Light Needs
Mature Height
Mature Spread
Growing Zones
Speckled Alder is a native on the east side of the Mississippi River and is common in areas with wet and sandy soils along streams and lakes. Alnus incana ssp. rugosa gets its common name from the white, raised lenticels on its dark-colored stems. This deciduous shrub has a glorious yellow fall color and brownish-colored catkins in spring that appear just before the leaves sprout.
Speckled alder can be grown as a single-trunk tree or left to spread naturally by its underground suckers. Use its spreading to fill in large areas and form a windbreak or habitat for local wildlife. The leathery leaves support the caterpillars of the green comma butterfly, while other small animals and insects eat the bark, seeds, and wooly aphids that may attack this shrub. The wettest zones of a rain garden and along ponds or streams are ideal locations to plant speckled alder.
Speckled Alder Care
Speckled Alder prefers wet soil with an average or sandy texture. At least 6 hours of direct sun is preferred. This shrub is cold tolerant and grows well in USDA zones 3-6; however, it does not tolerate high heat and humidity south of zone 6. Speckled alder requires acidic soil and will show signs of chlorosis in a pH level above neutral (7.0). Fertilizing is not necessary.
Pruning is only needed to control the spread and dense growth of speckled alder. Cut the oldest branches down to the base of the shrub in late winter, along with any dead, damaged, or diseased branches. Deadheading or thinning is not required when this shrub is grown to support wildlife habitat. Mulch the root zone annually with arborist chips or shredded leaves to improve moisture retention; this is especially beneficial for shrubs planted in drier locations of the garden.
Speckled Alder Spacing
Speckled Adler can spread 12-15 feet, which means each shrub needs to be spaced 12 feet from the center of the next. You can plant the shrubs closer for quick cover; however, pruning will need to be done seasonally to ensure the area does not become overgrown.
Speckled Alder Plant Facts
Growing Conditions
- Hardiness ZonesGrowing Zones
- USDA Zones 3 to 8 (perennial); grown as an annual elsewhere (outdoors year-round); grown indoors elsewhere (outdoors year-round); grown in containers elsewhere (grown as a seasonal crop)
- Sun Exposure
- Part Shade to Full Sun (3+ Hours Direct Sun)
- Mature Height
- 12-15 Feet
- Mature Spread
- 12-15 Feet
- Growth Habit
- , Upright
- Water Needs
- Consistently Moist
Flowers & Foliage
- Flower Colors
- , Green
- Flower Description
- Green
- Bloom Time
- Late Winter to Early Spring
- Blooms On
-
Old Wood
?
"Blooms on" tells you which stems produce flowers, which decides when it's safe to prune.
- New Wood: Flowers form on stems that grow this season. Prune in late winter or early spring without losing blooms.
- Old Wood: Flower buds form on last year's stems. Prune right after flowering. Pruning in fall or early spring removes next year's blooms.
- Both New and Old Wood: Blooms on last year's stems and again on new growth, so it flowers even after a hard winter or a mistimed pruning. Prune lightly after the first flush of blooms.
- When to Prune
- Right after flowering
- Foliage Color
- , Green
- Foliage Description
- Deep green on dark warty stems
- Foliage Type
- , Deciduous
- Seasonal Interest
- , Fall Interest
Garden Benefits
Plant Overview
- Common Name
- Speckled Alder
- Also Known As
- Alnus incana subsp. rugosa
- Botanical Name
- Alnus incana subsp. rugosa
- Plant Type
- Shrub
Simple Plant Spacing Calculator
Please Note: The pictures below are to give a general representation of the different container sizes. The actual size/ages of plants are estimates and will vary based on type of plant, time of year, last pruning & many other factors.
Also Known As:
Quart
Plant Age:
~ 6 months - 1 year
Plant Size:
~ 4"-8"
Pot Size:
~ 4.75"H x 4.5"W
Volume:
1.50 quarts
Also Known As:
2.5 Quart Pot
Plant Age:
~ 1 - 2 years old
Plant Size:
~ 8"-12"
Pot Size:
~ 6.5"H x 6.5"W
Volume:
2.20-2.30 quarts
Also Known As:
#1 Container
1 Gallon
Plant Age:
~ 1 - 2 years old
Plant Size:
~ 10"-14"
Pot Size:
~ 7"H x 7.75"W
Volume:
2.26-3.73 quarts
Also Known As:
#2 Container
2 Gallon
Plant Age:
~ 1.5 - 3 years old
Plant Size:
~ 12"-18"
Pot Size:
~ 9.5"H x 9.5"W
Volume:
1.19-1.76 gallons
Also Known As:
#3 Container
3 Gallon
Plant Age:
~ 2 - 4 years old
Plant Size:
~ 12"-30"
Pot Size:
~9.5"H x 11"W
Volume:
2.32-2.76 gallons
Also Known As:
#5 Container
5 Gallon
Plant Age:
~3-4 years old
Plant Size:
~ 20" - 60"
Pot Size:
~11" H x 10 1/2” W
Volume:
3.5 - 4 gallons
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