Wild Blueberry Phenology Tracker


Phenological Staging Data

Updated 9-24-2020

For past weeks, visit the 2020 Wild Blueberry Phenology Record

Location  Week of:   
Sept. 21st 2020  
Prune Cycle, Bud Development
Hope Average of 3.21 buds per stem.
Waldoboro Average of 3.04 buds per stem.
Searsport Average of 3.58 buds per stem.
Ellsworth Average of 3.80 buds per stem.
Deblois Average of 7.00 buds per stem.
Montegail Average of 4.60 buds per stem.
Jonesboro Average of 3.70 buds per stem.
Crawford Average of 3.79 buds per stem.
Marion Average of 3.54 buds per stem.

See development stages below.

Phenology Site Locations


Hildebrand et al. 1991 staging guide
Wild Blueberry Staging Guide by Hildebrand and Braun 1991.Hildebrand, P.D., and P.G. Braun. 1991. Factors Affecting Infection of Lowbush Blueberry by Ascospores of Monilinia Vaccinii-Corymbosi. Canadian Journal of Plant Pathology 13(3): 232–240.

Wild Blueberry Phenological Developement


  • Early green fruit stage

    Early Green Fruit

Development Key

Bud Stages

T0 Buds are dormant and dark with scales tightly closed.
T1 Buds continue to swell with scales separating. Flower parts start to round inside bud. 
T2 Buds continue to swell with scales separating.
T3 Bud scales separate fully with flower tips visible.
T4 Petals (corolla) in flower bud are visible, but remain closed.
T5 Pre-bloom; petals (corolla) extend beyond the green base of the bud (calyx), but remain closed.

Leaf Stages

V0 Buds are dormant and dark with scales tightly closed.
V1 Spikey green tissue emerges from a tightly closed buds along stem (spikes < 2mm).
V2 Green tissue continues to emerge and remains spikey (spikes 2-5mm).
V3 Tips of inividual leaves being to separate (emerged tissue > 5mm).
V4 Leaf shoots expand and enlarge in a whorl pattern.

* Sources include: Hildebrand and Braun 1991 and Rutgers University.

Hildebrand, P.D., and P.G. Braun. 1991. Factors Affecting Infection of Lowbush Blueberry by Ascospores of Monilinia Vaccinii-Corymbosi. Canadian Journal of Plant Pathology 13(3): 232–240.

Winter kill
Winter kill

Leaf Stages

  • early leaf tip

    Early Green Tip (V1)

  • late green tip2

    Green Tip (V2)

  • Shoot expansion

    Shoot Expansion (V4)

  • T4 Tight Cluster

    Tight Cluster (T4)

  • T5 Early Flower

    Early Flower Development (T5)

  • wild blueberry bloom, white petals

    Open Flower

  • Pin head stage following petal fall

    Pin head

Bud Stages

  • Bud Swell

    Bud Swell (T1)

  • Bud Break and leaf tip

    Bud Swell (T1)

  • Bud break

    Early Bud Burst (T2)

  • T3 Through Bud Break T3

    Bud Burst (T3)