What are the sun requirements for Ocimum basilicum 'Dark Opal'?

Ocimum basilicum 'Dark Opal' requires full sun.

How much water does Ocimum basilicum 'Dark Opal' need?

Ocimum basilicum 'Dark Opal' has moderate water needs.

Annuals

Ocimum basilicum 'Dark Opal'

Dark Opal Basil

UnknownAsia

At a Glance

Typeannual

Habitupright, bushy

Foliagedeciduous

Height12-18 inches

Width10-14 inches

Maturity0.16 years

Key Features

Attracts Pollinators

Attracts Butterflies

Fragrant (moderate)

Container Friendly

Maintenancemoderate

Overview

Ocimum basilicum 'Dark Opal' is a striking ornamental basil cultivar renowned for its deep burgundy to purple-black foliage that creates dramatic contrast in herb gardens and ornamental plantings. This compact annual herb typically reaches 12-18 inches in height with a bushy, well-branched habit. The ovate leaves are deeply colored, ranging from dark purple to nearly black with a glossy finish and prominent veining. The foliage emits the characteristic sweet, spicy basil fragrance when brushed or crushed. In mid to late summer, Ocimum basilicum 'Dark Opal' produces small spikes of pink to lavender flowers that complement the dark foliage beautifully. The flower spikes emerge from the leaf axils and terminal growing points, creating an attractive display that attracts pollinators. While primarily grown for ornamental purposes, the leaves are edible and provide a mild basil flavor with slightly spicy undertones, though the flavor is generally considered less intense than traditional sweet basil varieties.

Native Range

Ocimum basilicum is native to tropical regions of central Africa and Southeast Asia, particularly India, where it has been cultivated for thousands of years. The species has been widely distributed throughout tropical and subtropical regions worldwide through human cultivation.

Suggested Uses

Ocimum basilicum 'Dark Opal' works well as an ornamental accent plant in herb gardens, mixed borders, and container plantings where its dramatic dark foliage provides striking contrast. Excellent for edging pathways or creating bold color blocks in annual beds. The colorful foliage and flowers make it valuable for cutting gardens and fresh arrangements. Can be grown in containers on patios or windowsills, and the edible leaves can be used sparingly for culinary purposes, though primarily grown for ornamental value.

How to Identify

Ocimum basilicum 'Dark Opal' can be identified by its distinctive deep purple to burgundy-black foliage, which sets it apart from all other basil cultivars. The leaves are ovate with smooth margins and a glossy surface that reflects light. The stems are often tinged with purple, and the plant maintains a compact, bushy growth habit. When flowering, the pink to lavender flower spikes provide additional identification features, contrasting beautifully with the dark foliage. The characteristic sweet basil fragrance is present but may be slightly less pronounced than in green-leafed varieties.

Appearance

Size & Dimensions

Height1' - 1'6"

Width/Spread10" - 1'2"

Reaches mature size in approximately 0.16 years

Colors

Flower Colors

pink

lavender

Foliage Colors

purple

burgundy

black

Bloom Information

Bloom Period

SummerFall

mid summer to early fall

Detailed Descriptions

Flower Description

pink to lavender

Foliage Description

deep purple to burgundy-black

Growing Conditions

Sun Requirements

Full Sun

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range6.0 - 7.0(Neutral)

357912

Soil Types

loam

Drainage

well drained

Water & Climate

Water Needs

moderate

Frost Tolerance

tender

Time to Maturity

60-75 days

Care & Maintenance

Care Guide

Ocimum basilicum 'Dark Opal' requires warm conditions and full sun to develop its best foliage color and compact habit. Plant in well-draining, fertile soil with consistent moisture but avoid waterlogged conditions. Water regularly during dry periods, applying water at the base of the plant to prevent fungal diseases. Feed monthly with a balanced fertilizer to promote healthy growth and rich foliage color. Pinch flower buds regularly to encourage continued leaf production and maintain the plant's bushy form. This tender annual cannot tolerate frost, so harvest before the first expected freeze date.

Pruning

Prune Ocimum basilicum 'Dark Opal' regularly by pinching out flower buds as they appear to encourage continued leaf production and maintain plant vigor. Remove flowers by pinching just above a set of leaves to promote branching. Harvest outer leaves regularly, cutting just above a leaf node to encourage new growth. For ornamental use, allow some flower spikes to develop for their attractive pink-lavender color, but remove spent flowers promptly. Avoid cutting more than one-third of the plant at any one time to prevent stress.

Maintenance Level

moderate

Container Growing

✓ Suitable for container growing

⚠️ Toxicity Warning

Ocimum basilicum 'Dark Opal' is generally safe for humans and is edible in small quantities. However, basil contains compounds that may be harmful to pets in large amounts, particularly cats and dogs. While not highly toxic, consumption of large quantities may cause digestive upset in pets. As with all herbs, use culinary portions in moderation.

Planting Guide

Planting Methods & Timing

Planting Method

both

Indoor Start

6 weeks before last frost

Direct Sow Timing

after last frost when soil temperature reaches 65°F

Days to Maturity

60–75 days

Plant Spacing

8 inches

Companion Planting

Good Companions

tomatoes

peppers

marigolds

petunias

oregano

Avoid Planting With

rue

sage

fennel