Leucospermum harpagonatum is propagated by both seed and cuttings. Collect the seed 1 or 2 months after flowering. Seeds are rarely found in cultivated plants, maybe because of a lack of natural pollinators. The ripened seed can be seen when the individual florets are turning brown. Cut the heads and dry them and store the seed in a cool room for 2 weeks prior to sowing. The seeds are hard and covered with elaiosome. Soak the seeds in a 1% solution of hydrogen peroxide for 24 hours to soften the seed coat and remove the elaiosome by rubbing on them in the bags or by using your fingers. Remove all the soft or squashed seeds as these are immature. Treat the seeds with a light dusting of a fungicide before sowing and apply fungicide once a week after planting to prevent fungal infections. The seed should not be allowed to dry out and must be sowed immediately after dusting it with the fungicide. Both seed and plants are susceptible to fungal infections. Sow the seed in autumn (March to May) using a well-aerated growing medium and smoke the seed with dry and green fynbos materials. Use a smoking tent or smoking bags to treat the seed. The seedlings are ready for potting-up when they have produced their first true leaves. 

Take semi-hardwood cuttings in autumn and spring and treat them with a rooting hormone for at least 5 seconds to stimulate rooting. Because the leaves are curved in an upright position, it is easy to insert cuttings upside down. Take care to place the cuttings with the nodes pointing up. Plant cuttings in a well-drained and aerated medium of 70% perlite and 30% fine bark or coarse sand and finely milled pine bark. Insert the cuttings in multi-trays with sufficient space between each cutting to allow free air circulation. Place trays on heated benches of 25ºC with intermittent mist. Regularly treat the cuttings with a fungicide to prevent fungal infections. Remove the dead leaves and wilting cuttings while waiting for cuttings to root. Move the rooted cuttings to the hardening-off house for about 2 weeks and pot the cuttings into small nursery plastic bags, using a mixture of well-drained acidic planting medium.

The seedlings or cuttings are placed under a shade net in the nursery until they are ready to be planted in the garden after a period of 2 to 3 years. Net shade reduces the direct sun which can dry out the soil in the plastic bags and can scorch young plants.  The pH level of the planting medium should preferably be acidic, between 5–7 pH. 

Grow Leucospermum harpagonatum in a sunny position, in well-drained, sandy, acidic soil where there is free circulation of air. It is best suited to a north-facing slope, on terrace or gabion walls, and in rockeries. This creeping shrublet has potential for hanging baskets, as it cascades very well in a pot.

Keep the soil moist during the hot dry season, by applying a 5 mm thick mulch to the bed. The mulch will keep the roots cool, keep moisture in the soil and reduce the growth of weeds. Chipping mulch is commonly recommended, as it breaks down very slowly and also releases small amounts of nutrients to the plant. Prune creeping branches that are growing over the edges or to minimise the spread of branches.

Leucospermum harpagonatum is not prone to pest attacks. The plants are susceptible to root rot and grafted plants have a higher survival rate. L. harpagonatum can be grafted on the scion of the hybrid ‘Veld Fire’, a cross between Leucospermum glabrum and L. conocarpodendron subsp. conocarpodendron. Grafted plants live longer than rooted ones and can better resist fungal infections in the garden.