Understanding when and how to prune flowering shrubs is key to keeping them healthy and ensuring they produce the best possible blooms. The age of the wood plays a crucial role in this, as different shrubs flower on either old or new growth.

How Old Does the Wood Have to Be?

Shrubs That Flower on Old Wood

• These shrubs bloom on stems that grew in the previous season (or earlier).
• Typically, the flower buds are set in late summer or autumn and remain dormant over winter, ready to bloom in spring or early summer.
• In some cases, flowers can form on stems that are two or more years old.

Shrubs That Flower on This Year’s Growth

• These shrubs produce flowers on stems that grow in the current season.
• Their buds form in spring and early summer, blooming later in the same year.
• Since these shrubs don’t rely on old stems for flowering, they can be pruned hard without affecting the flower display.

How to Prune Shrubs Based on Their Growth Type

Pruning Shrubs That Flower on Old Wood

When to prune: Immediately after flowering, usually in late spring or early summer.

How to prune:

1. Remove spent flowers – Cut back flowered stems just above a healthy outward-facing bud.
2. Thin out old wood – Every few years, remove a few of the oldest stems at the base to encourage fresh growth.
3. Shape the plant – Trim lightly to maintain a balanced form but avoid cutting into stems with next year’s flower buds.

Examples: Forsythia, Lilac, Camellia, Wisteria, Rhododendron, Philadelphus.

Pruning Shrubs That Flower on This Year’s Growth

When to prune: Late winter or early spring, before new growth begins.

How to prune:

1. Cut back hard – Many of these shrubs benefit from being pruned back to a low framework (30–60 cm above the ground).
2. Encourage strong new shoots – Remove weak or spindly growth and focus on promoting fresh, vigorous stems.
3. Maintain shape – Some shrubs, like Fuchsia and Spiraea, respond well to a yearly tidy-up rather than severe pruning.

Examples: Buddleja, Fuchsia, Caryopteris, Hydrangea paniculata, Lavatera.

General Pruning Tips for All Shrubs

• Always use sharp, clean secateurs or loppers to make precise cuts.
• Cut at an angle just above a healthy bud or side shoot.
• For leggy shrubs, remove the oldest stems at the base to encourage bushier growth.
• Apply mulch and feed after pruning to support new growth.

Correct pruning not only ensures a good display of flowers but also keeps your shrubs healthy and long-lived.

Shrubs That Flower on Old Wood (Prune after flowering)

These shrubs develop flower buds on stems grown in the previous year or earlier. Cutting them too early (late winter or early spring) can remove the flower buds and reduce or eliminate that season’s display.

Spring and Early Summer Flowering Shrubs (Old Wood)

1. Forsythia (Forsythia spp.) – Bright yellow flowers in early spring.
2. Lilac (Syringa vulgaris) – Fragrant clusters of flowers in late spring.
3. Wisteria (Wisteria sinensis, Wisteria floribunda) – Cascading flowers in spring.
4. Camellia (Camellia japonica, Camellia sasanqua) – Blooms in late winter or early spring.
5. Rhododendron & Azalea (Rhododendron spp.) – Spring-flowering, often evergreen.
6. Philadelphus (Mock Orange, Philadelphus spp.) – Heavily scented white flowers in early summer.
7. Weigela (Weigela florida) – Trumpet-like pink or red flowers in spring/early summer.
8. Deutzia (Deutzia spp.) – Masses of small white or pink flowers in spring.
9. Kerria japonica – Golden yellow flowers in spring.
10. Magnolia (Magnolia stellata, Magnolia soulangeana, etc.) – Spring-flowering varieties bloom before leaves emerge.
11. Viburnum (Viburnum x bodnantense, Viburnum farreri, etc.) – Winter and early spring blooms.
12. Exochorda (Exochorda x macrantha ‘The Bride’) – White arching flowers in spring.
13. Chaenomeles (Japanese Quince, Chaenomeles speciosa) – Flowers in early spring before leaves appear.
14. Lonicera (Shrubby Honeysuckles, e.g., Lonicera fragrantissima) – Winter or spring flowering.
15. Ribes sanguineum (Flowering Currant) – Pink/red spring flowers.
16. Coronilla valentina subsp. glauca – Sweet-scented yellow flowers in late winter/spring.
17. Edgeworthia chrysantha – Late winter/early spring blooms on bare wood.
18. Hamamelis (Witch Hazel) – Flowers in late winter on previous year’s stems.
19. Hydrangea macrophylla (Mophead & Lacecap Hydrangeas) – Blooms on last year’s stems; prune only lightly.

Summer Flowering Shrubs (Old Wood)

20. Ceanothus (Evergreen types, e.g., Ceanothus ‘Concha’, ‘Puget Blue’) – Spring/early summer blooms on old wood.
21. Escallonia (Escallonia spp.) – Summer-flowering, lightly prune after blooming.
22. Fremontodendron (Flannel Bush) – Yellow cup-shaped flowers in summer.
23. Abelia x grandiflora – Lightly prune after flowering to maintain shape.

Shrubs That Flower on This Year’s Growth (Prune in late winter/early spring)

These shrubs bloom on fresh stems that develop in the same growing season. They can be pruned hard in late winter or early spring to encourage strong new shoots.

Summer and Autumn Flowering Shrubs (New Growth)

1. Buddleja davidii (Butterfly Bush) – Prune hard in early spring for summer blooms.
2. Fuchsia (Hardy types like Fuchsia magellanica) – Flowers throughout summer and autumn.
3. Caryopteris (Bluebeard, Caryopteris x clandonensis) – Late summer flowers on new shoots.
4. Perovskia (Russian Sage, Perovskia atriplicifolia) – Late summer flowers; cut back hard in spring.
5. Spiraea japonica (Japanese Spiraea) – Summer-flowering pink blooms on new wood.
6. Hydrangea paniculata (Panicle Hydrangea) – Prune hard in early spring.
7. Hydrangea arborescens (Smooth Hydrangea, e.g., ‘Annabelle’) – Flowers on new wood; prune in early spring.
8. Lavatera (Tree Mallow, Lavatera x clementii) – Tall, fast-growing summer flowers; prune hard in spring.
9. Hibiscus syriacus (Rose of Sharon) – Blooms late summer on current year’s growth.
10. Senna corymbosa (Cassia corymbosa) – Yellow flowers in late summer on fresh shoots.
11. Abutilon megapotamicum (Trailing Abutilon) – Can flower from early summer to autumn on new wood.
12. Lespedeza thunbergii (Bush Clover) – Late summer/fall flowering; prune hard in early spring.

Repeat-Flowering or Continuous Blooming Shrubs (New Growth)

13. Rosa (Modern Shrub Roses, Floribunda & Hybrid Tea Roses) – Most flower on new wood and benefit from early spring pruning.
14. Ceanothus (Deciduous types, e.g., Ceanothus x delileanus ‘Gloire de Versailles’) – Flowers on new shoots in summer.
15. Salvia (Shrubby types like Salvia microphylla, Salvia greggii) – Trim back hard in early spring.
16. Cistus (Rock Rose) – Blooms on new shoots but doesn’t like hard pruning.
17. Hypericum (St John’s Wort, e.g., Hypericum ‘Hidcote’) – Flowers on new stems in summer.
18. Artemisia ‘Powis Castle’ – Grown for its foliage; trim back in spring to prevent legginess.
19. Callistemon (Bottlebrush, e.g., Callistemon citrinus ‘Splendens’) – Flowers on new growth; light pruning after flowering.
20. Eucalyptus gunnii (Cider Gum) – Regular pruning encourages young, silvery foliage.

Key Takeaways

• Old Wood Bloomers → Prune after flowering (spring or early summer).
• New Wood Bloomers → Prune in late winter or early spring to encourage fresh growth.
• Avoid heavy pruning on shrubs that don’t respond well, like Witch Hazel, Daphne, and some Ceanothus.

Correct pruning at the right time helps your shrubs stay healthy and flower at their best year after year!