How to Grow and Care for Cat Whiskers Plant

Despite its common-sounding name, cat whiskers (Orthosiphon aristatus) traveled an exotic route before reaching American gardens. Native to China, Thailand, Malaysia, Indonesia, the Philippines, Papua New Guinea, and Australia, it is a perennial shrub that grows from 9 to 78 inches tall in the wild. Found along the edges of forests and thickets, it prefers full sun and warm temperatures.

In the garden, its height and conical-shaped, white or lavender, two-lipped blooms with hairy, whisker-like stamens, purplish stems, and dark green leaves make a statement in a perennial bed. The plant is hardy in USDA hardiness zones 9-12 and is considered tropical.

Cat Whiskers Care

A member of the mint family, cat whiskers is a tropical plant that works well in a warm climate garden or as a potted annual in colder areas. Cat whiskers should be planted in an area of full sun in well-draining soil. Place the plant at the back of a bed because it has a shrub-like shape and can reach heights over six feet; however, most garden plants reach two to three feet each season.

The flower spikes offer a good source of nectar for hummingbirds and butterflies in a pollinator garden. It is an easy-care plant requiring moderate water levels and feeding.

Light

Cat whiskers prefer a location in full sun but can tolerate some light shade. The blooms will be more profuse when the plant is grown in full sun.

Soil

The plant prefers a neutral soil pH that is well-draining. If you are growing it as a container annual, use good potting soil and a container with adequate drainage holes.

Water

Newly planted cat whiskers should be watered regularly until they become established. After they become well-settled, only moderate watering is required unless there are periods of extreme drought. Container-grown plants require more frequent watering because container soil dries out faster than garden bed soil.

Temperature and Humidity

As a tropical plant, cat whiskers requires warm temperatures and is not cold-tolerant. Warm, humid air will encourage bloom production. The unique flowers appear on new growth each spring as soon as the nighttime temps begin to warm and the days get a bit longer.

Fertilizer

If the soil is fertile, additional fertilization is usually not needed. To boost bloom production, mix in some compost into the soil or use a balanced fertilizer (8-8-8 NPK) during the growing season, especially on container-grown plants.

Types of Orthosiphon aristatus

• Orthosiphon aristatus var. aristatus: Native range is east Asia along the edges of forests and thickets.
• Orthosiphon aristatus var. velteri: Native range of this variety is Vietnam. It grows as a subshrub or shrub in a wet tropical environment.

Pruning

If you are growing cat whiskers as a perennial, remove spent blooms during the growing season. Before the warmer temperatures of spring, prune the stems back about one-third to encourage new growth and more blooms. In cooler zones, the foliage will die back when temperatures become colder. Cut the stems down to ground level.

Propagating Cat Whiskers

Propagation is usually done through stem cuttings.

1. Select young, healthy, vigorous, non-flowering shoots six to eight inches long in mid to late summer.
2. Remove the lower leaves leaving one to two leaves on the cutting, then dip the cut end in a rooting hormone.
3. Place the cutting in a mixture of perlite and coarse sand and keep the cutting moist, warm and in a shady location until roots develop.
4. In about 45 days, you can transplant the cutting into a large pot filled with a loam and sand mix and move it to a partially sunny area.
5. Transplant to a permanent location in the spring.
6. Space the plants 16-24 inches apart to accommodate its shrub form.

How to Grow Cat Whiskers From Seed

During the growing season, collect seed heads/pods when flowers fade and allow them to dry in a cool, dark place. Remove the seeds from the pods and store them in a small paper bag or envelope. About six weeks before outside temperatures reach a point where you can safely leave the plants outdoors to harden off, you will want to start the seed growing process.

1. Fill seed trays with seed starting medium and moisten the medium until it is damp but not soaked.
2. With a pencil or other pointy object, make a hole about 1/8th of an inch deep and place one seed in each one of the seed tray's cells.
3. Place the tray on top of a heating mat in front of a sunny window and cover the tray with its plastic cover.
4. Check daily to ensure the soil remains moist, misting with a spray bottle when needed.
5. Depending on the moisture content and temperature, your seeds should germinate in five to ten days.
6. Keep the seedlings covered until the plants touch the cover, at which point remove the cover and, if possible, let a fan circulate air around the plants to strengthen them

When plants are five to six inches tall, transplant them into individual pots taking care not to damage roots and continue to water until transplanted outdoors. When the temperature outdoors reaches a steady 50° Fahrenheit at night, place the plants outdoors gradually each day to allow them to harden off before planting them in the garden. After a week or so of hardening off, you can transplant your cat whiskers to the garden or a container.

Overwintering

If you are growing cat whiskers in USDA hardiness zones 9 through 12, you shouldn't have to do anything to overwinter this plant. The shrub is semi-deciduous and will drop some leaves during the winter but will not become completely bare.

If you live in USDA hardiness zone 9 or lower, when the foliage dies back, mulch around the plant to help protect it from cooler nights. Most container-grown plants should be considered annuals. You can take cuttings in autumn or collect seeds to start new plants in the spring.

Common Pests and Plant Diseases

There are no known serious disease or pest problems for cat whiskers. It is important to keep the area free of weeds to encourage good air circulation and soil moisture levels around the shrubs.

How to Get Cat Whiskers to Bloom

Place this plant in an area that receives six to eight hours of sun daily for the most proficient blooming. Add a layer of compost at the start of the spring growing season and again in mid-summer to promote blooming. Deadhead spent blooms to encourage more blooms.

Common Problems with Cat Whiskers

Cat whiskers can spread and overtake smaller plants in a perennial bed. Prune judiciously to keep them to a manageable size.