My hydroponic adventures (100% legal!)

Submitted by Andrea on April 14, 2013

One of the few things I miss about living in Arizona is my wee postage stamp of a garden. I had two raised beds, several fruit trees, and some lovely rose bushes. Like most Tucsonans we didn't try to maintain a lawn, instead covering most of the ground with gravel, and we watered the plants as little as possible using a drip irrigation system. I miss my roses most of all. I was initially surprised to learn you could grow roses in the desert since I always associated them with northern climes, but then I recalled that roses have thorns, and any plant that can hurt you will probably grow brilliantly in the desert. And they did, year-round! In fact, I'm not sure I'll ever grow roses again, since I'll never grow anything nicer than this fragrant beauty from 2009 (note scale): My tomatoes were not as uniformly successful as my roses. Arizona's growing season is enviably long (the last frost is mid-March), but tomatoes won't set fruit once the temperatures get too high, starting in June. They'll start fruiting again in September or so, assuming they didn't die from some other cause over the brutal summer. My best crop came from growing very small native tomatoes, but they grew so relentlessly that I was praying for frost by Christmastime, since my plants had sprung their banks and overtaken the entire back yard. May 2008 (note the blooming ocotillo trellis): December 2008 (yikes!): (Frost came a few weeks later, and overnight the entire jungle withered and my garden's balance was restored.) You can probably understand why gardening for only six months a year in Vermont seemed a little weak after my year-round Tucson shenanigans. My initial plan was to build a greenhouse, but I quickly realized I didn't want to heat a greenhouse. So we created a nice little garden space right inside the house, with huge south- and east-facing windows. I was curious to try hydroponic gardening, and after some exploratory Googling I built a simple deep-water culture system. Speaking of Googling, I suspect I'm now on a DEA watchlist, because nearly all the online information about hydroponic gardening is about growing your own pot. My browser history is riddled with sites like rollitup.org, 420magazine.com, and growherbsindoor.info, which really have a lot of helpful information (even for chard-growing squares like me). There's a lot of winking in the hydro world ("Here's what you'll need for your... tomatoes"), and mail-order sites cater to their customers' need for discretion: Here's what I bought, mostly from our local hydro dealer (cash only) and pet store. I divided the list into one-time setup items and repeat-purchase maintenance items: Setup items (one-time purchase)

Consumable items (repeat purchases)

When you set up your system, you'll need a power drill with a hole saw the same size as your net pots (3" in our case) to drill the circles through the tote lid. Don't try to cut the circles with a utility knife; many have tried and lived to regret it, or so I hear. Our system has a total of 22 plant bays, and underestimating the efficacy of store-bought seeds I started 50 seeds in the rapid-rooter plugs. This was unnecessary, since all of the seeds sprouted and I ended up discarding half of them. The seedlings in their hydroponic bays: I hadn't added the hydroton pebbles yet—our neighborhood hydro vendor said we could omit them, but our plants were rather wobbly inside the too-large 3" net pots, and I was concerned about sunlight streaming into the tub and causing algae to grow. This is why it's important to get opaque tubs rather than clear. We planted:

And within 4-6 weeks we had this: The arugula and Rouge d'Hiver lettuce turned out to be a poor choice, since you need a lot of plants to get a salad's worth of lettuce. The head lettuce varieties were better suited to our system, and after harvest I planted some more, along with some oak leaf lettuce. We've now eaten everything from the first round except for the chard, which I am slowly harvesting for banana-chard smoothies, which taste a lot better than they sound:

Energy use

As a passivhaus dweller who has not given up on achieving net-zero energy use, I was concerned about how much electricity my indoor garden would require. The answer: very little. The two aquarium pumps draw a combined 5 watts, and my abundance of natural light means I don't need supplemental lighting at all. If I were trying to grow fruiting plants like tomatoes, I'd need a 96-watt T5 fluorescent fixture as a bare minumum, and possibly quite a bit more, even with my huge south-facing window. I may try growing tomatoes indoors this fall, but I'll likely abandon the effort if it needs more than 100W several hours a day. I tried starting tomato seeds in dirt but managed to kill them by overwatering. Next time I'll stick to hydro!

Maintenance

Unlike tomatoes (and "tomatoes"), hydroponic greens require very little work and maintenance. Every few days I check and adjust the pH levels (a slightly acidic reservoir of pH 5.5-6.5 is ideal for nutrient uptake). I might add some water as well, but we haven't had a major problem with evaporation, and my hydroponic system hasn't affected the indoor humidity level. The biggest chore is to change the water every couple of weeks. I opted not to plumb the garden area for water, since it's not near the bathrooms or kitchen and I didn't want to introduce a risk of leakage anywhere else in the house. So I made a little cart out of a furniture dolly and an extra shelf and push the tubs to the hall bathroom: Then I remove the lid and rest it on some 2x4 scraps: This is a good opportunity to check out the size and density of your roots (such photos are known in the hydro world as "root porn"): (BTW, this is pretty tame as root porn goes, because most of those plants are new—only the two chard plants are mature.) First I remove the airstones and dump the water out of the reservoir, and then I give it a hearty rinse with the shower sprayer to clear away any algae or slime. I haven't had any reservoir issues yet, so I haven't bothered with soap or hydrogen peroxide. Then I rinse off the roots as well. Here's a look at the airstones. The idea is to introduce lots of oxygen bubbles into the reservoir, which the roots need. One of the best things for me about hydroponics (versus soil container gardening) is that you can't overwater the plants, and you can leave town for a few days or even a week without having to maintain the system. A long absence isn't ideal for pH management, but it probably wouldn't kill the plants in a system like mine. I could probably get away with a single airstone for each tub, but the gang at rollitup.org and every other hydro site says the more bubbles the better. Speaking of bubbles, the pumps are audible but not annoying. We started with a really cheap pump, but it was decidedly louder than the Fusion Quiet Power and maybe only $10 cheaper. I meditate in the next room, and the pump noise is not an issue.

Summer hiatus

Sadly I will have to suspend my hydroponic adventures in the next month or so—the solar angle will be too high and I probably won't get enough sunlight. I'll have to content myself with outdoor gardening, which frankly scares me. Growing 22 little plants in a weed-free environment (in more ways than one!) is so much simpler than going outside and turning our ~1,800 square feet of tire-compacted front yard into the garden of my dreams, which you can count on me to post about in, say, 20 years.