Part 1 — Bay Laurel (Laurus nobilis): What It Is and Why It’s Worth Growing
Bay laurel (Laurus nobilis) is the classic “bay leaf” plant used in soups, stews, sauces, marinades, and pickling. It is an evergreen Mediterranean shrub or small tree, prized for leaves that hold aroma even after drying. Outdoors in mild climates it can become large and woody; indoors in Sweden it behaves more like a slow-growing, long-lived potted shrub—ideal for continuous harvest if you manage light and watering correctly.
What makes bay laurel different from many common herbs
Most kitchen herbs (basil, cilantro, parsley) are fast-growing and short-lived indoors. Bay laurel is the opposite:
- Slow but durable: It grows steadily rather than explosively, and can live for many years in a pot.
- Woody evergreen: Its structure responds strongly to pruning; you can shape it like a compact shrub.
- Flavor develops with “firm growth”: Leaves tend to be more aromatic when growth is not overly soft (often caused by low light + too much nitrogen + constant wet soil).
Leaf quality: fresh vs dried
Fresh bay leaves are usable, but their aroma can be “greener” and sometimes less rounded than dried leaves. Many growers harvest mature leaves, then dry them slowly to concentrate the characteristic bay fragrance. Either way, the plant is most valuable when you can pick leaves continuously without stressing it.
A realistic indoor goal: a compact, harvestable shrub
In a ~1 m² apartment footprint, success typically means:
- A bay laurel kept 50–120 cm tall, pruned for branching.
- Stable leaf production year-round (slower in winter unless you provide strong light).
- A pot large enough to buffer watering mistakes, but not so large it stays wet for too long.
The two biggest indoor challenges
- Insufficient light (leading to leggy growth): Bay laurel needs more light than many people expect for compact, aromatic growth.
- Overwatering (leading to leaf drop and root stress): In indoor conditions—especially cooler Swedish winters—pots dry slowly, and bay laurel dislikes constantly wet roots.
If you solve light and watering, bay laurel becomes one of the most reliable “perennial kitchen plants” you can keep indoors.
Part 2 — How to Grow Bay Laurel Indoors for Continuous Harvest (Compact Growth + Low Fungal Risk)
This section is designed as a repeatable operating method: set targets, measure what matters, and use simple “if-then” rules to correct problems early.
1) Choose the right growth mode: vegetative maintenance
Your goal is not flowering or fruit. You want a stable, compact shrub producing leaves continuously. That means:
- Moderate, consistent growth
- Frequent pruning/pinching to drive branching
- Avoiding extremes: too dim (leggy) or too wet (leaf drop), too much nitrogen (soft growth)
2) Environmental targets (the “sweet spot” for bay laurel indoors)
Temperature
- Best range: 18–24°C
- Acceptable: 16–25°C
- Cooler temps are fine if light is reduced, but watering must also be reduced.
Relative Humidity (RH)
- Target range: 40–55%
- If your apartment runs dry in winter, bay laurel usually tolerates it—but monitor VPD (below).
VPD (Vapor Pressure Deficit) to reduce fungal risk
VPD is a more useful control variable than RH alone. It combines temperature and RH into a measure of how strongly the air “pulls” moisture from leaves.
- Target daytime VPD: 1.0–1.4 kPa
- Try to avoid long periods below: 0.8 kPa (especially at night)
Why it matters: when RH is high and VPD is low, leaf surfaces stay humid longer and fungal issues become more likely—especially if airflow is weak.
Airflow
- Run a small circulation fan at low speed to keep air moving through the canopy.
- The goal is gentle mixing, not blasting the plant.
3) Light: the main lever to prevent legginess and improve aroma
Bay laurel indoors becomes leggy primarily due to insufficient light intensity and/or too-short photoperiod. The fix is straightforward: provide adequate PPFD at the canopy and maintain it as the plant grows.
Canopy light targets
- Preferred PPFD (at top of canopy): 300–500 µmol/m²/s
- Minimum for decent compactness: ~250 µmol/m²/s
- Photoperiod: 12–14 hours/day
- Practical DLI (daily light integral): ~13–25 mol/m²/day for strong vegetative maintenance
Light-distance strategy (to maintain PPFD as the plant grows)
- Start by setting your lamp height/dimming to hit the PPFD target at canopy level.
- As the plant grows upward, adjust one of:
- lamp height (raise the light), or
- dimming percentage (reduce intensity),
so the canopy stays in the same PPFD band.
Uniformity matters
Even if the top gets enough light, shaded sides can produce weak, stretched growth. Improve uniformity by:
- rotating the pot weekly,
- using reflective surfaces around the plant,
- or using a wider fixture/arrangement that lights the sides better.
4) Soil and pot strategy: oxygen first, then water
Bay laurel wants roots that can breathe. Indoors, the biggest mistake is not “underwatering,” but keeping the pot continuously wet.
Recommended substrate characteristics
- Well-draining and airy (think: quality potting mix improved with perlite/bark)
- A pot with reliable drainage holes
- A saucer is fine, but never let the pot sit in water long-term
Moisture strategy (the rule that prevents most problems)
Water thoroughly, then wait for a meaningful dry-down before watering again.
A robust approach is to use pot weight (load cell) or a “lift test”:
- Water to saturation (a little runoff).
- Let the pot dry until it is clearly lighter before watering again.
This prevents the slow decline that happens when roots sit wet in cool indoor air.
5) Nutrition: steady and moderate, not aggressive
For continuous harvest, bay laurel generally prefers moderate feeding—enough to maintain leaf color and slow growth, but not so much that growth becomes soft.
Practical feeding plan
- Use a balanced fertilizer with micronutrients.
- Feed lightly during strong growth periods; reduce feeding when growth slows (often in winter if light is lower).
- If you use a slow-release fertilizer in the mix, supplement occasionally rather than frequently.
Common mistake: too much nitrogen
Excess nitrogen plus low light can produce:
- soft, weak growth,
- lower aroma density,
- more susceptibility to stress.
6) Pruning for a compact “leaf factory”
Pruning is not optional if you want compact growth indoors.
Rules of thumb
- Pinch or prune tips to encourage branching.
- Avoid letting one leader dominate (that’s how legginess starts).
- Aim for a shape that allows airflow through the canopy.
A good rhythm is “light pruning often” rather than a major cut once in a long while.
7) Instrumentation that actually improves outcomes (simple, high ROI)
You do not need a complex lab setup. A small set of sensors enables early detection and repeatability.
Tier 1 (recommended minimum)
- Air temperature + RH sensor (I²C, e.g., SHT3x)
- Lux sensor (I²C, e.g., BH1750) as a light proxy/trend monitor
- Load cell + HX711 (pot weight = the best watering signal)
- A small circulation fan (on/off or PWM)
Where to place sensors
- T/RH sensor: canopy height, shaded from direct LED radiation.
- Lux sensor: at canopy height facing upward, not shaded by leaves.
- Load cell: under pot with stable mechanics, protected from side loads/cable tension.
Why pot weight is a game-changer
It turns watering from guesswork into a controlled variable. Most indoor bay laurel failures involve watering errors; pot weight reveals them early.
8) Calibration and validation (keep it trustworthy)
- Load cell: calibrate with known weights; re-check weekly with a single reference weight.
- Lux-to-PPFD (if you don’t have a PAR sensor): do a one-time reference measurement if possible (borrow a PAR meter). Without that, treat lux as a trend/alert signal, not an absolute PPFD measure.
- Soil moisture probes: useful for trends but drift over time; validate against pot weight.
9) If–then diagnostics (fast troubleshooting)
If: the plant is leggy with long internodes
- Likely: PPFD/DLI too low, light too far away, poor side light
- Do: increase intensity (target 300–500 PPFD), maintain 12–14 h, prune tips, improve uniformity
If: leaves drop (especially older leaves) and soil stays wet
- Likely: chronic overwatering / low root oxygen
- Do: enforce dry-down, improve drainage/aeration, increase airflow, avoid cool wet substrate
If: leaf spots appear and RH is high at night
- Likely: low nighttime VPD + weak airflow increasing fungal risk
- Do: keep RH in check, run fan gently overnight, aim for nighttime VPD ≥ ~0.8 kPa when possible, avoid wetting foliage
If: leaf tips scorch
- Likely: salt stress (overfeeding) and/or air too dry (high VPD)
- Do: flush once, reduce feeding, bring VPD back toward 1.0–1.4
Summary: the indoor bay laurel success formula
If you want a compact bay laurel that produces aromatic leaves year-round in Sweden, focus on three controllable variables:
- Light: maintain canopy PPFD in a strong vegetative band and keep it there as the plant grows.
- Watering: water thoroughly, then enforce dry-down; prioritize root oxygen.
- VPD + airflow: keep humidity from spiking (especially at night) and maintain gentle canopy airflow to suppress fungal risk.