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How to Grow Rock Rose 'Sudbury Gem'

Rock Rose 'Sudbury Gem'

Helianthemum 'Sudbury Gem'

shrub

Rock Rose 'Sudbury Gem' is a compact, spreading evergreen shrub prized for its vibrant orange-red flowers with darker centers that bloom profusely in late spring through summer. This cultivar forms a low mound of fine-textured foliage and thrives in sunny, well-drained locations. It is excellent for rock gardens, borders, and Mediterranean-style landscaping.

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Example Rock Rose 'Sudbury Gem' timeline · Pittsburgh, PA (Zone 6b)

  1. Plant Rock Rose 'Sudbury Gem'

    Around Apr 17

    Near Pittsburgh's average last spring frost.

  2. Tend & protect

    Late spring–summer

    Watering, feeding, and pest-watch reminders.

  3. Harvest Rock Rose 'Sudbury Gem'

    Late summer into fall

    Before the first fall frost (≈ Nov 8)

Sample dates for Pittsburgh, PA. Sign up to get exact Rock Rose 'Sudbury Gem' dates for your own zip code.

Growing Conditions

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Sun: Full sun, 6-8 hours daily minimum; blooming decreases significantly in partial shade
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Water: Low to moderate water needs once established; drought tolerant. Water regularly during establishment (first season). Avoid overwatering; ensure soil dries between waterings to prevent root rot.
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Spacing: 18-24 inches
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Days to maturity: Plant matures within 2-3 years to full size
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Planting depth: Plant at same depth as nursery container; do not bury crown

Soil

Type: Well-draining sandy or gravelly loam
pH: 6.0-7.5
Amendments:
Coarse sand or gravel for drainage Perlite or pumice Minimal organic matter to prevent rot

Growing Zones

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Thrives in zones 6-8; hardy to zone 5 with protection; struggles in hot, humid zones 9+

5b 6a 6b 7a 7b 8a 8b 9a

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Growth Stages

1

Establishment

4-6 weeks

Young transplant settling into garden with slow initial growth and minimal flowering

Water regularly but not excessively; mulch lightly with gravel around (not against) stem. Protect from harsh winter winds in colder zones.

2

Vegetative Growth

Spring through early summer, year 1-2

Expanding mound of fine, needle-like foliage; increasing branch density and size

Reduce watering frequency as roots establish. Provide excellent drainage. No fertilizer needed; poor soil actually promotes better form.

3

Flowering

Late May through August

Abundant small, papery flowers (typically orange-red with darker eye) covering foliage

Deadhead spent flowers to encourage continuous blooming. Do not fertilize; high nutrients reduce flowering. Ensure full sun exposure.

4

Post-Bloom / Hardening Off

September through November

Flowering reduces; plant consolidates growth; foliage remains evergreen

Reduce watering gradually in fall. Light pruning after bloom to maintain compact form is optional but beneficial for shape.

5

Dormancy / Winter

December through March

Evergreen foliage persists; plant growth slows dramatically in zones 5-7

No water supplementing needed. In zone 5, consider winter protection (burlap, windbreak) on exposed sites. Ensure drainage remains excellent to prevent winter wet rot.

Companion Planting

Plan your garden →

Plant with:

Lavender Rosemary Sedum Sempervivum Catmint (Nepeta) Germander Thyme Dianthus Artemisia

Avoid planting near:

Plants requiring frequent watering (hydrangea, hostas) Plants preferring rich, moist soil Tall shade-casting plants that block sunlight

Common Pests

  • Spray with water to dislodge; use miticide if severe. Improve air circulation. Less common in well-drained sites.

  • Yellow sticky traps; insecticidal soap; neem oil. Typically minor issue outdoors.

  • Prevention is key: ensure excellent drainage, avoid overwatering, use well-draining soil. Remove affected plant and improve drainage in planting area. No fungicide cure once established.

Uses

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Rock Gardens & Alpine Displays

Ornamental

Ideal for rock gardens, alpine troughs, and raised beds where excellent drainage and full sun can be provided. The low, spreading habit and small foliage create authentic alpine garden aesthetics. [source]

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Mediterranean & Drought-Tolerant Landscapes

Ornamental

Perfect for Mediterranean, xeriscape, and drought-tolerant garden designs. Combines well with other sun-loving, drought-tolerant plants to create low-maintenance, water-wise borders. [source]

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Ground Cover & Edging

Ornamental

Used as a ground cover on slopes, in containers, or at garden edges where its spreading, low-mounding form can be showcased. Works well in hanging baskets and troughs. [source]

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Pollinator Support

Wildlife

The papery flowers are visited by bees and other pollinators, particularly in sunny, open sites. Provides early to mid-summer nectar and pollen for beneficial insects. [source]

Harvest Tips

Rock Rose is ornamental; no harvest for culinary or medicinal use. Deadhead spent flowers throughout bloom season to extend flowering. Cut back lightly (not into old wood) after bloom if desired to maintain compact shape, though not essential.

Fun Facts

  • 🌱 Rock Rose flowers open in bright sunshine and close at dusk or on cloudy days—a behavior called heliotropism, literally 'sun-turning.'
  • 🌱 'Sudbury Gem' was bred in England and is a cultivar selection chosen specifically for its vibrant orange-red coloring and reliable hardy performance.
  • 🌱 The common name 'Rock Rose' is misleading; these plants are not true roses but rather members of the Cistaceae family, and are completely unrelated to Rosa species.

Gardening Terms

New to gardening? Learn about terms used in this guide:

Cultivar Deadhead Full Sun Mulch Partial Shade Transplant
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