Growing Plants Hydroponically: David's Greenhouse Experiment

Jun 16, 2021by David Schulze

Can you build a practical hydroponic system without buying an expensive ready-made kit? That question inspired David's original greenhouse experiment at David's Garden Seeds®.

Hydroponics grows plants without garden soil, supplying roots with water, dissolved nutrients and oxygen through a managed system. Plants still need suitable light, temperatures, space and regular attention. Our early project offered lessons about construction and crop care, not a controlled comparison or a tested construction plan.

The Original Greenhouse Concept

David planned a pipe-based layout using shelving in a 12-by-12-foot greenhouse. The initial list included approximately 96 feet of 4-inch pipe, elbows, end caps, a five-gallon bucket, a small pond pump and a timer.

That list records a concept, not a complete specification. A working design also needs appropriate supports, drainage, root space, reservoir capacity, oxygen supply, nutrient management, electrical protection and cleaning access.

Layout, Connections and Leak Testing

David positioned pipes along shelving and included cleanout access. He initially hoped to leave joints unglued for flexibility, but they needed gluing in practice.

Verify that pipes, fittings and joining products suit the intended edible-crop growing application. Drainage or sewer pipe is not automatically appropriate for nutrient circulation; check manufacturer suitability information.

Establish the intended flow path before planting. Different systems require different slopes, water depths and operating schedules. Test with clean water, checking connections, pump output, return capacity and what happens when power goes off and returns. Allow reservoir space for returning water.

A timer and pond pump do not suit every design. Follow a documented design rather than copying an incomplete material list.

Mark Planting Sites and Plan Maintenance Access

David found that marking openings in advance would have made work easier. Lay out a straight reference line and spacing before cutting. Size openings for the actual net cups or supports and leave access to inspect roots and clean channels.

Use tools and accessories as their manufacturers direct. Secure work, disconnect power before adjustments and follow instructions for protective equipment. Do not reverse saw blades or improvise unsupported cutting methods.

Videos from the Original Build

These historical videos show project stages, not current equipment instructions or a complete safe design. Verify techniques and materials before copying them.

What Actually Happened

The planting list was ambitious, but recovery from surgery and running the business limited monitoring and recordkeeping. Plants became crowded, ventilation was inadequate and some plants went into the compost pile. The original system was taken down rather than continued in that condition.

Cherokee lettuce stood out in the notes as growing well and providing good eating. We did not record a complete comparison of all listed varieties, so the list is not a ranking of proven hydroponic performers.

Plans for a future restart at our country mini-farm belong to the project's history, not a report of what is currently growing.

The Original Vegetable Trial List

These varieties were selected or considered. Inclusion does not confirm successful harvests or current store availability.

Broccoli: Arcadia, Calabrese, De Cicco, Marathon and Raab Spring. Raab differs from heading broccoli.
Cabbage: Chinese Red Dragon, Dutch and Red Express.
Cauliflower: Amazing, De Purple, Flame and Sicilian Violet.
Collards: Champion, Georgian Southern, Morris Heading and Vates.
Cucumbers and related crops: Calypso, Suyo Long, Diva and Mexican Sour Gherkin. The latter, or cucamelon, is a different species from standard cucumber.
Eggplant: Patio Baby, Casper, Clara, Long Purple and Orient Charm.
Kale: Olympic Red, Winterbor, Red Russian and Toscano.
Lettuce: Buttercrunch, Cherokee, Crispino, Red Sails, Rouge D'Hiver, Encore, Premium Salad Mix and Fivestar Greenhouse Mix.
Peppers: Gourmet, Islander, Mad Hatter, Bangkok cayenne and Earl jalapeño were among the names recorded.
Spinach and substitutes: Abundant, Space and New Zealand spinach. New Zealand spinach differs from true spinach in crop type and preferences.
Tomatoes: Cherry Patio, Sun Gold and Campbell's 33.

Large brassicas, vines and fruiting plants require more space, support and maintenance than a small lettuce planting. David omitted beefsteak tomatoes from the trial because of size concerns, not because hydroponic production is impossible.

The Herbs on the Trial List

The list included several basils, garlic chives, cilantro, cutting celery, dill, oregano, parsley, rosemary, sage, winter savory, red shiso and thyme, along with dandelion, echinacea, epazote, lavender and rue.

These plants have different needs. Fast-growing basil should not automatically receive the same management as slow-growing woody herbs. Inclusion in a trial list is not advice to eat every plant or use it medicinally.

Begin with Fewer Compatible Crops

Lettuce and a few culinary herbs can make a manageable first trial, with less support and space than large fruiting crops. Choose a small group with compatible requirements and expand after establishing a workable routine.

A shallow channel intended for greens may not accommodate a mature tomato's roots, weight and long season. Even compact varieties need enough root space, light and nutrition.

Water, Nutrients and Oxygen All Matter

Use nutrients formulated for hydroponics and follow crop- and system-specific directions. Ordinary garden fertilizer may not dissolve or supply the right balance.

Monitor pH and electrical conductivity, or EC, with suitable equipment. Appropriate targets depend on crop, growth stage, source water and nutrient program. One setting does not necessarily suit lettuce, peppers and tomatoes equally well.

Roots need oxygen, supplied through aeration, moving solution or an intentionally managed air space depending on design. Check water levels, pumps and tubing and follow the actual system's operating instructions.

David's Notes on Static Hydroponics

David also described using static hydroponics, distinguishing it from the earlier pump-based build concept. Static systems do not necessarily require continuous pumping, but they still require attention to solution level, root oxygen, nutrients and plant health.

In his notes, David found that draining and refreshing the water at least every two weeks once plants were growing helped his routine. He also described roots becoming tangled and was concerned about water and nutrient uptake. Those are personal observations, not a confirmed diagnosis or a universal replacement schedule.

Follow a documented method for your particular static system. Do not assume every design keeps water at one constant level, needs identical refilling or guarantees ideal nutrient absorption without monitoring.

Space, Light and Ventilation

Plan for mature leaves, roots and supports, leaving room for inspection, cleaning and harvest. Empty pipes or young seedlings can look roomy but become crowded within weeks. Stagger plantings and harvest promptly.

A warm greenhouse may still lack enough winter light. Short days can limit production; supplemental lighting may be needed for the crop and location.

In summer, air and nutrient solution can overheat. Monitor conditions at plants and roots and use appropriate ventilation, shading and climate-suited design. Air movement does not make crops immune to disease.

Match Pollination to the Harvest

Lettuce and herbs grown for leaves do not need pollination for that harvest. Fruiting crops have different requirements.

Tomato flowers are self-fertile, and gentle vibration can help pollen release under suitable conditions. Fans help airflow but do not guarantee fruit set; heat, humidity and plant condition matter.

Many cucumbers need pollen transferred between male and female flowers; some varieties set fruit without pollination. Check the variety and use crop-appropriate methods rather than expecting a fan to do every job.

Keep the System Clean and Check It Often

Keep reservoirs and channels accessible. Limit unwanted light to discourage algae, remove dead material and inspect roots and plants. Follow equipment cleaning guidance between crops.

Hydroponics and greenhouses are not pest- or disease-proof. Identify symptoms before treating and use only products labeled for the crop and growing situation.

For edible crops, use suitable water, wash hands before harvest and keep pets and contaminated material away. Do not put untreated manure or improvised compost mixtures into the reservoir.

Keep Records You Can Maintain

A notebook can record varieties, sowing and transplant dates, solution changes, pH and EC, equipment faults and harvests. A few consistent notes beat an elaborate plan you cannot sustain.

Where practical, change one major factor at a time after a failure. This helps distinguish system, spacing and temperature problems from variety performance. The cheapest materials do not necessarily make the most economical system if maintenance becomes unmanageable.