Deep Water Culture (DWC): What Is It And How To Get Started

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If you’re new to growing plants hydroponically, words like “Deep Water Culture” can sound like they’re straight out of a science-fiction movie.  Compared to soil gardening, hydroponics looks more complex – but it’s really not.

There are many types of hydroponic systems, many of which have confusing sounding names (nutrient film technique, deep water culture, ebb and flow). But that’s what this article is here for!

Let’s take a look at one of the simplest and most popular methods of hydroponic gardening today – Deep Water Culture, or DWC.​

If you’re more of a visual learner (like me) you can check out this video I put together on my YouTube channel below. It gives you an overview of what’s going on in the system, and what you need to get started.

What Is Deep Water Culture (DWC)?

Before we get into the nitty gritty details, let’s get a high-level overview of this type of system.  In a DWC system, a plant’s roots are suspended in a well-oxygenated solution composed of water and nutrients.

There are three critical parts of this solution:

  • Oxygen: Because the roots are submerged in water and not soil (which has gaps and holes where air resides), the water needs to be well oxygenated so the plant doesn’t drown. This is accomplished with an air pump and air stone.
  • Water: Think of this system as if you’re growing in soil and permanently watering your plants – this is one of the reasons growing hydroponically is so beneficial – you never need to ‘water’ again.
  • Nutrients: A good quality soil contains all of the micro and macro nutrients that a plant needs to survive and thrive.  Because we have no soil, we need to supplement the oxygen-rich water with nutrients so our plants can grow.

This method is called Deep Water Culture for two reasons.  One, you typically grow with a reservoir that can hold a decent amount of water.  More water means more stability in your nutrient solution, which means less monitoring and maintenance for you!

The second reason is because of how much of the root mass you submerge in the water.  Other methods expose your plant’s root zone to air and drench them in water just a few times a day (ebb and flow systems are a good example of this).  In deep water culture, most of your plant’s root system is submerged 24/7 – hence the name!

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Benefits of Deep Water Culture

DWC systems are popular for many different reasons, the primary one being that they’re one of the simplest types of systems to start with. The only system that is simpler is a wicking system.

Here are a few other benefits to growing in a DWC system:

  • Very low maintenance once you set it up
  • Extremely fast growing time compared to soil (I’ve grown lettuce to harvest in 30 days instead of 60 in soil)
  • Very little moving parts and assembly

Downsides of Deep Water Culture

However, it’s not all sunshine and roses. There are some issues with this type of system that can cause you problems. These are mostly avoidable if you’re maintaining your garden, though:

  • In small systems, pH, water level, and nutrient concentration may fluctuate wildly
  • In small systems, opportunity to over or undercalibrate is VERY easy due to small scale
  • If you have an electricity outage or a pump failure, your roots may “drown” in low-oxygen nutrient solution
  • It can be difficult to maintain a consistent water temperature

Deep Water Culture Variations

The Traditional Method

How a Deep Water Culture (DWC) system works.
How a Deep Water Culture (DWC) system works.

Building a Deep Water Culture System

Traditional DWCs are the easiest to build. Here’s a list of the parts you’ll need to set up your first system:

Part

Where to Buy

Link

5 Gallon Bucket

Amazon or Home Depot

See Prices

Air Pump

Amazon or Pet Store

See Prices

Air Stone

Amazon or Pet Store

See Prices
Airline Tubing Amazon or Pet Store See Prices

Net Pots

Amazon or Hydro Store

See Prices

Growing Media

Amazon or Hydro Store

See Prices

Hydroponic Nutrients

Amazon or Hydro Store

See Prices

pH Control Kit

Amazon or Hydro Store

See Prices

PPM Meter

Amazon or Hydro Store

See Prices

Click here if you are interested in building a more robust deep water culture system that includes a grow tent and lights.

The method is simple: connect the pump to the tubing, the tubing to the airstone, and place the airstone in the bucket.  Fill up the bucket with water, properly pH and add your nutrients, and start your seeds.

​Once your plants start to germinate and the roots start to hit the water, you’ll see an explosion of growth.  Instead of spending energy growing the roots to search for pockets of water in soil, your plants can simply suck up as much water and nutrients as they need right away.

If the water is properly oxygenated, there’s no reason why your plant’s roots can’t remain submerged deep in the water (hence the name) for the entire life cycle of the plant!.

Why It Works

Because of the highly oxygenated and nutrient-rich solution, plants grown in a traditional DWC system can be harvested up to twice as fast as normal soil-grown plants!  I’ve personally harvested a head of lettuce in 30 days from germination

The fastest I’ve ever grown lettuce in soil is 60 days.

Recirculating DWC

The traditional method is amazing for beginners, but what if you want to scale your system to the next level?  Most people move to a RDWC, or Recirculating Deep Water Culture system when they want to upgrade their garden.

If you’re looking to grow at scale, the last thing you want to do is have 10 individual buckets, all requiring their own calibration and adjustment.  If you’re growing the same plant across 10 different buckets, doesn’t it make a lot of sense to have one main reservoir and feed that nutrient solution across all 10 buckets?

If you said yes…you just invented the RDWC system!

Here’s an example:

You’d have to have a love of torturing yourself to want to individually pH and calibrate each of these buckets!

You might be wondering how the oxygenation of the water occurs if you have multiple buckets chained together.  Just as it would be inefficient to have separate nutrient solutions for each bucket, it’s also inefficient to run an airstone system for each bucket.

This is where the recirculating part of the name comes into play.  As water moves from bucket to bucket, it’s shuttled around via spray nozzles that oxygenate the water.

The beauty of this modification to the classic DWC system is that you only have to calibrate, oxygenate, and add more water from one central location and it gets fed out to all buckets immediately.  The best analogy here is the power grid: we don’t run our own generators in our homes.  Power is generated from centralized locations and then ‘sent out’ through the power grid to our houses.​

Bubbleponics

Although many people don’t consider Bubbleponics to be all that different that the traditional DWC, I personally think that it has a few advantages and is important enough to talk about.  Despite its silly name, the adaptation that Bubbleponics makes is simple.

Instead of waiting for your plants to germinate and the roots to hit the top of the water in your reservoir, Bubbleponics aims to speed up that process by top-feeding the nutrient solution to your plants for the first few weeks.

​All that’s going on here is the addition of a water pump to the system, with drip lines running up out of the tank to the net pots that your plants are sitting in.  Simple, but very effective in speeding up the germination and seedling phase of a plant’s life cycle.

Common Deep Water Culture Questions (and Answers)

What type of nutrients should I use in my deep water culture system?

Companies offer a variety of hydroponic nutrients, so it can be hard to figure out which is best for you. In my opinion, it’s best to start out with something dead simple like the General Hydroponics Flora Series. It’s a three-part hydroponic nutrient that you mix in varying quantities based on your plant’s stage of growth.

Should I use a singular or modular system?

If you’re just starting out, go with a single reservoir setup. You can build them yourself or buy one of the many on the market. A modular DWC system is better for growers who know exactly what they want to grow and how much they want to grow. Start small and scale up as you get more experience.

Should my reservoir be sterile?

This is not a yes or no question. Some hydroponic gardeners want to keep their reservoir sterile. This means they won’t have any of the biological contaminants that might plague a hydroponic garden, like algae. But at the same time, they won’t be able to take advantage of beneficial bacteria. If you do decide to add beneficial biology to your reservoir, just be aware that it comes with the risk of having not-so-beneficial biological organisms tag along for the ride.

What should my pH and PPM / EC be for DWC?

Just because you’re growing in a deep water culture system doesn’t mean you need to adapt your pH and PPM / EC. The standard range that most plants prefer (pH 5.5-6.5) is fine, however you will want to customize and monitor this based on what stage of growth your plants are in. When they’re putting on vegetation, you want to keep your pH in the higher end of that range, and when they’re flowering, the lower end.

As far as your PPM / EC, don’t blindly follow the feeding schedule on the back of your hydroponic nutrients. They are typically higher than necessary. Try cutting that amount in half and seeing how your plants respond. You can always adjust upwards quickly, while adjusting downwards is more challenging as your plants may have already suffered from nutrient burn.

What should the temperature of my reservoir be?

This is one of the downsides of deep water culture: it can be hard to control the temperature of your reservoir. Aim for no higher than 68°F (20°C). If you get much higher, the oxygen level in your water starts to drop (even if you’re oxygenating with an air pump and air stone).

Also try to keep it above 60°F (16°C). If it goes any lower, your plants think that they’re moving into a new season, typically fall or winter. This means they’ll start to divert more energy towards flowering, which you may not want.

When should I change my nutrient solution?

The longest you should wait before changing out your solution is three weeks, but this is just a general case. It depends on:

  • ​The type of plants you’re growing
  • The stage of growth they’re in
  • The size of your reservoir

If you want to avoid a complete change, you can try to add water with some nutrient solution mixed in to get the right balance again, but this is difficult to do. A complete change may be the better route.

How do I know how much oxygen is in my nutrient solution?

Dissolved oxygen meters are available for sale, but they’re pricy and might be overkill unless you want extreme precision. I wouldn’t recommend purchasing a lower-end one though — they’re not very reliable. The best way to “monitor” your dissolved oxygen levels is simply to do the things that ensure that levels are good, namely keeping the solution at the right temperature and running your air pump.

How much of the roots should be submerged in my DWC reservoir and nutrient solution?

First of all, make sure that only the root matter is submerged in your nutrient solution — no stem, and certainly no vegetation. You don’t want to completely submerge the roots, either. I personally keep about 1-1.5″ of root above the water line. The bubbles from the air stone will typically pop and water will still land on the roots that aren’t submerged, so you don’t have to worry about them drying out.

How would I propagate plants if I don’t want to use a growing media in my DWC system?

That’s easy — use an aeroponic cloner. You’ll save money on growing media and the plants that you propagate will have nothing but bare root when you transplant them into your DWC

Are there any deep water culture specific issues to watch out for?

Monitor your garden for the following issues, all of which are common in DWC systems:

  • Root-related plant diseases like Pythium
  • Rapid fluctuations in pH or PPM / EC / TDS
  • Nutrient solution that is too warm

How much faster do plants grow in a DWC system?

Provided you’re doing everything right, plants grown in a DWC system (or most hydroponic systems) will grow at least 15% faster. I have seen my lettuce grow almost twice as fast in my deep water culture setup vs. my outdoor garden.

What plants grow best in a deep water culture system?

The obvious answer is anything that doesn’t have to flower. Many varieties of lettuce and lots of different herbs will work very well in DWC. They grow super-fast and healthy, making them a fantastic option. However, you can also grow tomatoes, peppers, and even larger fruits like squash…they just take a bit more effort.

Are there any other tricks available to the DWC grower?

A: Yes! DWC growers can easily manipulate the amount of moisture in the root zone. This, in turn, can trigger plant responses such as essential oil production, fruiting and flowering. A dryer root zone can increase essential oil production in aromatic crops such as basil and mint. (They do this as a means to conserve water.) A wetter root zone can cause plants to focus on vegetative production, particularly large fan leaves, which in turn speeds transpiration and photosynthetic potential.​

Header photo courtesy of David Offutt over at Gastronomic Gardener.


The Green Thumbs Behind This Article:


Kevin Espiritu
Founder

Deep water culture is one of the simplest ways to get into growing plants hydroponically, but it sounds very confusing and complex. Let's break it down!
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25 thoughts on “Deep Water Culture (DWC): What Is It And How To Get Started”

  1. Looking at yr video you do t start with tiny seedlings but with plants that have a serious rootsystem already. But…… If you just want to start from seed…… You can hardly throw a seed in growmedium that is above the water level and expect it to survive

  2. Guys, I really enjoyed that video presentation on DWC. It was very clear and very informative. Well done and thanks heaps.

  3. Hi, I started some veg seeds in my DWC system. Will they successfully germinate using this method? Or should I start them in a tray with some nutrient fluids instead?

  4. I live in a tropical country, where in summer temperature rises around 35 degree Celsius. I am growing like lettuce, bok choy, hybrid cabbage, celery etc wonderfully well as it’s winter. But I am worried what will happen in summer. Can you suggest me any vegetables apart from Cucumber to grow in summer in my NFT systems? Thanks in advance.

  5. Hey,
    so im having problems with my dwc, been at it a week now. Struggling with pH fluctuations (btw 5.5-7.8 in under 24 hrs).

    Topped my bucket up with 10ltrs of bottled water (RO)- pH was 7.1, ec-0.1 and ppm 0.05. I then mixed my nutes (GH) in, targeting an EC of 0.6, ppm 0.3. I let it sit for half n hour , measured my pH – 6.5.
    I then left a full glass of the the same nutrient water aside (pH – 6.5). All set I turned on the air pump for the DWC bucket.
    Half n hour later, the bucket pH read 7.0, and the glass still remained at 6.5.
    The only change here is the air, can it be altering my pH, and If it is , how do I deal with this , any information would be helpful ! Thanks!

    • pH fluctuates more the smaller the reservoir, so step 1 is to increase reservoir size. Step 2 is to recalibrate with new solution, to figure out EXACTLY how much pH buffer you need to get into normal ranges. Air does slightly alter pH, but not THAT much.

  6. I just bought everything I need to set this up, minus a reservoir (no Prime same-day ๐Ÿ™ ).

    I have the three big fox farm nutes, Grow Big, Tiger Bloom, and Big Bloom, and there is a weekly feeding schedule online. Does this mean I drain the entire reservoir and refill it every week with the new nutrient solution?

    Also, FoxFarm sells Grow Big (Hydro) and the only difference is that it is 3-2-6 instead of 6-4-4, I’m not sure if that difference really matters? or if I can just use the regular Grow Big.

    Thanks in advance ๐Ÿ˜€

    (Also if you have any info on how to mix nutrients I listed for kratky method, I would love to know, I’ll browse your site to see if I can find anything first, though)

    • Awesome Bryce! I’d drain and refill once a week if you want optimal growth, yes. The difference between the two is that the hydro one is higher in potassium and de-emphasizes nitrogen, which would boost flowering / fruiting growth phase considerably. Check out my YouTube channel for a video on preparing nutrients: https://www.youtube.com/c/epicgardening

  7. Thank you Kevin for your useful info on hydroponics in general and DWC in particular. I am new to this and am going to start my DWC with kale and lettuce in my bedroom balcony. As per your suggestion, I will use an air pump to oxygenate the water.

    I have two questions:
    1. Is it necessary to run the air pump 24/7?
    If it is okay to run it for ten minutes every one hour, I can use a microcontroller and make a circuit to do just that.

    2. Will the plants need direct sunlight for a few hours everyday or will they grow well even with only diffused sunlight?
    Depending on the answer, I can keep the plants at the most suitable location.
    Thanks.

    • 1. I would run it 24/7
      2. Yes, kale and lettuce will want as much sun as you can give them, though they will still grow in indirect light! You may want to consider an indoor grow light ๐Ÿ™‚

  8. I realize that this is from 3 years ago but I just found it. Fantastic information and just what I needed to get myself motivated to grow indoors this winter. I do have a question. Would you be for or against the addition of aquarium fish to the mix?

    Thank you for the article and your time.

    • What you’re talking about there Dan is called Aquaponics, using fish + water to grow plants. In a system like this you would feed the fish, the waste would be processed by various bacteria, and would be transformed into nitrates, which plants will use for food. I have an entire section of my site dedicated to aquaponics as well.

  9. I just want to say thanks i have bought 2 bubble buckets. I had trouble switching from soil to hydro. So basically you start water off with a low ppm. The thing i dont get is does it ever need drying out like with soil. Also would flushing it just be adding water to lower the ppm. Also do i need to take measurements like with a line or marker of the level. I would think if you put a few liters in at the begining you could write the levels down, but then i thought well then i would have to add the root mass and no way to tell that exactly. So i plant use hydroton. Use one of those squares to germ and stick inside the hydroton and i hear the bubbles bounce from the top a little to make it grow down into the water. Also the difference in this is really you don’t water them because they are constentaintly in water and oxygen just be sure to change often no old water. So to me watering would be flushing. Now waiting on amazon and see how i do.Also i bought 2 5 gals but i was wondering i am going to use same plants should i make my own resivour over 2 buckets, will they eat so much that i would need one??? i only ordered 2 buckets i get the concept. It just seems setting in nuts the whole grow isnt going to give me the whitest roots is that true. I never see just white roots there always yellow or brown. In soil with a lot of perlite my roots are white. Trial and error. I just thought you fed them then watered. Then i relized watering it is just flushing it so maybe that help the roots stay white. I watch greenhouse on there plant grows and they flush like ever week from week 4 to 8 on most strains. I assume there right about that. Thanks this put it together for me and also i am just lazy i could have made one for 22 bucks but I just pay 35 im to lazy but really i just have to go to home depot get some buckets then hit up the aquarium and get right size hoses. Thanks guys really i would have just watered the shit out of the plants and not have understood the method now i got my ppm meter my ph meter and some humboldt, some new expensive nute that you can use all way through. Yea sounded bs to me but im give it a try. If it doesn’t work i have all fox farms nutes they carry.

    • @disqus_jwGoAogynt:disqus Hey dude, it doesn’t need any drying out as long as it’s properly oxygenated and has the right amount of nutrition. You have a ton of questions here in a big block of text so it’s hard for me to go through them all, but feel free to email me at kevin@epicgardening.com with a couple of your questions! (And use paragraphs, dude)!

  10. I found this very informative. I would like to find out how suitable the Deep Water Culture is for growing tomatoes. Most sources online say it is not the best method for growing tomatoes. Due to the unavailability of growing media like coco coir for the most preferred system (Drip method), DWC remains the most accessible method for me. What are your thoughts on the use of DWC for growing tomatoes?

    • It totally works. Most people use different setups for tomatoes, but you can use DWC and have absolutely amazing tomatoes – not sure what the other sources mean by it’s not the best method. It might not be 100% optimal, but it will work really well!

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