Grevillea robusta Seeds
Grevillea robusta seeds harvesting period is July. Grevillea robusta (Proteaceae) is commonly known as silk oak, silver oak or silky oak. It is native to Eastern coastal Australia. It is not closely related to true oak (Quercus) but is a largest species in its genus. Their fruits are boat-shaped follicles and woody. Each fruit contains 2 seeds which are winged.
Grevillea robusta Overview
Grevillea robusta is an evergreen fast growing tree that reaches up to 5-40 m in height. The bark is dark grey in colour while leaves are fern-like. Each leaf is 10-34 cm long and 9-15 cm wide. Their leaves are also divided inti 11-31 main lobes. The tree shed their leaves before flowering. The flowers are arranged in one side of the branch in groups like “toothbrush”. The flowers are glabrous and yellowish orange in colour or sometime their colour become darker.
Propagation of Grevillea robusta through Seed
Grevillea robusta can easily propagated through seeds. Their seeds are usually not dormant but take some time for germination. However, some native’s tree seeds are dormant and require pre-treatment for germination. Therefore, specific conditions are made which are similar to their natural requirements. Soaking seeds for 24 hours in cold water before sowing, enhance their germination. Grevillea robusta can also grow through cuttings.
Germination of Grevillea robusta Seed
Grevillea robusta seeds should be sown in well-drained, shady containers or seedbeds. The best place to cultivate plant is to place it in greenhouse. The seeds are sown in the month of spring and avoided hottest and coldest months of the year. The optimum germination temperature for germination is around 18-22°C. Seeds take 2-4 or more weeks for germination. Once the seedlings becomes a week old, they should be pricked out in polytubes. The seedlings require shade for first 3 weeks. After 6-8 months, the seedlings become 20-30 cm tall, hence they can be transplanted to their permanent positions.
How to care for Grevillea robusta Seedlings
Best growth is obtain on sandy loam moist soil. They also succeeds in dry soils but dislikes heavy clay. The soil pH is maintain around 4.5-7.5. The seedlings dislike strong winds as they can cause damage to them. The seedlings require protection from frost and chills. The first flower appears after 6 years while in its natural habitat flowering occurs after a few weeks.
Requirements of Grevillea robusta
Grevillea robusta is distributed in warm humid to sub-humid climatic zones. It prefers full sun as it grows up. It prefers annual rainfall in the range of 700-2400 mm. The drought period more than 6 months will cause death of the plant. Therefore extremely hot temperature should be not exceeds than 4 months. However, it survive some extend of frost in temperate regions up to -8˚C. Whereas, temperature below -2˚C will cause damage to the seedlings. It can also be grown alongside maize in agroforestry systems.