Kratky Balcony Salad Garden

At a Glance

How This System Works

The Kratky method is passive hydroponics at its simplest — no pumps, no timers, no electricity. Plants sit in net cups inserted through holes in the lid of a storage tote filled with nutrient solution. As the plant drinks the water down over days and weeks, an air gap forms between the water surface and the lid. Roots in this air gap absorb oxygen while submerged roots take up water and nutrients.

This plan scales the Kratky approach to a full salad garden by using 10 small storage totes arranged on a balcony. Each tote holds 4–6 plants, giving you 40–60 plants producing salad greens and fresh herbs simultaneously. With staggered planting dates, you can harvest a complete mixed salad every few days throughout the growing season.

Why a balcony? Balconies receive natural sunlight (no grow lights needed), provide fresh air circulation, and the totes tuck neatly against railings or walls. Even a 4-foot-wide balcony has room for this setup when totes are arranged in two rows of five.

Materials List

Our philosophy: Use what you already have. Hydroponics does not require store-bought equipment. People around the world grow food this way using recycled containers, scraps of fabric, and seeds saved from last season's harvest. The links below are for convenience if you prefer to purchase, but we encourage you to improvise with what is available to you.

This page contains affiliate links. If you purchase through them, we may earn a small commission at no extra cost to you. Learn more

Containers

Use what you have: Any opaque plastic container that holds a few quarts of water works. Old takeout containers, ice cream tubs, small buckets, or even cleaned-out coffee cans. You need ten of them for the full garden, so raid your recycling bin. If they let light through, wrap them in aluminum foil or tape.

If you want matching totes: Dark storage totes look tidy on a balcony and block light without modification. Dollar stores often carry small dark totes that work just as well.

Net Cups

Use what you have: Cut the bottom off small plastic cups (bathroom-size Dixie cups work great) and poke holes around the sides. For leafy greens with small root systems, this is all you need.

Buying new: 3-inch net cups (25-pack) are cheap and last forever. You will need about 50 to 60 for the full 10-tote setup.

Growing Supplies

Use what you have: Wrap a seed in a small piece of damp sponge or cotton ball and tuck it into the net cup. Seeds will sprout in almost anything that stays moist. You can also start seeds in damp paper towels and transplant the sprouts once roots appear.

If you prefer starter plugs: Rapid Rooter plugs (50-pack) are convenient and give consistent results when you are planting dozens of seeds at once.

Nutrients: This is the one thing you really need to buy. Greens growing in water need dissolved nutrients to develop healthy leaves. One bottle goes a long way. General Hydroponics Flora Series (3-part kit) covers everything leafy greens need.

Monitoring

Use what you have: pH test strips from a pet store or pool supply aisle get the job done. For salad greens, being roughly in range (pH 5.5 to 6.5) matters more than hitting an exact number.

For precise readings: Digital pH and TDS meter kit is helpful if you plan to scale up or grow year-round.

Hole Saw

Use what you have: Trace a net cup on each lid and cut the circle out with a box cutter or sharp utility knife. A heated nail also works for poking starter holes. Just clean up rough edges so they do not damage roots.

For faster, cleaner cuts: 3-inch hole saw makes quick work of all 10 lids.

Additional Materials (no affiliate link)

• Hydroton (expanded clay pebbles) or perlite — to fill net cups around starter plugs
• Aluminum foil or black duct tape — to light-proof any totes that are not fully opaque
• Seeds: leaf lettuce, spinach, kale, basil, cilantro, arugula, or your preferred salad greens
• A small outdoor shelf or cinder blocks (optional) — to elevate totes off the balcony floor

Tools

• Drill with 2-inch hole saw attachment
• Scissors
• Measuring cup or syringe for nutrients
• Marker for labeling totes

Build Instructions

Step 1: Plan Your Balcony Layout

Measure your balcony space. A standard arrangement is two rows of five totes:

• Each 6-quart tote is roughly 12" x 8" x 6"
• Two rows of five fit comfortably in a 24" x 48" footprint
• Place totes where they receive at least 5–6 hours of direct sunlight daily
• South-facing or west-facing balconies are ideal

Tip: If your balcony has limited sun, prioritize lettuce and spinach — they tolerate partial shade better than herbs like basil.

Step 2: Light-Proof the Totes

If your totes are not fully opaque, block light from reaching the nutrient solution:

• Wrap each tote in aluminum foil secured with tape
• Or cover with black duct tape
• Dark grey or black storage totes typically do not need additional light blocking

Hold each tote up to a bright light — if you can see light through the walls, they need covering.

Step 3: Cut Net Cup Holes in Lids

Using a drill with a 2-inch hole saw, cut 4–6 evenly spaced holes in each tote lid. Space holes at least 3 inches apart to give each plant room to grow.

• For lettuce and spinach: 6 holes per lid work well
• For kale or large herbs: 4 holes per lid give more space
• Sand any rough edges so they do not damage net cups or roots

Step 4: Start Your Seeds

• Soak starter plugs in plain, pH-adjusted water (pH 5.5–6.0) for a few minutes
• Press 1–2 seeds into the top of each plug
• Place plugs in a warm, bright spot and keep them moist
• Lettuce and spinach sprout in 3–7 days; kale in 5–10 days; herbs in 5–14 days
• Seedlings are ready to transplant when they have 2–3 sets of true leaves

Step 5: Mix the Nutrient Solution

Leafy greens are light to moderate feeders:

• Use clean, room-temperature water
• Mix nutrients to half to three-quarter strength for leafy greens
• Target pH: 5.5–6.5
• Target EC: 0.8–1.4 mS/cm
• Each 6-quart tote holds approximately 5.5 quarts (5.2 liters) of solution

Step 6: Fill the Totes

Pour nutrient solution into each tote until the water level sits about 1/4 inch below the bottom of the net cups when the lid is snapped on. The bottom of each starter plug should barely touch or come within 1/4 inch of the water surface.

Step 7: Assemble and Place

• Set each starter plug into a net cup
• Fill around the plug with hydroton to hold it stable
• Place net cups into the holes in the tote lids
• Snap lids securely onto the totes
• Arrange totes on your balcony in their planned positions
• Elevate totes on a shelf or cinder blocks if the balcony floor does not get direct sun

Step 8: Stagger Your Plantings

For a continuous harvest, do not plant all 10 totes at once:

• Week 1: Plant totes 1–3 (lettuce mix)
• Week 2: Plant totes 4–5 (spinach and kale)
• Week 3: Plant totes 6–7 (herbs)
• Week 4: Plant totes 8–10 (second round of lettuce)

This gives you a rolling harvest rather than everything maturing at the same time.

Nutrient Guide

Salad greens prefer lighter feeding. Over-fertilizing causes bitter leaves.

Water top-off rule: As the water level drops, do NOT refill to the original level. The air gap that forms is essential for root oxygenation. If the tote runs very low (less than one-third full), add plain pH-adjusted water to about halfway.

Outdoor note: Totes on a balcony will lose water faster on hot, windy days due to increased plant transpiration. Check water levels more frequently during heat waves.

Crop Suggestions

Seasonal planning: In spring and fall, focus on lettuce, spinach, and kale. In summer, prioritize basil, herbs, and heat-tolerant lettuce varieties like romaine.

Estimated Cost

Tips & Troubleshooting

General tips:

• Harvest lettuce and greens in the morning for the crispest, sweetest flavor
• Use the cut-and-come-again method: snip outer leaves and let the center keep growing
• Rotate tote positions periodically if some spots get more sun than others
• Rain will not hurt the system, but prolonged heavy rain can dilute nutrients — check EC after storms
• Cover totes with shade cloth during extreme heat (above 90 F) to prevent bolting

Maintenance Schedule

Daily

• Quick visual check: do the plants look healthy? Any wilting or pest damage?
• On hot days (above 85 F), check water levels in the afternoon

Weekly

• Check water level in each tote — top off with plain pH-adjusted water if below one-third full
• Inspect for pests — aphids and caterpillars are common on outdoor greens
• Harvest mature leaves — regular picking encourages new growth

Every 2–3 Weeks

• Full solution change — dump old solution, rinse tote, refill with fresh nutrient mix
• Clean net cups if mineral buildup is visible
• Start new seed plugs to replace any totes that are finished producing

Monthly

• Inspect totes for cracks or light leaks
• Check that lids are still fitting snugly
• Assess which crops are performing best in your specific balcony conditions and adjust future plantings accordingly

Frequently Asked Questions

Can you grow a hydroponic garden on an apartment balcony?

Absolutely, and the Kratky method is one of the best approaches for balcony gardening because it requires no electricity, no plumbing, and no noisy pumps. Small storage totes arranged along a railing or wall take up minimal space, and natural sunlight eliminates the need for grow lights as long as your balcony receives at least five to six hours of direct sun per day.

How much salad can you grow on a balcony with Kratky totes?

A 10-tote Kratky balcony garden with 40 to 60 plants can produce enough salad greens for a household of two to four people on a near-daily basis when plantings are staggered every two weeks. Each tote of leaf lettuce yields enough for several large salads over a three to four week harvest window before the plants need to be replaced with fresh seedlings.

What happens to Kratky totes when it rains?

Light rain is harmless and the plants will benefit from the natural water. However, prolonged heavy rain can dilute the nutrient solution in your totes and lower the EC below effective levels, so it is a good idea to check your EC with a meter after a major storm and mix in a small amount of nutrients if the reading has dropped significantly below your target range.

What is the best lettuce variety for Kratky hydroponics on a balcony?

Leaf lettuce varieties like red and green salad bowl, oak leaf, and loose-leaf mixes are the best choices because they grow quickly, tolerate a range of temperatures, and can be harvested using the cut-and-come-again method for weeks of continuous production. Romaine and butterhead also work well but take longer to reach full size and are more sensitive to summer heat.