Leucospermum grandiflorum can be propagated from cuttings or seed but cuttings generally have a much higher success rate and are easier to obtain than seeds.

Make cuttings from December to March (summer to autumn). The cuttings should be semi-hardwood, 60-100 mm long, and taken from the current season's growth. Dip the cuttings into a rooting hormone solution or hormone powder and plant into a medium of 50% polystyrene and 50% finely milled bark. Place in a growing house with bottom heat (25ºC) and intermittent mist. Once the roots are well developed, remove from the mist unit and harden off for three weeks. Plant the cuttings into small bags and grow on until ready to plant into the garden.

Sow seed at the end of February when the days are warm and the nights start to cool down (late summer to autumn). Soak Leucospermum seed in smoke water to which hydrogen peroxide has been added, at the ratio of 1% of the total volume for 24 hours. This loosens the outer seed coat and oxygenates the seed. The softened seed coat is rubbed off. Dust the seed with a systemic fungicide. Sow on a well-drained medium consisting of 1 part loam, 1 part bark, and 2 parts sand, firm down and cover with a layer of sand or finely milled bark. Seed can be sown in an open seedbed, or in a seedtray placed in a sunny position. Germination begins after three to four weeks. Once two true leaves have grown, prick the seedlings out into small bags. The seedlings will have to be pricked out in batches, as the seeds germinate at different times. Place the seedlings in a lightly shaded area with good air circulation. When plants are ± 50-100 mm tall, or after one year's growth, they can be planted into the garden. Nipping out the tips of the seedlings will encourage branching and produce a neater shrub.

The best time to place the young plants in the garden is just before the rainy season. This enables plants to establish themselves and send down deep roots before the hot, dry, summer season. Leucospermum grandiflorum requires a sunny situation with well-drained soil. Add a scoop of well-decomposed compost at planting and water well for the first year. They do tend to get leggy and are best planted in a mixed fynbos bed amongst other lower vegetation that will hide straggly stems.

Leucospermum grandiflorum can be temperamental in a garden situation and is prone to Phytophthora (root rot). Once proteas become diseased they are very difficult to treat, and it is better to prevent disease rather than try to cure it. Make sure the environmental conditions are correct. This includes getting direct sunlight for most of the day, a well-drained soil which does not stay saturated and will not stagnate, and good air circulation ensuring that the above-ground parts of the plant dry quickly after watering. It is also important to ensure that the soil stays cool in the hot months and that roots are not disturbed by digging. A thick layer of mulch or groundcover planting can be used to keep the soil cool and prevent moisture loss. If any of these factors are not correct, the plants become weakened and stressed, and you can be sure to attract some form of pest or disease.

Pincushions in general are more tender to frost than other proteas and the uppermost branches, including flower buds, may burn and die back. Identify warmer, more protected spots in your garden to plant your pincushions. If your area experiences severe dry frosts, plants will need to be protected, especially while they are young. Cover plants with agricultural fleece, hessian or a cardboard box overnight, and uncover them in the day time. Once the shrubs have woody growth and are approximately three years old they should be hardy enough to survive without covering.