Populus alba is a large deciduous tree, usually grows 40 to 70 feet in height. A very broad, spreading tree, uneven rounded crown. Spreads by root suckers. Bark is green-gray to whitish, black fissures develop at the base of old trunks. The leaves are dark green on top, whitish and downy, below. Fall color is yellowish, not remarkable, flowers are inconspicuous. Does well under many conditions, prefers moist loam, salt spray tolerant and pollution tolerant. Prune in summer. Subject to many diseases: many cankers, gall, leaf blister, borers and others. Roots are known for finding their way to plumbing, and old septic systems. Not really recommended for small residential properties. Native to Europe and Siberia, has naturalized in North America.
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Size: Height: 70 ft. to 130 ft.
Width: 40 ft. to 50 ft.
Plant Category: trees,
Foliage Characteristics: deciduous,
Flower Color: greens, reds,
Tolerances: deer, heat & humidity, pollution, rabbits, seashore,
Bloomtime Range: Early Spring to Mid Spring
USDA Hardiness Zone: 4 to 9
AHS Heat Zone: Not defined for this plant
Light Range: Sun to Full Sun
pH Range: 4.5 to 8.5
Soil Range: Sandy Loam to Some Clay
Water Range: Normal to Moist
FertilizingHow-to : Fertilization for Established Plants
Established plants can benefit from fertilization. Take a visual inventory of your landscape. Trees need to be fertilized every few years. Shrubs and other plants in the landscape can be fertilized yearly. A soil test can determine existing nutrient levels in the soil. If one or more nutrients is low, a specific instead of an all-purpose fertilizer may be required. Fertilizers that are high in N, nitrogen, will promote green leafy growth. Excess nitrogen in the soil can cause excessive vegetative growth on plants at the expense of flower bud development. It is best to avoid fertilizing late in the growing season. Applications made at that time can force lush, vegetative growth that will not have a chance to harden off before the onset of cold weather.
LightConditions : Part Sun
Part Sun refers to filtered light, with most sun being received during the afternoon hours. Shade usually occurs during the morning hours.
Conditions : Sun
Sun is defined as the continuous, direct, exposure to 6 hours (or more) of sunlight per day.
Conditions : Light Conditions
Unless a site is completely exposed, light conditions will change during the day and even during the year. The northern and eastern sides of a house receive the least amount of light, with the northern exposure being the shadiest. The western and southern sides of a house receive the most light and are considered the hottest exposures due to intense afternoon sun.
You will notice that sun and shade patterns change during the day. The western side of a house may even be shady due to shadows cast by large trees or a structure from an adjacent property. If you have just bought a new home or just beginning to garden in your older home, take time to map sun and shade throughout the day. You will get a more accurate feel for your site's true light conditions.
Conditions : Full to Partial Sun
Full sunlight is needed for many plants to assume their full potential. Many of these plants will do fine with a little less sunlight, although they may not flower as heavily or their foliage as vibrant. Areas on the southern and western sides of buildings usually are the sunniest. The only exception is when houses or buildings are so close together, shadows are cast from neighboring properties. Full sun usually means 6 or more hours of direct unobstructed sunlight on a sunny day. Partial sun receives less than 6 hours of sun, but more than 3 hours. Plants able to take full sun in some climates may only be able to tolerate part sun in other climates. Know the culture of the plant before you buy and plant it!
Conditions : Types of Pruning
Types of pruning include: pinching, thinning, shearing and rejuvenating.
Pinching is removing the stem tips of a young plant to promote branching. Doing this avoids the need for more severe pruning later on.
Thinning involves removing whole branches back to the trunk. This may be done to open up the interior of a plant to let more light in and to increase air circulation that can cut down on plant disease. The best way to begin thinning is to begin by removing dead or diseased wood.
Shearing is leveling the surface of a shrub using hand or electric shears. This is done to maintain the desired shape of a hedge or topiary.
Rejuvenating is removal of old branches or the overall reduction of the size of a shrub to restore its original form and size. It is recommended that you do not remove more than one third of a plant at a time. Remember to remove branches from the inside of the plant as well as the outside. When rejuvenating plants with canes, such as nandina, cut back canes at various heights so that plant will have a more natural look.
Conditions : Light and Plant Selection
For best plant performance, it is desirable to match the correct plant with the available light conditions. Right plant, right place! Plants which do not receive sufficient light may become pale in color, have fewer leaves and a "leggy" stretched-out appearance. Also expect plants to grow slower and have fewer blooms when light is less than desirable. It is possible to provide supplemental lighting for indoor plants with lamps. Plants can also receive too much light. If a shade loving plant is exposed to direct sun, it may wilt and/or cause leaves to be sunburned or otherwise damaged.
Conditions : Full Sun
Full Sun is defined as exposure to more than 6 hours of continuous, direct sun per day.
WateringConditions : Regular Moisture for Outdoor Plants
Water when normal rainfall does not provide the preferred 1 inch of moisture most plants prefer. Average water is needed during the growing season, but take care not to overwater. The first two years after a plant is installed, regular watering is important. The first year is critical. It is better to water once a week and water deeply, than to water frequently for a few minutes.
PlantingHow-to : Pruning Trees After Planting
It is critical to prune trees correctly from the beginning to assure proper growth and development. Young trees can be transplanted in a number of forms: bare root, balled & burlap and in containers. The more stress the plant undergoes in the transplant process, the more pruning that is required to compensate.
Deciduous trees like maples (those that loose their leaves in the fall) can be dug up and sold with their bare roots exposed. Because most of the root system is lost in digging, sufficient top growth should be removed to compensate for this loss. This may be done at the nursery before you buy the plant or you may have to prune at the time of planting. Select and head back the best scaffold branches, i.e. those branches which will form the main lateral structure of the future mature tree. Remove all other extraneous side branches. If the tree seedling does not have branches, allow it to grow to the desired height of branching then pinch it back to stimulate the lower buds to form branches.
Ball and burlap trees are dug up with their root systems somewhat intact. This was mostly done for conifers and broadleaf evergreens, but has become common for deciduous trees as well. Since some root mass is lost in the digging stage, a light pruning is generally called for. Head back the plant to compensate for this loss and to promote branching.
Trees that are grown in containers generally do not loose roots in the transplanting phase. Therefore you do not generally have to prune them unless there is some root injury or limb damage in the planting process.
Once you have your trees planted, be patient. Do not remove shoots from the trunk early on as these allow the tree to grow more rapidly and also shade the tender young trunk from sun-scald. Wait a few years to begin training the tree to its ultimate form.
How-to : Planting a Tree
Dig out an area for the tree that is about 3 or 4 times the diameter of the container or rootball and the same depth as the container or rootball. Use a pitchfork or shovel to scarify the sides of the hole.
If container-grown, lay the tree on its side and remove the container. Loosen the roots around the edges without breaking up the root ball too much. Position tree in center of hole so that the best side faces forward. You are ready to begin filling in with soil.
If planting a balled and burlaped tree, position it in hole so that the best side faces forward. Untie or remove nails from burlap at top of ball and pull burlap back, so it does not stick out of hole when soil is replaced. Synthetic burlap should be removed as it will not decompose like natural burlap. Larger trees often come in wire baskets. Plant as you would a b&b plant, but cut as much of the wire away as possible without actually removing the basket. Chances are, you would do more damage to the rootball by removing the basket. Simply cut away wires to leave several large openings for roots.
Fill both holes with soil the same way. Never amend with less than half original soil. Recent studies show that if your soil is loose enough, you are better off adding little or no soil amendments.
Create a water ring around the outer edge of the hole. Not only will this conseve water, but will direct moisture to perimeter roots, encouraging outer growth. Once tree is established, water ring may be leveled. Studies show that mulched trees grow faster than those unmulched, so add a 3"" layer of pinestraw, compost, or pulverized bark over backfilled area. Remove any damaged limbs.
ProblemsPest : Aphids
Aphids are small, soft-bodied, slow-moving insects that suck fluids from plants. Aphids come in many colors, ranging from green to brown to black, and they may have wings. They attack a wide range of plant species causing stunting, deformed leaves and buds. They can transmit harmful plant viruses with their piercing/sucking mouthparts. Aphids, generally, are merely a nuisance, since it takes many of them to cause serious plant damage. However aphids do produce a sweet substance called honeydew (coveted by ants) which can lead to an unattractive black surface growth called sooty mold.
Aphids can increase quickly in numbers and each female can produce up to 250 live nymphs in the course of a month without mating. Aphids often appear when the environment changes - spring & fall. They're often massed at the tips of branches feeding on succulent tissue. Aphids are attracted to the color yellow and will often hitchhike on yellow clothing.
Prevention and Control: Keep weeds to an absolute minimum, especially around desirable plants. On edibles, wash off infected area of plant. Lady bugs and lacewings will feed on aphids in the garden. There are various products - organic and inorganic - that can be used to control aphids. Seek the recommendation of a professional and follow all label procedures to a tee.
Fungi : Rusts
Most rusts are host specific and overwinter on leaves, stems and spent flower debris. Rust often appears as small, bright orange, yellow, or brown pustules on the underside of leaves. If touched, it will leave a colored spot of spores on the finger. Caused by fungi and spread by splashing water or rain, rust is worse when weather is moist.
Prevention and Control: Plant resistant varieties and provide maximum air circulation. Clean up all debris, especially around plants that have had a problem. Do not water from overhead and water only during the day so that plants will have enough time to dry before night. Apply a fungicide labeled for rust on your plant.
Fungi : Powdery Mildew
Powdery Mildew is usually found on plants that do not have enough air circulation or adequate light. Problems are worse where nights are cool and days are warm and humid. The powdery white or gray fungus is usually found on the upper surface of leaves or fruit. Leaves will often turn yellow or brown, curl up, and drop off. New foliage emerges crinkled and distorted. Fruit will be dwarfed and often drops early.
Prevention and Control: Plant resistant varieties and space plants properly so they receive adequate light and air circulation. Always water from below, keeping water off the foliage. This is paramount for roses. Go easy on the nitrogen fertilizer. Apply fungicides according to label directions before problem becomes severe and follow directions exactly, not missing any required treatments. Sanitation is a must - clean up and remove all leaves, flowers, or debris in the fall and destroy.
Pest : Caterpillars
Caterpillars are the immature form of moths and butterflies. They are voracious feeders attacking a wide variety of plants. They can be highly destructive and are characterized as leaf feeders, stem borers, leaf rollers, cutworms and tent-formers.
Prevention and Control: keep weeds down, scout individual plants and remove caterpillars, apply labeled insecticides such as soaps and oils, take advantage of natural enemies such as parasitic wasps in the garden and use Bacillus thuringiensis (biological warfare) for some caterpillar species.
Fungi : Leaf Spots
Leaf spots are caused by fungi or bacteria. Brown or black spots and patches may be either ragged or circular, with a water soaked or yellow-edged appearance. Insects, rain, dirty garden tools, or even people can help its spread.
Prevention and Control: Remove infected leaves when the plant is dry. Leaves that collect around the base of the plant should be raked up and disposed of. Avoid overhead irrigation if possible; water should be directed at soil level. For fungal leaf spots, use a recommended fungicide according to label directions.
Pest : Scale Insects
Scales are insects, related to mealy bugs, that can be a problem on a wide variety of plants - indoor and outdoor. Young scales crawl until they find a good feeding site. The adult females then lose their legs and remain on a spot protected by its hard shell layer. They appear as bumps, often on the lower sides of leaves. They have piercing mouth parts that suck the sap out of plant tissue. Scales can weaken a plant leading to yellow foliage and leaf drop. They also produce a sweet substance called honeydew (coveted by ants) which can lead to an unattractive black surface fungal growth called sooty mold.
Prevention and Control: Once established they are hard to control. Isolate infested plants away from those that are not infested. Consult your local garden center professional or Cooperative Extension office in your county for a legal recommendation regarding their control. Encourage natural enemies such as parasitic wasps in the garden.
MiscellaneousConditions : Deer Tolerant
There are no plants that are 100% deer resistant, but many that are deer tolerant. There are plants that deer prefer over others. You will find that what deer will or will not eat varies in different parts of the country. A lot of it has to do with how hungry they are. Most deer will sample everything at least once, decide if they like it or not and return if favorable. A fence is the good deer barrier. You may go for a really tall one (7 to 8 feet), or try 2 parallel fences, (4 to 5 feet apart). Use a wire mesh fence rather than board, since deer are capable of wiggling through a 12 inch space.
Conditions : Pollution Tolerant
Air pollution is becoming a bigger problem each day. Pollutants in our air damage plants. The plants are damaged by absorbing sulfur dioxide, ozone, peroxyacetyl nitrate, ethylene, and nitrogen dioxide through their pores. Cell membrane damage may result in leaf drop, blotched or burnt looking leaves, or off-colored tissue between veins. Vehicles and industrial processes are the key culprits and conditions worsen on hot summer days. Though planting only pollution tolerant plants is not the solution to this problem, it is a visual band aid. Your Cooperative Extension Service may have a list of plants that are more pollution tolerant in your area.
Conditions : Rabbit Tolerant
As cute as they are, rabbits can really damage a vegetable garden. Young, tender lettuce plants seem to be their favorite. If a free-roaming dog is not a possibility for you, consider installing raised vegetable beds and covering tender shoots with netting. If you have ample room, you can opt to plant enough for you and the bunnies. Scents don't always repel animals, as they get used to them and are often washed off in the rain.
Conditions : Salt Tolerant
Anyone that lives close to the coast or in areas where soil salt content is high, can appreciate a plant that is salt tolerant. Salt damage is usually worse where the climate is arid: there is not enough rainfall to wash built up salts from the soil. It takes about 30 inches of rainfall a year to move salt through the soil. Plants that have salt damage usually have yellow leaves, brown tips or margins, and leaf drop. Soils may have a crusty white layer, too. Salt tolerant plants are often natives or introduced plants that have evolved in salty conditions.
Glossary : Backdrop
Backdrop is the term used to describe a plant or architectural element that is relatively neutral in appearance, that serves as a background for other plants. Backdrop plants are often taller, have dark or medium green leaves, and often of medium texture. However, this is not always the case. For a tropical effect, or to make a space more intimate, use a backdrop with coarse textured foliage. To make a space appear larger, use a small to medium textured leaf plant that is dark green.
Conditions : Erosion Control
Plants that help to control erosion have fibrous root systems that help to keep soil intact. Leaves and the overall form of a plant can prevent erosion by breaking up water droplets before they hit the ground, lessening splashing and runoff.
Conditions : Fall Color
Fall color is the result of trees or shrubs changing colors according to complex chemical formulas present in their leaves. Depending on how much iron, magnesium, phosphorus, or sodium is in the plant, and the acidity of the chemicals in the leaves, leaves might turn amber, gold, red, orange or just fade from green to brown. Scarlet oaks, red maples and sumacs, for instance, have a slightly acidic sap, which causes the leaves to turn bright red. The leaves of some varieties of ash, growing in areas where limestone is present, will turn a regal purplish-blue.
Although many people believe that cooler temperatures are responsible for the color change, the weather has nothing to do with it at all. As the days grow shorter and the nights longer, a chemical clock inside the trees starts up, releasing a hormone which restricts the flow of sap to each leaf. As fall progresses, the sap flow slows and chlorophyll, the chemical that gives the leaves their green color in the spring and summer, disappears. The residual sap becomes more concentrated as it dries, creating the colors of fall.
Glossary : Low Maintenance
Low maintenance does not mean no maintenance. It does mean that once a plant is established, very little needs to be done in the way of water, fertilizing, pruning, or treatment in order for the plant to remain healthy and attractive. A well-designed garden, which takes your lifestyle into consideration, can greatly reduce maintenance.
Glossary : Naturalizing
Naturalizing refers to planting in a random pattern, much as itwould occur in nature. If you spend any time in the woods, you've probably noticed that plants often grow in groups. The center of the group is dense and towards the edges, plants are located farther apart. Narcissus bulbs are easy to naturalize if you use this method: fill a bucket with bulbs and toss them out. Plant them where they fall. You will notice a portion of the bulbs are close together while the others have scattered farther away.
Glossary : Specimen
A specimen can be a tree, shrub, ground cover, annual, or perennial that is unique in comparison to the surrounding plants. Uniqueness may be in color, form, texture, or size. By using only one specimen plant in a visual area, it can be showcased. Specimen plants are accents in the landscape, just as statues, water features, or arbors.
Glossary : Loam
Loam is the ideal soil, having the perfect balance between particle size, air space, organic matter and water holding capacity. It forms a nice ball when squeezed in the palm of the hand, but crumbles easily when lightly tapped with a finger. Rich color ranges between gray brown to almost black.
Glossary : Clayey Loam
Clayey loam refers to a soil that retains moisture well, without having a drainage problem. Fertility is high and texture good. Easily forms a ball when squeezed in the hand, and then crumbles easily with a quick tap of the finger. Considered an ideal soil. Usually a rich brown color.
Glossary : Deciduous
Deciduous refers to those plants that lose their leaves or needles at the end of the growing season.
Glossary : Tree
Tree: a woody perennial with a crown of branches that begin atop a single stem or trunk. The exception to this rule is multi-trunk trees, which some may argue are really very large shrubs.
Conditions : Site Conditions
When setting criteria for site conditions, check boxes that apply to your planting area. This will narrow the search for appropriate plants. Naturally, you'll need to select a USDA Hardiness Zone. Selecting a specific soil type and pH are just as important as light and water conditions because they enable a search that will find plants best suited to your site.
Glossary : Plant Characteristics
Plant characteristics define the plant, enabling a search that finds specific types of plants such as bulbs, trees, shrubs, grass, perennials, etc.
Glossary : Large Tree
A tree is considered large when it is over 30 feet tall.
Glossary : Foliage Characteristics
By searching foliage characteristics, you will have the opportunity to look for foliage with distinguishable features such as variegated leaves, aromatic foliage, or unusual texture, color or shape. This field will be most helpful to you if you are looking for accent plants. If you have no preference, leave this field blank to return a larger selection of plants.
Glossary : Landscape Uses
By searching Landscape Uses, you will be able to pinpoint plants that are best suited for particular uses such as trellises, border plantings, or foundations.
Glossary : Soil Types
A soil type is defined by granule size, drainage, and amount of organic material in the soil. The three main soil types are sand, loam and clay. Sand has the largest particle size, no organic matter, little to no fertility, and drains rapidly. Clay, at the opposite end of the spectrum, has the smallest particle size, can be rich in organic matter, fertility and moisture, but is often unworkable because particles are held together too tightly, resulting in poor drainage when wet, or is brick-like when dry. The optimum soil type is loam, which is the happy median between sand and clay: It is high in organic matter, nutrient-rich, and has the perfect water holding capacity.
You will often hear loam referred to as a sandy loam (having more sand, yet still plenty of organic matter) or a clay loam (heavier on the clay, yet workable with good drainage.) The addition of organic matter to either sand or clay will result in a loamy soil. Still not sure if your soil is a sand, clay, or loam? Try this simple test. Squeeze a handfull of slightly moist, not wet, soil in your hand. If it forms a tight ball and does not fall apart when gently tapped with a finger, your soil is more than likely clay. If soil does not form a ball or crumbles before it is tapped, it is sand to very sandy loam. If soil forms a ball, then crumbles readily when lightly tapped, it's a loam. Several quick, light taps could mean a clay loam.
Glossary : Pruning
Now is the preferred time to prune this plant.