Ruby Dayze Crabapple
Full bloomMalus 'JFS KW139MX'
Rosaceae · broadleaf deciduous tree · introduced
Last updated
Quick Facts
Bloom Infection Window
Spring Emergence / Primary Infection
Pupation
Phenological Calendar
As of May 13, 2026, Puget Sound stations range from 1906.2 to 2098.2 GDD₃₂. Ruby Dayze Crabapple has passed full bloom (1305 GDD₃₂).
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of May 13, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 2,098 | Full bloom | — | — |
| Kent / Auburn | 2,089 | Full bloom | — | — |
| Seattle / UW | 2,063 | Full bloom | — | — |
| Olympia / Tumwater | 2,025 | Full bloom | — | — |
| Tacoma / Puyallup | 1,993 | Full bloom | — | — |
| Bellingham / Whatcom | 1,972 | Full bloom | — | — |
| Sequim / Rain Shadow | 1,906 | Full bloom | — | — |
| Stage | GDD32 | Typical Window |
|---|---|---|
| Beginning of flowering BBCH 61 | 990 | Late April (Puget Sound) |
| ● Full bloom BBCH 65 NOW | 1305 | Late April to early May (Puget Sound) |
Source: HortGuide regional interpretation based on Morton Arboretum bloom timing About GDD₃₂ →
Season tracker for Kent / Auburn as of May 13, 2026. Predicted dates use 16-day weather forecast through May 29, 2026, then climate normals.
Diseases: Regionally Documented (3)
Diseases: Other Associations (1)
Pests: Regionally Documented (3)
Ruby Dayze® is J. Frank Schmidt's purple-leaf-flowering-plum challenger — a relatively new cultivar (PP31,232, late 2010s) bred to offer the saturated purple foliage and bright magenta pink flowers characteristic of ornamental Prunus cerasifera 'Krauter Vesuvius' and similar purple plums but in a crabapple framework with the advantages of disease resistance and lower management requirements. Excellent disease resistance across all four major diseases per JFS supports reliable performance in maritime PNW. The flowers and foliage are nearly the same color, creating an integrated rather than contrasting spring display. Cross-reference with other modern purple-foliage crabapples: 'Royal Raindrops®' (15-20 ft cutleaf foliage, magenta-pink flowers, smaller scale), 'Purple Prince' (20 × 20 ft rounded, rose-red flowers), 'Raspberry Spear®' (20 × 8 ft narrow columnar, magenta pink). Ruby Dayze fits the upright tightly oval niche distinct from the rounded Purple Prince and the narrower Raspberry Spear. Cross-reference purple-foliage decision tree: 'Royal Raindrops®' (cutleaf, 15-20 ft), 'Purple Prince' (rounded 20 × 20 ft), 'Ruby Dayze®' (upright tightly oval 22 × 16 ft), 'Raspberry Spear®' (narrow columnar 20 × 8 ft).
— Chris Welch, ISA Certified Arborist