Origin
Physostegia virginiana (L.) Benth. var. granulosa (Fassett) Fern. is a species of perennial herb in the mint family, Lamiaceae. It is native to Eastern and Central North America, including Canada and the United States.
Common Names
Physostegia virginiana (L.) Benth. var. granulosa (Fassett) Fern. is commonly known as Obedient Plant, False Dragonhead, and Obiedientia.
Uses
The roots and leaves of the plant have been used medicinally by Native Americans to treat various ailments, including fevers, colds, and stomachaches. However, some parts of the plant can be toxic if ingested in large amounts.
Today, Physostegia virginiana (L.) Benth. var. granulosa (Fassett) Fern. is mainly grown as an ornamental plant in gardens and public parks. It is valued for its showy flowers and ability to attract pollinators such as bees, butterflies, and hummingbirds.
General Appearance
Physostegia virginiana (L.) Benth. var. granulosa (Fassett) Fern. typically grows to a height of 2-4 feet and has a spread of 1-3 feet. The plant has lance-shaped leaves that are green or tinged with purple, and it produces spikes of tubular flowers in late summer or early fall. The flower spikes can range in color from pink or white to purple, and individual flowers resemble dragon heads, hence the common name False Dragonhead. The plant's name Obedient Plant comes from the fact that the flowers can be bent and will stay in the new position for a short time.
Light Requirements
Physostegia virginiana (L.) Benth. var. granulosa (Fassett) Fern. thrives in full sunlight or partial shade. It can tolerate shade, but it blooms best in full sunlight. The plant requires a minimum of 6 hours of sunlight per day to maintain its growth rate and achieve maximum flowering potential.
Temperature Requirements
The plant is native to eastern North America's hot and humid climates, making it adaptable to a range of temperatures. It is frost tolerant and can withstand minimum temperatures of -28°C. Temperatures ranging from 20°C to 27°C are ideal for plant growth.
Soil Requirements
The ideal soil for Physostegia virginiana (L.) Benth. var. granulosa (Fassett) Fern. is well-draining loamy soil with a pH range of 5.5 to 7.5. It prefers moderately fertile, moist soils rich in organic matter. The plant has a shallow root system and requires regular watering, especially during periods of drought. It is essential to avoid waterlogged soil as it can lead to root rot and other fungal diseases.
Cultivation Methods
Physostegia virginiana (L.) Benth. var. granulosa (Fassett) Fern. is a herbaceous perennial plant that grows well in USDA hardiness zones 3-9. It prefers partial shade to full sun and thrives in well-drained soil with a pH level of 6.0-7.5. It is best to plant the Physostegia virginiana var. granulosa in spring or fall.
To ensure successful growth, prepare the planting area by digging a hole twice the size of the plant's root ball. Mix compost or aged manure into the soil to improve drainage and fertility. Gently place the plant in the hole and fill it with soil. Water the plant thoroughly.
Watering Needs
Physostegia virginiana var. granulosa requires regular watering to keep the soil moist but not waterlogged. The plant is relatively drought-tolerant and can withstand short periods without water. However, extended periods of drought may cause the plant to wilt and damage its growth.
Water the plant deeply once a week during the growing season, and reduce the frequency to once every two weeks in the winter. Avoid overwatering the plant, as it may cause root rot.
Fertilization
Using a general-purpose fertilizer during the growing season can help ensure that the plant is well-fed and healthy. Apply the fertilizer according to the instructions on the package. Avoid overfertilizing the plant, as it may cause excessive foliage growth but reduce flowering.
Alternatively, you may use compost or aged manure to feed the plant. Spread a 2-3 inch layer of compost or aged manure around the base of the plant, taking care not to touch the stems or foliage. Water the plant thoroughly after applying the compost or manure.
Pruning
Physostegia virginiana var. granulosa benefits from regular pruning to promote bushier growth and prevent the plant from becoming too leggy. Prune the plant in early spring before new growth appears. Cut back the entire plant to about 4-6 inches above the ground.
During the growing season, pinch back the tips of new shoots to encourage branching. Deadhead the faded flowers to promote more blooming throughout the season. Cut back the entire plant to the ground in fall after the foliage has died back.
Propagation of Physostegia Virginiana (L.) Benth. var. Granulosa (Fassett) Fern.
Propagating Physostegia virginiana (L.) Benth. var. granulosa (Fassett) Fern. can be done either through seeds or vegetative means. It is an easy-to-grow plant that can be propagated through several techniques, as discussed below:
Propagation via Seeds
The easiest way to propagate Physostegia virginiana (L.) Benth. var. granulosa (Fassett) Fern. is through seeds. The seeds should ideally be collected in fall when they start falling from the plant or when they change into brown. The collected seeds should be stored in a cool and dry place until spring when they are ready for planting. Before planting, the seeds should be stratified in a moist and cool place for around 2 to 3 months to break their dormancy.
The stratified seeds can then be planted in a nursery bed, seed trays, or pots filled with a well-draining soil mix. The soil should be kept moist but not waterlogged, and the seeds should be kept in a partially shaded area until they start germinating. Germination usually takes around two to three weeks, and once the seedlings are a few inches tall, they can be transplanted to their permanent location.
Propagation via Vegetative Means
Physostegia virginiana (L.) Benth. var. granulosa (Fassett) Fern. can also be propagated through vegetative means. The two most common techniques are division and stem cuttings.
Division: Division involves digging up the plant and dividing it into smaller clumps. This is best done during spring or fall when the plant is not actively growing. Each clump should have a few healthy rhizomes and some foliage. The divided clumps can then be replanted in their permanent location, making sure to keep the soil moist until the plants establish.
Stem Cuttings: Stem cuttings involve taking cuttings from the plant's stem and rooting them in a well-draining soil mix. This is best done during spring or summer when the plant is actively growing. Cuttings should be taken from healthy stems, around 4 to 6 inches long, and stripped of any leaves except a few at the top. The cuttings should be dipped in rooting hormone and planted in a well-draining soil mix. They should be kept moist, ideally by covering them with a plastic bag or a humidifier, until they start rooting.
Overall, Physostegia virginiana (L.) Benth. var. granulosa (Fassett) Fern. is an easy-to-propagate plant that can be propagated through seeds or vegetative means. The best propagation technique depends on personal preference, time, and resources.
Disease Management
Physostegia virginiana (L.) Benth. var. granulosa (Fassett) Fern. is susceptible to several diseases that can affect its growth and overall health. The following are some common diseases and ways to manage them:
- Powdery Mildew: This fungal disease appears as a white powdery substance on the leaves and stems. To manage, remove and destroy all the infected parts of the plants. Apply fungicides regularly as a preventive measure.
- Root Rot: This disease is caused by waterlogged soil and can cause the plant to wilt and die. To manage, improve soil drainage by adding organic matter to the soil or transplanting the plant to a new location. Avoid overwatering the plant.
- Leaf Spots: These fungal diseases result in brown or black spots on the leaves. Remove and destroy the affected parts of the plant and keep it dry by watering from the base or early in the day.
- Verticillium Wilt: This fungal disease causes wilting, yellowing, and eventual death of the plant. There is no cure, so prevent it by avoiding dense plantings, keeping the soil well-drained, and removing and destroying any infected plant parts.
Pest Management
Physostegia virginiana (L.) Benth. var. granulosa (Fassett) Fern. is also susceptible to pest attacks that can affect its health and growth. The following are some common pests and ways to manage them:
- Aphids: These small insects suck the sap from the plant and can cause wilting and stunted growth. To manage, spray the affected parts with water or use an insecticidal soap or oil. Introduce natural predators like ladybugs and lacewings.
- Spider mites: These tiny pests feed on the plant's sap, causing webbing and yellowing of leaves. To manage, wash the plant regularly with water and apply a miticide. Introduce natural predators like ladybugs and lacewings.
- Caterpillars: These pests can chew on the leaves and cause significant damage. To manage, handpick them and destroy them. Use insecticide as a last resort.
- Slugs and snails: These pests can consume large portions of the plant, leaving large holes in the leaves. To manage, remove hiding places for these pests and apply bait traps or copper barriers. Handpick them if necessary.
