Rhododendron ‘Grandslam’ is a bold, large-flowered rhododendron valued for its dramatic red blooms and robust growth habit. In mid to late spring, it produces impressive trusses of vivid crimson-red flowers, creating a striking focal point in gardens, borders, and woodland plantings.
This cultivar develops into a substantial evergreen shrub, reaching approximately 2.5 metres in height at 10 years, with a broad, upright growth habit and dense foliage. The dark green leaves provide year-round structure and a strong backdrop for the fiery spring blooms.
‘Grandslam’ performs best in free-draining, acidic soil enriched with organic matter and benefits from regular mulching. When positioned in a sheltered or partially sunny location, it thrives and delivers reliable flowering and ornamental presence in New Zealand conditions.

Shop online or visit us at the RhodoDirect nursery, where you can view mature plants and talk directly with rhododendron specialists.

When you purchase a rhododendron, you will receive a well-established four-year-old plant grown in a 6L pot, with a strong root system and often developing flower buds, ready to settle in and thrive in your garden.

To help you plan for the plant’s eventual scale, the mature heights listed in the Product Information are estimated 10-year sizes from the time of planting. For more detail, please refer to our Size Guide in the FAQs.

Learn More: Size Guide

All our rhododendrons are grown in pots, so you can plant them anytime, though autumn is ideal for encouraging strong root growth. Find the right spot based on your chosen rhodo, improve the soil generously with organic matter, gently tease out the roots, and plant shallow at or just below the original soil level. Finally, mulch well and water thoroughly to help your plant establish.

Read more here | Planting & Soil Preparation Guide

Rhododendrons are rewarding and easy to grow once their basics are right — most issues come down to watering, drainage, or planting depth. Follow our planting guide for a great start, prune as needed, mulch annually to keep roots cool, and feed lightly in spring for a spectacular bloom later in the year.

Keep an eye out for common issues like powdery mildew or thrip, and address them promptly. We have plenty of information on caring for your rhododendron, and if you can’t find what you need, we’re always happy to talk all things Rhodos. Find a full overview in our General Care Guide (link below).

Read More: General Care Guide

We offer hand delivery within Christchurch. Outside of Christchurch, plants are sent via Post Haste and carefully packed in sturdy boxes, with up to four 6L plants fitting per carton, making it most economical to order in multiples of two or four.

Orders are dispatched Monday to Wednesday to avoid weekend delays, and for larger orders (10+ plants) we may recommend a bulk freight option. For full details, including height limits and delivery timing, please see our Shipping FAQs.

Learn More: Shipping Information