant grows its roots will run into the reservoir through the holes in the bottom of the pot and it will drink directly from the reservoir. Particularly when the plant is young I recommend watering them from the top of the pot and allowing it to run into the reservoir through the growing media. It is wise to water in this fashion until the plants roots have visibly made it into the reservoir. 

On some wick feed pots the reservoir is removable and I recommend these as they are easier to clean when you are replanting. Do not remove it while you are growing in the pot as damaged roots will retard plant growth. Leave your plant roots as physically undisturbed as possible. 

Simple Reservoir

Simple Reservoir Passive Hydroponic MethodThe reservoir method is not much different to a wick feed system with the key difference being that there is no division between the reservoir and the root space. The reservoir is really the bottom of the grow bed and is filled with media. More suitable for media like hydroclay or gravel the roots grow down to below the high water mark and drink steadily during the day. A drain hole on the side of the grow bed determines the high water mark and I recommend that this is about 5cm (2") below the top of the growing media so that moss and algae wont take hold. 

I use a lot of passive reservoir systems like this in my own garden and I have found that they work quite effectively with growth rates at least as good as gardening in soil and generally much better. They are easy to make and very forgiving to the novice gardener. Drill a drain hole in an ice cream container, fill it with gravel, put a plant in it and see how you fare! 

Flood and Drain

Flood and drain hydroponic methodThe flood and drain method of hydroponics can be considered to be an active form of hydroponics, where the nutrient solution is pumped from a reservoir below to a tray which will hold either plants in individual pots containing media or alternately the tray itself may be filled with media. The nutrient is pumped into the tray which is filled until the return pipe is covered and the excess nutrient solution then returns to the reservoir. If you examine our flood and drain diagram to the right you will see that the return pipe protrudes into the tray, usually a distance of about 50mm or 60mm. This means that when the pump is running the tray will only fill up to 50-60mm before the nutrient returns to the tank. When the pump is switched off the water will drain completely out of the tray by flowing back through the pump. Do not use a pump that has a non return valve or the nutrient solution will be stuck there unable to drain away completely. 

Flood and drain is one of the simpler hydroponics methods to learn and it can be reasonably forgiving as far as pumping intervals and duration is concerned. Like all methods experimentation is the key to finding the optimal pumping intervals and durations for your particular environment. A good starting point would be to pump for 15 minutes every 2 hours during daylight hours and not at all during the night. 

Top Feed

Top feed hydroponic methodTop feed would have to be my most most favourite method of aquaculture. Flood and drain tends to develop massive root balls at and below the water line but top feed allows the entire growing media to be more thoroughly utilized. 

The water is pumped from the reservoir to feed bars that are positioned close to the base of the plant. The feed bar may simply be a tube (usually 10-13mm) that has holes approximately 3mm in size directed toward the base of the plant. I prefer a commercially available plastic dripper that is joined to the larger diameter feed bar by a length of 3mm ID flexible plastic tube. The nutrient solution should dribble onto the base of the plant and from there it will follow the plants root system. A flood and drain tray is a good place to place your plants however some growers find PVC tubing to be an economical option. The media may be place directly in the tray however 250mm plant pots can work just as well and be more cost effective with growing media. As top feed works on the media from the top to the bottom direct drainage is advised with the return pipe as pictured located directly at the bottom of the tray. 

Top feed hydroponics is also one of the simpler methods of hydroponics and can be a great starting point for learners. Experimentation is the key to finding an ideal pumping schedule that suits your environment. Pumping for 15 minutes every 3 hours during daylight hours and not at all at night is a good starting point. 


NFT hydroponic methodNFT stands for Nutrient Film Technique or Nutrient Flow Technique depending on who you talk to. NFT systems are one of the most productive hydroponic systems available and it is suggested that you experiment with one of the above systems and get a feel for hydroponics before jumping into NFT. 

The principle that NFT operates on is very simple. The plant is supported by a collar in the top of the grow chamber and the grow chamber itself is light proof. The roots grow into the grow chamber which has a shallow capillary mat on the bottom and the nutrient solution is pumped over the capillary mat constantly and drained immediately back into the reservoir. The majority of the roots will grow over the mat and nutrient will flow over them constantly allowing a maximum amount of air and nutrient to be absorbed. Growth rates achieved by NFT can be absolutely astounding with a little fine tuning. Once your current crop is completed the capillary mat and old root system is discarded, the grow chamber cleaned and sterilized and new matting is then placed on the bottom of the chamber ready for new seedlings or cuttings. Unfortunately, with no medium to hold water and nutrient, NFT is dependant on the flow of nutrient and if a pump or power failure causes the roots to dry out then the plants may die in a remarkably short time. 


Aeroponic hydroponic methodAeroponics is similar to NFT in that the plants roots are suspended in a light proof grow chamber and once again no growing medium is used. The nutrient solution is pumped into a feeder pipe that has misting nozzles that mist the plants roots at regular intervals. The humidity in the grow chamber is kept at 100 percent at all times and the plants have maximum potential to absorb nutrient solution in the presence of air. 

As with NFT the growth rates in aeroponics can be incredible but the system is not very forgiving particularly if the pump stops and some fine tuning is required to get the misting/airation cycle just right. Aeroponics can be particulary effective at rooting cuttings.

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