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Plant of the Month: Osteospermum 3-D

Osteospermum ‘3D’ series

Latin name: Osteospermum ecklonis ‘3D’ series
Common name: Osteospermum
Flowers: 2” double daisies of silver, pink or purple
Mature size: 12-16” tall by 18-24” wide
Hardiness: Cool-season annual
Soil: Well-drained
Exposure: Full sun 
Water usage: Low
Sources: Local nurseries

Guessing the date of the last frost in Texas is like buying a Lotto ticket and knowing you likely won’t win. Average last frost date for Dallas is March 15, but I’ve seen winters when our last frost was in January and other years when it occurred in mid-April. It is definitely too soon to buy our more familiar heat-tolerant annuals like lantanas, begonias or impatiens. They won’t take even a 40-degree night, much less a frost. My answer is to buy cool-season annuals like geraniums (Pelargonium), petunias, lobelias, alyssum and osteospermums. They can take our cooler spring nights and will flower until temperatures get warm enough for the more heat-tolerant plants.

In particular, there has been a lot of new breeding of osteospermums, or as I call them, “the little daisies with the big name.” Newer varieties have earlier and more blossoms. And they are taking the heat a bit more, too. One of the new stars of our trial program at the Dallas Arboretum is a new series called ‘3D’. An interesting name that you can instantly understand when you see the flowers — they are so doubled they seem almost stuffed with petals. The unique flower shape also keeps the flowers from closing up in the evening and on cloudy days, which is one of the major drawbacks of this genus. About the time you’ve headed home from work, most of the older Osteospermum varieties are closing up their flowers for the night. I’m never home early in spring, so I appreciate the large 2-inch flowers of the newer varieties greeting me with wide-open petals.

You can get ‘3D’ osteos in three colors: ‘3D Silver’, which has white flowers edged in purple, ‘Purple 3D’ and ‘Pink 3D’. The plants will quickly grow to about 18 inches tall and spread to 2 feet across over the course of spring. I find they are best used in containers and raised beds, where the soil drains better, since they do not like to sit in wet soil. They also make exceptional hanging baskets. Keep them well fed so they will stay in flower.

Don’t worry about a late frost damaging these plants; they can take the cold and keep on growing as long as we don’t have a hard freeze in the 20s. I’ve learned that once the horrid heat of summer starts to set in, you can move them to afternoon shade and they will continue to bloom a little while longer. Even last year, during the hottest summer on record, we were able to keep them through the summer, to re-flower in the fall, by moving our pots to an area with shade from noon on. Unfortunately once the day temperatures hit 100 and the nights near 90, they just stop blooming completely, so I personally compost mine at home and buy a different plant for the summer heat.
Osteospermum ‘3D’ should be available in quart pots or larger this spring. You can’t miss their distinctive flowers, which cover the plants. I know I’ll be buying some in the next couple of weeks to help ward off spring fever until I can start planting the more Texas-heat-tolerant summer plants.