Kratky Hydroponics Setup

The Kratky method is a low-cost way to grow lettuce, arugula, herbs, and other salad greens without soil or pumps. In a Kratky bucket (or jar, or storage tote), you simply suspend a plant over a nutrient solution and let it grow as the roots gradually reach down for water and oxygen. 

This system means minimal upkeep for you, but it still delivers big, fresh harvests in just a few weeks. In this guide, you’ll gather simple, inexpensive materials (all for under $50), and build your very own Kratky hydroponics setup step-by-step. You’ll also earn a few insider tips that make passive hydroponics work in a small home setup. 

I’ll be showing you how to grow lettuce in a DIY Kratky hydroponics setup. With a simple bucket and nutrient solution, fresh greens like this butterhead lettuce can thrive in just 4–6 weeks.

Gather Materials & Budget-Friendly Tools

You’ll only need a few readily available items to get started to set up a cheap Kratky system to grow veggies and veggies at home. Here’s the list of what’s needed with estimated costs:

• Container: A 5-gallon food-grade bucket (~$5) is ideal for a single head of lettuce. You can also use a plastic storage tote or even a large jar. The container must be dark or covered to block light. 

• Lid and net pot: Drill a hole in the lid to fit a net cup (mesh plant pot). 2″-3″ net pots are inexpensive (cost: about $1 each) and hold the seedling. If you don’t have net pots, you can hack one by cutting holes in a plastic cup or using foam collars to support the plant. You could even use a clean piece of plywood with holes for net cups. More on this later.
  
• Growing medium: Small cubes of rockwool, coco coir, or clay pebbles (cost:$5–$10). You’ll place your seed or seedling in this soilless plug inside the net pot. A pack of rockwool cubes or a bag of clay balls will last for many plants.
  
• Hydroponic nutrients: You’ll want to use a water-soluble fertilizer formulated for hydroponics (cost: $10–$20). You can use a premixed three-part nutrient or a general-purpose hydroponic feed. For lettuce, I’d recommend a nutrient strength around 1.3 mS (roughly 600–800 ppm) and pH of around of 5.5. A little nutrient goes a long way; a single bottle makes enough solution for dozens of pots.

Save money by repurposing what you have. Clean out old food containers, yogurt cups, or large glass jars for net pots and buckets. Even foam or plastic bottle lids can be cut to hold seedlings. Using household containers and DIY net pots can save most of the cost. A 5-gallon bucket is only ~$5, rockwool cubes ~$8, a small nutrient kit ~$15, and inexpensive tools round out under $50.

Prepare Your Container

Set up the reservoir that will hold your nutrient solution. If you’re using a 5‑gallon bucket, drill a hole in the lid for each plant. A 2″-3″ hole matching your net pot size is standard. 

For a single lettuce, one hole is fine. For multiple plants, like in a large tote, drill evenly spaced holes, about 8″ apart. Make sure the net pot sits securely in the hole. The pot’s lip should rest on the lid edge so the net cup hangs down and its bottom just touches the water/nutrient solution.

If your container has no lid, or if you’re using a tote, lay a clean piece of plywood or plastic over the top of the container and cut holes as needed. Some hydro growers even use large rocks or support braces under a polystyrene board to hold net pots in place. Nothing should drop fully into the water; the plant must sit up with air around the top of the roots.

Lightproof the reservoir: After cutting holes, make the reservoir light‑proof to prevent algae growth. Paint the bucket or tote matte black or any dark color or wrap it in aluminum foil. The University of Florida & the Institute of Food and Agricultural Sciences recommends using a dark-colored container or covering clear ones with opaque tape. 

Even if you’re using a mason jar, cover it with foil or paint so sunlight can’t reach the nutrient solution because exposed water will quickly get green with algae. And algae will starve your roots.

Before drilling, clean and rinse the container thoroughly. Use food-safe buckets or washed recyclables. Avoid any container that previously held pesticides, paints, or strong chemicals. You want a clean, neutral environment for your kratky plants. I listed my favorite Kratky vegetables in a previous post.

Next, determine your initial fill line. After placing the net pot in the lid, raise the lid so the bottom of the net cup barely touches the bottom of the container. Then, mark on the inside where the water will reach the net pot. This is your fill line. 

When you later mix nutrients, only fill to this line. If you overfill, the plug will drown, and if underfilled, the plant will dry out. Tip: Pour water in and mark it from outside with a Sharpie for easy reference.

Mix Nutrient Solution

Time to prepare the growth solution. Fill your container with fresh water up to the mark you made , leaving that air gap so roots can breathe. 

Use room-temperature water. If using tap water, let it sit 24 hours to off-gas chlorine. If your tap water is “hard” or high in dissolved salts, filtered or rainwater works best. Very low-salt water, like reverse osmosis water, gives you the cleanest start. Since this is a low-cost Kratky set up, I just let tap water to off-gas chlorine for a day and no problems so far. 

Add hydroponic fertilizer: Follow the product’s label for your water volume. For leafy greens like lettuce and arugula, you want a moderate nutrient strength, roughly 100–150 ppm nitrogen (N), which translates to about 1.2–1.8 mS/cm EC. 

How much is that? About 1/2 teaspoon of 20-20-20 fertilizer per gallon, but be sure to check your label. Stir or shake the bucket gently until all fertilizer is dissolved and the solution is uniform. You’ll have about 3–4 gallons in a 5-gallon bucket when done.

Check and adjust pH: Keep the pH around 5.5–6.0 for most hydroponic greens. A pH drop kit or cheap test strips cost $7-ish for a roll, and it does the job. 

Tip: Pour a little solution into a separate cup to test, to avoid contaminating the whole tank/reservoir. Check the water’s pH with a meter or test strips. The Oklahoma State Extension says that hydroponic solutions “should have a pH between 5 and 6, usually 5.5.”

If the pH is below 5.5, add a little pH-up. A pH-up is a liquid that makes water less acidic. If it’s above 6.0, add a little pH-down, a liquid that makes water more acidic. A pH-up and down kit costs $20-ish. Stir well and test again, repeating as needed until the pH is between 5.5 and 6.0. 

Mix the nutrients thoroughly and let the solution sit for a few minutes. This makes any undissolved bits settle, and the pH stabilizes. Only then fill fully to the mark so you know exactly how much solution you’ve added.

As the plant grows it will use up the nutrients in the water. The goal is to use up nearly all the water by harvest time.

Planting and Starting Seeds

Transplanting seedlings in Kratky: The most reliable method is to start your lettuce or arugula seeds in a germination cube (rockwool or coco coir) and let them grow until they have a couple of true leaves. The University of Minnesota Extension advises to start seeds separately and then move them into the system after germination.  

Soak your rockwool cube in pH 5.5 water for 30 seconds to remove extra alkalinity. Plant 1–2 seeds in the cube, keep it moist in a sunny spot, and wait 1–2 weeks for roots to appear at the bottom of the cube. 

When roots just show, move the cube into the net pot on your lid. Position it so the bottom of the cube just touches the nutrient water. Only the very end of the roots dip in.

Direct seeding in Kratky: You can also sow seeds directly into the rockwool in the net pot. You want 2–3 seeds per pot and keep the cube very moist until sprouts appear. Be aware that very young seeds risk rot if oversaturated, so this method can be tricky.

Place the net pot into the lid hole and secure it with the lid or retaining ring, so the plant sits upright above the water. The bottom of the net pot should just touch the water, not submerged, but enough so the roots can wick up moisture. 

This arrangement creates the air gap above the water line that supplies oxygen to the roots as they grow and establish. The roots will stay moist by capillary action, and as the plant grows, you’ll see the water level drop.

Cover the top of the bucket when you’re done planting to keep pests out.

Tip: If using seedlings from potting soil, gently rinse the soil off the roots before transplanting to avoid contaminating your nutrient solution. Also, handle tiny seedlings by their leaves, not stems, to avoid damage.

Placement and Lighting

Lettuce and most leafy greens need bright light to grow quickly, about 6–8 hours of direct sunlight or 12–16 hours under grow lights each day. So place your bucket in a south-facing window or under a steady LED lamp. 

According to the University of Minnesota Extension, a single 9‑W LED grow light (around $15) with ~16 μmol/s output can easily light 1–2 five-gallon buckets of greens. If using LEDs, go for 12–14 hours per day for vigorous growth.

Be careful about heat and weather. If outdoors, keep the system sheltered. Excess sun on a black bucket can heat the solution too much, causing nutrient burn or bolting. Most of us in the hydro community have found that lettuce goes bitter above 80°F. 

Provide ventilation or partial shade in hot weather. Also protect your Kratky system setup from rain, as rainwater will dilute your mix. Cover your system with a simple roof or bring it indoors when it storms, or else you’ll wash out nutrients and possibly drown the roots. And if the system is indoors, avoid hanging your bucket directly under heat vents or drafty windows.

For the seedling stage, a fluorescent shop light or standard LED panel will work. Once the plant’s grown a few inches tall, move it outdoors, if the weather permits, or set it under a grow light. Keep the light source at least 6–12 inches above the top of the leaves to prevent burning, and make sure to adjust as the plant grows.

White LEDs or full spectrum grow lights work best because they give a mix of blue for compact growth) and red for leaf production. If your plants stretch too tall and spindly, try adding more blue light. In my experience, more blue light gives me crisper lettuce leaves, while more red light gives them a milder flavor.

Maintenance and Troubleshooting

1.Check water level weekly: The reservoir will gradually drop as the plant drinks. This is normal, and the goal is to finish the water right as the plant matures. Ensure the net pot bottom remains in contact with the solution. 

If the level falls too low more than a week before harvest, top up with plain water and no extra nutrients. Simply pour water to the original fill line to dilute the solution slightly. Only do this as a last resort when the leaves look droopy or the nutrient solution is very low.

2. Monitor pH: Keep an eye on your solution’s pH. Lettuce grows best around 5.5–6.0, and it’s okay if it stays between 5.0–6.5. If the pH drops below 5.0, add a tiny pinch of baking soda to raise it. If it goes above 6.5, add a few drops of vinegar or citric acid to lower it. When you’re just starting out, test every day until you feel comfortable. After that, once a week is usually enough to keep your plants happy.

3. Watch for pests: Standing water can attract mosquitoes or flies, so keep the lid covered and use a fine mesh over any large holes. If you see mosquito larvae (they look like wiggly things) in the water, remove them immediately. Floating a single drop of vegetable oil on the surface helps deter bugs.

4. Prevent algae: Even a small light leak can spur algae. If you notice green film or slime on walls of the container, re-cover the container. Algae will consume nutrients needed by your plant.

5. Temperature and ventilation: Keep your growing area around 65–75°F. Any hotter and your lettuce might bolt, meaning it flowers and turns bitter. Make sure there’s a little air movement around your Kratky buckets. A gentle breeze or open window is enough to stop mold or mildew from forming on the leaves and keeps your lettuce healthy and tasty. 

A clear plastic straw or turkey baster can let you stir the water gently if it seems stratified (nutrients settled). Just don’t aerate continuously. The whole point is the roots get oxygen from the air gap, not a pump.

6. Nutrient issues: You shouldn’t need to add more fertilizer, but if leaves develop yellow edges or spots before harvest, there’s an issue. That could mean the plant used up all available nutrients. In that case, you can add a diluted nutrient top-up. However, avoid dumping strong concentrate late in the cycle. It’s almost always better to finish the plant and start fresh with a new solution.

You may also want to read this post I previously wrote on growing with soil vs hydroponics.

Harvesting and Growth Timeline

Leafy greens like lettuce grow fast in hydroponics. From the time your seedling is transplanted, expect roughly 30 days to a mature head of lettuce. Arugula and basil follow a similar 30–45 day cycle.

Microgreens (very young seedlings) can be harvested even sooner, about 2–3 weeks in. But pure microgreen growing is usually done in shallow trays rather than Kratky buckets. Check your lettuce. When it’s full-size, about 6–8″ diameter for loose leaf or butterhead, cut it off at the base, just above the nutrient line.

It’s expected that by harvest the water is nearly gone, and the roots have expanded throughout the solution. At this point, you can discard or dilute/refresh the old solution and reuse the bucket for a new crop. You can also toss the spent water onto outdoor plants, as it’s still nutrient-rich. 

Don’t wait too long. Over-mature lettuce can become bitter. Harvest when the leaves look full and green.

You can re-use the net pot and cube or replace with fresh cube and seed if replanting. 

Staggered planting: For a constant supply of greens, start seeds every 1–2 weeks so harvests are staggered.

Kratky Mason Jars and Storage Totes

Mason jar Kratky (Quart-Scale): If space is very tight or you want to grow a single plant (like basil or microgreens like arugula), a wide-mouth quart jar works as a mini Kratky system. 

Use a 2″-3″ net cup that fits in the jar opening. Some 3″ net pots fit directly under the metal lid ring. 

Follow the same steps: Fill the mason jar with nutrient solution only up to where the bottom of the plug just touches the liquid. You want to leave plenty of air above. 

Mark your fill line on the jar first. Then place your planted cube in the net cup and screw the lid ring down to hold it. Important: Paint or cover the jar with foil so light can’t penetrate. You’ll kill the plant if the solution stays clear in the sun. 

Because a mason jar only holds a pint or quart, it’s best to plan on just one small plant. Lettuce varieties that stay compact or herbs (basil, mint, parsley) are best. Expect slightly faster depletion of water, so check this mini-kratky system once every 1–2 weeks.

Storage tote Kratky: For growing multiple lettuce heads at once, a large storage tote or under-bed container (10–15 gallons) works great. Drill one net-pot hole per plant across the lid. A common rule-of-thumb is about 1 gallon of solution per plant. 

For example, if you drill 8 holes for 8 lettuce plants, use roughly 8 gallons of nutrient water. Leave the rest of the 10-gal space as air. Fill to 80% capacity, so you have plenty of air gap. 

This many plants under one lid will need more light, so consider multiple LEDs or a larger fluorescent fixture. The extra width is nice for letting roots spread and for managing a crop, but remember: the larger the volume, the heavier the filled container.

No matter what you use, always ensure the lid and holes fit snugly to prevent evaporation and insects. Label each plant with a marker or tag if you have different varieties, so you’ll remember what’s what at harvest time.

Whether you use a pint-sized jar or a 15-gallon tote, the core Kratky principles are the same: make it dark, plant just above the water, and use the right nutrient mix. Container size mainly affects how many plants you can grow and how often you water/top off. Adjust fill volume and number of net pots accordingly.

Final Thoughts

You’ve now built your own DIY Kratky system from start to finish. Trust these steps and you will succeed: use a clean, opaque container, mix the solution correctly, and give your plants enough light. 

Common mistakes like overfilling, using a clear bucket, or neglecting pH are all avoidable with the measures and tips I’ve shared above. If something goes wrong, learn and apply the knowledge for the next crop.

With this setup you can harvest a fresh salad every few weeks for pennies. You’ll be surprised by how simple it really is. Now it’s your turn: gather your bucket or jar, mix that nutrient water, plant your seedling, and watch it grow. If you follow the advice above,  you’ll finish with crunchy, homegrown leafy greens and microgreens and the know-how to do it all over again.

How to Set Up a Kratky Hydroponics System FAQs

What’s the Easiest Hydroponic System to Make?

The easiest hydroponic system for beginners is the Kratky method. It doesn’t need pumps, electricity, or constant upkeep. You simply place a plant in a net cup above a bucket, jar, or tote filled with nutrient water, leave a small air gap so the roots can breathe, and let it grow. With good light and the right nutrients, you can harvest lettuce, arugula, or herbs in about four to six weeks.

What Do I Need for a Hydroponic System?

A basic hydroponic setup needs a dark container to keep light out of the nutrient water, a lid with a net pot to hold your plant, and a growing medium such as rockwool cubes or clay pebbles. Fill the container with a hydroponic nutrient solution mixed with clean water, and keep the pH between 5.5 and 6.0. Give your plants strong light—either from a sunny window or an LED grow light—for 12 to 16 hours each day.

How Much Will It Cost to Build a Simple Hydroponic System?

A single-bucket Kratky setup can be built for under $50, and even less if you reuse containers and supplies you already have. A food-grade bucket runs about $5, net pots are around $1 each, and growing medium costs $5 to $10. A small bottle of hydroponic nutrients usually costs $10 to $20. If you need a grow light, you can find a basic LED light for about $15, and pH test strips are around $7. You can cut costs even more by using recycled containers and making your own net pots, like drilling holes into a clean yogurt cup. If you’re resourceful, you could have a working system for well under $50.

What Can’t I Grow Hydroponically in Kratky?

You can grow plenty of plants hydroponically, but the Kratky method works best for small, quick-growing plants. Large crops like corn, pumpkins, or fruit trees will outgrow the container long before harvest. You can grow full-size tomatoes, bell peppers, and cucumbers with Kratky, but you’ll need to add aeration with a pump, give them extra support, and top up nutrients regularly. For the most reliable results, stick with leafy greens like lettuce and arugula, herbs like basil, and compact plants like cherry tomatoes.

Are Kratky Buckets Worth it?

Yes, Kratky buckets are worth it if you want fresh greens at home without fuss. They’re inexpensive, and for plants that aren’t heavy feeders, you often won’t need to top them up before harvest. You can also reuse the same bucket over and over. If you don’t want to change nutrients every couple of days, like you would with a mason jar, Kratky buckets are well worth it.

Happy gardening!