Welwitschia mirabilis is a bizarre species of dioecious gymnosperm native to the Namibian deserts of S.W. Africa. In nature, the two strap-like leaves will reach up to 6-8 feet (1.82-2.43 m) in length (and eventually longer) and up to 3 feet (0.91 m) wide. The two leaves arise from a short woody obconical stem and continue to grow throughout the plants lifetime, which may be centuries long. Leaves will split lengthwise into many segments. The stems can reach up to 1.5 feet (45 cm) tall and up to 5 feet (1.52 m) across. Our plants are now 6 years old from seed. The leaves are 3.5 feet (1.06 m) long by 3 inches (7.5 cm) wide with the stem only 2 inches (5cm) tall. Although they are interesting plants, they are somewhat difficult to grow.
Blooming: In the greenhouse, our plants started to produce cones in December of last year. The cone stalk grew very slowly at first. We were not sure of the sex of the inflorescence until it started producing red 4 angled cones and micropylar tubes, characteristic of the female. Since we didn't have any pollen, we tried to get some from other growers, but to no avail. By May of this year the cones aborted.
Culture: Welwitschia mirabilis needs full sun with a very well drained soil. Welwitschia is grown from seed. The winged seed resembles a very large elm seed. To germinate the seed, it was placed in a soil mix of coarse sand and crushed lava rock. The container that we used was a 10 foot (3.04 m) long 12 inch (30 cm) diameter PVC pipe. We buried the PVC pipe 6 feet (1.82 m) into the ground leaving 4 feet (1.21 m) above ground. The pipe was filled with the sand and crushed lava rock. Seeds were surface sown with only the wings covered with the soil mix. The seeds were misted (no direct watering) on a daily basis until germination occurred at 45 days. As the new seedlings emerged, they were misted twice a day until the true leaves had started to grow. At this time, we started experimenting with a watering regime for the plants. Since they come from very harsh climate, we were not sure how much water they would need. We water the plant only once a month and that seems sufficient enough to get good growth. Every other month we fertilize with an organic fertilizer diluted to ˝ the strength recommended on the label. During the winter months in the greenhouse we water them only every other month and fertilizer is withheld during this period.
Propagation: Welwitschia mirabilis is propagated from seed. Fresh seed will germinate in 45-60 days at 85°F (30°C).
Welwitschia mirabilis was featured as Plant of the Week July 6-12, 2007.
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Cal's Plant of the Week was provided as a service by the University of Oklahoma Department of Microbiology & Plant Biology and specifically Cal Lemke, who used to be OU's botany greenhouse grower and an avid gardener at home as well. If the above links don't work, then try the overview site. You may also like to look at the thumbnail index. ©1998-2012 All rights reserved.