- Choose crops around environment and root space.
- Plan a real succession schedule.
- Measure usable harvest and losses.
01 / Choose the crop around conditions
Leafy crops and many herbs fit small hydroponic systems because their harvest does not require supporting a heavy fruit load. Start with a named lettuce cultivar or a manageable herb and keep its batch records separate. A method that grows lettuce well does not automatically suit a long-lived mint root mass or a warm-season basil crop.
Compare the crop’s preferred season, mature size, root habit, harvest type and expected disease pressure. University of Florida’s lettuce guide emphasizes system selection and growing conditions. Use crop-specific extension guidance for temperature, light and nutrient targets.
Reading: Growing Lettuce in Small Hydroponic Systems (HS1422) ↗ · Hydro hints: Nutrient film technique ↗
02 / Design a harvest sequence
Decide whether you want whole heads, repeated leaf cuts or harvested shoots. Whole-head harvest removes the plant and opens a clean replanting position. Repeated cuts keep roots in place longer and require a longer management horizon.
Work backward from desired harvest frequency to propagation batches. If a trial takes five weeks from transplant to the desired harvest size, five equal weekly cohorts are a scheduling example; it is not a promise that every cultivar finishes in five weeks. Keep a spare clean planting zone for interruptions.
| Crop group | Useful planning question | Common system implication |
|---|---|---|
| Head lettuce | What head diameter can each position carry? | Mature spacing and uniform light. |
| Cut greens | How many cuts before quality declines? | Longer root occupancy and clean cutting tools. |
| Basil | Can the warm growing conditions be maintained? | Match environment instead of copying lettuce settings. |
| Mint | How will expanding roots be contained? | Accessible channels or individual containers. |
| Cilantro / parsley | Which cultivar and harvest stage? | Plan germination and succession separately. |
03 / Nutrient targets with context
Use a complete nutrient program and observe the crop at a documented EC and pH. For published context, UF/IFAS HS1422 describes lettuce at an ideal EC of 1.4–1.8 mS/cm and pH 6.0–7.0, while the passive HS1488 example in the Kratky chapter uses roughly 1.25 mS/cm and pH 5.5–6.0, so two publications from one institution already differ. Oklahoma State’s EC and pH guide lists crop rows such as lettuce 1.2–1.8 mS/cm (pH 6.0–7.0), basil 1.0–1.6 mS/cm (pH 5.5–6.0) and parsley 1.8–2.2 mS/cm (pH 6.0–6.5). These are the sources’ own ranges, not targets for every cultivar, system or source water. The passive lettuce example in the Kratky chapter is source-specific; it should not become a blanket herb target. Record source-water EC before fertilizer so unwanted salts are not mistaken for nutrition.
If plants grow rapidly but develop edge injury or distorted new leaves, investigate environment, airflow and root condition as well as fertilizer. Increasing calcium concentration is not a reliable substitute for restoring the conditions that permit calcium transport.
Reading: Electrical Conductivity and pH Guide for Hydroponics ↗ · Growing Lettuce in Small Hydroponic Systems (HS1422) ↗
04 / Harvest, clean and measure
Inspect for pests and damage before harvest. Use clean tools and keep leaves off the reservoir lid, floor and nutrient water. Separate unusable material from saleable or kitchen-ready yield. Record fresh usable mass and occupied growing area.
After removal, pull roots from drains and channels and clean the empty position. Compare usable output per occupied area and time, alongside labor and input costs. A large leafy plant is not necessarily an efficient or high-quality harvest.
- Label the batch and define a harvest-quality target before planting.
- Measure establishment and discard failures before they become a shared-system problem.
- Inspect light distribution and root space as canopies close.
- Harvest with clean tools, record usable mass and replant from the next prepared cohort.
- Review quality, losses and labor before changing spacing or nutrient strength.
Reading: Small-scale hydroponics ↗
Parts & buying criteria
Build your own parts & cost worksheet →
Showing nutrient film technique. Quantities describe the teaching model. Specify real working volume, support, fittings and instruments for your installation.
01Reservoir1 · illustrated quantity+
Holds the recirculating nutrient solution. This is the common sampling and refill point for both channels.
Inspect: In cutaway view, compare the water surface with the pump intake. The drawing leaves room above the water; it does not specify a working volume.
Maintain: Record the level before adding water. Inspect the cover, clean accessible deposits and keep the intake submerged during use.
Opaque, cleanable container rated by its manufacturer for the intended use; accessible lid and drain.
Check size, materials and operating conditions with your chosen supplier before ordering.02Pump & supply1 · illustrated quantity+
Lifts solution from the reservoir to the channel inlets. Cyan packets indicate the direction of delivery.
Inspect: Follow the rising supply pipe and its branch to each channel. Both inlets need an observable supply.
Maintain: Disconnect power before opening the pump. Inspect its inlet screen and confirm both branches flow after reassembly.
Compare the pump curve at the installed lift and pipe resistance; include service access and replacement availability. Supply the pump, timer and any air pump through ground-fault protection (GFCI/RCD), keep plugs and cord connections above the water line with a drip loop, and switch off and unplug before reaching into the solution.
Check size, materials and operating conditions with your chosen supplier before ordering.03Growing channels1 · illustrated quantity+
Contain the shallow stream beneath the plants and guide it toward the return.
Inspect: Open the cutaway to find the channel floor beneath the roots. The slope is exaggerated for reading.
Maintain: Look along each channel for ponding, debris or an obstructing root mat; inspect the outlet before changing the pump.
Removable covers, supported slope, smooth cleanable surfaces and outlets accessible with plants in place.
Check size, materials and operating conditions with your chosen supplier before ordering.04Plant baskets6 illustrated · illustrated quantity+
Bridge the opening in the channel cover while allowing roots to pass through.
Inspect: In exploded view, the baskets lift above the channels. The open slats reveal the relationship between support and roots.
Maintain: Check that each rim sits securely and that roots are not pinched at transplanting or inspection.
Match the basket rim and hole diameter; allow removal without damaging adjacent plants.
Check size, materials and operating conditions with your chosen supplier before ordering.05Support mediumFor 6 baskets · illustrated quantity+
The illustrated expanded clay supports the seedling in its basket. The channels are not filled with aggregate.
Inspect: Select the brown pebbles and separate the basket in exploded view. Media texture is simplified.
Maintain: Remove loose particles before installation. Inspect whether the starter plug stays appropriately moist.
Select a stable grade that stays in the basket; compare water retention, dust and cleaning requirements.
Check size, materials and operating conditions with your chosen supplier before ordering.06Gravity return1 · illustrated quantity+
Collects channel outflow and brings it back to the reservoir without a second pump.
Inspect: Trace the low ends of both channels into the common return. Inspect the full path before assuming the circuit is clear.
Maintain: Remove obstructions and check for leaks. Test drainage with the pump off during commissioning.
Removable unions, supported pipe and sufficient drain capacity under the actual installation conditions.
Check size, materials and operating conditions with your chosen supplier before ordering.Evidence beside the lesson.
Source checks: September 2026. The geometry, inspection exercises and worksheets are original teaching material. The named organizations have not endorsed or reviewed this site.
Published recipe rates and planning ranges retain their source context. Calculator equations are accounting tools; they do not predict uptake, yield, toxicity or safe stocking. Model dimensions, water speeds, roots and fish counts are illustrative. Verify species, crop, source water and product labels for a real system.
- University of Florida IFAS ExtensionGrowing Lettuce in Small Hydroponic Systems (HS1422) ↗
Lettuce system choice and management.
- Oregon State University ExtensionHydro hints: Nutrient film technique ↗
Channel slope, root space and flow continuity.
- Oklahoma State University ExtensionElectrical Conductivity and pH Guide for Hydroponics ↗
Water analysis, salinity, pH and monitoring.
- University of Minnesota ExtensionSmall-scale hydroponics ↗
Root support, transplanting, light, aeration and cleaning.
The next useful connections.
Kratky: manage the water and the air gap
Grow a short-cycle crop without circulation, with enough starting solution and a fixed support that preserves the developing air zone.
6 min + guided practice →Media & propagationFrom seed to a working root system
Start consistent seedlings, establish root contact and transplant without importing avoidable problems.
6 min + guided practice →Crops & environmentLight, temperature and humidity
Measure the growing environment at the canopy and root zone, then adjust one limiting condition at a time.
Interactive tool · 6 min + guided practice →Build, operate & troubleshootOperating costs and sensible scaling
Build a complete cost ledger, measure energy and labor, and expand from usable production evidence.
Interactive tool · 6 min + guided practice →ComparisonsReady-made kits vs DIY hydroponics: sites, light, pods and repairs
A boxed countertop garden and a drilled bucket meet the same needs; they differ in who chooses the light, the consumables, the meter and the spares.
8 min + guided practice →Crops & environmentHydroponic lettuce from seed to harvest: EC, pH, timing and spacing
A lettuce-only crop plan: published germination, transplant, solution, temperature, light and harvest figures, and the calendar that ties them together.
7 min + guided practice →Crops & environmentBasil in deep water culture: warmth, EC, pinching and downy mildew
Basil thrives in an aerated root bath if you treat it as the warm-season crop it is, feed it at its own published range and cut it so it branches instead of flowering.
8 min + guided practice →