How to Plant and Grow Diascia

With delicate, prolific blooms reminiscent of open-face snapdragon flowers, diascia is a colorful option for early spring containers, hanging baskets, or garden beds. Most often diascia is used as a cool-season annual, but in a warm climate, it can be grown as a perennial.

The flowers come in a range of pinks, whites, corals, and oranges. Diascia is sometimes referred to as twinspur because the flowers feature two spurs coming out of the back of the blossoms. Within these spurs, the plants produce an oil that is collected by a species of bee that has evolved alongside the plants.

Where to Plant Diascia

Unless you live at the upper end of the plant’s zone range, it is best to plant diascia in full sun. The soil should be well-draining and slightly acidic. 

With small, showy flowers on low-mounding to sprawling plants, diascia can be used interchangeably with alyssum, pansies, nemesia and other cool-season annuals in garden beds and containers.

How and When to Plant Diascia

Diascia appear at nurseries and garden centers in the spring and that’s when they should be planted. Wait, however, until there is no more danger of frost before planting them. Dig a hole that is at least the size of the nursery pot or flat and has the same depth. Water the plants well in their pots and let them drain before placing them in the hole and backfilling with the original soil. 

Space the plants at least 10 to 12 inches apart and increase the space for more sprawling varieties.

Diascia Care Tips

Light

Diascia performs best in full sun but it also grows in part shade. In areas with a warm summer, plants will perform best in part sun, as this keeps plants cool, although it is at the expense of fewer blossoms than plants in full sun.

Soil and Water

This South African plant grows best in fertile, well-drained soil with consistent moisture and a pH between 6.0 and 6.5. Diascia tolerates drought once established.

Temperature and Humidity

Diascia may not survive the intense heat of a hot summer. During cool spring weather, the plants are covered in blossoms. Once warm summer weather begins, though, plants tend to slow down on flowering or stop blooming completely and enter a period of dormancy. If they make it through a hot summer, there is a chance that they will bloom again when cool fall weather begins. The plant can survive a light frost but it’s not winter-hardy. They prefer a climate with low humidity.

Fertilizer

Especially during the spring, the plants will benefit from regular applications of a balanced complete fertilizer. For the amount to use, follow product label directions.

Pruning

While they do not require deadheading to encourage more blossoms, diascia will benefit from a shearing back to encourage a flush of new growth. This helps to promote better flowering in the fall, especially when done just before the hottest part of the summer, and after the initial heavy bloom cycle.

Potting and Repotting Diascia

Diascia is an excellent container plant. It can be planted on its own or as a filler in a mixed container. Make sure to use containers with large drainage holes and well-draining potting mix. Keep in mind that potted plants need much more watering and also more frequent fertilizer than plants in the landscape.

As diascia is usually grown as an annual, repotting won't be necessary.

Pests and Problems

Other than attracting snails and slugs, diascia does not have major pest or disease problems.

How to Propagate Diascia

Many of the diascia varieties are protected by plant patents and their propagation is not legal. Make sure that the variety you are propagating is not one of them before you propagate it from stem cuttings.

Propagating diascia makes the most sense if your climate is mild enough to grow it as a perennial. The best time to propagate the plant is in the spring. Cut 4- to 6-inch cuttings from non-flowering shoots and dip the cut ends in rooting hormone powder. Fill a 4-inch pot with damp well-draining potting mix and insert the cuttings about halfway in the pot.

Place the pot inside a clear plastic bag with a few holes poked into it for ventilation to create a warm, moist microclimate, and place it in a well-lit location but out of direct sun. Keep it moist until the cutting develops roots. When you see new growth, the cutting has rooted, and you can remove the bag. Place it in a sunny location and transplant it to a larger pot or in the landscape once it has become a vigorous little plant.

Types of Diascia

'Coral Belle' Diascia

This variety has shiny foliage and coral blooms on 10-inch-tall plants.

'Flirtation Orange' Diascia

'Flirtation Orange' is an extremely floriferous variety with great heat tolerance. It practically covers itself in orange blooms and grows 1 foot tall and 2 feet wide.

'Flirtation Pink' Diascia

Bred to be more heat-tolerant, this variety bears masses of pink flowers. The plant gets 12 inches tall and 20 inches wide.

'Sun Chimes Coral' Diascia

Diascia 'Sun Chimes Coral' bears coral-pink blooms on spreading, 12-inch-tall plants.

'Whisper White' Diascia

'Whisper White' bears pure-white flowers on 10-inch-tall plants.

Diascia Companion Plants

Gerbera Daisy

Gerbera daisies are so perfect they hardly look real. They bloom in nearly every color (except true blues and purples) and produce fantastically large flowers on long, thick, sturdy stems. They last for a week or more in the vase, making them a favorite of flower arrangers. This tender perennial will last the winter in only the warmest parts of the United States, Zones 9–11. In the rest of the country, it is grown as an annual. It does well in average soil; it likes soil kept evenly moist but not overly wet. Fertilize lightly.

Snapdragon

Few gardens should be without the easy charm of snapdragons. These cool-season annuals come into their own in early spring when the warm-season annuals, such as marigolds and impatiens, are just being planted. They're also great for fall color. In mild climates, the entire plant may overwinter if covered with mulch. Snapdragons often self-seed in the landscape if not deadheaded, so they come back year after year, though the colors from hybrid plants will often will be muddy-looking.

Stock

Stock offers a wonderfully spicy, distinctive scent. Plant it in spring several weeks before your region's last frost date—this annual thrives in cool temperatures and stops blooming once hot weather arrives. It's especially wonderful in window boxes and planters at nose level, where its sometimes subtle effect can best be appreciated. Stock is slightly spirelike and comes in a wide range of colors. It makes a great cut flower, perfuming bouquets as well as the border. It grows best in full sun or part shade and moist, well-drained soil.