Intro: Solar Powered Vertical Drip Hydroponics With French Ironwork Details *Updated!*
I really wanted a way to grow a substantial amount of produce without using any power that required a plug to do it, and to make it look good - more like furniture that you would want inside the house. So I built this.
There are a million ways to set up some recyclables and an aquarium pump to grow a few plants. I've done this plenty of times. It wasn't good enough for the power it was using, and the materials never lasted that long. Plastic bottles are only intended to be used once - many bottles even say to not reuse them on the label. This system does use new materials for the initial build, but once it's set up it only requires water, fertilizer, seeds/cuttings and the occasional sheet of rockwool from then on out. Using new materials also reduces the chances that surprise contaminants will make it into the food (at the very least it should be better than grocery store equivalents.) The pump is solar powered - it pulls the solution from the reservoir below to trickle over the roots of the plants inside the box. The footprint is 36" by 8" and it accommodates 50 plants. The inspiration came from a book of old French ironwork that I have. I figured that if I was going to do this I might as well make it as spectacular as I could. I'm running it outdoors over the summer, but then it's coming inside to keep working near a sunny window to keep me eating fresh and healthy all year long.
*After a last frost over 20 days past the 'normal' they tell you to plan for when you garden the weather here has finally gotten nice! It froze one night and was over 90 degrees the next day, so now I have pictures of everything up and running! Yay!*
Step 1: Materials List
This materials list will is based on the 50 plant system I built - don't forget to adjust if necessary!
- solar powered pump with batteries - this one lifts water about 18" and that number determines the height (ebay)
- fiberglass water reservoir - this is really what made the project convenient. It's got a long, narrow footprint so it's not like having a big clunky rubbermaid bin or something.
- 50 adjustable tubing clamps
- 50 1/4" irrigation hose adaptors
- 1/4" irrigation tubing (I bought a 100 foot roll but didn't use all of it)
- 1/4" irrigation connection hole punch
- 1/2" or larger tubing - a few feet will do it
- connections to go from your pump to the 1/2" tubing
- 1/8" acrylic sheet in green and black
- acrylic cement/solvent and a needle style applicator
- aquarium sealant (just to fill in any leaks)
- 2 12" long acrylic piano hinges
- an acrylic latch - - padlock or magnetic style will work
- an assortment of acrylic cornerreinforcement blocks
- acrylic handles
- black acrylic paint or india ink (to make the engraved nameplates stand out)
- 1.5" by 1.5" rockwool/grodan cubes
- seeds or cuttings (with rooting hormone)
- good quality hydroponic fertilizer (miracle grow isn't going to keep things going for very long)
- black dry erase marker
Step 2: Building the Box
This version of the project really needs to be laser cut. When I started looking at the time I was spending on projects versus the cost of having a service like Ponoko cut them it was silly to keep making so much by hand. (I talk about the cost breakdown in a later step if you want more on why I made this choice.) After you submit your file you get a box full of parts that are like a giant puzzle. That's where this step starts.
Rub a bit of the black ink into the engravings that are on some of the panels. This helps them to stand out - these are just areas that can be used to write the name of your plant in dry erase marker. Did you know that many young plants and herbs are identical to the minimally trained eye? Labeling my plants has paid off EVERY TIME I've done it ;-)
I've included an image this is basically all of the parts where they align. The whole thing is to put the pieces together and cement them in place. Sets of three small squares make up the holder for each block of rockwool - there are small holes in them to allow you to skewer the cubes into place with a toothpick as necessary (making it easy to pull blocks out or move them around as necessary.) I didn't glue my box onto the base so that i can pull things apart later for cleaning and such. I also didn't glue the lattice to the top.
Once everything is glued into place start adding the reinforcing blocks. Put one anywhere that seems weak or wobbly. It needs to be as solid as possible now - there will be plants and water weighing it down later.
Follow the diagram and you'll have an assembled box in an almost disappointingly short amount of time. I love building things, I really wish this had taken longer.
The two large back doors are attached with the piano hinges and held closed with the latch. Add handles so you can get it open again. You may need to add an additional support for the top inside the box depending on how it all fits together.
Once it's solvented in place and set give the whole thing a rinse down with some clean water to get rid of any chemical residue that you can.
Both a jpg and a dxf file are included - you'll want to click on the jpg and view it at full size to see the details. The parts are arranged in the order they go together, and the red lines indicate an engraved line. Right click and download the dxf if you want to see it.
Step 3: Water Lines
The general idea is that a large tube runs up from the pump and across the top - you can use the small holes in the vertical black connectors to tie it into place. Holes are punched into this large tube to accommodate each plant - an irrigation connector goes into each hole and then onto a piece of 1/4" tubing that runs from there to the larger hole on the box around the rockwool cube. Slide an adjustable hose clamp onto each piece of tubing so that you can reduce the water flow to each plant to make sure all of the plants get enough water. This also lets you shut off water to a location completely if it doesn't have an active plant in it. It will probably take some time and attention to get this all balanced out but then it should be set. I filled mine with plain water first. I balanced out the water flow and found all of the places water seeped at the bottom. Once it all dried I filled the gaps with aquarium sealer.
I tested this out in a smaller version before - the water absorbs into the rockwool and runs over the roots. It seems to be plenty to keep the plants healthy and happy.
Step 4: Grocery Shopping for the Future (Choosing Plants)
A while ago my sister (antibromide) got us both into the habit of grocery shopping once a week. Every single Tuesday is grocery day. This was a GREAT idea. I know how much of each perishable I use per week. We plan a weeks worth of meals at once. We've almost eliminated wasted food that we don't get to before it expires. We're making a lot fewer trips to the grocery store, too.
This was very helpful when I was picking plants to grow. For example, I know that we can easily make it through a head of lettuce and a single cucumber every week. When reading seed packets/catalogs it tells you how long it takes to go from seed to a head of lettuce. Most of what looked good to me was about 60 days. At my current rate of consumption I should have at least 8 spaces dedicated to lettuce. On the other hand, a quick google search tells me that an average American slicing cucumber vine will give me 6 large cucumbers in a 2 to 3 week period, and that I should grow a couple of them to ensure good pollination. Since I don't care for pickles and I don't know of any other good way to preserve cucumbers these would be an awful choice for me. Just two plants would require me to at least quadruple the amount I like to eat. (I know I could donate them to a food bank or give them away to friends, but the point I'm working on is determining how much is consumed in my house and covering as much of it as possible.)
After considering my standard groceries, climate and preferences, I developed a list.
I included 10 different herb varieties - fresh herbs are expensive, dried herbs aren't as good as fresh, and if I really grow too much I can preserve them. I LOVE cooking with fresh herbs. I add them to everything when I have them. That made herbs a total win.
Bell peppers were next on my list because they don't grow terribly well in the ground here, they tend to get eaten by woodland creatures, and I love sweet red bell peppers. Two plants each of two varieties - that should be about right for my use and if I don't get to them in time it's easy to clean them up, cut them into wedges and pop them in the freezer. I've even put whole peppers in the freezer before and they come out in great shape for cooking into things, but I wouldn't expect them to be the glossy perfection they were when they went in.
Tomatoes are delicious and I can eat and save an almost unlimited amount of them. Cheap 'imperfect' tomatoes at the farmer's market have always been something worth turning into sauce so there's no consumption based reason to limit my tomatoes. This system isn't really large enough to have many tomato plants but I've developed a compromise. Three plants that are bush (as opposed to vine) style that grow small-but-larger-than-cherry tomatoes. Great for salads and baking into bread, good enough to save if need be. These may be moved later into more substantial housing, but they're fine in here for now.
Three or four spinach plants because spinach is nutritious and tasty in salads. If I'm growing it I can use young leaves.
A few squares worth of bunching onions because I love onions and I wanted to test them out in this system.
I chose a few loose leaf lettuce variety seed packs. I especially went for colorful choices for two reasons - they look good (and there's a heavy interest in aesthetics here), and more colors generally equates with more nutrition in produce. I can't stand iceberg lettuce but I'll find lots of ways to use the fancy stuff. This also very significantly frees up some fridge space in the house - no need to refrigerate this stuff at all, just go out and pick the leaves I need when I need them. A less full fridge can increase the efficiency a bit there, too.
I also added in a hearty sampling of mesclun and 'microgreens'. They're small and fit into the gaps between the big plants and they come with pretty rapid gratification. These spicier and brightly colored greens are growing at unbelievable speed so far - I'm looking forward to salad time.
Fundamentally, I'm still working more healthy/fresh food into what I eat so I need to be really careful to pick things I'm sure I will like. In the future I'll keep experimenting with more choices (some strawberries that have grown past their boundaries in the garden for starters) and quite possibly adding a second system to my life. Cooking with fresh ingredients eats fridge space and I would be delighted to help remedy that.
Step 5: Seed Starting
Rockwool is magical. It can be soaking wet but dry and airy at the same time. It's the cotton candy of the volcanic rock world. The seeds I started in it are the best seedlings I've ever had. I get close to a 100% success rate from my seeds. Things that might otherwise 'damp off' or be eaten by ground dwelling bugs (like my constant battle with melons) are safe and sound.
For convenience and seed safety I started my seeds in a seed tray. Mix up a very weak fertilizer solution, put the rockwool you'll be using in the tray, and keep drizzling solution over it until it stops absorbing. Drop your seeds into the holes (you can add holes if you want to - I did for bunching onions). WRITE DOWN WHAT YOU PLANT AND WHERE. I've found that hydroponic plants can grow a bit closer together than the package says because they don't have to compete for resources as much.
Check the tray daily - I generally pour a bit of solution into the tray (not over the rockwool) daily to keep things evenly moist. If there is unabsorbed moisture in the bottom of the tray don't add any more. Once you've got seedlings turn the tray daily to help keep them upright-ish. Once they're big and solid (or you're tired of waiting) pop them into the box and skewer them in place, being gentle about the roots.
Gratuitous seedling pictures - this is the best I've ever done, these were taken just under a week after planting them.
Step 6: Maintenance
You'll need to keep the reservoir full of solution - that's what the 1" hole in the base is for. I keep old gallons containers around (that have been well cleaned), fill them with water, let them sit open for a few days to evaporate out any weird stuff that will go, add the fertilizer and keep them capped until I need them. Every two weeks or so I empty the reservoir into the garden and star with fresh solution.
Obviously double check that the pump is working right and clean, and you may eventually need new batteries for the solar panel, but other than that you're pretty much set to keep it planted and let it work. The dark plastic enclosure is there to reduce algae growth but you may need to give it the occasional interior wipe down.
Step 7: Return on Investment
It's probably not a secret that this wasn't cheap to build. I wanted something that looked good and would last forever. I want it in my living space looking nice. I know that pretty presentation makes foods more appealing. I chose plants, in part, based on great colors. Before I went ahead with the project I considered a few things:
A head of nice hydroponic lettuce goes for $5 at my grocery store. This isn't organic or anything special, just good. If I buy one of those every week for a year that's $260, which, on it's own more than covers the cost of the system. And I anticipate getting a lot more than that in production. One bell pepper are as much as $3, one per week is another $156. In general, fresh foods are the most expensive per calorie available, so it can be fast to make up the cost.
Having a constant supply of fresh things makes me feel obligated to eat them which will hopefully displace some other, less healthy choices. Not letting them sit in the fridge means they don't decrease in quality, don't go bad from being hidden and forgotten, and don't take up space. I know they don't have an pesticides or herbicides on them. If they come with food poisoning it's my own fault.
Every bite of produce I eat came from somewhere. It probably came by truck, and possibly by other transportation as well. It's stupid to haul this stuff half way around the world if you could be measuring how far it moves in feet. I'm working toward figuring out how much space it would take for me to grow all of my fresh produce. How many people would have to do this to get a truck off the road? How much gas/pollution/etc could be saved?
Seeds are cheap and cuttings from other plants can be free. I would never buy shallots (or even $5 lettuce most of the time) because it's seems to excessive. If I grow them I can eat them all the time, and my cost is a fraction of what I would be paying otherwise.
There are even tiny ways this helps - I drag less weight home from the grocery store every week (a 7.5 mile drive without public transportation option.) Having my parts laser cut almost eliminated waste plastic. The water I change out from my system just goes into the nearby garden space. If I skip over a processed food for something I grew I save the energy that went into that processing, too.
*The photo is a mid-late summer image, after I had eaten a lot of the lettuce (it was much more overgrown at the top) but before the tomatoes came in. You can see a few yellow flowers low in the picture. Before the frost hit there were a lot of tomatoes to eat, but the season was quite disappointingly cut short by a series of brutal and early overnight freezes. By then the whole thing was so overgrown that I couldn't move it.*