Basil
Ocimum basilicum
Lamiaceae · mint family
- Matures
- 60–90 days
- Harvest
- Continuous · Annual
- Sun
- 6–8+ hrs
- Spacing
- 8–12 in
Planting window
When to sow, by microclimate — foggier blocks run a different calendar than sunnier ones.
| Jan | Feb | Mar | Apr | May | Jun | |
|---|---|---|---|---|---|---|
| Foggy | ◐ | ◐ | ||||
| Sunny | ◐ | ● | ● |
| Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|
| Foggy | ◐ | ◐ | ◐ | |||
| Sunny | ● | ● | ● | ◐ |
Well-suitedMarginalNot suited
Sunlight
How well it does at each level of direct sun per day.
<2 hrsNot suited
2–4 hrsNot suited
4–6 hrsMarginal
6–8 hrsWell-suited
8+ hrsWell-suited
Well-suitedMarginalNot suited
Soil depth
Root room it needs — useful for sizing raised beds and containers.
6–10"Well-suited
10–15"Well-suited
15–18"Well-suited
18–24"Well-suited
Well-suitedMarginalNot suited
Spacing
Room each plant needs — along the row and between rows — for sizing beds.
- In-row
- 8–12 in
- Between rows
- 18 in
Growth habit
The shape it makes in the bed and how tall it gets — what tells you whether to give it a trellis, a stake, or just room.
- Habit
- Upright
- Mature height
- 1–2 ft
Stands on its own; the tallest types appreciate a stake in wind.
How to start it
Sow it where it grows, or raise it under cover and set it out — and how far ahead to start the seedlings if it's the latter.
- Usually
- Transplant
- Start indoors
- 6 weeks ahead
Direct-sowMarginal
TransplantWell-suited
Started under cover, then set out as a seedling.
Well-suitedMarginalNot suited
Getting started
How it goes in the ground — how deep to sow or set it, and the soil temperature it needs to wake up. The cold-soil floor is the real limiter for direct-sowing in a foggy SF spring.
- Started from
- From seed
- Ideal soil temp
- 75–85°F
- Sow depth
- 0.125 in
- Time to emerge
- 10–14 days
Germinates between 65–90°F; happiest around 75–85°F.
30°F110°F
IdealWorkable
Pests & diseases
What tends to trouble this crop — what it is, what you'll see, and what to do about it, least-toxic first.
USU: Basil is not susceptible to many production problems provided you rotate planting locations and maintain hygienic conditions near the plants.
Pests2
Japanese Beetles and Grasshoppers
- What you'll see
- Holes eaten in the leaves.
- What to do
- Apply a ground treatment that kills immature insects developing underground. For adults, cover plants with garden fabric.
Slugs
- What you'll see
- Soft-bodied or shelled mollusks that chew holes in leaves.
- What to do
- Control with appropriate pesticides or traps. Avoid moist conditions that favor these pests.
Diseases2
Root Rot Diseases
- What you'll see
- Fungal diseases that cause decay and rotting of the roots and premature plant death.
- What to do
- Do not over water, practice crop rotations, and solarize the growing area.
Basil Shoot Blight
- What you'll see
- Fungal diseases that cause leaf spots and premature leaf loss. Dark streaks appear on stems of older plants.
- What to do
- Keep the plants spaced far enough apart for adequate air circulation to keep plants dry.
Sources
Every figure above is backed by these.
- UC Integrated Pest Management (UC IPM)backs plantingWindow, sunlight, daysToMaturity, inRowSpacing, rowSpacing · UC Statewide IPM 'Cultural Tips for Growing Basil': 'Spring is the ideal time to plant, when frost is no longer a concern' with North/North Coast 'May-June' and South Coast 'April-June' (warm-season window; SF sunny microclimate mirrors coastal Apr/May-Sep, foggy stays marginal = maybe). 'Basil grows best if the plant receives full sun to partial shade (at least 4 to 6 hours a day)' (sunlight; 4-6 = maybe floor, full sun 6-8/8+ = yes). 'When planted from seed, most basil varieties take 60 to 90 days to mature' (daysToMaturity). 'For transplants, use young plants and place 12 inches apart in 18 inch rows' (inRowSpacing). Between-row spacing 18 in from the same source: 'place 12 inches apart in 18 inch rows'.
- UC Master Gardeners, Santa Clara Countybacks plantingWindow, sunlight, inRowSpacing · UC MG Santa Clara Basil page: 'Sow seeds indoors six weeks prior to transplant, March to May' and 'Plant seedlings from April to June when the soil is well warmed' (transplant Apr-Jun = warm-season window). 'Full sun; late afternoon shade is okay' (sunlight). '8 to 12 inches wide, depending on variety' (inRowSpacing 8-12 range). No SF foggy/sunny herb calendar exists, so the microclimate split (sunny summer yes vs foggy maybe) is judgment: basil is heat-loving and foggy SF summers stay too cool for it to thrive.
- UC Master Gardeners, Marin Countybacks plantingWindow, sunlight, soilDepth, inRowSpacing · UC Marin MG Basil grow sheet: 'Plant seedlings outdoors April through June when soil is well-warmed and the danger of frost is past' (Apr-Jun window). 'Plant in full sun approximately 12 inches apart' (sunlight full sun; inRowSpacing 12). Rooting depth from UC Marin MG Planting & Spacing (knowledge-base/uc-mg-marin/data/planting-spacing.json): basil listed among shallow-rooting edibles 'approximately 12 inches or less', so all bands 6-10 through 18-24 = yes (soilDepth).
- UC Master Gardeners, Sonoma County (Planting Summary)backs daysToMaturity, sunlight, lifecycle, harvestStyle · UC MG Sonoma Vegetable of the Month, Basil: 'Plant-to-harvest is about 10 weeks' (~70 days, within the 60-90 range). 'Grow basil in well-drained soil enriched with compost in full sun' (sunlight). Sonoma's inland 'sown indoors in May and planted out in June' timing skews warm and is not used for the SF window. Habit and harvest: annual, continuous — consistent with this source's planting-summary row.
- Garden for the Environment (San Francisco)backs plantingWindow · Garden for the Environment (SF) spring starts (knowledge-base/garden-for-the-environment/data/spring-starts.json): Basil listed under 'start_indoors_from_seed' — confirms basil is started indoors in spring for later transplant in the SF Bay, corroborating the spring/summer transplant window rather than direct winter sowing.
- Utah State University Extensionbacks germination, plantingDepth · USU Extension basil: germinate best at 75–85°F soil, ~10–14 days; min 65°F floor from Iowa State germination table. Planting depth 1/8 in: 'Sow seeds 1/8 inch deep.'
- USDA GRIN Taxonomybacks botany
- NC State Extension — Plant Toolboxbacks growthHabit · Ocimum basilicum entry: Height '0 ft. 4 in. - 3 ft. 0 in.' (4-36 in across all basil types; the common sweet-basil range 12-24 in is stored here), Habit/Form 'Ascending' — a self-supporting upright herb, so upright.
- UC Master Gardeners, Santa Clara Countybacks startMethod · Start method: Planting chart: Basil carries a Transplant row only; From seed to transplant 6 weeks. No direct-seed row is listed, hence direct-sowing rated marginal rather than ruled out.
- Garden for the Environment (San Francisco)backs startMethod · Start method: March-April spring list: Basil appears under start indoors from seed.