Dark Opal

Family: Lamiaceae Herb

Planting Schedule

Provide your location or planting zone to unlock dates and add Dark Opal to a garden.

Sink your senses into Dark Opal’s velvety, deep-plum leaves—an aromatic purple basil that perfumes the air with a rich, sweet-herbal fragrance.

The foliage is tender and lush, with a softly serrated, slightly cupped texture that looks as sumptuous as it smells. Grow it for standout fresh garnishing, vibrant flavor in sauces and finishing swirls, and striking color that holds its beauty when dried or lightly roasted for bold, fragrant impact.

Light: Full SunMaturity: 60 DaysHabit: Upright

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Dark Opal Planting Dates by USDA Zone

Estimated US hardiness-zone windows for sow, transplant, and harvest. Enter a US ZIP above for exact local dates, or open a zone below.

Zone	Start Indoors	Sow / Transplant	Harvest
Zone 1a	May 4th	Aug 10th	Oct 9th – Jul 15th
Zone 1b	Apr 20th	Jul 27th	Sep 25th – Aug 1st
Zone 2a	Apr 13th	Jul 20th	Sep 18th – Aug 29th
Zone 2b	Apr 3rd	Jul 10th	Sep 8th – Aug 25th
Zone 3a	Apr 3rd	Jul 10th	Sep 8th – Sep 1st
Zone 3b	Apr 7th	Jul 14th	Sep 12th – Sep 21st
Zone 4a	Apr 3rd	Jul 10th	Sep 8th – Sep 24th
Zone 4b	Apr 1st	Jul 8th	Sep 6th – Sep 27th
Zone 5a	Mar 27th	Jul 3rd	Sep 1st – Sep 30th
Zone 5b	Mar 23rd	Jun 29th	Aug 28th – Oct 5th
Zone 6a	Mar 20th	Jun 26th	Aug 25th – Oct 10th
Zone 6b	Mar 14th	Jun 20th	Aug 19th – Oct 16th
Zone 7a	Mar 9th	Jun 15th	Aug 14th – Oct 20th
Zone 7b	Feb 27th	Jun 5th	Aug 4th – Oct 28th
Zone 8a	Feb 18th	May 27th	Jul 26th – Nov 5th
Zone 8b	Feb 9th	May 18th	Jul 17th – Nov 12th
Zone 9a	Jan 23rd	May 1st	Jun 30th – Nov 26th
Zone 9b	Dec 29th	Apr 6th	Jun 5th – Dec 9th
Zone 10a	Continuous Production
Zone 10b	Continuous Production
Zone 11a	Continuous Production
Zone 11b	Continuous Production
Zone 12a	Continuous Production
Zone 12b	Continuous Production
Zone 13a	Continuous Production
Zone 13b	Continuous Production

Crop Details

Trait	Value
Days to Maturity	60
Sun Requirements	Full Sun
Growth Habit	Upright
Support Needed	None
Planting Depth	Normal
Germination Temp (°F)	70
Min Soil Temp (°F)	60
Min Night Temp (°F)	50
Harden Off (days)	10

Culinary Notes

Chef's Note

Dark Opal purple basil brings a richer, sweeter clove-basil aroma with a clean, peppery finish—choose it when you want basil that reads loud on the tongue. Chop it fine or stir it in off-heat so the leaves stay tender and aromatic instead of turning flat under heavy cooking.

Best Uses

hand-chopped finishing basil for salads and bowls where it stays green (and glossy)
blitzing into quick sauces and oils—add at the end to keep the perfume intact
lightly roasted or quick-dried topping on flatbread, rice, or roast squash for bold herbal impact
muddled into vinegar-based dressings for a fragrant, lightly spicy lift

Flavor Profile

sweet, clove-leaning basil aromatics slightly peppery bite in the finish tender, softly cupped leaves for easy tearing purple-leaf herbal sweetness that stays fragrant when warmed

Kitchen Pairings

garlic lemon olive oil parmesan mozzarella chicken

Frequently Asked Questions

Why are my dark opal basil leaves turning black or developing blotches, and what should I do?

Basil (Ocimum basilicum) is prone to fungal leaf spots and downy mildew, especially when foliage stays wet. Water at the soil line and space plants for airflow, then remove badly infected leaves to slow spread. If conditions are humid, start a preventive regimen with a copper-based fungicide labeled for basil and apply according to the label’s timing and intervals.

How often should I water Dark Opal basil during peak growth (after it’s established)?

During its main growth phase, keep the top 1 inch of soil lightly moist but not soggy; basil roots need steady moisture with good drainage. In typical summer conditions, that’s often about 1–2 times per week, increasing frequency if the soil dries faster under full sun and containers. Water deeply to wet the root zone, and stop once water runs out of the bottom of pots to avoid root problems.

How do I know when Dark Opal basil is ready to harvest?

Start harvesting around day 60 when plants are well-leafed and reach about 8–12 inches tall, but you can take light “leaf pinch” harvests earlier to encourage branching. Harvest in the morning by snipping above a pair of leaves so the plant can produce new shoots. If flowering starts, harvest promptly and keep picking to maintain tender leaf quality and prevent bitterness.