Greetings from the botanical world! We are the Grevilleas, a diverse and vibrant genus hailing from the ancient soils of Australia. While our home is far away, we can thrive in the American landscape with the right understanding and care. To form a beautiful, symbiotic relationship with you, here is our guide to happiness in your garden.
First and foremost, we adore the sun. We are sun-worshippers by nature, requiring a minimum of six hours of direct, unfiltered sunlight each day to perform at our best. This abundant light fuels our spectacular blooms and keeps our foliage dense and healthy. Please plant us in the brightest spot you have. While a few of our smaller, woodland-dwelling cousins can tolerate a little light shade, most of us will become leggy, sparse, and fail to flower without full sun.
This is non-negotiable for our survival. Our roots are highly susceptible to root rot fungi that thrive in wet, heavy, or compacted soil. We insist on exceptionally well-draining soil. If your native soil is heavy clay, you must amend it generously with coarse sand, gravel, and organic matter like composted pine bark. Alternatively, consider planting us in a raised mound or a container with excellent drainage holes. A potted life is perfectly fine for many of our compact cultivars.
Once established, we are remarkably drought-tolerant. The key phrase is "once established." For the first few months after planting, we need regular, deep watering to help our root system expand into the surrounding soil. After that, please let the soil dry out completely between waterings. In many parts of America, natural rainfall will be sufficient. Overwatering is the single greatest threat to our well-being. In winter, we need even less water, so please turn off those automated sprinklers.
We are adapted to life in low-phosphorus soils. Many common fertilizers, especially those designed for flowering plants or vegetables, contain phosphorus levels that are toxic to us. They can quickly cause yellowing leaves, defoliation, and death. If you feel we need a nutritional boost, seek out a native plant fertilizer, a slow-release fertilizer with very low phosphorus (look for a P value of 0 or 1 in the N-P-K ratio), or simply top-dress with well-composted organic matter in the spring.
We respond very well to thoughtful pruning. The best practice is to give us a light trim or tip-prune immediately after a main flowering flush has finished. This encourages us to produce dense, bushy new growth and prepares us for the next round of blooms. Avoid hard pruning into old, bare wood, as many of us do not readily shoot anew from these areas. Instead, regular light shaping is the secret to a magnificent, floriferous specimen.
