Hey everybody, I finally finished my first window farm (WF). It consists of an air lift and 2 rows of plant containers, with 5 containers in each row.
I put together a DIY guide, see it here (pdf).
I also made a Danish version of the guide (pdf), which includes prices and where to get the parts in Denmark.
I started figuring out how to build a WF, from scratch, about 3 months ago. I live in Denmark so buying a kit was out of the question. It took me a while to understand how the system was supposed to work, and then another while to figure out how I was going to build one myself. I had no experience working with the stuff needed to do this. Stuff like air pumps, tubes, and valves so it was all very confusing to begin with. I didn’t know anything about growing hydroponically either but ever since I saw the TED talk with Britta Riley, about a year ago, I have been interested in the project.
Now my WF is finally up and running and the plants grow bigger every day. So I want to thank this lovely community and the people behind the WF project for teaching me. It has been a lot of fun, and a little infuriating from time to time, when something just wouldn’t work the way I wanted it to.
I went through a couple of test systems, all of the air lift type, before landing on the one I am using now. At first I tried anchoring a tube on the bottom of a big water reservoir, but even though I knew this worked for others, I never managed to make it stable. The air from the pump kept flowing back into the reservoir, instead of lifting the water upwards. I then tried putting a small reservoir at the end of the row of plant containers. This worked very well; the reservoir had a tube in the bottom that went into a U-bend, which prevented air back flow to the reservoir. Unfortunately this setup forced me to reduce the number of plant containers I could have in a row, and I had to add water to the reservoir often, which was annoying. My current setup looks like this:
I put the reservoir, the air pump, and the U-bend below a shelf at my windowsill. There is a small gap between the shelf and the windowsill, where the tubes can get from below to above the shelf.
For reservoir I am using a 10 l (2.6 gallons) water container with a tap that is big enough for 2 tubes to fit into it. I made a plug of silicone sealant around the ends of the 2 tubes, to make a water tight fit (see info. box 1 on the sketch). To make sure the plug stays in place I wrapped some duct tape around the joint.
After leaving the tap of the water container each of the 2 tubes goes into a U-bend. *The U-bend needs to be at least 30 cm (12 inches) from top to bottom to prevent air back flow. (Thank you, Brian White, for sharing this information, the diagram you made really helped me a lot: http://our.windowfarms.org/files/2012/04/contest-with-u-April-7th.jpg)
After the U-bend there is a t-joint, where the water meets the air from the pump. I put a check valve on each of the 2 tubes leading the air to the t-joint, to prevent water reaching the pump (see info. Box 2 on the sketch).
In an effort to decrease the amount of plastic in my WF, and because I thought it would look good, I tried using coconut shells as plant containers. I hollowed out 10 coconut shells, cleaned them, and coated them on the inside with mineral oil to prevent them from absorbing water. I made a braided rope and nets for them to hang in. It looked really good but unfortunately the shells cracked. I think it happened because the shells I got were very old and dried out. I bought them all the same place but later on I tried with a shell bought at another place and it did not react the same way as the others. So I still think it could work with coconut shells, but I grew too impatient and my seedlings grew too big for me to do it all again with other coconuts. I turned to the well known plastic bottle instead, and I am very satisfied with the result.
I reused the rope I used to hang the coconut shells from but had to find another way to attach the new plant containers to the rope. I ended up with a kind of button on system which allows each plant container to be removed without dismantling the entire row. This highly modular system has the advantage that I don’t need net pots in the containers. I couldn’t find any net pots that would fit so I had to do without. If I do get my hands on some good net pots I will use them, though.
So I wanted to use coconut shells as plant containers, partly, because I wanted to reduce materials that could leak toxins into the water and plants. About this I have now come to think that the plant containers are actually the least important part. Most of the time, the water is in the reservoir or the tubes, so it’s more important that these parts don’t contain anything that will leak into the water. As the water drips into a plant container it goes straight through the clay pebbles and into another tube. Most of the clay pebbles that come into contact with the container are dry, as the water runs through the center part. I therefore don’t think the plastic bottles will be able to leak anything into the water, and if it does it will be minimal, compared to the reservoir and tubes.
These are the things I used to make my WF:
1 Air pump: Sera air 275 R plus. It has 2 outlets, a power regulator, and it comes with 2 check valves
2 Water container with tap: 10 l (2.6 gallons). (It has the glass and fork symbol, which means it’s intended for food contact; http://en.wikipedia.org/wiki/Food_safe_symbol)
3 Tube: 4/6 mm (0.15 inches/0.23 inches). I used about 6 m in total (19.6 feet)
4 Tube close up: It has the glass and fork symbol too.
5 T-joint and check valve: I used 2 of each.
6 Water bottle: 2 l (0.5 gallons). I used 10 of these.
7 Twine: 2 mm. (0.08 inches). I used about 10 m in total (32.8 feet).
8 Hooks: I used 7 in total (2 for each row, 2 for the water container, and 1 for the pump)
9 Spray paint: 1 can
10 Buttons: About 1 cm in diameter (0.4 inches). I used 40 of these.
11 Wire: 0.3 mm (0.01 inches). I used about 2 m in total (6.5 feet).
12 Power drill
13 Drill bit (4 mm – 0.15 inches) and screw bit (6 mm – 0.23 inches).
14 Hobby knife
16 Belt punch
17 Duct tape
18 Silicone sealant
19 Clay pebbles (Leca): I used about 5 l in total (1.3 gallons).
20 Nutrients: Biosevia grow and Biosevia bloom
21 PH test kit (I didn’t use this to make the WF but it’s good to have afterwards)
22 Seeds, soil, egg shells, and egg tray.
23 Planted seeds in egg shells. This is how I grew my seedlings.
The essentials for making an air lift type WF: air pump, water container, tubes, valves and t-joints, grow medium, and nutrients.
The rest (tools, plant containers, plants) can be improvised.
After making the plant containers and assembling the system I transplanted the seedlings into the WF by carefully uprooting them, cleaning the soil from the roots, and putting them into the clay pebbles. The seedlings I have transplanted have all survived, it’s been about 2 weeks now. I also tried transplanting some cuttings from grown plants into the WF. One cutting was from a tomato plant and the others were from a basil plant. The tomato plant cutting had been growing in soil for a while and had become rather large. I thought it had grown too big to survive the transplantation and for a couple of hours it looked like it would die. Then it suddenly started getting better and the next day it was definitely on the mend. After 2 days it was back to normal. (The bend on the stem is caused by the way it has been growing before being put in the WF).
1 hour after transplantation
The next day it looks better
2 days later it's back to normal
The basil cuttings (3 in total) had different reactions: the first had grown pretty big in soil but it had no problem adjusting to the new environment. The second had not developed roots yet and for a long time, after putting it in the WF, it looked like it was dead. All the leaves fell of but I just let it be and now it has developed new leaves and looks like it will survive. The third already looked rather droopy when I put it in the WF and like the second one it dropped its leaves and looked like it was dying, but now it has developed new leaves too.
Besides tomato and basil I am growing chives, thyme, chili, and lettuce.
Row 1, from the top: chili, basil, thyme, chives, and tomato.
Row 2, from the top: chili, basil, thyme, lettuce, and chili again.Later I want to grow more lettuce and some strawberries, cilantro, mint, and pepper.
I don’t have a timer on my system at the moment but I will probably invest in one later on.
Pdf guide (English)
Pdf guide (Danish)
Thanks for reading and happy window farming.