Purple Basil 'Dark Opal' (Ocimum basilicum)
An attractive annual herb with very fragrant, dark purple leaves. Pink flowers appear in late summer, complementing the rich hue of the foliage. Both the leaves and flowers make a delightful garnish on the dinner plate.
Culinary herb for gardens and containers. Excellent for adding flavor to soups, sauces, fish and meat dishes. Use leaves fresh, or dry and keep in an airtight container. Wash fruits, vegetables and herbs thoroughly before eating.
Once every month during growing season.
Light, well-drained soil.
Basic Care Summary
Very easy to grow in virtually any location. Does best in light, well-drained soil. Keep soil moist, watering freely in dry weather. Harvest foliage as needed.
Annual herbs can be planted in the garden in spring. Annual herbs are also ideal for containers. Pots can be brought indoors for the winter and placed near a sunny window for harvesting through the cold months. Return the plants outdoors in the spring when the danger of frost is past, or simply replace with fresh plants
Prepare the garden by breaking up the existing soil (use a hoe, spade, or power tiller) to a depth of 12-16” (30-40cm). Add organic matter such as manure, peat moss or garden compost until the soil is loose and easy to work. Organic ingredients improve drainage, add nutrients, and encourage earthworms and other organisms that help keep soil healthy.
Check the plant label for suggested spacing and the mature height of the plant. Position plants so that taller plants are in the center or background of the landscape design and shorter plants in the foreground. To remove the plant from the container, gently brace the base of the plant, tip it sideways and tap the outside of the pot to loosen. Rotate the container and continue to tap, loosening the soil until the plant pulls smoothly from the pot.
Dig the hole up to two times larger than the root ball and deep enough that the plant will be at the same level in the ground as the soil level in the container. Grasping the plant at the top of the root ball, use your finger to lightly rake apart the lower roots apart. This is especially important if the roots are dense and have filled up the container. Set the plant in the hole.
Push the soil gently around the roots filling in empty space around the root ball. Firm the soil down around the plant by hand, tamping with the flat side of a small trowel, or even by pressing down on the soil by foot. The soil covering the planting hole should be even with the surrounding soil, or up to one inch higher than the top of the root ball. New plantings should be watered daily for a couple of weeks to get them well established.
Finish up with a 2” (5cm) layer of mulch such as shredded bark or compost to make the garden look tidy, reduce weeds, and retain soil moisture.
If planting the herbs in a container, start with a good quality, commercial potting soil. These are usually lighter in weight than topsoil, sterile and pest-free. Many are available with a mild starter fertilizer in the mix.
Select a container with a drainage hole or be prepared to drill holes for drainage if there are none.
Prepare the container by filling with potting soil up to 2” (5cm) from the rim of the planter. Remove the plant from its pot or pack. Make a small hole in the soil slightly larger than the root ball either by hand or using a trowel. Insert the plant into the hole and press soil firmly around the roots and just covering the root ball. When all the plants are potted, water thoroughly to settle the soil and give plants a good start.
New plantings should be watered daily for a couple of weeks. After that, depending on the weather and soil type, watering may be adjusted to every two or three days. Clay soils hold moisture longer than sandy soils, so expect to water more frequently in sandy settings.
Different plants have different water needs. Some plants prefer staying on the dry side, others, like to be consistently moist. Refer to the plant label to check a plant’s specific requirements.
Thoroughly soaking the ground up to 8” (20 cm) every few days is better than watering a little bit daily. Deep watering encourages roots to grow further into the ground resulting in a sturdier plant with more drought tolerance.
To check for soil moisture, use your finger or a small trowel to dig in and examine the soil. If the first 2-4” (5-10cm) of soil is dry, it is time to water.
Plants in containers can dry out quickly, depending on the weather, and may need water more frequently than plants in the garden bed. Apply water at the soil level if possible to avoid wetting the foliage. Water the entire soil area until water runs out the base of the pot. This indicates that the soil is thoroughly wet.
Herbs planted in the garden don’t require additional fertilizer. Apply a 1-2” (3-5cm) layer of mulch or compost. As mulch breaks down it supplies nutrients to the plants and improves the overall soil condition at the same time.
Herbs in containers can be fed lightly with a general purpose fertilizer at half the rate suggested on the package directions.
Invest in a good, sharp hand pruner or knife for harvesting. Pinching the stems off can cause damage to the main plant.
Herbs can be harvested throughout the growing season to be used fresh, dried, or frozen. It’s best not to prune more than 50% of the foliage at one time. This keeps the plant healthy and producing new growth for continuous harvesting.
Unless you are growing an herb specifically for its flowers (such as lavender), or seed production (such as fennel), it is best to remove flower buds as they appear. This keeps the plant’s energy focused on foliage production instead of blooms and seeds.
Harvest herbs in the morning, when the plant oils are at their peak. Prepare herb cuttings for use by gently washing and drying the foliage. If planning to preserve the herbs, check foliage for insects or eggs as well. Herbs can be dried or frozen for future use. The general rule for use in cooking is: use twice as much fresh or frozen herb as compared to dried herb.
Harvest seeds when the flowers start to fade and turn brown, but before the seeds fall from the plant.
|Bloom Time:||Late summer|
|Height Range:||12-15" (30-38cm)|
|Space Range:||10-15" (25-38cm)|
|Lowest Temperature:||20° to 30°F (-7° to -1°C)|
|Plant Light:||Full Sun|
|Companion Plants:||Tomato, Pepper, Oregano, Marigold, Coleus|