Contrary to various sources, Oldenburgia grandis germinates easily from seed. Seedlings have even been found germinating in the old flower-head while still attached to the plant. Seed germinates readily when smoke treated or treated with Seed Primer containing smoke extract. Sow seed onto a well-drained, acidic, growing medium consisting of a combination of river sand and well-decomposed pine bark or washed peat in roughly equal proportions. Seeds germinate in about six weeks, emerging as small, fleshy cotyledons that must be lightly watered with a watering can. The seedlings should be carefully potted into small individual pots at cotyledon stage; before the first pair of true leaves develop, as this species does not react well to disturbance. Young seedlings are encouraged to grow, by feeding them with diluted organic fertiliser. Keep in a well-ventilated, warm, sunny position where the seed and young plants are protected from rain. Oldenburgia does not like too much water which will cause the young plants to rot. Water the plants well and then allow the medium to dry out between watering. In other words treat them like succulents.

It is good practice to protect the seeds from rotting by treating them with a pre-emergence fungicide to prevent damping off. These fungicides are available at your local nursery. This species is slow growing and should be kept in the smallest possible container and only re-potted when it becomes well established in its container.

Oldenburgia grandis has also been propagated by truncheon. This is obviously only possible when a large plant is available. It has been reported that a branch that broke from a mature specimen at Kirstenbosch rooted when put into the ground.

Truncheons are branches, about as thick as a human arm that can be rooted and grown into new plants. Truncheons are usually taken when the plant is dormant or in its resting stage. The erythrinas in the Kirstenbosch Avenue were propagated in this way. Truncheon sections are about 1.7–1.8 m long, with the top of the branch cut at a slant, which prevents water from rotting the truncheon. Before planting the truncheon, it should first be kept in the shade for a few days to develop a hard layer over the cut end. If the cut end is not covered with this hard layer, the truncheon may not root. The truncheon should be planted into a narrow hole about 600 mm deep. The best time for this method is the end of the dormant season just before the plant begins active growth.

With Oldenburgia grandis, some of the terminal leaves should be left on the truncheons. These may fall off before new leaves develop, but it is important to be patient because they may take a few months to establish. The basal cut of the truncheon should be treated with a fungicide and then dried out to prevent the stem from rotting. Plant the truncheon directly into the garden or into a large pot containing well-drained potting media. Water the truncheon well, but allow the media to partially dry out between watering. The success of this method of propagation varies, but if the truncheons root then one has a reasonably large plant instead of the much longer process of growing from seed. Plants grown from seed at Kirstenbosch reached 300 mm after five years growth.

Oldenburgia grandis makes a striking specimen. It is slow growing and long lived and suitable for rockeries and other warm, dry and well-drained positions in the garden. This very handsome, decorative tree can also be planted in a small garden, courtyard or in a large pot. It must be grown in a ventilated position in full sun and well-composted, sandy loam. This unusual, decorative tree is only occasionally available in limited numbers at the Annual Plant Fair.

Oldenburgia grandis needs to be grown in full sun with good ventilation in well-composted, sandy loam. This species needs to be watered moderately when in growth and kept dry in winter. In winter, the temperature needs to be maintained at a minimum of 7-10 º C.

O. grandis is propagated from seed and semi-hard cuttings in sand. Seed is difficult to germinate. This little decorative tree grows here at Kirstenbosch and is not commonly available in nurseries.