PlantSowGrow
How to grow Basil (Purple Dark Opal)
Ocimum basilicum
🌿 Herb
🌱 Grown each year
A handsome purple-leaved basil with a sweet, spicy flavour — as good in a flower pot as in a caprese salad.
At a glance: Sow early May to mid June, harvest from late June.
When to sow, plant and harvest
JanFebMarAprMayJunJulAugSepOctNovDec
Sow outdoors
Harvest
Timed for a typical UK garden (last frost mid-April). The app uses your own town's frost dates.
Growing Basil (Purple Dark Opal): what it needs
- Light
- Full sun · 6+ hours a day
- Watering
- Keep evenly moist; water pots daily in hot weather
- Soil
- Fertile, well-drained soil
- Spacing
- 20 cm
- Height
- 40 cm
- In pots
- Grows well in containers
- Feeding
- A liquid feed every two weeks for pot-grown plants
- Harvest
- About 60 days from sowing
- Hardiness
- USDA zones 10–11
- Difficulty
- Easy
Step by step
- Early May – mid June · 3 weeks after the last spring frost
Sow Seeds Outdoors
Sow thinly in shallow drills where they are to grow. Sow on the surface and keep at 20°C.
- 5–10 days after “Sow Seeds Indoors” · Mid May
Check Germination
Seedlings should appear in 5–10 days. Keep the compost moist. If sown outdoors, thin to 20 cm apart.
- 50–71 days after “Check Germination” · Late June – late July
Start Harvesting
Pick regularly — little and often keeps plants bushy. Take a photo for the journal.
- 21–35 days after “Start Harvesting” · Late July – early August
Pinch Out Flower Buds
Pinch out flower buds to keep the leaves coming.
- Mid October – early November · around the first autumn frost
End of Season
When plants run to seed or the frost gets them, pull them up for compost — leave a few to self-seed if you like.
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