Hydrangea Care Calendar
Alabama Hydrangea Society / Compiled by David Doggett / Updated 2018
Bigleaf or "French" or Blue/Pink Hydrangeas –
Hydrangea macrophylla, Hydrangea serrata
Mophead or lacecap blooms of blue, pink, or white appear in May on "old wood."
March – apply a slow-release fertilizer such as
Osmocote for 4-month feeding.
May – remove dead stems that show no sign of life
May – propagation: greenwood cuttings can be rooted.
June – deadhead fading flowers of repeat bloomers to
promote more new flowers this season.
June – "Prune immediately after bloom." 3 Shorten
stems by ¼ to ½. Cut 1/3 of oldest stems to the
ground if old hydrangea requires rejuvenation.
Examples: Nikko Blue, Penny Mac, Sister Theresa, Bluebird, Endless Summer, Merritt's Supreme, Fuji Waterfall, Preziosa.
Flower buds are set at the end of the previous year's growing season and too often are damaged by our fluctuating winter cold.
Alternatively, apply light fertilizer in March, May, and June.2
"[Bigleaf hydrangeas] requires moderate to high nutrient levels."1
Don't be too quick to remove dead-looking stems. Some stems will just be late to leaf out.
From late April through July cuttings can be prepared for rooting.1
Repeat bloomers include: Endless Summer series, Penny Mac, Mini Penny, David Ramsey, Oak Hill, Decatur Blue, and Nantucket Blue.
Complete any pruning by end of July. "Next year's flower buds begin forming in August." 2
Oakleaf Hydrangeas – Hydrangea quercifolia
White conical blooms appear in June on "old wood."
April – apply a slow-release fertilizer such as
Osmocote for 4-month feeding.
July – complete pruning (rarely needed) by end of July.
December (dormant season) – can propagate by
dividing their rooted, underground stems.2
Examples: Snowflake, Harmony, Snow Queen, Pee Wee, Alice.
Flower buds are set at the end of the previous year's growing season.
Alternatively, apply two light applications of fertilizer in April and June.2 Native plants like Oakleaf hyd. generally need less fertilizer.
"Prune right after bloom." 4 Pruning is rarely needed except to rejuvenate a large, mature plant. To rejuvenate, cut 1/3 of oldest stems to the ground each year for 3 years.
Take advantage of oakleaf hydrangea's colonizing habit to cut off and pot up self-rooted stems from mature shrubs.
Smooth Hydrangeas – Hydrangea arborescens
White blooms appear in May/June on "new wood."
Feb./March – prune old stems to 6-12" tall.2
March – one annual fertilizer application.2
December (dormant season) – can propagate by
dividing their rooted, underground stems.2
Examples: Annabelle, Incrediball, Hayes Starburst, Bella Anna.
Blooms appear on new season's stem growth. A native plant.
Blooms on new growth. "Hard pruning produces bigger flowers." 4
Follow suggested application rate. Apply as leaves emerge.
Take advantage of Hydrangea arborescens' colonizing habit to cut off and pot up self-rooted stems.
Panicle Hydrangeas – Hydrangea paniculata
White blooms from July-October on "new wood."
Feb./March – annually prune back to about 18-24" tall.
April – apply a slow-release fertilizer such as
Osmocote for 4-month feeding.
Examples: Limelight, Little Lime, Tardiva, PeeGee, Firelight, Bobo.
Blooms appear on tips of current season's stems.
Blooms on new growth which pruning stimulates. "Do not massacre the plant by reducing it to stubs."1 Create branching structure.
Alternatively, apply two light applications of fertilizer in April and June.2
Climbing Hydrangeas – H. anomala petiolaris, Schizophrgma, and Decumaria species.
White lacecap-like blooms in spring on "old wood."
March – one annual fertilizer application with slow-
release fertilizer.2
June – selective pruning if necessary just after flower-
ing to keep in bounds.
Examples: Schizophragma Roseum, Moonlight
These vines are very slow to get established and may take years before beginning to bloom for the first time.
Typically this plant requires little or no pruning. Light pruning may help stimulate the vine into blooming.
References:
1. Michael A. Dirr, Hydrangeas for American Gardens, Timber Press, 2004.
2. Hydrangeas, Alabama Cooperative Extension System publication ANR-1276, www.aces.edu, 2017.
3. The Southern Living Garden Book, edited by Steve Bender, 2nd edition.
Planting tips:
In Alabama, Hydrangeas (except panicle hyd.) generally prefer shading from hot mid-day and afternoon sun. October through March is the best time to plant shrubs in the south – the earlier the better to allow the plant several months to establish its root system.2
Bigleaf or "French" Hyd. – Dig hole 2' wider than container, or use a raised bed if soil drains poorly. Amend soil generously with organic matter. To promote blue Bigleaf Hyd. blooms, add peat moss to soil and mulch with pine straw to help make soil pH more acidic. To promote more pink or red Bigleaf Hyd. blooms, mix lime into the planting soil.
Oakleaf Hyd. – must have excellent drainage to thrive. They are very sensitive to wet feet.
Panicle Hyd. – the least particular hydrangea regarding soil. Needs minimum half-day direct sun to bloom its best.
Fertilizer tips:
Use a general purpose fertilizer such as 12-4-8 or 16-4-8 or slow-release Osmocote Outdoor & Indoor 19-6-12. If you want blue Bigleaf Hyd. blooms, use a fertilizer low in phosphorus (indicated by the middle number) and where the nitrogen is in nitrate form rather than ammonium. A fertilizer designed for azaleas, camellias, and rhododendrons can help acidify the soil, if needed for blue blooms. For more red/pink Bigleaf Hyd. blooms, add dolomite lime twice a year and fertilize with a 10-10-10 formula or Osmocote Flower & Vegetable 14-14-14 slow release fertilizer.
All Hydrangeas:
Propagation – softwood cuttings can be rooted from late-April through July.1
Fertilizing – "Nothing is fertilized after Aug. 1 in the Dirr garden."1 Allow earlier growth time to harden off before cold weather.
Alabama Cooperative Extension System has two great publications on Hydrangeas. Go to www.aces.edu then click on "Publications and Services" tab, then click on "ACES Publications". Where is says "Search ACES Publications" type in the word "hydrangea" and click Search. Hydrangeas (bulletin ANR-1276) is a great document describing the varieties of hydrangeas. Diseases of Hydrangeas (bulletin ANR-1212) describes how to diagnose and treat certain problems. Click on desired title and select High-Res or Low-Res PDF file to open.
Alabama Hydrangea Society / Compiled by David Doggett / Updated 2018
Bigleaf or "French" or Blue/Pink Hydrangeas –
Hydrangea macrophylla, Hydrangea serrata
Mophead or lacecap blooms of blue, pink, or white appear in May on "old wood."
March – apply a slow-release fertilizer such as
Osmocote for 4-month feeding.
May – remove dead stems that show no sign of life
May – propagation: greenwood cuttings can be rooted.
June – deadhead fading flowers of repeat bloomers to
promote more new flowers this season.
June – "Prune immediately after bloom." 3 Shorten
stems by ¼ to ½. Cut 1/3 of oldest stems to the
ground if old hydrangea requires rejuvenation.
Examples: Nikko Blue, Penny Mac, Sister Theresa, Bluebird, Endless Summer, Merritt's Supreme, Fuji Waterfall, Preziosa.
Flower buds are set at the end of the previous year's growing season and too often are damaged by our fluctuating winter cold.
Alternatively, apply light fertilizer in March, May, and June.2
"[Bigleaf hydrangeas] requires moderate to high nutrient levels."1
Don't be too quick to remove dead-looking stems. Some stems will just be late to leaf out.
From late April through July cuttings can be prepared for rooting.1
Repeat bloomers include: Endless Summer series, Penny Mac, Mini Penny, David Ramsey, Oak Hill, Decatur Blue, and Nantucket Blue.
Complete any pruning by end of July. "Next year's flower buds begin forming in August." 2
Oakleaf Hydrangeas – Hydrangea quercifolia
White conical blooms appear in June on "old wood."
April – apply a slow-release fertilizer such as
Osmocote for 4-month feeding.
July – complete pruning (rarely needed) by end of July.
December (dormant season) – can propagate by
dividing their rooted, underground stems.2
Examples: Snowflake, Harmony, Snow Queen, Pee Wee, Alice.
Flower buds are set at the end of the previous year's growing season.
Alternatively, apply two light applications of fertilizer in April and June.2 Native plants like Oakleaf hyd. generally need less fertilizer.
"Prune right after bloom." 4 Pruning is rarely needed except to rejuvenate a large, mature plant. To rejuvenate, cut 1/3 of oldest stems to the ground each year for 3 years.
Take advantage of oakleaf hydrangea's colonizing habit to cut off and pot up self-rooted stems from mature shrubs.
Smooth Hydrangeas – Hydrangea arborescens
White blooms appear in May/June on "new wood."
Feb./March – prune old stems to 6-12" tall.2
March – one annual fertilizer application.2
December (dormant season) – can propagate by
dividing their rooted, underground stems.2
Examples: Annabelle, Incrediball, Hayes Starburst, Bella Anna.
Blooms appear on new season's stem growth. A native plant.
Blooms on new growth. "Hard pruning produces bigger flowers." 4
Follow suggested application rate. Apply as leaves emerge.
Take advantage of Hydrangea arborescens' colonizing habit to cut off and pot up self-rooted stems.
Panicle Hydrangeas – Hydrangea paniculata
White blooms from July-October on "new wood."
Feb./March – annually prune back to about 18-24" tall.
April – apply a slow-release fertilizer such as
Osmocote for 4-month feeding.
Examples: Limelight, Little Lime, Tardiva, PeeGee, Firelight, Bobo.
Blooms appear on tips of current season's stems.
Blooms on new growth which pruning stimulates. "Do not massacre the plant by reducing it to stubs."1 Create branching structure.
Alternatively, apply two light applications of fertilizer in April and June.2
Climbing Hydrangeas – H. anomala petiolaris, Schizophrgma, and Decumaria species.
White lacecap-like blooms in spring on "old wood."
March – one annual fertilizer application with slow-
release fertilizer.2
June – selective pruning if necessary just after flower-
ing to keep in bounds.
Examples: Schizophragma Roseum, Moonlight
These vines are very slow to get established and may take years before beginning to bloom for the first time.
Typically this plant requires little or no pruning. Light pruning may help stimulate the vine into blooming.
References:
1. Michael A. Dirr, Hydrangeas for American Gardens, Timber Press, 2004.
2. Hydrangeas, Alabama Cooperative Extension System publication ANR-1276, www.aces.edu, 2017.
3. The Southern Living Garden Book, edited by Steve Bender, 2nd edition.
Planting tips:
In Alabama, Hydrangeas (except panicle hyd.) generally prefer shading from hot mid-day and afternoon sun. October through March is the best time to plant shrubs in the south – the earlier the better to allow the plant several months to establish its root system.2
Bigleaf or "French" Hyd. – Dig hole 2' wider than container, or use a raised bed if soil drains poorly. Amend soil generously with organic matter. To promote blue Bigleaf Hyd. blooms, add peat moss to soil and mulch with pine straw to help make soil pH more acidic. To promote more pink or red Bigleaf Hyd. blooms, mix lime into the planting soil.
Oakleaf Hyd. – must have excellent drainage to thrive. They are very sensitive to wet feet.
Panicle Hyd. – the least particular hydrangea regarding soil. Needs minimum half-day direct sun to bloom its best.
Fertilizer tips:
Use a general purpose fertilizer such as 12-4-8 or 16-4-8 or slow-release Osmocote Outdoor & Indoor 19-6-12. If you want blue Bigleaf Hyd. blooms, use a fertilizer low in phosphorus (indicated by the middle number) and where the nitrogen is in nitrate form rather than ammonium. A fertilizer designed for azaleas, camellias, and rhododendrons can help acidify the soil, if needed for blue blooms. For more red/pink Bigleaf Hyd. blooms, add dolomite lime twice a year and fertilize with a 10-10-10 formula or Osmocote Flower & Vegetable 14-14-14 slow release fertilizer.
All Hydrangeas:
Propagation – softwood cuttings can be rooted from late-April through July.1
Fertilizing – "Nothing is fertilized after Aug. 1 in the Dirr garden."1 Allow earlier growth time to harden off before cold weather.
Alabama Cooperative Extension System has two great publications on Hydrangeas. Go to www.aces.edu then click on "Publications and Services" tab, then click on "ACES Publications". Where is says "Search ACES Publications" type in the word "hydrangea" and click Search. Hydrangeas (bulletin ANR-1276) is a great document describing the varieties of hydrangeas. Diseases of Hydrangeas (bulletin ANR-1212) describes how to diagnose and treat certain problems. Click on desired title and select High-Res or Low-Res PDF file to open.