Can you grow spilanthes hydroponically? Yes. Spilanthes hydroponics is well studied in Brazil, where jambu (*Acmella oleracea*) is a commercial hydroponic crop. A 2021 study found the most leaves, flowers and biomass at 125% Hoagland strength (EC 3.3 dS/m), with pH 5.5 to 6.5 and harvest 56 days after germination.
Key takeaway: Spilanthes hydroponics lets you grow the “toothache plant” (*Acmella oleracea*), whose buzz-button flowers cause tingling and numbness, year-round indoors. NC State Extension says the plant grows 1 to 1.5 ft (30 to 46 cm) tall and comes from regions averaging 82°F (28°C) with 85% humidity. It also says it has no significant pest problems.
| Factor | Spilanthes Target | Source |
|---|---|---|
| Nutrient solution | Hoagland & Arnon, best at 125% strength | Horticultura Brasileira, 2021 |
| EC | 3.3 dS/m (125% strength); 3.5 mS/cm best in a 2024 study | Hortic. Bras. 2021; J. Agric. Food Res. 2024 |
| pH | 5.5 to 6.5 | Horticultura Brasileira, 2021 |
| Native climate | Average 82°F (28°C), 85% humidity | NC State Extension |
| Light | Full sun to partial shade | NC State Extension |
| Transplant | 21 days after germination | Horticultura Brasileira, 2021 |
| Harvest | 56 to 72 days from sowing | Hortic. Bras. 2021; J. Agric. Food Res. 2024 |
Can You Grow Spilanthes Hydroponically?
Yes. *Horticultura Brasileira* researchers note that hydroponic jambu is promising because it gives better yield and quality than the rustic field crop. In their 2021 study, plants in silica sand fed with Hoagland & Arnon solution showed no deficiency symptoms even at 25% strength, which means spilanthes hydroponics is forgiving for beginners.
- Leaves: pungent and edible raw or cooked, per NC State Extension.
- Flowers: edible sparingly; they cause tingling, salivation and numbness.
- Height: 1 to 1.5 ft (30 to 46 cm), so it fits small systems.
- Easy systems: Kratky, deep water culture or drip into inert media.
What pH, EC and Temperature Does Hydroponic Spilanthes Need?
In spilanthes hydroponics, keep pH at 5.5 to 6.5 and push EC higher than for lettuce. In the 2021 study, shoot fresh mass, flowers and leaf area all rose in a straight line with strength, peaking at 125% Hoagland (EC 3.3 dS/m). A 2024 *Journal of Agriculture and Food Research* study tested EC 0.5 to 4.0 and found best growth near 3.5 mS/cm.
- pH: 5.5 to 6.5, checked daily as in the study; see pH control.
- EC: 2.0 to 3.3 mS/cm for leaf and flower yield; see EC and TDS.
- Temperature: 75 to 85°F (24 to 29°C) (our guidance, based on the 82°F (28°C) native average and the 79°F (26°C) study site).
- Humidity: high, near the 85% of its native range, per NC State.
Note the trade-off in spilanthes hydroponics: the 2024 study reported that higher EC cut spilanthol, the tingling compound, by 25.65%.
How Do You Start Spilanthes Hydroponics From Seed?
Start spilanthes hydroponics by sowing seed into small plugs and feeding lightly. The 2021 team sowed six achenes per cell in coconut fiber, fed seedlings 25% Hoagland, thinned to one seedling at 7 days and transplanted at 21 days after germination. NC State says the plant also grows from stem cuttings, which root fast in water.
- Sow seed on the surface of coco coir plugs or rockwool; keep moist.
- Feed seedlings at quarter strength.
- Thin to the strongest seedling after a week.
- Transplant at about 3 weeks into net cups.
- Raise strength gradually toward full or 125% strength, as spilanthes hydroponics research suggests.
See our germination methods guide for plug options.
How Long Does Hydroponic Spilanthes Take to Harvest or Bloom?
About two months, which makes spilanthes hydroponics one of the faster herb projects. The 2021 study harvested at 56 days after germination, with up to 37.8 flower heads per plant at 125% strength. The 2024 study harvested at 72 days after sowing. Spilanthes hydroponics gives repeat harvests with regular picking (our guidance).
- Leaves: pick from about 5 to 6 weeks.
- Flowers: pick when the cone is fully colored; NC State lists summer and fall bloom outdoors.
- Repeat picking: cut back by a third to push new shoots (our guidance).
- Yield: up to 2.25 oz (63.9 g) shoot fresh mass per plant in the 2021 study.
Which Spilanthes Hydroponics Setup Works Best?
Any recirculating or still system that keeps roots oxygenated works. The Brazilian study used 0.5 gal (2 L) pots of silica sand wrapped in foil to keep solution cool and stop algae, with solution renewed weekly. For home spilanthes hydroponics, a small DWC bucket or Dutch bucket is simple (our guidance).
- Cover the solution: block light to prevent algae, as the study did.
- Change solution: weekly, matching the study.
- Spacing: one plant per 0.5 gal (2 L) or about 8 in (20 cm) apart (our guidance).
- Light: full sun or a strong LED; NC State lists full sun to part shade.
What Problems Should Spilanthes Growers Watch For?
Spilanthes hydroponics has few problems. NC State lists no significant pest or disease problems, and the 2021 team saw no nutrient deficiency symptoms across 25 to 125% strength. Stem length peaked at about 90% strength and fell above it, so very strong feed can make plants shorter while still raising leaf and flower yield.
- Weak flavor: lower EC slightly; high EC reduced spilanthol in 2024.
- Leggy plants: add light and pinch tips.
- Aphids or spider mites indoors: check leaf undersides; see spider mites in hydroponics.
- Escapes: NC State notes it can spread into wet areas outdoors.
FAQ About Spilanthes Hydroponics
Is spilanthes the same as jambu?
Yes; both names refer to *Acmella oleracea*, the toothache plant.
What EC is best for hydroponic spilanthes?
About 3.3 to 3.5 mS/cm for maximum growth in two studies.
What pH does spilanthes need?
5.5 to 6.5.
How long until harvest?
About 56 to 72 days from sowing.
Can I eat the flowers?
Yes, sparingly; they cause tingling and numbness.
Can spilanthes grow from cuttings?
Yes; NC State lists seed and stem cuttings.
Sources
- Horticultura Brasileira, 2021 — Productive and physiological responses of jambu (Acmella oleracea) under nutrient concentrations in nutrient solution
- Journal of Agriculture and Food Research, 2024 — Electrical conductivity effects on hydroponic jambu growth and spilanthol
- NC State Extension — Acmella oleracea (Toothache Plant)
- Photo credits (Wikimedia Commons, edited with titles): Acmella oleracea Grugapark by Tuxyso (CC BY-SA 3.0); Acmella oleracea kz05 by Krzysztof Ziarnek, Kenraiz (CC BY-SA 4.0)