Louisa Weeping Crabapple

Full bloom

Malus 'Louisa'

Rosaceae · broadleaf deciduous tree · introduced

Last updated

‘Louisa’ is the standard recommendation among weeping crabapples for Puget Sound landscapes — when a client or designer asks for a "weeping crabapple," this is the cultivar to specify by name. The weeping form is genetic (not a top-graft like many compact "weeping" cultivars sold commercially), which means mature trees develop a graceful fountain-shape silhouette that ages well rather than the often-awkward lollipop-on-a-stick appearance of staked top-grafts. The 10-15 ft mature size accommodates small residential yards where larger crabapples wouldn't fit, and the cascading branch habit pairs well with water features, pond margins, and entry alcoves where the flowing texture reads from a distance. True-pink fragrant flowers from red buds are visually saturated and the cultivar's signature ornamental feature. Disease resistance is among the best in the weeping category — JFS rates scab Excellent and fire blight, rust, mildew all Good — meeting or exceeding most upright crabapple cultivars in commerce. For Puget Sound clients looking for a small ornamental tree that reads dramatically from a distance, has true weeping form, fragrant pink spring bloom, and reliable disease resistance in PNW conditions, Louisa is the default. Maintenance note: weeping branches reach ground level on mature trees and may need occasional pruning to maintain mowing or walking clearance under the canopy. The cultivar's Polly Hill provenance is a useful design story for clients who value horticultural history.

— Chris Welch, ISA Certified Arborist

Plant Profile

Size & Form

Height
10-15 ft
Spread
12 ft (weeping branches typically equal or slightly exceed height)
Growth Rate
Medium (typical malus growth rate; reaches mature size in 15-20 years)
Size at 20 yr
10-15 ft (typically reaches mature height around 15-20 years; weeping habit limits height accumulation)
Lifespan
50-80 years typical for ornamental crabapples

Site Requirements

Light
Full sun (best flower production and disease resistance)
Soil Drainage
Well drained; tolerates a wide range of soil textures
Soil pH
5.5-7.5 (slightly acidic to neutral); tolerates wide pH range typical of Malus cultivars
Water
Moderate
Drought Tolerance
Moderate; established trees tolerate seasonal drought
Hardiness
Zones 4–8 (Polly Hill Arboretum origin supports Zone 7 maritime climate performance)

Ornamental Interest

Bloom Time
Late April to mid-May (Puget Sound); mid-season blooming
Fall Color
Green-yellow-orange transition; modest but present autumn interest
Origin
Cultivar; discovered by Polly Hill at her arboretum on
Watch for this season

Bloom Infection Window

Active Conidial Spread

First Flight

Diseases: Regionally Documented (3)

Diseases: Other Associations (1)

Pests: Regionally Documented (3)

Phenological Calendar

As of June 3, 2026, Puget Sound stations range from 2435.5 to 2672.8 GDD₃₂. Louisa Weeping Crabapple has passed full bloom (1305 GDD₃₂).

Regional Season Tracker

GDD₃₂ accumulation across 7 Puget Sound stations · as of Jun 3, 2026
Station GDD₃₂ Current Stage Next To Go
Issaquah / East King 2,673 Full bloom
Kent / Auburn 2,665 Full bloom
Seattle / UW 2,610 Full bloom
Olympia / Tumwater 2,570 Full bloom
Tacoma / Puyallup 2,535 Full bloom
Bellingham / Whatcom 2,533 Full bloom
Sequim / Rain Shadow 2,436 Full bloom
View full calendar (2 stages)
Stage GDD32 Typical Window
Beginning of flowering BBCH 61 990 Late April (Puget Sound); mid-season blooming
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 Jun 3, 2026. Predicted dates use 16-day weather forecast through Jun 19, 2026, then climate normals.

Data Maturity
Structured Multiple sources. Expert review underway.