Wick System Hydroponics: A Complete Guide for Beginners

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Brock Ingham
Brock Ingham

You don’t need the outlay of a Nutrient Film Technique setup if you’re keen on trying hydroponic growing. Low effort systems like wick hydroponics are an easy starting point that are easily as productive. They’re environmentally friendly with great water saving properties and are cheap to built to boot. Who can say better than that?

Wick System Hydroponics
Wick System Hydroponics

What Is Wick System Hydroponics?

A wick system uses a shallow bed of growing medium watered and nourished using a number of wicks instead of a pump or filter system. You do need an air stone is going to help oxygenate the water and keep the roots of the plants aerated. But there really aren’t a lot of moving parts for a beginner to worry about.

“A hydroponic wick system is the simplest of all, as nutrients are passively given to the plant from a wick or piece of string running up to the plant from the water reservoir. In this system, plants are grown in an inert growing medium such as sand, rock, wool or clay balls that help anchor the plant roots.”

Valentina Lagomarsino, Harvard University Graduate School of Arts and Sciences

How Does Wick System Hydroponics Work?

Wick system hydroponics
Wick system hydroponics

All hydroponic systems need a way to get the nutrient solution from the reservoir to the root system of the plants no matter what you’re growing. In active systems a pump supplies the roots. Wick hydroponics use a wick and the power of capillary action to get the job done.

In basic terms it all comes down to how water is attracted to itself. You can see this when you wet a glass surface and it forms beads. It’s the water molecules clumping together.

Once you add a wick to a vessel of water some of it is attracted to the fiber. The molecules cling to its surface as well as the other water molecules. They drag each other along into the fiber. Some water molecules will settle above the first. They also will grab onto the fiber and pull a few little buddies along too. Some of the new guys will land higher and in time this repeating chain of attraction draws water all the way up the length of the fiber.

This friendly interaction between water and fiber is how a wick system works. The wicks are placed into the growing medium at one end and down into the nutrient reservoir at the other. Water is drawn up the fiber through the medium taking its load of fertilizer with it. It’ll then spread providing water and nutrients to the growing plants.

What Are The Advantages Of Wick System Hydroponics?

Slow and Steady

A wick system is ideal for crops that grow slowly and consistently like herbs and lettuce. They’re also good for larger plants that don’t need to be harvested entirely at the end of the season. Other passive setups have a use-by date, but with care you can grow indefinitely with a wicking hydroponic system.

Cheap

It’s possible to build build a wicking hydroponic setup quite cheaply from recycled bits and pieces. Any container with enough room for the roots to spread will do. Plastic tubs and totes are fantastic but large food containers or old buckets work too. Your reservoir doesn’t need to be fancy either. If you can get wicks and an air pump in it its origin doesn’t matter. So long as the plants get what they need they’ll be happy all the same.

Simple

This system is a good starter choice because it’s so simple. If you can drop a rope in a bucket you can set up a wick system. It’s really that simple. They don’t take a lot of technical know-how to knock together not tricky to maintain either. Keep the water topped up and the aeration system bubbling along and it’ll mostly take care of itself.

Saves Water

A wick hydroponic system is a very water-wise way to grow. They use very little fresh water even when compared to other hydroponics systems. Because the reservoir in a wick system is sealed there’s little water lost to evaporation. Furthermore, since that water travels up the wick deep into a plant’s roots it gets straight to where it’s needed without any waste.

How To Build A Hydroponic Wick System

Red and green leaf indoor lettuce
Red and green leaf indoor lettuce

To build a wick system, you will need:

  • A growing tray
  • Growing medium
  • Reservoir tank
  • Seedlings or rooted cuttings
  • Wicks – natural materials like cotton or hemp are best, but nylon rope will do for a wick material in a pinch.
  • Nutrient concentrate
  • Clean water
  • An EC/pH monitor
  • Aquarium air stone
  • Grow light (optional)

Step 1

First prepare your materials. Select your growing tray and reservoir. Stacking containers are a great start, especially ones that stack without lids – it’ll make it easier to place your wick later.

Wash both and allow to dry. Soak your medium overnight in clean water.

Step 2

Cut or drill a hole in the bottom of your tray to accommodate the wicks. Distribute evenly at around two wicks per plant.

Step 3

Measure and cut your wicks. The length of the wick should run from inside your tray right down inside the reservoir. Thread them through the holes cut in the previous step, and fill your tray with moist medium.

Step 4

Mix your nutrient solution and add it to the reservoir. I recommend beginners start with commercial blends designed for leafy greens. Follow manufacturer’s instructions as this will give the best concentration of nutrients and the right pH. Once it’s all dissolved check the pH and EC and adjust if needed.

Step 5

Plant your seedlings and place the tray over the reservoir so the wicks are submerged. Add the air stone and switch it on along with any grow lights.

Which plants do well in wick system hydroponics

Hydroponic lettuce 2
Hydroponic lettuce

Lettuces

Lettuces are a fantastic choice for wick systems. They love consistent moisture and don’t need a rich nutrient solution. They will just plod along in even the most basic wick setup without needing too much attention at all.

Herbs

A small wick system is great for herbs like thyme, parsley and coriander. They love the gentle support provided by consistently moist soils. Consider two wicks for each large plant for best results.

Pak Choi

Pak choi requires the right sort of gentle nutrients and even moisture that a wick system supplies. They’re also best eaten as fresh as possible. Growing with hydro will put this crisp crop on the table while it’s at its peak.

Fussy Indoor Plants

While we tend to think of hydroponic gardening as a farming technique it’s just as good at helping maintain house plants too. Fussy ornamentals like calatheas, alocasias and begonias do wonderfully in passive systems due to the even moisture. Indoor plants aren’t generally heavy feeders compared to food crops too so a wick method won’t leave them malnourished. I’ve had a lot of success growing smaller plants in wicking pots made from a large soda bottle and one wick. These small scale rigs don’t even need an air stone – they’re the ultimate passive system!

Which plants will not do well in wick system hydroponics

Root vegetables

Root veggies like carrots or onions need deep, healthy substrates to grow well. Not only do they need a deep container to hold their ever-expanding roots, but they are very vulnerable to root rot. The steady moisture of a wick system is liable to produce disease, not crops.

Fast Growers

A slow and steady wick system is relatively frustrating for fast growing plants. These plants require more nutrients and more often than a wick rig can provide. You’ll have far better results growing them in another form of hydroponics like ebb and flow or a Deep Water Culture technique like a Kratky rig.

Heavy Feeders

Similarly heavy feeders will struggle in a wick bed. Plants like tomatoes, peppers and other fusspots need specific fertilization at specific points in their lives. They also need richer beds that a wick system can provide. Tomatoes especially do far better in more active types of hydroponic systems.

What is the best growing medium for Wick System hydroponics?

Coconut Coir
Coconut Coir

To get your best from a wick system you’ll need a growing medium that has good capillary action. While your air stone will get most of the work done an airy medium will provide solid insurance against root problems.

Organic materials like coco coir, peat, and the like are an ideal starting point. They’ll draw up and distribute moisture through the blend very effectively indeed. Blend in 1/3 coco coir or peat with 1/3 perlite and 1/3 vermiculite and you’ll have a blend that holds water and nutrients well while still keeping lots of air around the roots.

What Are The Disadvantages Of Wick System Hydroponics?

Over-watering

Plant roots in this system are constantly moist. Get your medium or plant choice wrong and you’re likely to over-water. While air stones and other techniques can help, patches of cool weather or poor light can reduce the water needs of the plants you are growing. Plants absorb only the water the need and leave the rest behind but the wick doesn’t know that. If the conditions are out those plants are going to have wet feet pretty quickly.

Root Problems

With soggy roots come root disease. Pythium and phytophthora are common problems for hydroponic farming at all scales, reducing plant growth and destroying crops with ruthless precision. Both diseases cause a general loss of plant growth before killing everything off entirely.

Hazardous nutrient buildup is another problem in a wick hydroponic setup. There’s no flow through of fresh water to remove excess fertilizer from the growing medium. Over time leftover mineral salts will start to damage the roots of the plants and result in chemical burn like scalds on leaves and other tissue. Commercial systems use self-correcting reservoirs, so for us at home, we need to flush the medium regularly and watch the EC of what comes out.

Can you over-water your grow tray with wicking systems?

Hydroponic romaine lettuce
Hydroponic romaine lettuce

It’s absolutely possible to over-water plants in a wicking system.

Simply having the wrong plants in the wrong medium is a surefire way to cause problems. Pure coco coir holds a lot of water and it’s best mixed with other components. If you have too many or the wrong type of wick the medium will draw too much moisture from the reservoir to the plants. Two per plant is enough for most species and most growing situations. The wick length is important too. Up to the roots is enough. Running it in laps around the tray is a bit of overkill.

Final Thoughts

I constantly marvel at just how versatile hydroponics can be. The tray and reservoir can be made of many materials and don’t require a lot of outlay or complex maintenance. Wick hydroponics work beautifully to get folks sprouting plants anywhere there’s a bit of light and room for a couple of tubs. It really does help make hydro easy for just about anyone to try.

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