Diascia, sometimes called Twinspur, is a delicate, frothy type of plant. Some varieties will spill over pots and others tend to grow more upright. It's a relative of the snapdragon and about 70 different species exist in South Africa, where it is a native. The varieties of Diascia you see popping up at garden centers have been bred rather recently. They’re coming out with new colors and better bloomers every year.
Overview and Description
Diascia is quickly becoming a popular plant, especially for containers and hanging baskets. Here are some more general details of this favorite flower:
- Botanical name: Diascia
- Common name: Twinspur
- Leaves: Small, oval-shaped leaves that are dark green.
- Flowers: The flowers are small but profuse. Colors include pastels, vivid oranges and reds, and deep plums. It’s kind of an odd looking flower up close. There’s one long top petal that makes it look like the flower is sticking out its tongue. Below it are two side petals with horn- or spur-like projections, which give Diascia its common name of Twinspur. Under these is one more petal that holds the sexual organs.
Diascia is reliably hardy in USDA Hardiness Zones 9 through 11. Some varieties may be hardy down to Zone 7, however, Diascia is a short-lived, tender perennial plant that is usually grown as an annual flower.
You'll get the most blooms in full sun, but in really hot weather, Diascia does best when grown in partial shade, particularly afternoon shade.
Different varieties of Diascia range from about 6 to 12 inches tall and 18 inches wide. Be sure to check your specific plant's description for size specs before purchasing, as you'll want to make sure you have enough space in your designated planting spot.
Diascia repeat blooms throughout the summer, although it performs best in the cool weather of spring and fall. If your plants start to look leggy or spent, shear them back by half and they will soon start blooming all over again.
Suggested Diascia Varieties
There are plenty of Diascia cultivars to choose from. Here are some of the most popular, hardy examples:
- Diascia barberae 'Blackthorn Apricot' - Soft pink flowers. Received the Royal Horticultural Society Award of Garden Merit (AGM).
- Diascia hybrid Dew Drops - Clear white with a yellow center. A Proven Winners plant
- Diascia hybrid ‘Flirtation Orange’ - Another Proven Winners plant with soft orange flowers.
- Diascia integerrima 'Pink Adobe' - A tall, soft pink Diascia that is cold hardy to Zone 5.
Diascia is a natural for containers. You can fill an entire container with one variety or use a Diascia plant as your spiller, in a mixed container. Diascia also makes a lovely edging plant and will elegantly flop over sidewalks and walls or throughout rock gardens.
Diascia Growing Tips
You can start Diascia from cuttings. However, plants are readily available in the spring.
- Soil: Diascia prefers a slightly acidic soil pH. Something between 6.0 and 6.5 seems to be ideal.
- Planting: 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. The hybrid Diascia won’t grow true from seed.
- Light: Diascia seed needs light to germinate, so just press the seed firmly on top of the soil, don’t cover it. It’s very important to keep the soil moist since there’s nothing insulating the seed. Diascia seed should germinate within two weeks.
Caring for Diascia Plants
Diascia needs regular water, but it doesn’t like to sit in wet soil. If growing in a container, make sure there are good drainage holes.
A time release fertilizer seems to work best. If you prefer to hand fertilize, don’t over do it or you’ll get leggy plants. Leggy plants can be pinched back, to keep them attractive and full.
Diascia prefers cooler temperatures and 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 threatens, they will last even longer.
Although not hardy down to Zone 6, gardeners in Zones 6 through 8 may be able to over-winter plants with some winter protection.
Pests and Problems
Diseases don’t seem to be a major problem unless it’s an especially wet season. Snails and slugs are the biggest problem growing Diascia. Lift plants off the ground, to avoid them.