|DWC grown bud... ready for harvest!|
Put simply, Deep Water Culture is a growing method whereby the roots of the plant are constantly submerged in a highly oxygenated nutrient solution (hence the term; ‘Deep Water'). Very little growing medium is used, other than a propagation cube and a few clay pebbles. The initial root ball of the plant is started in a net pot, suspended above a reservoir or bucket. The roots of the plant grow out of the pot and into the reservoir where there is constant availability of water, nutrient and oxygen; delivered via an air pump.
Deep Water Culture is most commonly used to grow plants full cycle, but can also produce great results when used to propagate clones.
Plants that are grown in Deep Water Culture have constant access to nutrient solution and oxygen; taking up much more water and nutrients than plants that are hand watered. The more oxygen, water and nutrients that a plant can absorb, the more bud they will produce.
The most common and readily available form of DWC system, often known as oxy pots or bubbler buckets; these consist of a 20L black bucket with a net pot moulded into the lid and an air pump. The plant is placed into the net pot along with some clay pebbles; the bucket is filled with nutrient solution until the level is a couple of inches under the base of the net pot, this forms the reservoir that the plant feeds from. Air stones are attached to the bottom of the tanks with suckers and the pump is left on 24 hours a day.
The bucket needs to be black to ensure that no light can penetrate the root zone, as light damages the roots. After a few day the moist atmosphere in the bucket will encourage the roots to grow out of the pot and down into the oxygen rich, nutrient solution - although most growers will prefer to give some water from above, just to make sure that the roots don't dry out before they hit the reservoir.
Bucket systems are great for growers who want to get big yields off a few large plants. Each bucket fits a single plant into it and, because the buckets aren't connected to each other, they can be moved around individually. Another advantage is that the plants aren't sharing the same reservoir, so if one plant gets root problems, like pythium, you don't lose your entire crop.
|A high quality air pump is the heart of a DWC system|
Usually consist of a tray or a bucket that is filled with water to create a small reservoir, air stones are placed in the reservoir and clones are held upright in a tray - using neoprene clone collars - that sits on top of the reservoir. The stems of the clones are suspended underneath the tray, just above the level of water. When the air pump is turned on, the ‘bubbling' effect in the reservoir creates a moist, humid atmosphere in the root zone.
This humid atmosphere, combined with the lack of restrictive growing medium, encourages roots to develop rapidly from the stem of the clone.
Growers can benefit from a much improved success rate, as the lack of growing medium used means the propagation environment is kept sterile and the fast root development allows you to get your grow started earlier.
DIY Bubbler Systems
For the grower that enjoys to put their own set up together, DWC provides a great option. All your need is a reservoir, a lid, some net pots and an air pump with air stones. Plastic storage boxes are available from most supermarkets or DIY centres and create a ready-made reservoir and lid, just make sure that they are a dark colour so that light cannot penetrate the root zone.
Simply drill holes into the lid and file them out so that they fit the net pots. Use air stones or soaker hose to aerate the reservoir. Soaker hose is a great option for larger tanks as it creates a ‘wall of bubbles' that covers a larger area than a single air stone.
The benefit of building your own bubbler system is that you can space out the plants how you want; grow one or two big plants in the system or put lots of plants close together in system and grow a sea of green.
These are becoming more and more popular amongst growers who have had successful crops using bubbler systems and are now refining the technique. The hybrid system uses a drip ring to feed from above whilst also utilising the DWC technique. Instead of using net pots like in a bucket or DIY system, the plants are placed in a deep tray, or planter, with holes drilled in the base. The planter sits above the reservoir.
The young plant is placed in the planter, which is then filled with clay pebbles. Air stones are placed in the reservoir below. A water pump delivers nutrient solution from the reservoir out of the drip ring and over the roots of the plant. The roots grow down amongst the clay pebbles, through the holes in the bottom of the planter and into the aerated reservoir below.
The hybrid system offers several benefits over a regular DWC system;
Hybrid systems are also known as ‘bubbleponics' in certain areas of the UK.
1. Invest in some decent EC and a PH meters. There is no buffer around the roots in a DWC system, so the strength and PH of the nutrient solution must be constantly maintained.
2. Leave the pump on 24/7. To get results in DWC, the air pump must be left on constantly. A plant's roots need constant access to water, nutrient and - most importantly in DWC - oxygen. Remember that DWC is a ‘bare rooted' technique and the roots are constantly submerged. Turning off the pump, even for a short period, can damage them.
|DWC cloners propagate clones rapidly|
|Flo Gro systems make the ideal hybrid growing system|
3. Make sure that your starting EC is low; it's easy to overfeed in DWC. Remember that the nutrient solution is the growing medium; there is no ‘buffer' between the roots and the food. Any mistakes in dosage can potentially damage the plant and there is no medium to flush through. If you overdose on nutrients, you'll need to change all the solution in the reservoir.
4. Only use mineral nutrients and additives. Organic feeds and supplements aren't suitable for DWC; the liquids will spoil in the reservoir after a few days and can, potentially, damage the roots.
5. Keep your grow room temperatures in check. Any temperature fluctuations in the grow room will directly affect the roots of a plant grown in DWC. Use a heater in the winter to raise the night time temperatures and increase the size of your extraction fan in the warmer months to reduce the temperature in the grow room. The optimum root temperature to maintain is 18°c - 22°c.
6. Transfer at the right time. Growers that use an aeroponic (or DWC) cloner can transplant as soon as the roots are three or four inches long. Take the cutting out of the cloner and place it into the net pot of the DWC system, using clay pebbles to hold the young plant in place. Take extra care when handling the roots as any broken or damaged roots are susceptible to attack from pathogens. By using a cloner, and not having to wait for a cutting to root out into a propagation block, you can cut the veg period by a good few days. If plants have been started in a propagation medium like rock wool cubes, then they are ready to transfer into the system as soon as the outside of the medium is covered in white roots. If you transfer before white roots are visible, then the roots in the cube can become saturated and starved of oxygen.
|DWC bubbler bucket|
7. Only use an inert growing media, like rock wool and clay pebbles. If you transplant from soil or coco, the media will break down and could block the pump. You also run the risk of introducing soil borne pathogens into a ‘bare rooted' environment.
8. Space plants out taking into consideration the faster growth expected. The water within the reservoir will act as a support for the roots - although the plant won't be as stable as it would in soil or coco - there is no immediate need for plant supports - like there is in NFT or aeroponics. But, considering the big yields experienced in DWC; pea netting, roller hooks or yoyos may well be needed to support those monster buds!