We have been harvesting lettuce regularly since August, and at peak we were able to almost 20 kg of leaves from our 5 rooftop systems. We have also started expanding behind the office on the ground floor as we ran out of roof space.
All this expanding means more plants. More plants means more seeding, which involves putting one or two seed at the center of a 20x20mm foam cube. That took 2 to 3 hours a week. So to ultimately reduce time I researched and built an automated lettuce seeder which I have open sourced on hackaday.
It takes about 3 minutes to seed a tray of 150 lettuce. To see it in action watch this video:
A lot has happened since our last post. In early may our whole greenhouse roof blew off during a storm. We then had to shut the system down while we rebuilt it all this time with a solid metal structure. We now have about 1600 holes for growing lettuce and rucola, over 25 buckets for basil, tomatoes and cucumbers as well as mint and Kangkong.
The automation is fully operational since months. The main 3 NFT beds are fully controlled, this includes filling up water when needed, adding nutrients and acid, and monitoring temperature, pH, EC, and nutrient stock tank volumes.
One bucket system is also connected to the automated reservoir - we have 13 buckets in series, water trickles in one end and back out to the nutrient reservoir at the other end.
The NFT system suffered a bit in summer because the water temperature was quite high, above 33 degrees C at times, but we were still able to grow lettuce although they did not get very large before bolting.
On average we harvest about 6kg per week of leaves from the system. We sell it as gourmet lettuce with 4 or 5 varieties (romaine, oakleaf, butterhead, salad bowl) all mixed together. They are packed in 200g bags and when refrigerated will stay fresh for up to 2 weeks.
We have also sourced good quality foam for the seedlings and developed our own mold to cut the foam into cubes, we have foam pieces with 150 cubes, of 2x2 cm each. Germination works extremely well even in very warm weather, with fresh lettuce we have close to 100%.
We have also started packaging our own brand of nutrient mix for leafy greens and we plan to sell that on ebay or to whomever is interested. We have two mixes, one for summer and one for winter with slight variations in the nutrient content to account for temperature and light.
In the next post we will share a bunch of pictures of the various topics discussed in this blog post. Thanks for reading!