First Timer Hydroponics: the Raft System

For those who don't know First timer Hydroponics serie, please refer to the first I'ble I have written or to the early start of this collection of I'ble about my Urban Garden.

I am a first timer. What is below is the fruit of active readings of books, internet websites and conversations with some very passionate shopkeepers... So please, let me know if I did (or do) something wrong or if you have lessons learned to share ;-)

In this third I'ble about hydroponics I have build another DWC system. DWC stands for Deep Water Culture. This is a fairly old technique and widely used, from lettuces to flowers. Here is my project about building a Raft System. A raft system is a very simple hydroponic system which presents a floating net cup with growing medium and plant. The plant is immersed all time, roots hanging in the nutrient solution.

In this I'ble I will build one raft system and grow mint using worm tea as nutrient solution.

What you will need:

• a net cup
• a floater (I use a simple piece of polystyrene)
• a reservoir(I used a TROFAST from IKEA with lid)
• a nutrient solution
• a plant of course ;-)
• air pump with tube and air stone

If it happens that you like this I'ble, please share it, favourite and vote!

Please check also my whole collection about my organic urban garden.

As a good drawing is better than long writing, I come back to the presentation of DWC technics I have made in the previous I'ble about DWC Hydroponics.

Deep Water Culture is a method to grow plants in hydroponics.
Plants are immersed or just in contact of a nutrient solution put in a reservoir. The plants are in a soil-less net cup, either floating on the surface or in a container.

On the above scheme, the system (a) doesn't require absolutely air stone and oxygenation of the nutrient solution as the plants have what I call areo-roots which can provide oxygen for the whole plant.

The system (b) is our I'ble Raft system. It absolutely requires air pump and air stone as their is no other way for the roots to be oxygenated.This is the only difference with the first DWC project I did. However I realized very fast than whatever the theory is, you need an air pump.

DWC is a low cost and efficient hydroponic system.

I have used a Styrofoam piece I had to shape my floater.

As I have little room on my balcony and had extra IKEA Trofast box, I decided to use it as reservoir. I first cut the approximate shape of the box on the Styrofoam and then made the (more or less) exact shape by using a utility knife, full blade. You don't damage your box doing so and you have the more precise shape. I realized later that there is tops for the Trofast lines that could be used more conveniently. But I do believe that the Styrofoam will be of interest during the hot summer by insulating as much as possible the nutrient solution. As I don't want to have some kind of pollution inside my reservoir (such as pollen, leaves, insects...) I let the Styrofoam very tight inside my reservoir.

As net pots I use some plastic pot I have received with my new plants (chamomilla, lavander...). Watched, drilled to allow more water to reach the roots, it makes the perfect low-cost net pot. I have cut just a little bit smaller than their diameters on the Styrofoam to house them tightly.

If you have read my other I'bles about First timer Hydroponics with vermiponics, this section is a reminder, you can jump to the next step.

As I told you in n°1, I don't like the chemical aspects of hydroponic. I am not saying that I will never try but I feel more confident in using organic and sustainable resources of nutrients. That's why I use worm tea. I usually filter the tea and then just water my hydroponic systems from above, allowing any extra tea to go to the reservoir.

Let's speak a bit more about worm tea and why it is a good way to feed plants in hydroponic. I will write a full I'ble about how to get true compost tea. The point here is to discuss what benefits you can expect from your compost tea.

The tea is obtained by brewing worm compost in water. The tea is then filtered off to make the fertilizer. It contains many minerals and nutrients and may be more importantly many helpful bacteria and microbes. this nutrient solution is alive and will enhance your soil and leaves if you use it as a spray. Worm tea seems to be an insect repellent but I have never tested this.

The compost tea is full of nitrogen fixing bacteria and others microorganisms who loves oxygen. So there is a benefit in oxygenating your tea to enhance its natural properties. The organisms living in the tea also produce all kind of things incl. hormones, vitamins, nutrients, enzymes, amino acids and minerals. Those things are highly recommended for young plants.

The symbiotic relationship between the plant and the microbes in the root zone make the whole system a wonder: when plants are feeding the microorganisms, they produce in return nutrients and micronutrients. In addition, they occupy the space leaving little room to unfriendly bacteria.

If worm tea is a wonderful nutrient solution, you don't have a lot of risks of burning roots and plants if overused. That's the beauty of the tea.

There is a very interesting Wikipedia article about Vermicomposting (not only about tea... not really about tea... not at all about tea...)

I have experienced bad situations with my setting regarding my previous hydroponic system. So setting an hydroponic system should be done with an extreme care.

For my raft system I have decided to order a plant of mint which is already quite strong. Some of my first lettuces went bad because they were too small and weak (that's my diagnosis at least). In the mean time I have read a lot of books about soil-less culture. Thus I have adapted my technique in order to try to achieve much better results.

I have this time placed the plant inside the empty pot and then pour the granulates. Carefully taking care of the roots it allows to fill the cup with granulates while ensuring a good stand for the plant to grow.

My mint was bad when I decided to set up my system. It went back quickly on good tracks.

As I have a second pot, I decided to use the same technique with a lamb's lettuce to compare with my other projects.

Once done, I have set up the water level just a bit higher than the bottom of the pots. Is that good? I hope. If you have feedback to give about it, let me know.

I have made a nutrient solution using my leachate. However I realize that my compost will not provide enough tea for all my system. I might be obliged at some point to feed my plants with hydroponic fertilizers... Let's see that later.

I think I have made several first-timer errors, despite all my readings and thinkings.

First of all, I have wait too long before transplanting my plants into their gowing beds. Mint wasn't fresh at all and still have issues to cure. Lettuce was good but I think that I was again not careful enough not damaging the roots when transplanting.

That's one of the main lesson learned of those projects about hydroponics: Take an extreme care to your roots!!

Like the 2 other projects I ran in parallel, I wanted to use worm tea to feed my plants. I stop that early because I realized I wasn't producing enough of worm tea as well as vermiponics (worm tea + hydroponics) seems to be much harder to master. I already have difficulties with "normal" hydroponics... So I am now using standard hydroponic fertilizer.

Talking with some people at my local grow shop, I realize that having a air pump was really important for this kind of system as their is not other way for the roots to catch oxygen. I bough a very standard one...

Today my plants are still fighting to get healthier but going the good way.

I will post soon here some updates about this project.

I started this project 4 weeks ago and now things are running half better.

The mint recovered completely and is now booming. Good quality, fresh and white roots are showing up.

The lettuce is still weak but shows good signs. I hope it will start to grow soon.

Just take a look at the picture.

You will see a beautiful lettuce which we will harvest soon and a even more beautiful mint we already started to harvest from time to time.

The Raft system works perfectly. However I think that the DWC system we made is more efficient. So we will recycle our raft system in the near future

First timer hydroponic is a serie of three projects I have made regarding hydroponic. You will soon see them on I'bles.

I have had 3 systems running in parallel but I kept only two of them.

In the summer I plan to grow other vegetables on my existing systems such as paprika.

This is a great endeavour for me and my sons. They love taking care of our balcony garden and I hope it will worth all that love.

You can find the 2 other projects here:

1. the wick system
2. the DWC system