Penaea mucronata is grown for the fynbos garden beds at Kirstenbosch. Although it is not used in horticulture, it is easily cultivated from seed but very difficult from cuttings, which are best taken as heel cuttings specifically selected from the plant’s branches that grew right after fire.

The seeds should be sown in late summer, autumn or spring. Germination will be triggered by the application of smoke, either by placing them in a smoke tent or soaking in a solution of smoke water, which mimics the positive effects of fire on fynbos in nature. Seeds are sown onto a well-drained, fynbos soil mix, consisting of a combination of river sand and well decomposed pine bark in equal proportions. Seed germinates in about 4–6 weeks. The seedling will develop from the cotyledon stage until it has true leaves, when the seedlings should be transplanted into small individual pots. Young seedlings are encouraged to grow by feeding weekly with a diluted organic fertilizer.

Penaea mucronata may be rooted from cuttings in autumn or spring, and even other times of the year, although it is difficult. They are rooted in multi-trays, washed and cleaned with a disinfectant, such as Terminator, to kill excess bacteria, placed on heated benches with a temperature of 22–25°C and placed under mist spray running every 15 minutes for 5 seconds, to keep the medium moist, and the leaves cool and moist. Experience has shown that the only way to successfully root cuttings, is to take heel cuttings from the above-ground stem next to the rootstock, in the morning. Cuttings may only be collected when one has a valid permit from the relevant authorities, such as Nature Conservation, Cape Nature or SANPARKS and with the landowner’s agreement where applicable. A powdered, root-stimulating hormone is used to propagate 5–7 cm long cuttings. Visible flower parts are removed, and the cuttings are dipped into a seaweed extract solution, such as Kelpak, before propagation. The cuttings are placed in a medium suitable for fynbos plants, such as a mixture of fine-milled bark and perlite. The excess powder should be allowed to stay on the cutting where it is placed in the moist medium, by first making a thin hole with a sterile wire and then placing the cutting in it. The tray with cuttings will be labelled and then placed in the propagating house. The cuttings root after 8 to 12 weeks, are hardened off for a week in a shady area and then potted into 2 kg plant bags using fynbos soil mix (e.g. pine bark mixed with river sand with nutrients suitable for fynbos). They must be watered regularly, and be given organic fertilizers once a month for increased growth, and can be planted in the garden when ready.

Penaea mucronata has not been cultivated extensively, and experience may be limited to Kirstenbosch National Botanical Garden and Fernkloof Nature Reserve. Kirstenbosch is still experimenting with the best cultivation methods. It is best suited to fynbos gardens, and must be grown in well drained, sandy soil in a sunny, well-ventilated position, with fynbos companions such as Erica, Metalasia, Stoebe, Leucadendron, Leucospermum, Protea and restios, with as little disturbance of the roots as possible, such as growing it amongst rocks or in rockeries on slopes.