A warm-season annual herb that produces fragrant, tender leaves from early summer until the first frost, rewarding frequent harvests with bushier, more productive growth.
Ocimum basilicum · also called sweet basil, common basil
Windows are counted from the average date of your last spring frost.
Home-grown basil harvested minutes before use has a depth of fragrance that store-bought, refrigerated bunches cannot match. A single plant kept well-pinched can supply a household through the entire summer.
A little history. Native to tropical Asia and widely cultivated across the Mediterranean basin; a member of the mint family, Lamiaceae. Leaf oil glands are visible as translucent dots when a leaf is held to light.
Press seeds lightly onto moist mix; do not bury deeper than ¼ inch. Keep surface evenly moist — let it dry even once and germination stalls. Seedlings emerge in 5–10 days in warm soil.
Sow seeds ¼ inch (6 mm) deep.
Either works well — needs at least 8 inches of soil depth and excellent drainage; containers warm faster in spring. In containers: 2-gallon pot minimum; 5-gallon for multiple plants. Space plants 12 inches (30 cm) apart.
Water deeply when the top inch of soil feels dry, roughly every 2–3 days in warm weather. Water when leaves begin to droop slightly and the top inch of soil is dry to the touch. Aim for about 1 inch per week; increase in heat or containers.
Side-dress (scatter fertilizer along the base and water in) every 3–4 weeks once plants are 6 inches tall. What to use: balanced 5–5-5 organic granular or diluted compost tea; avoid high-nitrogen feeds that reduce leaf fragrance.
Pinch out the growing tip (the topmost cluster of leaves) once the plant has 3 pairs of true leaves (the full-shaped leaves that follow the first rounded seed leaves). Repeat whenever a stem reaches 6 inches. Remove flower buds the moment they appear — once a stem flowers, leaf production on that stem stops.
It's ready when harvest once a stem has at least 3 pairs of leaves. Leaves are at peak fragrance just before flower buds open. Do not wait for buds to open. Cut each stem just above a pair of leaves, leaving at least one pair below the cut. This forces two new shoots from the remaining leaf axils (the joint where leaf meets stem), doubling the branching.
Do not refrigerate — cold blackens leaves within hours. Stand cut stems in an inch of water at room temperature, loosely covered, for up to 5 days. Freeze as pesto for longer storage.
Sow a new batch of seeds every 3–4 weeks from last frost through midsummer to maintain a continuous supply and replace plants that bolt (shift from leaf growth to flowering).
Tomato
Basil's strong leaf scent can help hide tomatoes from thrips and whiteflies that locate hosts by smell, and trials show modest reductions under low pest pressure. Both crops want the same heat, sun, and steady water, so they are easy to tend side by side.
Bell Pepper
The aromatic foliage can help confuse aphids and thrips hunting peppers by scent. Basil also stays low and bushy under a pepper's open canopy, so neither shades the other out.
Oregano
Oregano allowed to flower often draws in hoverflies, lacewings, and tiny parasitic wasps that hunt the aphids and thrips found on basil. Give each plant its own 12-inch space so the spreading oregano does not crowd basil roots.
French Marigold
French marigold roots have been shown to reduce root-knot nematodes in the soil, but only when the bed is planted thickly with them or the plants are chopped and turned in at season's end. A few flowers along the edge will not do it.
Sage
Old charts keep these two apart, with no measured mechanism behind it. The practical reason to separate them is water: sage wants lean soil that dries between drinks, while basil sulks the moment it does, so one plant is always being watered wrong.
Fennel
Fennel roots release substances that stunt most garden vegetables, basil included, and it competes hard for water besides. Grown well away in its own corner it earns a place, since its flat flower heads feed hoverflies and tiny parasitic wasps.
Lavender
Basil wants steady moisture and rich soil; lavender wants neither. Watering to keep basil happy keeps the ground around lavender's crown damp, which is the fastest route to root rot.
French Lavender
Basil needs rich soil and steady moisture; watering to keep basil happy holds lavender roots wet and invites root rot, while watering to suit lavender leaves basil wilted and stunted.
Bee Balm
Bee balm spreads by shallow runners and can reach 3 feet or more, shading and out-rooting a young basil plant before midsummer. Keep basil in its own bed or pot where it gets uncontested sun and water.
Rosemary
Basil wants rich soil and steady moisture, while rosemary declines in wet, well-fed ground. Sharing a pot usually means one of them is watered wrong, and rosemary is the one that rots. Grow them in separate containers.
Lemon Thyme
Basil wants rich soil and steady moisture; thyme wants lean soil that dries between waterings. Sharing a pot means one of them is always being watered or fed wrong, and thyme usually loses first to root rot.
Thyme
Basil wants steadily moist, richly fed soil, while thyme needs to dry out almost completely between waterings. Sharing a pot or row means one plant is always wrong, and thyme is the one that rots.
Easy-going — Basil can grow almost anywhere in the rotation without a strict rest.
The pea and bean family, the cabbage family or the tomato family thrive in this ground next season.
A light feeder that takes little and leaves soil in good shape, with only shallow roots and soft stems to break down. Leave one season before basil returns to the same spot, longer where wilt has shown up. Beans, cabbage-family greens, or tomatoes all follow well.
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