Basil care

Light

Basil is a sun-lover and needs the brightest spot in the home to thrive. 6+ hours of direct sun or a strong grow light indoors. Low light produces leggy plants with weak flavour. Indoors that almost always means a south or west-facing windowsill in the northern hemisphere. Plants moved abruptly from low light to direct sun will scorch — acclimate them over 7-10 days by giving a little more sun each day.

Watering

Water basil when the top 1 cm of soil is dry, often every 1-2 days in summer. The actual day count varies with pot size, light level, and the season — the finger test (or, better, lifting the pot to feel its weight) is more reliable than a calendar. Empty any drainage saucer after watering so the pot is never sitting in water. Basil wilts dramatically when dry but recovers quickly with water. Avoid wetting leaves at evening to prevent fungal disease.

Soil and pot

Basil grows best in rich free-draining potting compost or garden loam. Standard potting compost or compost-amended garden soil; pH 6.0-7.5. A pot with a working drainage hole is non-negotiable for this species — even free-draining mix will turn soggy in a closed planter. If you love the look of a decorative pot without a hole, use it as a cachepot around an inner nursery pot you can lift out to water.

Humidity and temperature

Basil sits happiest at around 40-60% (outdoor) humidity and 18-30°C (65-85°F). Average outdoor humidity is fine. If you keep the room above 18 year-round and avoid placing the plant near a cold draught, a hot radiator, or an air-conditioning vent, you have already handled the two biggest indoor stressors.

Fertilising

Feed basil sparingly. Half-strength balanced liquid feed every 2-3 weeks during the growing season; nothing fancy needed. Skip fertiliser entirely on a stressed, recently-repotted, or actively wilting plant — fertiliser salts make damage worse, not better. Wait for a round of healthy new growth before resuming a feeding rhythm.

Common problems

Below are the issues we see most often on basil in the Growli community. Where a problem matches one of our diagnostic guides, click through for the full step-by-step recovery plan written for basil specifically.

• Yellow lower leaves — Overwatering, nitrogen depletion, or downy mildew.
• Curling leaves — Heat stress, aphids, or thrips.
• Brown leaf spots — Bacterial leaf spot or downy mildew — water at the soil line.
• Drooping leaves — Either underwatering or fusarium wilt; check soil moisture first.
• Bolting (flowering) — Pinch flower buds the moment you see them to extend leaf production.

Companion plants

Basil pairs well with Tomato, Pepper, and Marigold. These are species with similar light and water needs, so you can grow them in the same bed or container without conflict.

Propagation

Direct-sow seed after the last spring frost, or root tip cuttings in water in a week. Propagation is the cheapest, most satisfying way to expand a collection — and it doubles as insurance against losing a mature plant to an accident. Take a backup cutting once the parent is established and healthy.

Toxicity to pets

Basil is pet-safe. ASPCA lists Ocimum basilicum as non-toxic to cats and dogs. Safe to grow on the kitchen windowsill. If you keep cats, dogs, or curious children in the house, weigh placement carefully — a high shelf or a hanging planter is enough for casual safety. For severe ingestion incidents, call your local vet and the ASPCA Animal Poison Control Center (in the US, 888-426-4435).

Pet-safety status is sourced from the ASPCA Toxic and Non-Toxic Plant List, which catalogues the most-asked-about plants for cats, dogs, and horses.

Basil deep-dive guides

Every aspect of basil care, each with its own calibrated guide:

• Basil watering schedule
• Basil light requirements
• Best soil mix for basil
• Basil fertilizing guide
• When to repot basil
• How to propagate basil
• Basil growth rate & size
• Basil cold hardiness
• Basil temperature & humidity
• Is basil toxic to cats & dogs?

Related guides

Basil is also commonly called sweet basil or Genovese basil.

• Diagnose basil symptoms — yellow leaves, drooping, brown spots, and more
• Herb garden care — light, water and common problems
• Mint care — light, water and common problems
• Rosemary care — light, water and common problems
• All 200 plant care guides in the Growli library