Diascia is a short lived, tender perennial that is usually grown as an annual. A relative of the snapdragon, Diascia is native to South Africa, where about 70 different species exist. 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 and Diascia is quickly becoming a favorite plant, especially for containers and hanging baskets.
Diascia is a delicate, frothy type of plant. Some varieties will spill over pots and other tend to grow more upright.
Leaves: Small, oval shaped leaves are a dark green.
Flowers: The flowers are small, but many. 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 sex organs.
Full sun to Partial Shade. Does best in partial shade during hot weather.
Different varieties range from about 6" - 12" (h) x 18" (w).
Diascia repeat blooms throughout the summer, although it performs best in spring and fall. If your plants start to look leggy or spent, shear them back by half and they’ll start blooming all over again.
- D. 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.
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, so avoid them.
Soil: Diascia perfers 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, abou 6-8 weeks before your last expected frost. In warm climates, Diascia can be direct seeded. The hybrid Diascia won’t grow true from seed.
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 2 weeks.
You can also start Diascia from cuttings. However, plants are readily available in the spring.
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, it will last even longer.
Although not hardy down to Zone 6, gardeners in Zones 6 - 8 may be able to over-winter plants with some mulch protection.