Basil

Think about...

Loves it hot

Basil thrives in warmth and sulks in the cold. Grow it only when temperatures are consistently warm and protect from nights below 10–12°C.

No cold feet

Plant outdoors only once soil and air are warm. Cold stress slows growth and permanently weakens plants.

Pinch for bush

Regularly pinch the growing tips to encourage branching. This gives a bushier plant and much higher leaf yield.

No flowers, please

Once basil flowers, leaf production drops and flavor changes. Remove flower buds as soon as they appear.

Even water wins

Basil dislikes extremes. Keep soil evenly moist but never soggy—dry spells followed by heavy watering stress the plant.

Feed gently

Basil prefers fertile but not overly rich soil. Light, regular feeding gives good growth without soft, weak leaves.

Harvest early, harvest often

Frequent harvesting keeps plants productive and flavorful. Never remove more than about one-third of the plant at a time.

Overview

Size (cm): 30 cm width · 50 cm height
Comfort temperature: 18-30 C
Temperature limit: 5 C
Planting temperature: 15 C
Germination time (days): 7

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General

Basil is a tender annual herb native to warm climates. It thrives in heat, strong light, and consistently moist, fertile soil. In Sweden it is best grown in pots, greenhouses, or warm microclimates outdoors.

Light

Full sun; at least 6 hours direct light, more for strong flavor.

Soil type

Well-drained, fertile loam enriched with compost.

Water requirement

Medium; consistent moisture without waterlogging.

Nutrient requirement

Medium; lightly fertile and regularly refreshed soil.

Precultivation

Sow 6–8 weeks before planting out. Use a sterile seed-starting mix and keep 20–25°C until germination. Basil requires strong light (14–16 h grow lights) and slightly reduced temperatures after emergence (18–20°C). Water lightly and allow surface to dry slightly between waterings. Avoid cold drafts.

Planting

Plant out only after nights are reliably above 10–12°C (best around 15°C). Space plants 20–30 cm apart. Basil thrives in warm, sheltered spots or containers with rich, well-drained soil. Harden off for 5–7 days before planting outdoors.

Pruning

Pinch out growing tips regularly to encourage branching. Remove flower buds promptly to maintain leaf production. Harvesting is the main form of pruning.

Maintenance

Water deeply but allow the upper soil layer to dry slightly between waterings. Mulch lightly to retain moisture. Feed with mild, organic fertilizer every 2–3 weeks. Protect from cold wind and night temperatures below 10°C.

Harvest

Harvest leaves or whole tips once plants are 15–20 cm tall. Take no more than one-third of the plant at a time. Frequent harvesting encourages vigorous, leafy growth.

Common issues

Cold stress causes leaf drop and slowed growth; avoid temperatures below 10°C. Overwatering can cause root rot. Aphids and spider mites occur in warm indoor conditions. Downy mildew can be a problem—ensure good airflow and avoid wet leaves.

Rotation schedule

Rotate annually with non-Lamiaceae herbs and vegetables. Avoid growing basil repeatedly in the same potting soil.

Pollination

Self-pollinating; grown mainly for leaves, flowering is usually discouraged.

Companion plants

Tomato, pepper, oregano, marigold.

Incompatible plants

Avoid planting close to rue (Ruta graveolens).

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