Wick System Classroom Science Kit

At a Glance

How This System Works

This classroom-friendly wick system transforms recycled 2-liter soda bottles into self-watering hydroponic planters. Each bottle is cut in half — the bottom half becomes the nutrient reservoir, and the inverted top half becomes the planting chamber. A cotton or nylon wick threaded through the bottle neck draws nutrient solution upward into the growing medium by capillary action.

Students can observe root growth through the clear bottle walls, track plant development over days and weeks, and learn the fundamentals of plant science without soil. The system uses no electricity, no pumps, and produces zero noise — ideal for any classroom environment.

Why recycled bottles? They are free, transparent (great for observing roots and water levels), and teach students about repurposing materials. Each student or small group can build and maintain their own bottle garden.

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.

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Containers

Recycled 2-liter soda bottles, one per student or group:

No purchase needed. Collect clean, empty 2-liter bottles from the cafeteria, students, or staff. Remove labels and rinse thoroughly.

Wick Material

Cotton or nylon wick cord draws the nutrient solution into the growing medium. The wick is the easiest part of this whole system to improvise. Strips of an old cotton t-shirt (cut 1 inch wide), cotton shoelaces, cotton rope, or even strips of felt all wick water effectively. The whole point of a wick system is simplicity, so use whatever absorbent material you have on hand. If you would rather buy a spool, cotton wick cord (50 ft) gives you enough for dozens of bottles.

Growing Supplies

Starter plugs: Sponge pieces or cotton balls hold seeds just fine until they sprout. For a classroom, this is a great way to teach resourcefulness. If you want something purpose-made, Rapid Rooter plugs (50-pack) are easy for students to handle.

Nutrients: This is one item you do need to purchase. Plants in perlite have no natural source of minerals, so they need a dissolved nutrient solution. One bottle lasts an entire school year. A General Hydroponics Flora Series (3-part kit) is the classroom standard.

Monitoring

A pH/EC meter helps students learn about water chemistry (one per classroom is sufficient). pH test strips from a pet store are a budget option and still teach the concept of pH measurement. For digital readings, a digital pH and TDS meter kit makes a great shared classroom tool.

Additional Materials (no affiliate link)

• Perlite or vermiculite, lightweight growing medium, one small bag is enough for 10+ bottles
• Cotton string, cotton shoelaces, or strips of cotton t-shirt, alternative to purchased wick cord
• Seeds: basil, lettuce, parsley, or radish microgreens
• Permanent markers for labeling bottles
• Masking tape or stickers for labeling and decorating

Tools

Simple tools safe for classroom use:

• Scissors or utility knife (teacher use for cutting bottles)
• Nail or pushpin, for poking the wick hole if needed
• Ruler for measuring
• Measuring cup or syringe for mixing nutrients

Build Instructions

Step 1: Collect and Clean Bottles

• Gather one clean, empty 2-liter soda bottle per student or group
• Remove labels by soaking in warm water for 10 minutes and peeling
• Rinse the inside thoroughly with clean water
• Let bottles dry completely

Step 2: Cut Each Bottle in Half

• Using scissors or a utility knife (teacher or adult supervision required), cut each bottle roughly in half, about 4 inches up from the bottom
• The bottom half becomes the reservoir (it should hold about 2 cups of liquid)
• The top half (with the neck and cap) becomes the planting chamber
• Cut edges may be sharp — fold a strip of masking tape over the cut edges for safety

Step 3: Prepare the Wick

• Cut a piece of wick cord about 8–10 inches long
• Thread the wick through the bottle neck opening from the outside
• About 3–4 inches of wick should hang below the neck (into the reservoir)
• About 4–5 inches should extend upward inside the planting chamber, fanned out
• If the wick slides through too easily, tie a small knot on the inside to hold it in place

Alternative wicks: Cotton shoelaces, strips of old cotton t-shirts (cut 1 inch wide), or cotton twine all work. Avoid synthetic materials that do not absorb water.

Step 4: Add Growing Medium

• Fill the inverted top half (planting chamber) with perlite or vermiculite
• Fill to about 1 inch below the cut edge
• The wick should be buried in the medium and fanned out for maximum moisture distribution
• Do not pack the medium tightly — loose fill wicks better

Step 5: Mix the Nutrient Solution

Keep it simple for the classroom:

• Use clean water at room temperature
• Mix hydroponic nutrients to quarter strength for young seedlings
• Target pH: 5.5–6.5 (use this as a teaching moment about pH)
• Target EC: 0.5–0.8 mS/cm

Prepare about 1 cup (250 ml) of solution per bottle.

Step 6: Assemble the System

• Pour the nutrient solution into the bottom half of the bottle (reservoir) until it is about 2 inches deep
• Invert the top half (planting chamber with wick) and nest it into the bottom half
• The bottle neck should point downward, with the wick hanging into the solution
• The top half should sit securely inside the bottom half

Step 7: Plant Seeds

• Make a small depression in the center of the perlite surface
• Place 2–3 seeds in the depression and cover lightly with medium
• Mist the surface gently with water to start germination
• For larger seeds (basil, lettuce): push seeds 1/4 inch into the medium
• For microgreens: scatter seeds densely across the entire surface

Step 8: Label and Place

• Have each student label their bottle with their name, the plant variety, and the date
• Place bottles on a sunny windowsill, or under a classroom grow light
• Arrange bottles in a tray to catch any drips and keep the area tidy

Nutrient Guide

Young plants and classroom crops need gentle feeding.

Classroom tip: Have students measure and record pH and EC weekly as part of a science journal. This teaches data collection and scientific observation skills.

Crop Suggestions

For short projects (1–2 weeks): Choose microgreens — radish, sunflower, or broccoli. Students will see results within the typical unit timeframe.

For semester-long projects: Choose basil or lettuce for sustained growth, observation, and multiple harvests.

Estimated Cost

Classroom Integration Ideas

This project supports multiple curriculum standards and subjects:

Science

• Plant biology: photosynthesis, transpiration, root structure, nutrient uptake
• Chemistry: pH measurement, solution concentration, dissolved minerals
• Scientific method: form a hypothesis (which plant grows fastest?), collect data, draw conclusions

Math

• Measure and graph plant height daily or weekly
• Calculate growth rates (inches per day)
• Compare averages across different plant varieties or nutrient strengths

Environmental Studies

• Discuss water conservation — hydroponics uses up to 90 percent less water than soil farming
• Explore food systems and where produce comes from
• Talk about recycling and repurposing materials

Journaling and Writing

• Students maintain a plant journal documenting observations, measurements, and drawings
• Write a summary report at the end of the project

Tips & Troubleshooting

General tips:

• Pre-soak wicks in water before building to ensure they start wicking immediately
• Clear bottles let students see root growth and water levels — use this as a teaching tool
• If algae becomes an issue, wrap only the reservoir portion with opaque material and leave the planting chamber clear
• Have students compare a wick system plant to a soil-grown plant side by side for a great experiment

Maintenance Schedule

Daily (student responsibility)

• Observe and record: is the plant growing? Any changes in leaf color, height, or appearance?
• Check that the wick is still in contact with the reservoir solution

Every 2–3 Days

• Check reservoir level — the solution should be at least 1 inch deep; top off with fresh nutrient solution as needed
• Mist the surface lightly if the medium appears dry on top (especially during the first week)

Weekly

• Measure and record plant height and number of leaves in a science journal
• Test pH of the reservoir and discuss findings as a class
• Rotate bottles for even light exposure

Every 2 Weeks

• Replace the nutrient solution — pour out old solution, rinse the reservoir, refill with fresh mix
• Inspect wicks — replace if they feel stiff or are no longer drawing moisture

End of Project

• Harvest any edible crops and taste-test as a class
• Discuss results and have students present their journal findings
• Clean and store bottles and materials for the next class or semester

Frequently Asked Questions

How much does a classroom hydroponic project cost per student?

A wick system using recycled 2-liter bottles costs approximately one to three dollars per student once you have a shared bottle of hydroponic nutrients on hand. The bottles are free, a small bag of perlite covers 10 or more planters, and a single packet of seeds provides enough for an entire class, making this one of the most affordable hands-on science activities available.

What is the best plant to grow for a school science project on hydroponics?

Radish microgreens are the best choice for short projects of one to two weeks because they sprout within 24 hours and are ready to harvest in 7 to 10 days, giving students visible results within a single unit timeframe. For longer semester projects, basil is ideal because it grows quickly, smells great, produces multiple harvests, and keeps students engaged over several weeks of observation.

Can kids build a hydroponic system without electricity?

Yes, the wick system described in this plan requires absolutely no electricity, pumps, or timers. Nutrient solution is drawn from the reservoir to the roots entirely by capillary action through the cotton wick, and the plants rely on natural sunlight from a classroom window or a simple desk lamp for their light needs.

Is hydroponic growing safe for a classroom with young children?

Hydroponic wick systems are very safe for classroom use because they involve no electricity near water, no sharp moving parts, and no heated elements. The only precautions are adult supervision when cutting bottles with scissors or a utility knife, reminding students to wash hands after handling perlite to avoid dust irritation, and using the nutrient concentrate at the recommended dilution rate.