Populus
( PAW - pew - luss )
At-A-Glance InformationThis genus of deciduous trees, commonly called Poplar, Cottonwood, or Aspen, needs full sun and regular water. The flowers will attract butterflies and other pollinators to your garden. These are fast-growing, hardy trees that are best suited to rural areas which experience hot summers and cool winters. Many species have great fall color, and leaves are triangular and toothed (for the most part). Catkins appear in springtime before leafout, and female trees produce fluffy, cottony seeds that can make a mess on patios and other hardscaped areas. Take care when planting these trees in the landscape, as some species have plant parts that are toxic to animals if ingested.
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populus Species and Varietals
The genus Populus is a member of the plant family Salicaceae and includes between 25 and 30 species. Populus Tree growing zones vary depending on the species. For more information, see the descriptions below. To find your zone, click here: Zone Map.
Populus x acuminata (Populus acuminata) (Lance-Leaf Cottonwood, Lance-Leaf Poplar) This species is a hybrid of Populus angustifolia and Populus deltoides; it does well in zones 1-11 and 14-21 and reaches 40-60 feet tall and 35-45 feet wide. Leaves are glossy and dark green above, pale green underneath, and turn yellow in autumn. This is a seedless species, and is native to the Rocky Mountains of North America. |
Populus alba (White Poplar, Silverleaf Poplar, Silver Poplar) This species does well in zones A3, 1-11 and 14-21, and is native to Europe and Asia. These trees top out around 40-70 feet tall and wide. Leaves are beautiful, and flutter in the breeze, revealing white undersides (hence the common name). This species produces a lot of suckers; a good quality if planted as a windbreak. Varieties include 'Raket' (cone-shaped tree to 15 feet tall), and Populus alba pyramidalis (commonly called Bolleana Poplar, with a columnar shape and white or light grey trunk). |
Populus angustifolia (Narrowleaf Poplar, Narrowleaf Cottonwood) This species does well in zones 1-11 and 14-21 and is native from Alberta, Canada down to Mexico (mostly in the Rocky Mountains at around 8,000 feet of elevation). These trees reach 50-60 feet tall and 35-45 feet wide, with narrow, willow-like leaves and green bark when young. |
Populus balsamifera (Balsam Poplar, Bam. Bamtree, Eastern Balam-Poplar, Hackmatack, Tecamahac Poplar, Tacamahaca ) This species does well in zones A2, A3, 1-9 and 14-24 and is native from to the northern areas of North America (mostly in Canada and Alaska). This species reaches between 30-100 feet tall and 25-30 feet wide, with furrowed dark gray bark. Wood is brittle; protect from strong winds. Leaves are deep green on top and silvery underneath. Gold-yellow fall color. |
Populus x canadensis (Canadian Poplar, Carolina Poplar) This naturally occurring hybrid is a cross between Populus nigra and Populus deltoides, and is a vigorous grower. These trees are broadly columnar and reach up to 130 feet tall. Commonly grown cultivars of this hybrid include 'Robusta' and 'Aurea' (also called Golden Poplar or Golden Carolina Poplar). |
Poplar x canescens (Grey Poplar, Abele, Silver Poplar, Silverleaf Poplar, White Poplar) This species is a natural hybrid between White Poplar (Populus alba) and Common Aspen (Populus tremula). It is capable of reaching up to 130 feet tall with a trunk diameter of over 5 feet. Most trees in cultivation from this species are male. |
Populus ciliata (Himalayan Poplar) These large deciduous trees have tall, straight trunks and are native to the Himalayan region in Asia. It is used in landscapes as an erosion-control tree, as it easily establishes in shallow soils, has a fast growth rate, and produces strong lateral roots. Crown is widely rounded. |
Poplar deltoides (Eastern Cottonwood, Necklace Poplar) This species is native to southern Canada, eastern, central and southwestern United States, and northeastern Mexico. These large trees reach between 65 and 100 feet tall when mature, making them one of the largest North American trees. Bark is silver-white on young trees and turns dark grey and deeply fissured with age. |
Populus euphratica (Euphrates Poplar, Desert Poplar, Diversiform-Leaved Poplar, Poplar Diversifolia) This species of Poplar is native to North Africa, the Middle East, Central Asia, and western China, where it grows in mixed temperate broadleaf forests and subtropical forests in dense thickets. Trees are commonly used as windbreaks, to control erosion, and for forestation programs in desert areas. |
Populus fremontii (Western Cottonwood, Fremont Cottonwood) Best in zones 1-12 and 14-21, this species is native to California and Mexico. It reaaches 40-60 feet tall and 30 feet wide. Foliage is yellow-green and turns lemon yellow in cooler temperatures. Leaves last almost through the winter in mild climates. Varietal 'Nevada' is a good male (and therefore seedless) variety. |
Populus grandidentata (Large-Tooth Aspen, Big-Tooth Aspen, American Aspen, Canadian Poplar, White Poplar) This medium-sized tree species is native to eastern areas of North America, and typically reaches between 60 and 80 feet tall. Bark is thin and olive-green on younger trees, maturing to gray, thick grooved bark at maturity. |
Populus heterophylla (Swamp Poplar, Downy Poplar, Swamp Cottonwood) These large deciduous trees are native to temperate regions of eastern North America and reach between 50 and 100 feet tall at maturity. Leaves are medium to deep green on their upper surface and pale green on their lower surface. The roots of these trees can take more water than other native poplars in their range. |
Populus lasiocarpa (Chinese Necklace Poplar) This species is native to the humid forests in China, and is closely related to Wilson's Poplar (Populus wilsonii). These trees produce large leaves for the species which are also hairy on their undersides. Flowers bloom from March through May, and fruits ripen from May to June in the tree's native range. |
Populus nigra 'Italica' (Lombardy Poplar, Black Poplar) This species is best in zones A3, 1-11, 14-24 and is native to Europe. This is a male varietal (does not drop seeds). It has a column-shape and reaches 40-100 feet tall and 15-30 feet wide, with branches that reach up towards the sun. Great along driveways, as a windbreak, and a good choice for dry, cold, interior climates. Leaves are bright green and turn gold in fall. Suckers profusely. |
Populus tremula (European Aspen, Aspen, Common Aspen, Eurasian Aspen, Quaking Aspen) This species is native to Africa, Asia, and Europe, and has dainty, glossy green leaves and grey-green bark. Can be grown as a single-trunked or multi-trunked tree. Variety 'Erecta' (also called Swedish Columnar Aspen), is a narrow selection with great red fall color. |
Populus tremuloides (Quaking Aspen, Trembling Aspen, American Aspen, Mountain Aspen, Golden Aspen, Trembling Poplar, Popple) Grows well in zones A1-A3, 1-7 and 14-19 and is native to mountainous areas of the western United States (up to 9,000 feet in elevation). Short-lived and performs poorly in lowland regions. Smooth, pale bark and glossy green leaves. Reaches 20-60 feet tall and 15-20 feet wide, and makes a good background tree for wild-looking gardens and landscaped mountain properties. Commonly grown varieties include 'Mountain Sentinel' (narrow, upright to 35 feet tall and 8 feet wide at 30 years), and 'Prairie Gold' (40 feet tall and 15 feet wide, bred to tolerate lowland conditions and resist common diseases). |
Populus trichocarpa (Black Cottonwood, Western Balsam-Poplar, California Poplar) This species is native to western North America, and is commonly used as a timber tree. Individuals reach between 98 and 165 feet tall. Bark is grey and quite hard. These trees are valued for their fast growth and scented foliage in springtime. Roots are invasive, and can cause damage to nearby foundations and hardscaped areas. |
Caring for and pruning Populus Trees
The best time to plant Poplar trees is in springtime once soil can be worked. Poplar trees should be placed in full sun or partial shade. They will perform, grow, and flower better when situated in a spot that receives full sun (at least 6 hours each day). These trees are tolerant of a wide range of soils, from clay to loam to sand, though are generally short-lived in urban or residential landscapes due to the fact that they grow better in natural, native landscapes. They do not like disturbed or poor soils, and have issues with intense temperature and water fluctuations. Apply a thick layer of mulch around the base of trees to suppress weed growth, increase soil moisture retention, and help to regulate soil temperatures. Newly planted trees should be watered regularly (about 10 gallons once a week) in their first year or so in the ground. At maturity, some species can tolerate dry spells, but they typically will perform better if provided with regular deep irrigations.
Poplars do not require fertilizing other than a yearly application of organic compost around the base of trees. They will grow quickly even without fertilizer. The best time to prune these trees is in late winter or early springtime. Remove dead, damaged, diseased, or crossing branches at this time, and lightly shape if necessary. These are considered to be weak-wooded trees, and will often drop branches or entire limbs after a strong storm.
Poplars do not require fertilizing other than a yearly application of organic compost around the base of trees. They will grow quickly even without fertilizer. The best time to prune these trees is in late winter or early springtime. Remove dead, damaged, diseased, or crossing branches at this time, and lightly shape if necessary. These are considered to be weak-wooded trees, and will often drop branches or entire limbs after a strong storm.
Propagation
Poplar trees can be propagated either by using cuttings or from seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the cutting method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant. To propagate your Aspen tree, follow the instructions below:
Propagating Poplar by Cutting
Propagating Poplar by Seed
Propagating Poplar by Cutting
- Gather your materials. You'll need a clean, sanitized, sharp pair of garden shears, rooting hormone, a pencil, and a 3-inch pot filled with well-draining compost or other organic material. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand.
- In spring or early summertime, choose the plant that you'd like to propagate. Ensure that this plant has had a good watering the night before, as this will improve the chances your cutting will take root. Cut one or more 6 inch portion(s) of the end of a non-blooming branch and strip the leaves off of the lower half. Make a hole in your planting medium by pushing your pencil into the soil. Dip the end of the stem in rooting hormone, and plant it in your pot. Fill in soil around the cutting to support it, but do not pack it down too much.
- Moisten with water, and ensure that the pot has good drainage. Your pot should be kept in warm, sunny conditions indoors (and not in direct sunlight). Water whenever your soil is dry under the top layer. After about four to six weeks have passed, your cutting should be rooted. When you notice new growth, you'll know you have roots.
- Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring, when you can transplant it to its new home. Ensure that the last frost of the year has occurred before doing this, as it can seriously damage your new shrub.
Propagating Poplar by Seed
- Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. If you don't have any potting medium on hand, you can make some. Just mix together equal parts (by volume) moss peat and horticultural-grade sand or grit sand. You will also, after a few weeks, need individual 3-inch pots for each seedling that grows.
- Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes 7-14 days from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
- Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 55 and 70 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.
Problems and Pests
Before installing Poplar trees in the landscape, make sure to check with a local authority about their invasiveness in your area. Not every species of Poplar tree is invasive, but many are in specific states. These trees also have the tendency to produce many seedlings, which can quickly become a nuisance in the landscape if not hand-pulled frequently.
Poplar trees are susceptible to developing issues with the following pests and diseases:
Poplar trees are susceptible to developing issues with the following pests and diseases:
- Powdery Mildew
- Aphids
- Anthracnose
- Cytospora Canker
- Verticillium Wilt
- Forest Tent Caterpillar
- Bronze Birch Borer
- Leaf-Feeding Caterpillars
- Twiggal Fly Gall
- Rabbits
- Deer
Gallery
Videos
Learn all about these great landscape trees.
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Lean about Poplar trees in this video out of Tennessee.
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Resources
The New Sunset Western Garden Book: The Ultimate Gardening Guide (2012) - Page 525, Populus
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