05 January 2012

Windowfarms: grow food all year

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There are some really cool ideas for growing food indoors at the Windowfarms website. The basic idea is to take a series of pots (frequently built from pop bottles or other repurposed containers) and suspend them, one above the other, in a window, then use a drip irrigation system to run hydroponic nutrient fluid through the pots to feed the plants. Voila: your downtown apartment now has a garden in the window!

This is indeed a very cool idea. I have a really (really) big front window that is just begging to have some plants in it: it faces south, gets full sun all day, and is behind the couch so if there were plants there they wouldn’t be in anybody’s way and would add some nice visual interest to the room. Plus, I love growing things. And I love eating fresh salad. And I have the gardening bug worse than usual this year.
So … I set about designing a windowfarm that would work in our house. First of all, no pop bottles. It needs to be pretty enough to look at regularly and not upset the rest of the household with my weird experiments. The Widowfarms kits are lovely, but pricey, and anyway, I have room for a lot of plants - the window is seven feet wide. I did a lot of research into hydroponics setups and found that a series of troughs set one above the other with each trough on a slight incline is pretty common: you put water in the top and it runs down each channel into the next and ends up in a reservoir at the bottom, kind of like a marble-run.
Aren’t these gorgeous? They are from a company in California, Vertical Earth Gardens.

So, after several nights lying awake and pondering options, I decided to make a trip to the store and see what I could find that would work.
I was going to use PVC piping, like the Vertical Earth Garden, but the first store was out of the size I needed and the next place had the pipe, but didn’t have enough end caps. Then I remembered that some people use vinyl window gutters instead, so I headed to the lumber aisle and found those. Same price as the PVC, even with the end caps – and this way I wouldn’t have to cut any holes and I would be able to easily clean the troughs when the time comes. The nice man cut the 10’ lengths in half for me, so I had enough materials to build four troughs.
I also picked up two metal shelf supports to mount in the space between the window panes: I needed something to hang the troughs on, and though I intended to use the little shelf support things that come with the metal rail, they are too wide for my purposes. I found a different solution, which I will explain below.
Next there is the water: most hydroponics setups use a pump to get the water from the reservoir at the bottom back up to the top to make another run. These are usually put on a timer, and depending on the plants you are growing, how big and thirsty they are, and the type of growing medium you have them sitting in, you run the water through the system anywhere from constantly (as is done in the nutrient film technique) to once or twice a day (as you would with an ebb and flow system). Well, I don’t want a pump going all the time, so NFT is out. Due to the fact that we have a farm and animals, someone is here every day anyhow, so a manual system (perhaps with a pump for backup in case of long absences) is workable … and affordable. So, gravity feed is our starting assumption, and the growing medium needs to be selected to provide reasonable water retention while not drowning the plant roots. I found a hydroponics shop in the city and made a trip there to pick up some Hydroton growing medium: a big bag of clay marbles, basically. They hold water and nutrients while allowing air to get to the roots. I also got some rockwool cubes to start the seedlings in, though I will probably use peat pellets later on. Rockwool is a really good starter medium as it also holds water, air and nutrients really well, but the spaces between the rockwool threads are very tiny, so the little seedlings can get a good start. Once they have roots sticking out of the cubes they can be nestled in among the Hydroton pellets but for starters, the seedlings need a bit more coddling.
Okay, I had my supplies and it was time to start the construction. The troughs had to be put together by attaching the end caps to each end of the gutter and sealing with silicone, and then drains added by drilling a hole in the bottom of one end and fixing a piece of tubing in place with more silicone.

At the upper left of the window is the top reservoir, where the nutrient solution (water with fertilizer in it: for starters I bought stuff from the hydroponics store, but come summer I will brew up my own with compost tea – I am not doing that now, as it would stink up the house to brew it indoors and it’ll freeze outside!). The reservoir is a black plastic jug that held protein powder, suspended on a curtain rod hanger mounted inside the window frame. In the bottom of the jug is the business end of an IV drip set: there are some advantages to living in the same household as an EMT when it comes to drip irrigation systems! Right now the tube is dripping into the bottom plant tray, because the top two trays are empty of plants.

The troughs are supported by loops of metal cut from an old venetian blind wired to the shelf brackets. By adjusting the length of the loops a bit of an angle can be created so that the water will drain down and do the marble-run thing.

Until the seedlings get roots long enough to reach the bottom of the tray I will need to give them a bit of water through the top of each pot. The hydroton will wick some of the water from the tray, but it’s not a very deep stream of water and they may get thirsty without some help. There are only three seedlings so far, so it’s easy enough to help them out.
The other seedlings are in their rockwool cubes in a turkey roasting pan that the Reluctant Farmer got for me at the grocery store, on sale for $1.90, complete with plastic lid! It’s the perfect seedling greenhouse, and because the tray is metal, I can set it on top of my gas stove where the pilot lights give off just a bit of warmth. Once those seedlings are established and have roots sticking out of the cubes, they can be nestled in the trays as well, and then we’ll start the water flowing from the top and doing the full marble-run routine.
The system’s been well flushed now, and I think it’s time to mix up the first batch of nutrient solution and feed those little pea seedlings. Then it’s time to get back to knitting … there’s a book deadline coming up!


  1. Anonymous8:24 pm

    Can you grow strawberries in one of these? Now that would be good!
    Love your adventures in growing things - the rest of our family support Farmer's Markets!

  2. Strawberries are one of the 'famous' window crops ... I hope to grow some!

  3. I picture salad greens. Fresh beans in the winter would be awesome, but probably too big in a window. I'm doing some sprouts in my window now just for something salad-y.

  4. Yep, lettuce plants have a big presence in this setup. :)

    Those pea plants may get too large, I'm not sure ... I figured if I started them now and they got out of hand I could always transplant them outside - but maybe, if I put them along the outside edge of the setup they can climb a string and fill the window!

    I started some sprouts the other day too, just in a jar with some screening over the opening held on with a jar ring. So far they are a centimtre long and it's only been a few days! Gonna have me a sprout sandwich soon.


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