Exotic shrubs that bloom year round
We are fascinated with this genus of plants native to Australia. The vast majority of the nearly 400 species are shrubs which are what we grow. Australia is a big country but the areas that receive truly cold weather are restricted to the highest mountains and alpine valleys. Not surprisingly species from the highest elevations of the Australian alps have proven to be fantastic shrubs in our climate- and there are many more species and cultivars waiting to be tested here.
Grevilleas are members of the Proteaceae. That family which is ancient is almost exclusively from the southern hemisphere. Proteaceaous plants have several peculiarities that are important to understand to succeed with them. The soils they are adapted to are universally old and poor and to thrive in those conditions they even form what are called Proteoid roots. These are fine, fine, clusters of roots that can extract the most microscopic nutrients from depleted soils. This has made them very sensitive to overly enriched soils and the substance phosphorus is particularly toxic. Avoid all fertilizers.
So, what they require to thrive- and we’ve grown them in this climate for more than 20 years- is just a whole lot of neglect. Do not enrich the soil, even with compost. Our native unimproved soils are exactly what they require. The best way to approach planting a Grevillea (or any Proteaceaous plant) is simply to dig the hole, plant, and water the plant if it gets dry until you see good new growth. Then cease. Grevilleas are supremely drought adapted and are best left to subsist on only what falls from the sky. Its important to avoid watering them in hot weather. The combination of wet/hot soil will kill them- almost immediately. Neglect. It works.
We love them for their varied textures as well as propensity in our climate to bloom continuously- including all through winter. Give them a slightly protected location such as a south or west facing aspect in as much sun as possible. During the winter I have a permanent “flock” of Hummingbirds who harass my shrubs- one of the few nectar sources in winter- and they know it. If you want hummingbirds this is the number one shrub to plant.
They all grow very very fast, even without irrigation and it is advisable to prune them regularly to make sure that underground root growth mass matches top growth. If above ground growth is too rank it can rock the whole plant in gusty weather. Also, if your plant is shy to flower we have found that tip pruning, even very lightly, will spur them into bloom.
Climate Adapted Plants for Gardeners in the PNW