Best Cascading Annuals for Window Boxes: Color, Sun & Care Guide

A homeowner has three vinyl window boxes ranging from full sun to part shade. Wants pink, white, blue/purple cascading plants for a long summer show.

Top Cascading Annuals (Full Sun to Part Shade)

Plant	Colors	Notes
Wave / Supertunia Petunias	Pink, white, purple, blue	Vigorous, self‑cleaning, all‑season bloom
Million Bells (Calibrachoa)	Pink, white, purple, blue	Best non‑stop flowering, heat tolerant
Bacopa	White, pink, lavender	Small flowers, loves consistent moisture
Sweet Alyssum	White, purple, pink	Fragrant, dense carpet, attracts beneficials
Lobelia	Blue, white	True blue, prefers cooler temps, may pause in extreme heat
Trailing Verbena	Purple, pink, white	Heat lover, butterfly magnet

Soil: Quality potting mix with moisture crystals + slow‑release fertilizer.
Drainage: Ensure boxes have holes; add 1 inch gravel base.
Water: Check daily. Boxes dry 2x faster than ground. Water deeply until drainage. In heat, may need 2x/day.
Fertilize: Weekly with bloom‑booster (high P) at half strength. Stop fertilizing in extreme heat (>90°F)—plants are heat‑dormant.
Deadhead: Not needed for self‑cleaners (Wave, Calibrachoa), but helps others.

Blue is rare in cascading annuals. Lobelia is your best bet. For purple, use Verbena, Calibrachoa, or Petunia.

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