- Prepare consistent, labelled seedlings.
- Establish moisture contact in different methods.
- Measure propagation losses and establishment.
01 / Start with the final system
Select a crop and cultivar suited to the light and temperature you can maintain. Work backward from the basket, collar or pot that will receive it. A plug that fits at sowing may be too large for the final opening or too short to contact water.
Use clean trays and a uniform propagation medium. Label cultivar, seed lot and sowing date. Start a few extra seedlings to allow selection without crowding the final system.
Reading: Small-scale hydroponics ↗ · Growing Lettuce in Small Hydroponic Systems (HS1422) ↗
02 / Germinate evenly
Prepare plugs according to their instructions, wet them evenly and avoid a pool that submerges the seed. Sow at the crop’s recommended depth. Maintain germination temperature and humidity, then provide appropriate light as seedlings emerge.
A humidity cover can help initial moisture retention but needs management after emergence. Persistent condensation and stagnant conditions are not a substitute for observing plug moisture and seedling health.
- Clean the tray and prepare labelled plugs. Keep seed and clean tools away from used root debris.
- Sow at the recommended depth and maintain uniform moisture without flooding the seed.
- After emergence, provide light and ventilation appropriate to the crop; avoid suddenly drying plugs while removing the cover.
- Introduce the crop’s seedling nutrition as its guidance requires. Measure dilute batches accurately.
- Select compact, actively growing plants with intact roots. Reject diseased or damaged starts rather than sharing their drainage.
Reading: Small-scale hydroponics ↗
03 / Make the moisture connection
Inspect the destination before moving a plant. In NFT, the roots or plug must actually reach the shallow wet zone. In DWC, roots reach the solution while the crown stays above it. In drip media, pre-wet the receiving medium and locate delivery where the initial root system can access it.
Handle a seedling by its plug or support rather than squeezing the stem. Guide roots through openings without pulling. Keep plugs supported so watering cannot wash them into a drain. Record the transplant date and source of every batch.
| Destination | Check at transplant | Check the next day |
|---|---|---|
| NFT | Root or plug reaches the film | No dry upstream or downstream plugs. |
| DWC / raft | Lower roots contact solution; crown clear | Air delivery and level remain correct. |
| Drip bucket | Moist receiving medium and emitter contact | Moisture spreads beyond the small plug. |
| Kratky | Initial root contact beneath fixed support | Seedling remains moist before roots elongate. |
04 / Establish and evaluate
Observe new transplants more often during their first exposure to the final light and airflow. A nursery-grown seedling may need a gradual transition. Check the least vigorous plants rather than treating the average appearance as proof all positions work.
Record germination percentage, transplant losses and days to establishment. Compare batches with the same cultivar and conditions before blaming the growing method. These simple records expose a propagation bottleneck that a larger production system would otherwise amplify.
FIELD QUESTIONWhat is the first check when a new NFT seedling wilts but the pump is running?
Confirm its roots or plug actually touch the shallow nutrient film. Pump operation does not guarantee contact at each planting position.
Parts & buying criteria
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.
Supplier links can be added by the publisher. The criteria stand independently.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.
Supplier links can be added by the publisher. The criteria stand independently.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.
Supplier links can be added by the publisher. The criteria stand independently.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.
Supplier links can be added by the publisher. The criteria stand independently.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.
Supplier links can be added by the publisher. The criteria stand independently.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.
Supplier links can be added by the publisher. The criteria stand independently.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 Minnesota ExtensionSmall-scale hydroponics ↗
Root support, transplanting, light, aeration and cleaning.
- University of Florida IFAS ExtensionGrowing Lettuce in Small Hydroponic Systems (HS1422) ↗
Lettuce system choice and management.
The next useful connections.
From reservoir to roots.
Follow a nutrient film system from its first inlet to its last root. Learn what each part does, what to inspect, and how the pieces work together.
12 min + model exploration →Crops & environmentLeafy greens and herbs: plan a repeatable crop
Choose a first crop, manage spacing and harvest timing, and avoid forcing every herb into lettuce conditions.
6 min + guided practice →