The Practical Guide to the Kratky Method – Part 2: Initial Set-up

The beauty of the Kratky method is its hands-off nature. It does require some sweat equity to get started, however. Specifically, you’ll need to put together a growing apparatus. That may sound expensive, but really it is just a few plastic storage containers with some holes cut in them and possibly some lights and pest repellent. This article will walk you through the first time set-up procedures for setting up your own growing equipment.

Outdoor vs Indoor

Before you get too far, you need to decide where you will be growing your plants. Kratky plants can be grown indoors or outdoors. Each method has its own set of advantage and concerns.

Indoor Kratky

One of the reason many folks turn to hydroponics in general, and Kratky more specifically, is it allows them to extend their gardening into the winter. When it drops below freezing outside, you’re going to have a hard time growing most plants without an expensive greenhouse set-up that will often require electrical heating. Growing plants indoors using sunlight through the windows and / or grow lights is an economical alternative.

Indoor growing also offers you more control over your results. You get to set the exact light, temperature and air movement you would like for your plants. Pests like bugs, rabbits, gophers and deer are not likely to make their way indoors either. You also get some additional protection from diseases. In general, I really like the scientific feel of growing indoors. You get to pick all the variables, set them in motion, and see (and eat!) the results. It can be a very rewarding experience.

There are a few downsides to growing indoors. The most obvious one is cost — you’ll need to purchase grow lights as well as the electricity to run them. You’ll also need to provide space for your plants to grow. This can be on a large windowsill or a glass door on the sun side of the house to save electricity costs. It can also be an unused closet, cubby, basement or even attic. Just make sure that wherever you choose to grow doesn’t freeze (or get too hot)! Finally — without very expensive grow lights, you simply will never be able to supply the same amount of light as the sun. Plants grown indoors can be formidible, but will never trump the growth rate and size of those plants grown under natural sunlight. With proper set-up, this is a minor point to be sure, but it is still true.

Outdoor Kratky

Growing Kratky plants outdoors is in many ways the polar opposite of growing indoors. You use the sun for your light and the natural wind for air movement. In most ways these are superior to what you can provide plants in an indoor setting and you will be rewarded with faster growth rates and better yields. You also won’t be surprised by any abnormal electricity bill spikes.

You will also at the mercy of the elements – and the bugs. Hard freezes in the late spring can and will kill Kratky plants. In fact, they are more vulnerable to these events because normal plants in a garden can stay warm due to their proximity with the ground and all the stuff in it that creates heat. Kratky plants are generally lifted up into the air and will easily freeze – then die.

Pests are another concern for outdoor growers. Being that Kratky plants are grown off of the soil and thus away from the natural homes of most bugs, you will generally have less problems with bugs than a normal garden. However, if you grow outside, they will eventually find your plants if left unprotected. The same goes for larger animals like deer if they are a problem in your area. I have found that putting together an enclosure covered with tight netting will go a long way towards keeping bugs, birds and animals away from your garden.

Choosing Your Grow Tubs

The grow tub is the one essential component to all Kratky systems — indoor or outdoor. A grow tub can be made from any watertight container with a lid which you can cut holes into. Most first-time Kratky farmers will start with cheap plastic storage containers which can be purchased at any big box store. When choosing your grow tubs, you’ll need to consider two things:

  1. How many plants you want to grow in each tub.
  2. How long you expect the plants to live before harvest.

These factors will determine how much solution your tub will need to hold in order to allow a plant to fully grow without having to do any refilling. As we will discuss later, refilling the solution in a Kratky grow can often cause the plants you are growing to die, so it is to be avoided if at all possible.

The average temperature and humidity will determine how much water your plants will need. My personal experience is with growing perhaps the worst conditions in the country: in the dry, hot desert southwest. In my climate, a single lettuce will use about 1 gallon of solution in a 35 day growing cycle. Since this likely represents the worst case scenario you will encounter, I would recommend you plan for a 1 gallon per plant burn rate.

Therefore, if you want to grow 4 plants in one grow tub, you’ll want to find a 4-gallon tub. If all you can get is 2-gallon tubs, then plan on only having 2 plants per tub. If you live somewhere very humid or cool, you can probably get away with stretching these requirements a bit. I would recommend doing one grow first to see, and adding holes later.

Making Your Grow Tubs

Once you’ve picked out your grow tubs and decided how many plants you want in them, you’ll need to do a little bit of construction. This consists of cutting holes in the lids of the tub. If you are using the 2" net cups I recommend in the last article, your holes will need to be circular with a 2″ diameter support the net cups.

If you have a sharp box cutter and some patience, you can make some passable holes by sketching them out and cutting. Heating up the blade makes cutting plastic much easier. The best way to cut the holes, however, is to use an electric drill and a 2" hole saw. This will make cutting these holes an afterthought. Hole saw sets are also very useful to have around for home maintenance — if you need a reason to plop down the $50 USD or so.

One more construction step will need to be followed if you purchased transparent grow tubs. It is critical that your grow tubs be opaque to light so that your nutrients are spent growing your plants, and not algae. Algae not only consume nutrients, they also consume what little oxygen is able to dissolve in your nutrient solution, which will stunt your plant growth and can even cause death. To fix a transparent grow container, simply paint the outside. Spray paint is probably the easiest way to do this, but just about any paint that will stick to plastic will work. When painting, make sure you don’t forget your lid. I recommend you cut your holes before you paint as well.

Grow Lights For Indoor Kratky Plants

If you are growing indoors, you’ll need to pick up some grow lights. This is an extensive topic we will cover on this site at some point in the future. For now, I will make a simple suggestion – stick to CFL lights. These are the most cost-effective grow lights on the market, both in terms of up-front cost and electricity usage. LED lights can be cheaper to run, but often are missing parts of the light spectrum needed for optimal vegetative growth. You want your plants to grow fast when growing via the Kratky method.

I have successfully grown several Kratky lettuce crops using the “Jump Start” T5 grow light system from Hydrofarm. You can pick this up from Amazon by clicking here.

There are cheaper alternatives available, though. Pretty much any T5 system will work. If you get grow lights without a stand, make sure you pick up some way to hang them from a rack or the ceiling. I really rope clip hangars, which allow you to easily adjust the light height as your plants grow. You can also get these from Amazon by clicking here.

Other Considerations

There are a few other things you may want to think about for your Kratky set-up. Whether you are growing indoors or outdoors, I strongly suggest finding a way to elevate your grow tubs off of the ground. This will make your plants more accessible and will prevent you from tripping over them. It also makes the plants more difficult for bugs to get to — even indoors. A large rack will also allow you to several rows of Kratky plants concurrently. I found wire metal shelving racks are the most cost-effective ways to get the plants off of the ground.

For folks growing outdoors, you might want to consider some netting to further restrict access from bugs and animals. I prefer fine netting like this one. It comes in a sheet format which you can drape over whatever shelving you decide to use.

Attaching plastic labels to your grow tubs is an effective way to keep things organized.

One other thing to consider is how you will keep track of your plants. Being that I love the scientific side of gardening, the effects of different nutrient concentrations, water pH, and other factors on growth rates and plant yields interests me greatly. To this end, I like attaching plastic inserts onto my grow tubs which I can insert data cards into. I can update these cards as the plants grow and compare my results once things are finished. You can pick up self-adhesive plastic inserts from Amazon or more shipping supply stores.

Alternative Approaches

The way I am suggesting you grow your first Kratky lettuce in this series of articles is not the only way to grow Kratky style! People have gotten very creative with Kratky growing, and there are a ton of different set-ups you can view across the Internet. Here are a few of our favorites:

Raft Systems

The Kratky method can be combined with floating rafts, often made from foam. The rafts float on huge reservoirs of nutrient solutions. Plants are grown through the rafts in huge numbers. This is an excellent way to scale up your yield, if you have the space.

5 Gallon Buckets

Image courtesy of CancerUncensored.

5 gallon buckets offer an interesting grow tub. They are a bit deep, so plants must grow roots quickly to keep up, but they can be a very economical way to get started.

Mason Jars

Image courtesy of Soothing Leaf.

Smaller plants can be grown inside of mason jars via the Kratky method. This is great for growing herbs in the kitchen for use while cooking and as a neat decoration.


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