Botanical Name: Penstemon hybrid ‘Rock Candy® Blue’

Common Name: Beardtongue

Hardiness Zone: Perennial in Most Climates (USDA Zones 4–9)

Size: 12–16" Tall × 12–18" Wide

Growth Habit: Compact, Upright, Well-Branched

Sunlight: Full Sun to Partial Sun

Soil: Well-Drained Soil; Tolerates Average to Poor Soils

Water Needs: Low to Moderate; Drought Tolerant Once Established

Bloom Season: Late Spring to Early Summer

Fertilizer: Light Feeding in Spring; Avoid Excess Fertility

Features: Clear Blue Flower Spikes, Compact Habit, Excellent Uniformity, Deer Resistant, Pollinator Friendly

Uses: Borders, Containers, Pollinator Gardens, Rock Gardens, Mixed Beds

Patent: ✔ Patented

Propagation: ❌ Propagation Prohibited Without License

More About Penstemon ‘Rock Candy® Blue’

Penstemon ‘Rock Candy® Blue’ is one of my go-to choices when I want strong color in a smaller, more controlled plant. The flowers are a true, clean blue—something that’s surprisingly hard to find—and they show up in late spring right when the garden needs a lift. The bloom spikes rise neatly above the foliage, giving the plant presence without making it feel bulky or top-heavy.

What really sets this variety apart is its size and structure. Unlike taller penstemons that can feel sparse at the base, Rock Candy® Blue stays full and well-branched from the ground up. That makes it especially useful in the front to middle of borders or in containers, where everything needs to look intentional from every angle.

It prefers full sun and well-drained soil and performs best when conditions aren’t overly rich. Once established, it handles heat and short dry spells with ease. Good drainage is essential, especially in winter, but with that in place, it’s a dependable perennial that comes back strong each year.

Why We Like It (Our Trials)

At Garden Delivery, Rock Candy® Blue has proven to be one of the most reliable compact penstemons in our trials. It bloomed evenly, held its shape through the season, and didn’t thin out or flop. The flower color stayed clear and bright, even as temperatures climbed.

We also appreciate how easy it is to place in designs. It works just as well in containers as it does in the ground, and pollinators—especially bees—find it quickly. For gardeners who want bold color without extra height or maintenance, this one is hard to beat.

Rock Candy® Blue vs. Other Penstemons

Rock Candy® Blue is the most restrained and design-friendly Penstemon that we carry, especially when balance and scale matter. The clear blue flowers read noticeably cooler and calmer than the reds, which makes them easy to layer into mixed plantings without overpowering nearby colors—especially when placed beside Rock Candy® Ruby. While it doesn’t have the dramatic foliage contrast of Husker Red or the high-impact blooms of Red Riding Hood, it fills an important middle ground where neither extreme is needed. The plant stays compact, upright, and well-branched, so it looks intentional from every angle rather than loose or unfinished. That consistency makes it especially valuable in front-to-mid border positions and containers. I reach for Rock Candy® Blue when I want crisp color that supports the overall design instead of competing with it.