This time, we’re checking in on the recent day-by-day progress of Zach Yohannes’ Gro-Mart prototype. Gro-Mart is a “ revolutionary sustainable food production model that produces a poly-culture of crops utilizing advanced soilless growing methods. It will consist of a system of multi-story buildings that serve as both the growing site and point of sale, eliminating food miles while also providing an economically enriching and educational service to the community.” This summer Zach is testing a partial floor of Gro-Mart, determining what works best, and assessing its feasibility. Below you can read Zach’s daily updates and get a sense of how challenging and all-consuming this project is.
Thursday, June 28th
Today was a pretty busy day. We decided to redo all the trays in the racks where we’ll be growing lettuce, basil and herbs. The trays are 30 inches x 8 feet x 8 inches (depth). Previously I’ve used plastic liners, but that’s hard to do with so many trays. And there’s too big a chance that one will spring a leak.
Actually that’s exactly what happened. Last night I filled up one side of the racks and this morning the ground was full water. That’s a real problem because there are lights and other electrical. Nutrient solution is also quite expensive so you don’t want to waste that.
Friday, June 29th
We finished the electrical today. Now we have outlets by all the main reservoirs that will run circulation pumps and air stones to continuously mix the nutrient solution in the big 250-gallon reservoirs.
We’re just waiting on plants. Later today I’ll seed more plants. Last week I seeded about 600 lettuce and basil and 50 tomatoes. The tomatoes will be grown in Rockwool.
I also purchased the rest of the NFT (nutrient film). Now I just need to weld the racks together that will hold the tubes and the structure to support the plants as they grow.
I’m trying to fix this by using spar varnish, traditionally used to seal boats. I’m hoping that this will make a nice watertight seal. And that this will provide a cleaner environment for growing. Today we applied a coat of thinned down spar varnish. Then we’ll use an oil-based Rustoleum black paint and on top of that 3 more coats of un-thinned spar varnish. The black paint will help absorb light and prevent unwanted microbial growth.
Monday, July 2nd
Finished welding the NFT racks. Tomorrow we’ll put on brackets to hold each pipe in place. Also we’ll slightly angle the entire structure (2-4 inches over 8 feet) to ensure adequate drainage. This will avoid stagnant water build up by the plants’ roots.
I’m really interested to see how much solution we can put through here. Like everything else this is a big trial. NFT is one of the rigs I first started working with and this design is the result of many adjustments so hopefully it will work well. Tomorrow we’ll put the tubes together and later this week we’ll be putting in the plants.
Tuesday, July 3
Tomorrow I’ll drill the holes for the plants to go in. I’m debating whether to use baskets to hold the roots of the plants or just to try and drill a hole the right size so I can stick in my Rockwool plug or peatmoss – that would be ideal. Baskets are expensive and any time I can get rid of a cost – that’s awesome. That’s what I’m doing, seeing what I can get rid of.
The deep water culture is up and running without any baskets. The peatmoss and Rockwool medium is placed into the foam board floating in the water. It’s held in place by friction. When it’s ready to harvest I can just pull it out. No baskets, very little medium, and pretty low cost. Hopefully this will help make the concept feasible.
Also I applied the last coat of spar varnish. This will dry for several days to make sure no chemicals leach into the water.
Thursday, July 5th
We’ve got a lot of stuff going on today and we’re getting close to being done with the entire facility. It’s really starting to look pretty cool. All the electrical is done and the trays are finished and installed. The drains and the fill tubes are all set. So water should go only where we want it to go. My only worry is whether the spar varnish will hold. It looks like it will.
I did a little price check to see what it would cost to buy the trays premade. About $100 per tray and I’m spending about $25 per tray. Finding ways like this to reduce costs will really help feasibility and scalability.
The NFT rigs where I’ll be growing a tomato and soybean polyculture are nearing completion. I just need to hook up the plumbing and drop in the baskets and seedlings.
On Friday we’ll be able to plant some lettuce. We’re on schedule. Lots of little housekeeping tasks until next week when we’re up and running full speed!
Sunday, July 8th
Yesterday and today we’re pretty busy. Unfortunately the lacquer and varnish didn’t work at all. I filled it up on Saturday and it was just a catastrophe. It was terrible. Luckily the facility is made to handle floods – all the electrical is raised off the floor (in fact, I sometimes flood the floor and turn the fans on as a way to cool the facility if it gets above 90 degrees – we don’t need AC). But I felt very frustrated, even though in the end it was a good thing. This trial by fire (or water, really) let to another small design modification and one that simplifies the whole system.
We had to go through and put brand new liners in. I did some late night work with my dad yesterday, which was really nice. Hopefully this will work. This puts us back a little, but not too bad.
Wednesday, July 11th
I’m about to close up right now. Both of the big deep water culture rigs are up and running and so far there are no leaks. It looks good – thanks for that. The first two levels are planted and all the seedlings look OK.
There are 2 different grow mediums you can use in deep water culture. Peatmoss blocks are superior but about 20 times more expensive. Rockwool is much less expensive, so we’re using that.
I planted soybeans today.
There are 3 different lights that we’re using. Two are 1000W high pressure sodium bulbs. They’re cheaper than metal halides. Also it’s more important to have the yellow color spectrum for fruiting and reproduction. Because I want a nice compact plant I don’t need the plant to grow too much during the vegetative stage. I also made a bamboo trellis system.
Tonight is the first night that I’ll leave the system on and going all night. Hopefully everything will go well. I’m really in it now.
Next week, you’ll get to learn more about the planting process, expected growing cycles, and crop selection. Please share with your friends, follow us on Facebook (link), and subscribe to our blog. We welcome comments (email Mark Feldman or Zach Yohannes at markfeld at stanford.edu / yohannes at stanford.edu).
Zach Yohannes is a junior Earth Systems major who comes from a long line of farmers. Two years ago he started experimenting with hydroponic agriculture.
Mark Feldman is the director of this blog and a lecturer in the Program in Writing and Rhetoric. He is interested in ecology, art, and urbanism.