How to Grow Hydrangea Penny Mac

Hydrangea Penny Mac

Hydrangea macrophylla 'Penny Mac'

shrub

Penny Mac is a compact bigleaf hydrangea cultivar known for its ability to bloom on both old and new wood, providing reliable flowering even after harsh winters or pruning. It produces large, showy mophead flowers that can shift from pink to blue depending on soil pH. This deciduous shrub reaches 3-4 feet tall and wide, making it ideal for smaller landscapes and containers.

Growing Conditions

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Sun: Partial shade, 4-6 hours of morning sun daily; afternoon shade critical in hot climates

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Water: Keep consistently moist but not waterlogged; water 1-2 inches per week depending on rainfall and heat; more frequent watering needed during blooming and heat stress

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Spacing: 36-48 inches

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Days to maturity: Blooms the first year after planting; full size in 3-4 years

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Planting depth: Same depth as root ball; do not plant deeper

Soil

Type: Moist, well-draining soil rich in organic matter

pH: 5.5-7.0 (acidic soil produces blue flowers; neutral to slightly alkaline produces pink)

Amendments:

compost peat moss aged bark aluminum sulfate for blue flowers lime for pink flowers

Growing Zones

Find your zone →

Thrives in zones 5-9, with best performance in zones 6-8

5a 5b 6a 6b 7a 7b 8a 8b 9a 9b

Growth Stages

Spring Emergence

4-6 weeks

New shoots emerge from buds on previous year's wood and new canes; foliage is bright green and tender

Wait until danger of late frost passes before pruning; apply mulch to regulate soil temperature; avoid late-season nitrogen fertilizer that encourages tender new growth

Vegetative Growth

6-8 weeks

Rapid leaf and stem development; plant reaches full size; deep green foliage with prominent veining

Maintain consistent moisture; apply balanced or low-nitrogen fertilizer (10-10-10); prune lightly if needed for shape; monitor for pests

Bud Formation & Flowering

2-4 weeks for bud formation, 4-8 weeks for active blooming

Large flower buds form at stem tips; flowers open in mid to late summer in pink, blue, or purple hues depending on soil pH and aluminum availability

Continue regular watering; feed with phosphorus-rich fertilizer to support blooms; remove faded flowers to encourage continued blooming; deadhead spent flowers but leave stems for winter interest if desired

Late Summer to Fall

8-12 weeks

Flowers fade but retain ornamental papery texture; foliage may show fall color (burgundy or bronze tones); wood hardens and buds set for next year

Reduce watering slightly as temperatures cool; do not fertilize; leave faded flowers on plant to help harden wood for winter; apply mulch in late fall in colder zones

Winter Dormancy

12-16 weeks

Plant goes dormant; leaves drop; stems show brown coloration; flower buds remain visible at branch tips

In zones 5-6, protect with burlap or mulch mound to protect flower buds from extreme cold; no watering needed unless soil is bone dry; prune only in late winter if needed

Companion Planting

Plan your garden →

Plant with:

azaleas rhododendrons Japanese maple hostas ferns astilbe bleeding heart liriope

Avoid planting near:

black walnut butternut walnut tree of heaven

Common Pests

Spray with horticultural oil in late winter before growth begins; prune out heavily infested branches; monitor regularly
Increase humidity with misting; spray with water forcefully to dislodge; use insecticidal soap if severe; avoid over-fertilizing with nitrogen
and (Erysiphe cichoracearum)
Improve air circulation by pruning interior branches; avoid overhead watering; remove infected leaves; apply fungicide in severe cases; water at soil level only
Hand-pick beetles in early morning; use Japanese beetle traps away from plant; avoid insecticides that harm beneficial insects; neem oil may help

Uses

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Cut & Dried Flowers

Household

Penny Mac's large mophead flowers are excellent for fresh floral arrangements and dry beautifully for long-lasting dried arrangements. The flowers retain color and structure well when dried properly. [source]

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Ornamental Landscaping

Household

The compact size and reliable blooming habit make Penny Mac ideal for hedges, foundation plantings, container gardens, and mixed shrub borders. Its extended bloom time provides summer and fall color. [source]

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Pollinator Support

Wildlife

Hydrangea flowers attract bees, butterflies, and other beneficial insects throughout the blooming season, supporting local pollinator populations in the garden. [source]

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Floral Design & Crafts

Craft

The large, showy flowers are prized by florists and craft enthusiasts for wedding arrangements, wreaths, and other decorative projects. Their color-changing ability allows customization based on soil chemistry. [source]

Harvest Tips

Hydrangea Penny Mac is grown for ornamental flowers, not harvest. Cut flowers for arrangements once they have fully opened and hardened; early morning cutting preserves freshness. Cut stems at 45-degree angle above a set of buds. Flowers can be dried by hanging stems upside down in a warm, dry location for 2-3 weeks.

Fun Facts

🌱 Penny Mac's flower color is determined by soil pH and aluminum availability: acidic soils (pH below 6.0) with available aluminum produce blue flowers, while neutral to alkaline soils (pH above 7.0) produce pink flowers. You can shift colors by amending soil with aluminum sulfate or lime.
🌱 Unlike many bigleaf hydrangeas, Penny Mac is noted for its ability to bloom on both old and new wood, making it more reliably floriferous even in colder climates where winter damage might kill flower buds on wood-bloomers only.
🌱 Hydrangea flowers were historically used in traditional medicine in Asia, and the plant's name comes from Greek words 'hydro' (water) and 'angea' (vessel), referring to the plant's water-loving nature and cup-shaped seed pods.

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