Torenia ‘Summer Wave® Trailing Large Blue’: shade-loving color that blooms from planting to frost
Torenia ‘Summer Wave® Trailing Large Blue’ is a heat-loving Wishbone Flower that never seems to quit. This trailing hybrid piles on vivid royal-blue trumpets with pale throats from late spring until frost. It shines in hanging baskets, window boxes, railing planters, and the shadier edges of beds where petunias stall. As a member of the Linderniaceae family, Torenia brings fine, fresh foliage, an easy, self-cleaning habit, and reliable performance in humidity. Gardeners also meet this plant as Summer Wave® Trailing Large Blue, Blue Wishbone Flower, Summer Wave Trailing, and by its cultivar code ‘Sunrenilabu’. SUMMER WAVE® is a registered trademark of Suntory Flowers Ltd., and this selection comes from their vegetatively propagated series.
Why choose Torenia ‘Summer Wave® Trailing Large Blue’
Choose this Wishbone Flower when you want nonstop blue in part shade. The plant mounds to 20–25 cm (8–10 in) and trails 50–90 cm (20–36 in), so it spills beautifully over pot rims and softens hard edges. Flowers read as true blue—a rare color in summer annuals—and each bloom shows the classic “wishbone” where the two stamens meet. It thrives through heat and high humidity, keeps blooming without deadheading, and stays neat with minimal pinching. Bees visit the open throats for nectar. Hummingbirds work the trumpets on warm mornings. Deer usually ignore the leaves, which adds peace of mind in open yards.
Torenia ‘Summer Wave® Trailing Large Blue’ at a glance
Expect a compact crown with many branching shoots. Stems carry small, bright-green leaves that hold their color all season. Flowers measure 3–4 cm (1¼–1½ in) across and appear in a steady stream rather than in short flushes. In warm climates (USDA Zones 10–11), plants can live through winter; elsewhere gardeners grow them as summer annuals. Because the blooms clean themselves, containers stay tidy with little effort. You can plant once in late spring and enjoy color until the first hard frost.
Wishbone Flower is the everyday name for Torenia. The genus sits in Linderniaceae, a small family of mostly herbaceous plants. This cultivar is a modern interspecific hybrid often written as Torenia hybrida. Breeders selected it for larger flowers, stronger trailing, and tolerance to both heat and shade. In the trade you will see series names like Summer Wave®, Summer Wave® Trailing, and specific color tags such as Trailing Large Blue. All point to the same garden goal: bold color in the warm months with little maintenance.
Growth habit, size, and seasonal rhythm
In good conditions, plants reach 20–25 cm (8–10 in) tall and 25–30 cm (10–12 in) wide at the rim of the pot, then trail 50–90 cm (20–36 in) over the season. The habit stays naturally full and rounded. Shoots branch freely, especially if you give one light pinch after transplanting. Bloom begins when days warm to about 18–21 °C (65–70 °F). It continues through midsummer heat and into autumn. In deep shade, flowering slows; in a few hours of morning sun plus bright afternoon shade, it reaches peak output.
Design ideas with Wishbone Flower
Use Torenia ‘Summer Wave® Trailing Large Blue’ as the “spiller” in mixed containers. Pair it with silvery foliage like Helichrysum, Dichondra ‘Silver Falls’, or Artemisia for a cool palette. For contrast, tuck in chartreuse Coleus or Lysimachia nummularia ‘Aurea’. In window boxes, weave it between upright Salvias or Angelonias to get a classic “thriller–filler–spiller” look. Along shady paths, plant it at the front of beds, 30–45 cm (12–18 in) apart, so the blue edge pulls the eye and ties areas together. In hanging baskets, one plant in a 30 cm (12 in) basket makes a soft cascade; two or three plants create a lush skirt of bloom from rim to base.
Environmental tolerances you can rely on
This hybrid tolerates heat, humidity, and brief dry spells once established. It also tolerates light salt spray in coastal gardens when shielded from strong winds. However, it does not tolerate frost. Temperatures below about 4–5 °C (40 °F) can damage flowers and foliage, and a hard freeze will end the show. It performs best with steady moisture in a well-drained medium. In strong, direct afternoon sun in hot inland areas, the flowers may fade; give dappled shade after lunch to keep color rich.
How to Grow Torenia ‘Summer Wave® Trailing Large Blue’
Light
Place it where it receives morning sun and afternoon shade, or bright open shade all day. Aim for 3–6 hours of direct light, preferably before noon. In cool coastal zones, it can take more sun. In hot, dry interiors, protect it from intense 1–4 p.m. rays to prevent leaf scorch and wilting.
Soil for Torenia
Use a fertile, well-drained mix. In containers, choose a peat- or coir-based potting media with perlite for porosity. Avoid heavy garden soil in pots; it compacts and holds too much water. In beds, improve drainage with compost and fine bark. A pH near neutral (6.0–7.0) suits the plant. Very alkaline soil can slow nutrient uptake.
Watering
Water deeply, then let the top 2–3 cm (¾–1¼ in) of mix dry before watering again. In warm weather, expect to water baskets daily; during heat waves, you may water morning and late afternoon. A 30 cm (12 in) hanging basket typically needs 1–1.5 L (1–1½ qt) per watering to reach the root zone. In beds, provide 2–3 cm (¾–1¼ in) of water per week from rain or irrigation. Mulch garden plantings 3–5 cm (1–2 in) deep to moderate evaporation, keeping mulch a couple of centimeters off the stems.
Fertilizing
Feed little and often for continuous bloom. In containers, mix a slow-release fertilizer into the potting medium at planting, then supplement with a balanced, water-soluble fertilizer every 2–3 weeks at half strength during peak growth. In beds, top-dress with compost at planting and again midsummer, or apply a slow-release product per label. Avoid high-nitrogen formulas that push leaves at the expense of flowers.
Temperature and hardiness
Grow as a warm-season annual in Zones 3–9. It overwinters outdoors only in mild regions (Zones 10–11). Ideal daytime temperatures range from 21–29 °C (70–85 °F) with nights above 13 °C (55 °F). If a cool snap drops nights below 10 °C (50 °F), growth pauses; flowering resumes as temperatures rebound.
Planting and spacing Torenia ‘Summer Wave® Trailing Large Blue’
Transplant after danger of frost when nights stay above 10 °C (50 °F). In containers, allow one plant per 25–30 cm (10–12 in) of basket diameter for a refined look, or two to three for a lush, quick-fill display. In garden beds, space plants 30–45 cm (12–18 in) apart, depending on how fast you want coverage. Water immediately after planting to settle the mix around roots.
Pinching and grooming
Give a soft pinch (remove 1–2 cm / ½–¾ in of the growing tip) one week after transplanting to promote branching. After that, the plant stays self-cleaning. If hot spells stretch stems, shear the basket lightly by 5–8 cm (2–3 in) and feed; new blooms return fast in warm weather.
Containers, baskets, and window boxes
Choose a basket 30–35 cm (12–14 in) wide with several drain holes. Line with coco fiber or use a rigid plastic basket; either way, ensure water exits freely. In window boxes, pair Torenia with upright Angelonia (for sun to part sun boxes) or with Plectranthus and Begonia (for shade boxes). Water at soil level to keep foliage dry and reduce disease pressure.
Propagation of Torenia ‘Summer Wave® Trailing Large Blue’
Nurseries produce this cultivar vegetatively. You can take tip cuttings 6–8 cm (2½–3 in) long from non-flowering shoots in late spring. Remove the lower leaves, dip in a mild rooting hormone, and insert into a sterile, fine mix of perlite and peat. Keep evenly moist at 21–24 °C (70–75 °F) with high humidity. Roots form in about two weeks. Note that series plants often carry intellectual property protections; home propagation for personal use is generally permitted, but commercial propagation may be restricted. Check local regulations if you intend to sell plants.
Pests and diseases on Torenia ‘Summer Wave® Trailing Large Blue’
This hybrid is naturally resilient, yet routine checks keep it pristine. Aphids sometimes cluster on tender tips in spring; rinse with a firm jet of water or apply insecticidal soap. In hot, dry spells, spider mites can stipple leaves; increase humidity around baskets and wash the undersides of leaves. Thrips can crease petals during heat waves; keep plants evenly watered and avoid heavy overhead irrigation at midday.
Diseases are uncommon when you water at the soil line and provide airflow. Prolonged wet foliage in cool spells can invite Botrytis on crowded baskets; thin gently and let morning sun dry leaves. Constantly wet soil can cause root rot; ensure sharp drainage and allow slight drying between waterings. If lower leaves yellow while the mix stays wet, ease back on irrigation and check for blocked drain holes.
Torenia ‘Summer Wave® Trailing Large Blue’ in pollinator gardens
Wishbone Flower offers open throats that small native bees and hoverflies can access. The blue hue also stands out to bees, which helps draw activity to shaded decks where pollinator color is often scarce. Hummingbirds sip the shallow trumpets, especially during warm mornings. Because the plant blooms continuously, it supports insects during mid- and late-summer gaps when spring perennials have finished.
Companion planting that works
For part shade baskets, combine Torenia with Bacopa (Sutera), Lobelia, and trailing ivy-leaf Pelargonium. For bright shade beds, weave it around Heuchera, Hosta, and Carex for a cool understory. In patio pots, the blue looks sharp against chartreuse Coleus, golden Lysimachia, or silver Dichondra. If you need heat lovers for mixed sun and shade, Angelonia and Calibrachoa can share the same container as long as you keep moisture steady.
Seasonal care calendar
Early spring (after frost): Transplant hardened-off plants once nights exceed 10 °C (50 °F). Pinch lightly one week after planting. Start a two-week feeding rhythm if you are not using slow-release fertilizer.
Late spring to midsummer: Water deeply and consistently. Feed every 2–3 weeks with a balanced liquid fertilizer at half strength. Shear lightly if baskets become wind-tattered. Scout for aphids and mites.
Midsummer to early autumn: Maintain moisture during heat waves; baskets may need twice-daily water. If growth stretches, give a 5–8 cm (2–3 in) trim and feed; blooms rebound quickly in warm nights.
Late autumn (before frost): Enjoy the last flush. Compost tired annuals after the first hard frost, or move a favorite basket indoors to a bright window to extend bloom a few more weeks.
Quick troubleshooting for Wishbone Flower
Few flowers: Increase light to at least bright open shade with morning sun. Check fertilizer—too much nitrogen suppresses bloom. Ensure you are not letting the mix swing from bone-dry to sopping wet.
Wilting at midday: Common in hot weather, especially in baskets. Water early, then again late afternoon during heat waves. Consider a larger basket with more soil volume.
Leaves bleaching or crisping: Too much afternoon sun in hot interiors. Shift to morning sun and afternoon shade.
Yellow leaves with green veins: Possible high pH or overwatering. Flush pots, feed with a complete fertilizer that includes micronutrients, and let the top of the mix dry slightly between waterings.
Leggy growth: Provide more light and give one soft pinch. Resume a regular feeding schedule to support branching.
Planting recipes and spacing tips
For a 30 cm (12 in) hanging basket, plant one Torenia ‘Summer Wave® Trailing Large Blue’ for a clean silhouette, or two for an instant full skirt. For a 40 cm (16 in) basket, three plants create a billowing cascade. In window boxes 90 cm (36 in) long, use three plants spaced evenly, then thread a contrasting filler between them. In beds, plant at 30–45 cm (12–18 in) spacing, closer on the shadiest sites where growth is slightly slower.
Sustainable care notes
Because this selection thrives in part shade, it reduces irrigation demand compared with thirsty sun annuals. Mulch bed plantings to save water. Choose slow-release or organic feeds to limit runoff from containers. Encourage natural pest control by attracting hoverflies and lacewings with companion flowers like Alyssum and small-flowered Salvias nearby.
Final thoughts: blue that thrives where many annuals fade
Plant Torenia ‘Summer Wave® Trailing Large Blue’ when you need reliable blue in warm, shady spaces. Give it bright morning light, a fertile, well-drained mix, and steady moisture. Pinch once, feed lightly but often, and let its self-cleaning habit do the rest. In return, this Wishbone Flower delivers a long season of color, from porch baskets to path edges, even when summer turns steamy. Few annuals offer so much bloom with so little fuss in part shade—exactly why this Summer Wave® standout earns a spot on every container shortlist.
