Indoor Herb Garden 101: Growing Basil, Cilantro, Parsley, Mint and More Without Soil

If you only remember one thing: grow herbs hydroponically in slightly acidic water — roughly pH 5.5–6.5 — under bright LED light of a few hundred µmol/m²/s, keep the nutrient strength moderate, and let an all-in-one kit hold those numbers steady so you can focus on harvesting.

Growing herbs indoors without soil ("hydroponics") means the roots sit in nutrient-enriched water instead of dirt. That removes the two hardest variables for a beginner — inconsistent soil and unpredictable watering — and replaces them with three numbers you can actually read and control: pH (how acidic the water is), EC (how concentrated the dissolved nutrients are), and light intensity (how much photosynthetic light reaches the leaves). Get those into range and most culinary herbs thrive on a windowless kitchen counter. This guide covers the setup and the target parameters for the common herbs; pests and diseases are out of scope here and are handled in dedicated companion guides linked at the end.

The soilless setup, in plain terms

A complete indoor hydroponic system gives every herb the same four things: clean water, dissolved nutrients at the right strength, a stable pH, and enough light. The Elfsys smart indoor hydroponic grow kit (MK1 / grow kit v1.4) is an app-controlled, all-in-one version of this — everything needed is in the box, including net cups, clay growing medium, and starter nutrients, so there is nothing to source separately. Elfsys specifies each grow layer at 59.9 cm wide × 30 cm deep × 35 cm per layer, holding 14 plants per layer (28, 42, or 56 across two, three, or four layers), fed from a 26 L reservoir (33 L on the three-layer configuration). The lighting is rated by Elfsys at 200–400 µmol/m²/s per layer (peak 450) drawing 45 W per layer — these are manufacturer specifications, not research findings.

That per-layer light rating matters because it brackets the intensities the herbs below actually want, which is exactly the useful contrast to keep in mind as you read the numbers.

pH: keep the water slightly acidic

pH governs whether dissolved nutrients stay available to the roots. Herbs are forgiving here, but they cluster in the mildly-acidic band.

For basil, a controlled study reports that a pH of 5.8 is optimum ^[1], and separate work notes that for nitrogen, zinc, manganese, potassium, iron, boron and copper together, a pH between 5.5 and 6 is most desirable ^[2]. A greenhouse extension source gives a wider working window of pH 6.0 to 7.0 for basil ^[3]. These do not truly conflict so much as describe a tight optimum (≈5.8) inside a broader tolerable range; foreground the ~5.8 target and treat the top of the 6–7 range as an outer bound rather than a goal.

For cilantro (coriander), one source reports good results at pH 5.5–6.5 ^[4] and another narrows the target to pH 5.8–6.0 ^[5] — essentially the same slightly-acidic band as basil.

Practical takeaway: aiming for pH ~5.8–6.0 keeps both basil and cilantro comfortable, which simplifies a mixed herb tray considerably.

EC: get the nutrient strength right

EC (electrical conductivity, in mS/cm or the equivalent dS/m) measures how concentrated the nutrient solution is. Too weak and growth stalls; too strong and it can stress the plant.

For basil, one hydroponic study maintained the nutrient solution at an EC of 2.0 dS/m ^[6]. A separate finding is a cautionary ceiling rather than a target: irrigation water with electrical conductivity exceeding 0.8 dS/m negatively impacted basil biomass production ^[7]. Read together, these say the starting water should be clean and low-EC, and the nutrient solution is then built up to a moderate working strength.

For oregano, the greatest biomass was achieved at an EC of 1.5 dS/m ^[8] — a slightly leaner solution than basil's.

Light: bright, but not blinding

Herbs need far more light than a typical room provides, which is why a dedicated grow light is part of the kit. Intensity is measured as PPFD (photosynthetic photon flux density) in µmol/m²/s at the leaf canopy.

Basil was grown well at approximately 250 µmol/m²/s at canopy level ^[9]. Cilantro reached its greatest growth at 300 µmol/m²/s ^[10]. Both sit comfortably inside the 200–400 µmol/m²/s per layer that Elfsys specifies for its grow light — so the kit's rated output covers the retrieved targets for these two herbs, with headroom.

Head-to-head: basil vs. cilantro at a glance

Default recommendation hierarchy

If you want a fallback ranking to start from and adjust later:

1. Set pH first, to ~5.8–6.0. It is the single lever that unlocks nutrient uptake for both basil and cilantro.
2. Then set light intensity into the low-to-mid hundreds of µmol/m²/s — the range the retrieved basil (~250) and cilantro (~300) targets fall in.
3. Then dial EC to a moderate solution strength (basil ran well at 2.0 dS/m; oregano leaner at 1.5 dS/m), starting from clean, low-EC water.
4. Then temperature and everything else — important, but the retrieved facts here don't pin a number, so treat published herb ranges as a starting point (see Further reading).

If X → choose Y: a quick decision engine

• If you want one pH setpoint for a mixed basil-and-cilantro tray → choose pH ≈ 5.8–6.0, which is inside every retrieved range for both.
• If your basil looks pale and slow despite good light → check EC; the retrieved basil solution strength was 2.0 dS/m, and starting water above 0.8 dS/m has been shown to cut basil biomass.
• If you're growing oregano alongside basil → run a slightly leaner solution (oregano peaked at 1.5 dS/m vs. basil's 2.0).
• If your herbs are leggy and reaching → raise light intensity toward the 250–300 µmol/m²/s the retrieved basil and cilantro targets used.
• If you don't want to manage any of this by hand → choose a complete, app-controlled kit that holds pH, feeding, and light on a schedule.

Exclusion boundaries — when each choice is not ideal

• A single pH setpoint is not ideal when you grow herbs with genuinely different pH preferences in the same reservoir; the shared water forces a compromise.
• The basil EC of 2.0 dS/m is not ideal when your source water already starts high in dissolved solids — building nutrients on top of hard water pushes total EC past what the retrieved evidence supports.
• High light (~300 µmol/m²/s) is not ideal when seedlings are just emerging; young herbs establish under gentler light before ramping up.
• A soilless kit is not ideal when you specifically want woody perennials (rosemary, thyme) as long-term shrubs rather than as harvestable indoor herbs — their soilless parameters were not retrieved for this article.

Pests and diseases — covered elsewhere

Pests and diseases are deliberately out of scope for this setup-and-parameter guide. For the two most common indoor problems, see the companion guides: basil downy mildew at /blogs/news/basil-downy-mildew-indoor-growing, and fungus gnats and shore flies at /blogs/news/hydroponic-lettuce-fungus-gnats-and-shore-flies.

FAQ

Do I need to know anything about pH before I start? No. The targets are simple — aim for roughly pH 5.8–6.0, which suits both basil and cilantro — and a complete kit ships with everything needed to reach and hold it, so a first-time grower doesn't have to master the chemistry.

What's the easiest herb to start with hydroponically? Basil is a reliable first herb: it has well-documented targets (pH ~5.8, ~250 µmol/m²/s of light, ~2.0 dS/m nutrient EC) and it grows fast enough to give a beginner quick, encouraging results.

Can I grow several different herbs in the same system at once? Yes. Basil and cilantro share nearly the same pH and light band, so they co-exist happily in one tray; a single grow layer holds 14 plants, and the kit scales to 28, 42, or 56 across additional layers.

How much light do indoor herbs actually need? More than a windowsill provides. Retrieved targets put basil near 250 µmol/m²/s and cilantro near 300 µmol/m²/s at the canopy — both within the 200–400 µmol/m²/s per layer that the Elfsys grow light is rated to deliver.

References

1. Europe PMC — basil optimum pH is 5.8 (KB fact #762)
2. Europe PMC — basil pH 5.5–6.0 is most desirable for nutrient availability (KB fact #764)
3. UMass Center for Agriculture, Food & the Environment — basil working pH range of 6.0–7.0 (KB fact #1972)
4. OpenAlex — cilantro (coriander) pH balance of 5.5–6.5 (KB fact #920)
5. OpenAlex — cilantro pH 5.8–6.0 (KB fact #1578)
6. OpenAlex — basil nutrient solution maintained at EC 2.0 dS/m (KB fact #782)
7. Europe PMC — basil biomass fell when irrigation water EC exceeded 0.8 dS/m (KB fact #657)
8. OpenAlex — oregano best biomass at EC 1.5 dS/m (KB fact #1082)
9. Europe PMC — basil grown at ~250 µmol/m²/s PPFD at canopy (KB fact #632)
10. Europe PMC — cilantro greatest growth at 300 µmol/m²/s PPFD (KB fact #827)

• Companion guide: basil downy mildew (indoor growing) — /blogs/news/basil-downy-mildew-indoor-growing
• Companion guide: hydroponic fungus gnats and shore flies — /blogs/news/hydroponic-lettuce-fungus-gnats-and-shore-flies

Further reading (from model knowledge — not retrieved, not verified)

The points below come from general horticultural knowledge, not from the knowledge base retrieved for this article. They were not retrieved and are not verified here — treat them as starting points and confirm against a trusted source before relying on them.

• Temperature targets were not retrieved for this article. Most culinary herbs are grown as warm, comfortable-room crops rather than in heat or cold, but no specific temperature value survived relevance filtering for this brief, so no number is asserted here.
• Parsley parameters (pH, EC, light) were not retrieved for this article. Parsley is a slow-to-germinate, cool-tolerant herb commonly grown hydroponically, but its target values were not retrieved here.
• Mint parameters, including its daily light integral (DLI), were not retrieved for this article. Mint is vigorous and spreads readily, which is why growers often give it its own reservoir space; specific setpoints were not retrieved here.
• Chives, rosemary, and thyme — their DLI (daily light integral, the total daily light dose) was queried and returned nothing usable for this article. Chives are grass-like and forgiving; rosemary and thyme are woody Mediterranean herbs that generally prefer brighter light and leaner feeding, but no retrieval-grade DLI value is available here.
• Cilantro DLI was queried and returned nothing usable for this article, and cilantro EC was not retrieved here — only cilantro's pH and PPFD targets came back with recommendation-grade values.
• Oregano light — both its PPFD and its DLI were queried and returned nothing usable for this article. Only oregano's nutrient EC (1.5 dS/m) was retrieved; its light targets were not, so pair the retrieved EC with a herb light level in the same general range used for basil and cilantro until a verified oregano figure is available.