Welcome to the Rockwall County Extension Master Gardener research trials, in partnership with Texas A&M AgriLife Extension Service.
Our trials are located in the circular flower beds along the sidewalk between the Rockwall County Courthouse and Library.
Check back for updates as we share our findings. In the meantime, view the list of annuals and perennials selected for their ability to thrive with minimal care. Plants were watered only during initial establishment—no supplemental water has been added since.
Center Flower Beds 
Sweet Potato (Ornamental) Limon Wedge and Purple.– (HxW: 10-12” x 2-3’) Full sun. Texas Superstar®. Plant 10-36” apart. Handles a wide variety of well-drained soil types. Prolific growers. Prune to keep shape. Drought tolerant once established. Will require more water if in a container. Trailing plant. Thrives in our summer heat. Annual.
Angelonia Serenita® Purple. (HxW: 12-14” x 12-14”) Full sun. Plant 9-12” apart. Prefers moist, fertile soils with good drainage. Some drought tolerance once established. Heat and humidity tolerant. Annual.
English Lavender ‘Lavender Blue’ (HxW: 12-18” x 12-18”) Full sun. Plant 9-12” apart. Prefers well-draining, dry soils. Allow soil to dry out between watering. Consider planting in raised beds or mounds to help with drainage. Drought tolerant. Prune back to 6-8″ in late winter/early spring. Prune again in late summer to remove spent flowers. Perennial.
Vinca Cora® XDR (Extra Disease Resistant) White. (HxW: 14-16” x 18-20”) Full sun. Texas Superstar®. Plant 12-18” apart. Prefers well-draining soils. Heat loving. Drought tolerant once established. Avoid overhead irrigation. Plant in late spring/early summer after the soil has thoroughly warmed. Annual.
Outer Circle Flower Beds
Artemisia (HxW 1-2′ X 3-4”) Full sun. Semi-evergreen with attractive, silvery foliage. Thrives in dry, well-drained conditions. Drought tolerant once established. Spreads by rhizomes and grows back from the crown in spring. Perennial.
Catmint ‘Walker’s Low’ (HxW 18” X 18”) Full sun to part shade. Can benefit from part shade during hottest part of summer. Thrives in well-draining, dry soil. Drought tolerant once established. Will die back in winter and return from roots in spring. Spreading growth habit. Perennial.
Flame Acanthus (HxW 3-5′ X 3-4′) Full sun. Texas NATIVE. Thrives in well-draining, dry soil. Also called Hummingbird Bush because hummingbirds love it! Drought tolerant once established. Will die back to the ground in winter and regrow from the roots in spring. Prune in early spring to encourage more blooms. Perennial.
Lantana ‘New Gold’ (HxW: 2-3’ x 2-3’) Full Sun. Texas Superstar®. Prefers well-drained soil. Drought tolerant once established. Space 3-5’ apart as ground cover. Dies back to the ground in winter. Prune to the ground. New growth occurs late spring when soil has warmed. Mounding habit. Non-invasive, sterile hybrid. Tender Perennial.
Rosemary Upright ‘Tuscan Blue’ (HxW: 3-5’ x 4-5’) Full sun. Plant 24-48” apart in well-drained soil. Rosemary does not like its roots to stay wet, so water thoroughly then allow to dry out between watering. Makes a good container plant and is cold hardy. Perennial.
Rudbeckia ‘Goldsturm’ Black-eyed Susan (HxW: 2’ x 2-3’) Full sun. Texas NATIVE. Plant 18-30” apart in well-drained soil. Will die back in winter and return from roots in spring. Stems can be cut back or left as protection and food for wildlife in winter. Disease and drought resistant. Deadhead to encourage reblooming. Perennial.
Russian Sage (HxW: 3-4’ x 3-4’) Full sun. Plant 3’ apart in well-drained soil. Don’t overwater. Blooms heavily all summer. Cut back in winter after dormant to 6’’ or 12” in spring. New growth comes from the crown. Perennial.
Turk’s Cap Red (HxW: 2-9’x 3-5’) Full sun to shade. Texas NATIVE. Blooms heavily and grows vigorously in full sun. Heat and drought tolerant once established. Hummingbird attractant. Will die back to the ground in winter and regrow from the roots in spring. Perennial
Salvia Henry Duelberg (HxW: 3’ x 3’) Full sun. Texas NATIVE. Texas Superstar®. Plant 24” apart in well-drained soil. Doesn’t like wet feet. Drought and sun tolerant. Will die back in winter. Grows taller than most other salvias and is known for its resilience. Perennial.
Salvia Greggii (Autumn Sage) (HxW:2-3’ x 2 x3’) Full sun. Texas NATIVE. Plant 18-24” apart in well-drained soil. Allow to dry between watering except in extreme heat. Likes high nitrogen fertilizer. Trim to thicken. Beginning the 2nd year trim back plants by 1/2 in early February and 1/3 in August. Hummingbirds and butterflies love them. Perennial.
Verbena Homestead Purple (HxW 10-12” X 18”) Full sun. Thrives in well drained soil. Well suited for hot dry summers, supplemental watering when needed. Sprawling, ground cover habit. Regular pruning will encourage more blooms. Will die back in winter and return from roots in spring. Perennial.
Yarrow ‘Milly Rock’ Yellow and Rose (HxW: 1-2’ x 2-3’) Full sun. Compact size. Thrives in well drained, dry soil. Drought tolerant once established. Remove spent flowers to encourage more blooms. Dies back to the ground in winter and regrows from the roots in spring. Divide clumps every 2-3 years. Perennial.