I’ve tried quite a few different lettuces using the Kratky Method, growing them in individual containers, and Gaviota is by far my favorite. Not only does it grow well in the nutrient solution, but it grows fast. The leaves are perfect for salads. If you just rip the end off of it, it breaks down into perfect bite-size pieces. If you were to cut the entire head off at a certain point, all the leaves come apart. No chopping, no fuss, just a single cut. Starting at 3-4 weeks it’s great for cut & come again harvesting. I like to harvest 1/4-1/3 of a plant and put it in water in a bowl in the fridge and overnight it becomes even more crisp.
I’m not one to harvest lettuce seed for reuse, as I like to try out new varieties but I have been curious about how the flowers look, and how the seeds develop so I let some go to seed.
It took weeks before I caught some flowers actually open. Most of the day the flowers are tightly closed. Since I never saw any flowers open I was beginning to think that they never really opened.
Conveniently I had one plant with open blooms and another with fully formed seed heads at the same time for the photographs.
The seed head I pulled the seeds from contained 18 seeds. One plant going to seed would be more than enough to supply for any garden the next year.
I have grown hydroponic lettuce successfully and really enjoyed it, but that was all indoors, and while I found the lettuce acceptable, it was a not as crisp as I would like from not having the normal stresses of outdoor life to toughen the leaves up. I had a fan blowing over them once an hour, but that can only do so much.
I started a couple Reine des Glaces and Green Towers from seed outside in January and they did great, but got infested with countless hordes of aphids. I washed them off quite a bit, but you can only do so much at that point.
I wanted to find out how large organic operations managed to grow lettuce and control for aphids without sprays and after quite a bit of research I found this video.
I started my own Sweet Alyssum plants the next day. I have a standalone pot of it growing so I can move it around, and planted some below a couple tomatoes. According to the research that should be way more than necessary. I have one lettuce plant growing hydroponically outside at the moment and haven’t seen a single aphid on it in the last couple weeks. The plant definitely had a few aphids colonizing it when I started the Sweet Alyssum, so this is a good sign that it does work.
Now I have some lettuce starts nearly ready to transplant outside.
The other issue I had with growing lettuce outdoors is with cut worms taking the plants down. I’m going to try either planting then with collars made from the plastic shot glasses, or planting toothpicks next to the stems.
I am really happy I started growing lettuce with the Kratky method. I really like good, clean lettuce. You just can’t get it from a store anymore. What you can get from a store is “triple washed”, bruised, sad looking, sometimes decaying leaves. No matter how hard I examine a bag or container in the store, I don’t see the carnage until I pour it out.
Now that I’ve grown some full size lettuce, I’m going to scale back the amount of solution I use to 1.5-2 liters, down from 4. They might need 4 if they’re grown outside with windier or warmer conditions, but indoors they don’t drink much.
Now that there are longer days, the lettuce is growing faster. Gaviota grew out to a full size from seed in 40 days. Gaviota is an awesome lettuce. It grows loose and bushy, with slightly curled leaves. You can cut it at the base, and all the individual leaves are all separated at once. The slightly ruffled leaves make for a light and fluffy salad. It grew awesome with hydroponics. I don’t think this will work well for periodic harvesting.
Red Sails is a pretty leaf. It also grew awesome with hydroponics. The leaf size is huge so you have to tear it down for a salad. It is a little slower to grow, I’m letting it go for another 10-14 days for 50-54 total.
Three months ago I first posted about doing Kratky on a small scale of one container per plant. A short time afterwards I got a whitefly infestation in my indoor garden, and had to cut everything down. It was a shame, since the lettuce plants were just starting to get big.
It’s been six weeks now since I started new plants from seed, and I am trying four different varieties to see which grow better with this method.
Harmony MTO lives up to the reputation of bib lettuce varieties doing the best in hydroponics. Almost nearly as good, the Multigreen 3 MTO is getting quite big now. Buttercrunch and Green Towers look okay, but are slow growers. These varieties are 60-68 days to maturity, but they have been growing in winter light, so I’m giving them a few more weeks than that.
With Kratky, the plant should consume all the liquid provided to it and be ready to harvest when it is gone. Harmony has used a liter, during an estimated half of its lifespan, while Green Towers has barely used any. It will be interesting to see if Harmony can actually consume all that water before I am ready to harvest.
I will be starting 4 new varieties of lettuce in a few weeks so they will be ready to be transferred in after these are harvested.
March 2015 Update:
I have started to “cut and come again” these lettuces. Altogether they make a great mix. The Harmony is a huge leaf, so I tear those up, they are neutral flavor. Multigreen is a nice frise style that is slightly bitter. Buttercrunch is quite nice, though nothing special. Green Towers is nice and crisp – I’m going to grow 3 of these to a container next time. If I had more room, I would probably rotate 3-4 of these in every 3-4 weeks or so to have a regular supply.
I tried to grow lettuce in soil in my indoor garden once, and failed miserably. I haven’t tried again since. It seemed a waste to dedicate a full pot for such little return, and it was easier to buy. Bulkier greens like Swiss Chard are an exception as they are great for continuous harvest, and do great in the pots.
I have previously made and used an ebb and flow hydroponic system and grown many tomatoes, and herbs. It worked great, but took some work to maintain the solution, keep the aerators clean, the pump working, and was only good for a larger scale operation. I’ve since moved into a smaller space, and have tried to keep accumulations of stuff to a minimum, so I definitely didn’t want to go that route again.
I discovered the Kratky method for lettuce production and decided to give that a go. There are no air or water pumps, no circulation, and all the solution you mix is consumed by the plant. The water level starts at the base of the net cups and as the plant absorbs the solution, the roots grow down into it, exposing the growing roots to more air. When the solution is gone, either the plant is ideally mature enough for a full harvest, or you add some more solution if you are doing a continuous harvest.
I went to Daiso in search of appropriate sized containers to act as the reservoirs. Daiso is a great Japanese store that I’m lucky to have in my area. Odds are you can find exactly what you want there or something that will work for your project. I managed to find an opaque CD/DVD container that holds 4 liters, and purchased four of those. Doing individual containers will allow me to stagger the growth while maintaining optimal levels of solution for each set of plants. Ideally there will be one lettuce plant per 4 liter container. If you have multiple lettuce seeds germinate in a container thin it out to a single plant. I’ve grown multiple plants in a container and they don’t produce as well as a single plant – too much competition for space & resources.
The container prep is really simple, just drill a hole into the lid of your container at the appropriate place.
To start the plants, soak a Rapid Rooter until it is moist enough so that when you gently squeeze it, drops form on the surface, but don’t create a torrent of water. Then place individual seeds in a Rapid Rooter and put it into a humidity dome until it germinates. After a couple days post-germination, put the Rapid Rooter into a net cup and drop that into the reservoir. Make sure that 1/8″ to 1/4″ of the net cup is covered by the solution, if not, add more.
- Rapid Rooter Seed Plugs
- 2″ Net Cups
- Base nutrient (Lettuce Fertilizer 8-15-36)
- Calcium Nitrate supplement 15.5-0-0
- Epsom Salt
- Micro nutrient supplement
- Reservoirs (Note: the volume of the linked containers is 7.4 liters, so you can fit two lettuce plants in one box, adjust the nutrient + water recipe accordingly)
- 1 7/8″ hole saw
I have broken down the formulas of each nutrient below. To mix, I pour each element, one at a time, into a container to weigh it, and then pour it into the mixing container. That way I don’t accidentally add too much of one thing into the mix since you can’t take it out once you put it in.
I am mixing them into a total of 1 liter of concentrate solution (using the 16 liter formula), for easy mixing and measuring – each 4 liter container will get 250ml of solution. Then I pour out the measured solution into the reservoir and fill it up the rest of the way with water and mix it up.
|Hydro Lettuce||adjust pH to 5.8|
|Liters||Jungle Juice (ml)||Epsom Salt (g)||8-15-36 (g)||15.5-0-0 (g)|
Check my other posts regarding growing hydro lettuce for updates and comments on specific varieties.