Today will be a guide on how to grow Kratky Method lettuce. As with our other growing guides, we will show you how it’s done, some things to consider when starting, and some helpful tips to make your experience a good one.
First off, what is the Kratky Method? In a nutshell, it is a passive hydroponics system where you grow plants suspended inside a container filled with water and a liquid nutrient solution. This hydroponic system does not require a water pump, or any electricity to work(unless you use grow lights). The best part is once you set it up, you can literally leave it alone and the plant will grow by itself without any hands-on work. You can literally save a lot of time growing plants this way, and in this day and age where everything can feel fast-paced at times, it’s great to know that those plants will take their time growing slow and steady without your constant input.
As I may have mentioned in a previous post, the Kratky method is great for leafy greens and herbs, and since we are covering lettuce today, I think this is a great way to show you how it’s done. Let’s get started.
What will you need?
Since the Kratky method is very simple, you might have everything you need right at home. You may need some tools, such as a sharp blade for cutting, or a grow light, if you lack sufficient lighting in your home. If you’re lucky, you might not have to buy any of those Kratky starter kits that you find online. While they are certainly one way to get started, here is a rundown of the essentials that you need:
Container. Your best bet is an opaque container, so that sunlight cannot get through and touch the roots of the plant. You can start small with something as simple as a mason jar, or you can go as large as a 5 gallon bucket, but if you are growing lettuce, anything bigger than a mason jar is overkill. It’s always important to choose a container in relation to the size of the mature plant. If you don’t have an opaque container to work with, you can always use a transparent one, just make sure to cover it with some tin foil or something that will keep sunlight out.
Net Pot. These are plastic pots with a net-like pattern, allowing plant roots to reach through and absorb the water in the container. If you plan on growing lettuce in a mason jar, the size of the net pot should be large enough to fit inside the rim of the jar. That way, you won’t have to make a lid for your container. If you use an AeroGarden, you can even reuse any old seed pod cages that you might have!
Lid/Cover for the Container. If you aren’t using a mason jar/net pot combination, you may want to ensure that your chosen container has a lid that can fit over the top of the container. If you have none, you can always make one with plastic or even styrofoam. The lid should be opaque, and you will need to cut a hole in it later.
Growing Media. There’s a lot of options out there, from rockwool to clay pebbles. In some cases, you can even use a combination if that works best for you. I often start my seeds in an AeroGarden, so I like to take the growing sponges, cut it to fit in the net pot and fill the rest of the net pot with another growing medium such as clay pebbles. Whichever you use, make sure that is a pH-neutral growing medium, so that it doesn’t mess with the liquid fertilizer that will be used in the container.
Liquid Fertilizer. Since we are dealing with a simpler form of hydroponics, you will need to have a solution of nutrients that will ensure your lettuce plant is fed throughout its life. Since we are growing lettuce, you can go with a hydroponic fertilizer that has a decent amount of Nitrogen. I like using AeroGarden’s Liquid Plant Food, personally, as it has a well-rounded ratio of ingredients.
Finally, you’ll need those lettuce seeds! That probably goes without saying!
Building the Kratky Container
- If you have a lid or cover for your container, you will need to cut or drill a hole large enough to be able to fit your net pot, but not too big that the pot will fall though. If you are using a container that can already fit your net pot (ie: mason jars), then this step can be skipped.
- Next, you will need to fill up the container with water and your chosen liquid fertilizer. Remember to check the instructions on the liquid plant food to ensure that you are putting in the right amount for the volume of the container. The container will need to have enough water to be able to touch the net pot and growing media. I like to keep the net pot submerged by about half an inch.
- Finally you will install the net pot into the container.
Setting up the Net Pot
This can also be done before building the Kratky container, but I personally like to wait until after, that way I can use the net pot for measuring if needed.
- Place the growing media into the net pot. Depending on what you use, you may need to cut it to fit securely inside the net pot. I find that clay pebbles are a great way to fill any gaps.
- Place your seeds inside the growing media. Keep in mind that if you sow multiple seeds, you will need to thin them out as they grow larger.
- Place your net pot into the container you built. If all goes well, the net pot should be able to sit securely inside, and should be able to touch the water just enough that the growing media will soak it up. You can top up the water if needed.
If you plan on growing multiple Kratky containers, you will want to repeat all of the above for each additional container.
Finding a good location for your Lettuce
Now that we’ve set up our Kratky system, you’ll want to find a suitable place in your home for your container to get light. Ideally, you will want a sunny spot that gets about 12 hours of light a day, such as a window sill that faces south. If you have grow lights, you can use those as well, and if you have an AeroGarden, you might even be able to have your plants “piggyback” on those lights too!
How long does it take for lettuce to grow?
Usually by 4 weeks, you should have small lettuce plants that should be ready for harvest, depending on the cultivar. Until then, it’s a good idea to closely monitor your Kratky system to ensure that the seeds have germinated. Once you start seeing small seedlings, make sure to thin them out, as you should only grow one plant inside a container.
Harvesting Lettuce
If you are growing loose leafed lettuce, the easiest way to harvest is by picking the outer leaves on the bottom. Some cultivars may require you to grow a whole head of lettuce before harvest, while others can be harvested using the “cut-and-come-again” method.
Well, that’s about all I have to share on growing lettuce the Kratky way. I really hope this helps you out in your own endeavors.
If you feel that I might have missed something, or you’d like to see more guides like this on how to grow plants, feel free to leave a comment down below, and I’ll see what I can do!
Until next time, wherever you live in the world, enjoy life and happy gardening!