How to Choose a Kratky Kit
Kratky kits range from a single jar with one net pot to multi-site reservoirs that look like a small appliance. Knowing how to choose a Kratky kit comes down to a few features that decide whether plants thrive or struggle.
Start with what you want to grow
The plant decides everything else. Lettuce, basil and most herbs are small, fast and light drinkers, so a modest reservoir will carry them to harvest. Fruiting plants such as peppers and tomatoes grow large, drink a lot and stay in the container for months. Before comparing kits, decide what you want to harvest. The best plants for Kratky guide lists which crops suit a passive system.
Reservoir size
In a Kratky system, the reservoir is the plant's entire supply of water and nutrients, ideally for the whole crop. A bigger reservoir means more solution per plant and less chance of it running dry before harvest. When you compare kits, look at how much solution each plant gets, not just the total size. A large reservoir with many planting holes can give each plant less than a small jar with one. The Kratky containers guide gives rough sizes by plant type.
| Kit type | Plants | Best for |
|---|---|---|
| Single jar kit | 1 | Trying Kratky, one herb, a gift |
| Multi-jar kit | 3 to 6, separate jars | Several herbs, each in its own solution |
| Tote or tub kit | 4 to 8 in one reservoir | Lettuce and greens in quantity |
| Bucket kit | 1 large plant | Peppers, tomatoes and other long crops |
| Countertop kit with a light | Several | Rooms without a bright window |
Kits for children and classrooms are covered in the article on a Kratky kit for kids.
Opacity and light blocking
Light reaching the nutrient solution feeds algae, which competes with the plant and can clog roots. A good kit has an opaque reservoir and a lid that fits without gaps. Clear jars look attractive, but they need a sleeve, paint or wrap to block light. If a kit has a clear container, check whether it includes a cover.
The lid and net pots
- Net pot size. Common sizes are 2 inch and 3 inch. Larger pots give bigger plants more support.
- Spacing. Planting holes close together crowd mature plants. Lettuce heads and basil bushes need room to spread.
- Fit. The net pot should sit firmly in the lid so the plant does not tip as it grows.
- A way to check the level. Some kits have a water level indicator or a small viewing slot that can be covered. This makes it easy to watch the air gap form without lifting the lid and disturbing the roots.
Grow media
Most kits include either rockwool cubes, clay pebbles, coco coir plugs or a combination. Rockwool and plugs are good for starting seeds. Clay pebbles hold a transplant steady in the net pot. Any of them can work; what matters is that the kit includes enough for the number of planting sites. The comparison of rockwool and clay pebbles goes into the trade-offs.
Nutrients and pH supplies
A kit that includes a hydroponic nutrient saves a separate purchase, but check that it is a complete hydroponic formula and that there is enough for more than one fill. pH test strips or drops are useful; a digital pH pen is more convenient but costs more. If a kit has no nutrient, you will need to buy one. The Kratky nutrients guide explains what to look for.
Buying for someone else? The Kratky kit gift guide matches kits to the person.
Lights: included or not
Some countertop kits include an LED light on an arm. Others are just a container and expect you to use a window or a separate grow light. A built-in light is convenient indoors, but it has to be bright enough and adjustable in height as plants grow. Read the Kratky grow lights guide before paying extra for one.
Weighing a passive kit against a powered countertop garden? See Kratky kit vs AeroGarden.
Be careful with kits that are not really Kratky
Some kits sold for beginners include an air pump and air stone. Those are deep water culture (DWC) systems, not Kratky. They can grow well, but they need power and the water level is managed differently. If you want a truly passive system, choose a kit with no pump. See Kratky vs DWC kits for how the two differ.
Boxed kit or do it yourself?
A Kratky kit is easy to build from a food-safe container, a lid, net pots, grow media and a nutrient. Building your own lets you size the container to the plant. A boxed kit saves time and usually looks tidier on a counter. Both follow the same rules. The article on building a DIY Kratky kit from a mason jar shows how simple a homemade one can be.
Frequently asked questions
Should a Kratky kit include a grow light?
Only if the kit will sit away from a bright window or be used in winter. A separate LED light can be added to any kit later.
Are Kratky kits with clear jars worth buying?
They work if you cover the jars, because light on the solution causes algae. A sleeve or an opaque reservoir solves it.
What should I check in a Kratky kit listing before buying?
How much solution each plant gets, whether the reservoir is opaque, what grow media and nutrient are included, and that there is no air pump.
Is a Kratky kit good for beginners?
Yes. With no pumps or timers, a Kratky kit is one of the simplest ways to start hydroponics. The main things to get right are container size, nutrient mixing, pH and letting the water level drop.
A quick checklist
- Does the reservoir hold enough solution per plant for the crops you want?
- Is the reservoir opaque, or does it come with a cover?
- Do the net pots fit firmly, with enough space between planting sites?
- Is there grow media for every site?
- Is a complete hydroponic nutrient included, and how many fills does it make?
- Are pH test supplies included?
- Is it passive (no pump), if that is what you want?
Once you have a kit, move on to Kratky kit setup, and use the supplies checklist to see what else you may need.