Tall and elegant, the poplar tree is an ideal way to bring structure, focus and shade into your garden. An attractive deciduous plant, the poplar tree is a great choice if you want to introduce privacy or shelter to an outdoor space.
Thriving in warm weather and moist soil, most varieties are hardy in USDA Zones 3 to 9.
Most poplar tree varieties are easily identified by their foliage. This is often heart shaped, and if you look closely, edged with small teeth. Green in the autumn, the foliage turns a golden or yellow shade, depending on the variety, in the fall. Interestingly the poplar tree sets both male and female flowers, meaning that it can self pollinate. This leads to the plant producing yellow flowers and small fruit.
The poplar has long been used to add height and structure to an outdoor space. As well as a great way to introduce natural privacy, they can also be used to line paths and driveways.
With over 35 different species, as well as numerous hybrids, to choose from, you are sure to find a plant that suits your situation. Here is your complete guide to growing a poplar tree.
Different Poplar Tree Varieties
Fast growing but not long lasting, these plants have a lifespan of around 50 years. Selecting the right variety for your garden and caring for it correctly can help to extend this lifespan for as long as possible.
While there are over 35 recognised species, very few are commonly grown in domestic settings.
The most commonly grown are
- White (Populus Alba), this cultivar is native to Southern and central Europe and South Asia. With a distinctive pale grey bark, the leaves of this plant can reach up to 20 cm in size. Its colorful flowers, or catkins, turn red if they are male and yellow green if they are female. Following fertilization the plant produces masses of cotton like seeds. This cultivar can reach a height of 65 to 100ft, depending on growing conditions.
- Eastern or Cottonwood (Populus Deltoides). Reaching a height of around 80 ft, and a spread of 60 ft, this is another large specimen. Pleasingly drought tolerant, its dark green leaves turn a pleasing shade of yellow in the fall. The bark of mature plants turns ash-gray in color.
- Lombardy (Populus Nigra Italica) is a reliable and popular cultivar. A fast growing plant, growing roughly 6 ft a year, Lombardy is a good choice if you want to create a wind break or a privacy screen. Helping to create the iconic column shape of the poplar tree, Lombardy has an unusual branching structure. The branches start close to the ground and grow upwards, in parallel to the trunk. While the foliage does yellow in the fall, the plant is not, unlike other cultivars, grown for its autumn foliage. Another distinctive feature of the Lombardy is the trunk which blackens as it ages.
- Balsam (Populus Balsamifera) reaches heights of up to 100 ft. Balsam grows in an attractive, cylindrical shape. This is also a fragrant cultivar. During the spring, as the buds open the resin which coats them emits a distinctive, almost exotic smell. The Balsam cultivar is commonly found in damp or swamp-like conditions.
The distinctive pale foliage of the Populus Alba. Take the time to find a variety that best suits your growing conditions and situation.
Source your saplings from a specialist supplier or plant nursery. They will be able to help you select the ideal variety for your situation.
Be careful when selecting your sapling. Some nurseries sell male only plants. This means that the plant won’t produce masses of cotton like seeds which can be scattered on the wind. However male plants produce lots of pollen, which can be a problem if, like me, you suffer from hayfever.
Saplings are usually sold as 10 inch plants. If your garden is prone to foraging deer and other pests, select larger saplings, about 18 inches tall. The larger the sapling, the quicker it grows.
Where to Position Your Poplar Tree
If planted in the right location, care is pleasingly simple.
The poplar tree does best in a fertile soil. Use a soil test kit to assess the condition of your soil. The soil should be either acidic or neutral, a pH reading of between 5 to 7.5 is ideal. These plants struggle in extremely acidic soils.
Your chosen location should be a full sun position. Low lying moist ground is perfect. While they prefer well draining soil, these plants can also cope well with wet and boggy conditions.
Remember, when selecting your location to consider the final size of the plant. The poplar tree can be 50 to 165 ft in height. It’s trunk can achieve a diameter of 8 ft. To maintain this spread and size the plant must grow a large and extensive root system.
This root system can easily disrupt foundations, paths, pipes and sewers. Make sure that your chosen site has enough empty space for the plant and its root system to grow into. If you are unsure what is beneath your soil, contact your local utility or water company. They can mark out exactly where any pipes and sewers are, helping you to avoid any costly planting mistakes.
To minimise root spread dig a planting trench and line the sides with a durable, heavy duty material such as Deeproot Bamboo Barrier.
These plants do best in light, sunny positions. If you are planting more than one, be sure to space them out correctly.
If you are planting a windbreak, aim to plant the saplings at least 50 ft, but no more than 200 ft, away from the area you want to shade.
How to Plant
Before planting, prepare the ground by digging over the soil and weeding well.
The poplar tree should be planted during its dormant season. This lasts from November until mid-May. Try to plant as early in the dormant season as you possibly can. This gives the saping time to settle and establish itself before the first frosts hit. Alternatively, wait until the last frost date has passed before planting. Whenever you plant, the soil temperature should be above 50 ℉.
Dig a hole deep enough to hold the saplings root ball. Ideally, the finished hole will be twice as wide as the root ball. Use a shovel to roughen up or loosen the sides of the hole. This helps the roots to spread more easily. When placed in the hole, the sapling should sit at roughly the same depth as when it was in the pot.
Position the sapling in the center of the hole. Carefully backfill the hole, being careful not to disturb the plant too much. You may need someone to hold the sapling in place as you do this.
After planting mulch around the base of the plant. This helps to suppress potentially damaging weed growth.
Planting is the ideal time to install a stake or support such as the Kradl Tree Staking Kit. This is an easy to use kit that is both robust and reusable.
You may also need to cover the trunk of the spaling with a guard or mesh to protect it from rabbits or other destructive pests. Tree Guard’s Plastic Mesh Bark Protector is easy to install and protects against both rabbits and deers.
If you are planting more than one poplar tree, space them at least 3 ft apart. The exact distance varies depending on the variety that you are growing. For example Lombardy’s require spacing of at least 8 ft.
Caring for a Poplar Tree
Weed regularly around the base of the plant. Weeds sap the soil of moisture, causing plants to struggle, particularly during warm weather. After weeding, laying a 2 to 3 inch thick layer of mulch helps to suppress weed growth.
When to Water
Water newly planted saplings regularly until they are established. This can take several weeks.
Once established water requirements are minimal. These plants require about 1 inch of water every two weeks. You may only need to water during particularly dry or warm periods.
Fertilizing Your Plants
A poplar tree in good or rich soil is unlikely to require fertilizing every year. If you apply an organic mulch to the soil around your plant it will gradually break down through the year, adding nutrients to the soil.
If the distinctive heart shaped foliage is not as large or as green as it should be, you may need to fertilize the plant.
If the stem adds less than 6 inches of new growth in the spring, or if the foliage seems small and pale, you may need to fertilize the plant. This is best done in the fall.
To fertilize, work a multi purpose granular fertilizer onto the soil, under the poplar tree canopy. Cover as much of the area under the branches, also known as the drop line, as possible. Don’t allow the fertilizer to contact the trunk.
Alternatively, you can apply a water soluble or liquid fertilizer.
Do not fertilize during the first season.
The amount of fertilizer you need to apply varies depending on the size of the plant and the product you are using. Consult the information on the fertilizer packet before applying.
Pruning Your Plant
The poplar tree is a surprisingly low maintenance plant. Most cultivars develop and maintain their own structure. However Lombardy cultivars are known for dropping leaves and twigs which will need to be cleaned away.
Regularly inspect your plant for signs of disease or broken limbs. Use a sharp pole saw to remove diseased and damaged sections as soon as you notice them. This helps to keep the plant healthy and prevents serious issues such as canker from developing.
How to Propagate a Poplar Tree
While the poplar tree does produce seeds, propagation via cuttings is a lot easier.
Take hardwood cuttings in late spring. The cutting should be about 6 inches long, and taken from a healthy stem about a quarter inch in diameter. Use a sharp pair of garden scissors to take a cutting just below a pair of leaves.
Remove leaves from the lower three quarters of the cutting, leaving about 4 or 5 leaves on the top half.
Pot the cutting in a 6 inch pot filled with well draining, fresh potting soil. You can also plant the cuttings in an even mixture of coarse sand and perlite. Firm your chosen potting mixture down and water well.
Place the pot in a shaded, sheltered position, either indoors or outdoors. Mist it regularly, keeping the leaves moist. Water the soil only when it feels dry.
Roots should form within two weeks. To check that roots are present, gently tug the cutting. If you feel resistance it is a sign that roots are forming.
Once roots have formed, transplant the cutting into a 6 inch pot and continue to grow on in a shaded position for up to 3 months. The cutting can be transplanted into its permanent location in the fall, in milder climates, or in the early spring in cooler USDA Zones.
Common Poplar Tree Problems
Borers, bacterial wet wood and canker can all affect the poplar tree. Many varieties will develop stem canker at some point. If allowed to go untreated, this issue can cut the plant’s lifespan significantly.
Canker can cause physical deformities and can be a sign of a serious disease. Initially canker causes dark or sunken areas to form on a branch or trunk. This gradually spreads across the plant. If allowed to cover over half of the plant’s circumference the plant will be almost impossible to save.
Different varieties of poplar tree are prone to different strains of canker. For example the Silver Leaf, Lombardy, Carolina and Simon cultivars are more likely to develop Cytospora chrysosperma or Leucocytospora nivea than other forms of canker. Lombardy cultivars can also develop Crytodiaporthe populea. Most other poplar tree species are resistant to this issue. White cultivars tend to develop Hypoxylon mammatum. European aspens and pussy willows are also prone to this canker strain.
Regularly inspect your plant for signs of damage or disease. Noticing problems early is vital if you want to keep your plants as healthy as possible.
While canker can’t be cured, you can stop it from spreading. Weak or sickly trees are more likely to develop this as well as other health issues.
To keep your plant healthy, water only during dry periods and fertilize sparingly. Also take care when pruning and tidying up your plants. Canker is caused by fungi entering the plant through open wounds.
Regularly inspect your plant for signs of disease and canker. Prune away broken or diseased branches as soon as you notice them. Also remember to sterilize your tools before and after use.This helps to prevent the disease from spreading.
If a plant is severely affected, dig it up and destroy it before the disease can spread to other plants. Do not place the plant on the compost heap.
Attractive and easy to care for, these plants bring structure and color to a garden throughout the year.
Elegant and attractive, the poplar tree is a great way to add structure and definition to a garden. A useful way to introduce shelter or privacy to a space, once planted the poplar tree is also pleasingly easy to care for. By following the advice laid out in this guide you will be able to enjoy the cool shade of the poplar tree for years to come.