Grevillea New Blood

Culture:

Grevillea New Blood is best planted in spring, after the last frost. It prefers soil with an acidic to neutral pH, sandy, gravelly, loamy or poor and very well-drained. The presence of limestone in the soil causes a yellowing of the foliage, chlorosis, which weakens the bush until it dies. This condition can be corrected by regularly adding iron in its chelated form (sequestrene). In regions where the soil and subsoil are limestone, dig a large hole of 60 cm (23.6 in) in all directions, filled with ericaceous soil or peaty compost and non-limestone sand. Like all plants in the Proteaceae family, the Grevillea dislikes soils rich in phosphorus. Growing in a pot allows better control of the substrate and the plant can be stored frost-free in a borderline hardiness zone (down to -10/-11°C (14/12.2 °F) for a well-established plant).

Grevilleas are drought-resistant plants once well established: monitor watering in summer for the first 2 summers, watering will become optional or even unnecessary later on. In the ground, they appreciate a thick layer of mulch. Use wood chips or grass clippings. It is recommended to use a fertilizer very low in phosphorus, as it can reduce the plant's resistance to drought by destroying the dense root hairs that develop just below the surface of the soil. An N-P-K type fertilizer with proportions of 18-2-10 is well suited.

For pots, choose Grevillea species and varieties with low development. Use a light, well-drained potting mix that remains moist. We recommend the following mix: 60% pine bark, 20% coarse river sand, 10% fine river sand, and 10% clay soil for its water retention capacity. The pH should be 7 or less.

Insects and diseases:

Grevilleas can have black leaf spots, caused by a rarely lethal fungus: a fungicidal treatment will solve the problem.

Rotting of the collar can also occur, a deadly disease, also caused by fungi that develop in wet and warm soil. Avoid burying the plant's collar, keep it well-aerated. Avoid watering too often in hot and dry weather, let the soil dry out between 2 waterings.

Phytophthora (cinnamomi), a disease also caused by a fungus, affects many plants in dry areas. The parasite destroys the roots during excessively rainy winters or hot and humid summers. The plant may suddenly wilt in summer due to lack of water, as a result of the destruction of part or all of its roots. Partial or complete death of the vegetation or branches can be observed in severe cases. Prevention is crucial, as the disease is almost impossible to eradicate: ensure that the soil drainage is perfect, remove excess water from the saucer placed under the pots, and remove dead or diseased parts.

Pruning:

Grevilleas tolerate annual pruning well, during their growth period or just after flowering. Shorten the branches by one-third of their length. A regularly pruned bush will be more branched and more floriferous.

Propagation: by sowing in spring, or by taking heel cuttings in June-July. To improve the germination rate of fresh seeds, they can be immersed in boiling water.

About sowing: Grevilleas are plants linked to fire ecology: as such, they produce seeds that often need the action of intense and brief heat to break their dormancy.