Diascia, sometimes called twinspur, is a delicate, frothy type of plant. Some varieties will spill over pots, and others tend to grow more upright. The genus, a relative of the snapdragon, comprises about 70 different species native to South Africa. The varieties of diascia you see popping up at garden centers are newly bred hybrids that are popular for use in containers and hanging baskets. Some varieties may be hardy down to zone 7 but the plant is usually grown as an annual flower. As such, it is planted in the spring after all danger of frost has passed.
|Botanical Name||Diascia spp.|
|Plant Type||Perennial, annual, herbaceous|
|Mature Size||6-12 in. tall, 18 in. wide|
|Sun Exposure||Full, partial|
|Bloom Time||Spring, fall|
|Flower Color||Pink, white, orange, red|
|Hardiness Zones||9-11 (USDA)|
Diascia (Twinspur) Care
Diascia should be planted in well-drained soil with consistent moisture at least until the plant is established. After that, it can withstand some drought. Fertilizing, especially in the spring, is equally important.
While the plant grows best in full sun, it does not do well in extreme heat. Therefore, in hot climates, or during the peak of the summer, the plants should be located in some shade, even if that curtails their bloom somewhat. If you grow diascia in containers, move the container to a protected spot.
You'll get the most blooms by keeping your diascia in full sun, but in really hot weather, the plant will do best when grown in partial shade, particularly afternoon shade.
Diascia prefers a slightly acidic soil pH between 6.0 and 6.5. The soil should be fertile and well-drained.
Diascia needs regular water, but it doesn’t like to sit in wet soil. If growing it in a container, make sure there are adequate drainage holes. As a general guide, water when the top 1 inch of soil or potting mix feels dry.
Temperature and Humidity
Diascia prefers cooler temperatures, and it flowers best in the spring and fall. If your plants start to fade in the heat, cut them back to a few inches and keep them watered. They will perk back up when it cools off.
Diascia is somewhat frost-tolerant and can be kept going well into the fall. If you’re willing to move your pots into the garage whenever a hard frost is in the forecast, they will last even longer.
A slow-release fertilizer works best. However, don't fertilize more frequently than directed on the label, or you’ll get leggy plants.
Types of Diascia (Twinspur)
The genus Diascia comprises 70 species, both annuals and perennials. Different varieties of diascia range from about 6 to 12 inches tall and 18 inches wide. Be sure to check the specific plant description for size specs before purchasing to ensure you have enough space in your designated planting spot. Popular varieties include:
- Diascia barberae 'Blackthorn Apricot' with soft pink flowers
- Diascia 'Picadilly', a hybrid with large white flowers
- Diascia ‘Flirtation Orange’ with soft orange flowers
- Diascia integerrima 'Coral Canyon' with salmon-pink flowers
- Diascia personata, a species with pink flowers that gets up to 4 feet tall
Diascia does not require deadheading but if your plants start to look leggy or spent, shear them back by half and they will soon start blooming all over again.
Diascia can be propagated from cuttings. It you live in a climate where the plant's life cycle will naturally end with a strong fall frost, the best time to propagate it is in the spring so you take full advantage of the entire growing season:
- Clip off four to six-inch cuttings from non-flowering shoots.
- Dip the ends of the cuttings in rooting hormone, and plant them into 4-inch pots filled with well-draining potting mix, lightly dampened.
- Place the pot inside a plastic bag, then set it in a room temperature location until the cutting develops roots. Open the bag to ventilate if you notice moisture condensing on the plastic from the inside.
- Once the cutting is rooted, remove the pot from the plastic and continue to grow it in a sunny location.
Growing Diascia From Seeds
It’s rare to find seed for diascia, but there are some out there. Start seeds indoors, about six to eight weeks before your last expected frost. In warm climates, diascia can also be direct seeded. Note that seed collected from any hybrid diascia won’t grow true from seed.
- Fill seed flats or pots with sterile potting mix for seed starting. Diascia seed needs light to germinate, so just press the seed firmly on top of the soil; don’t cover it.
- Keep the soil evenly moist at all times. Depending on the variety, the seeds should germinate within two weeks.
Potting and Repotting
Diascia is a natural for containers. You can fill an entire container with one variety, or use a single diascia as your spiller in a mixed container. To ensure good drainage, use containers with large drainage holes and well-draining potting mix.
As diascia is mostly grown as an annual container plant, repotting won't be necessary.
In USDA zones 9 through 11, the plant can survive the winter as a short-lived perennial whereas in cooler climates, it is grown as an annual and cannot be overwintered.
Common Pests & Plant Diseases
While disease typically is not a concern for diascia, the wet environment that these plants like is also attractive to snails and slugs. You often find these slimy critters under the plant's foliage. The simplest way to mitigate the problem is to lift the plants off the ground. Otherwise, you can employ any number of standard remedies for snails and slugs to help keep them out of the area.
How to Get Diascia to Bloom
If your diascia does not bloom, or blooms poorly, it could be lack of sunlight or lack of fertilizer. Apply a fertilizer high in phosphorus to encourage blooming.
Common Problems with Diascia
The plants are relatively care-free and do not have any particular issues.
Will diascia bloom all summer?
It repeat blooms throughout the summer, although it performs best in the cool weather of spring and fall.
Is nemesia the same as diascia?
Where does the name twinspur come from?
The flowers have a single long top petal that makes it look like the flower is sticking out its tongue. Below this are two side petals with horn- or spur-like projections, which give diascia its common name of twinspur.