Landscape Horticulture -- Trees

 

How deep should I plant my trees?

Never transplant ornamental trees and shrubs any deeper than they were already planted. After digging the planting hole only as deep as the root ball, backfill around the root ball using existing soil so that the plant will sit in the hole at the same level it was growing in the container. Research indicates that the addition of organic amendments is not needed.

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A recently planted crape myrtle has developed a sooty-looking mildew. What should we do to protect the remaining leaves?

If the pot is big enough, you can allow the new shoots to continue growth around the mother plant. This bromeliad grows well in a cluster, and a number of shoots flowering at the same time adds to its beauty. Move the plant to a bigger pot when necessary.

You can also form new plants from the pups, but wait until they are 6 - 8" tall, and then snap them from the mother plant.

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The bark on my Chinese elm is splitting and peeling off, and it is orange where the bark has come off. Is this a disease?

Splitting and peeling bark and variation in bark color on Chinese elm and other plants like crape myrtle and sycamore is normal and needs no treatment.

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We planted a maple tree two years ago that has just started to grow. It's getting quite tall. Would it be alright to top the tree and keep it smaller in size?

We normally do not top trees. The new shoots that develop tend to be weaker and become susceptible to storms. Also the maple is a medium-size tree. It will want to grow to its maximum size of 40 feet tall and 30 feet wide. You can remove lower limbs that overhang walkways, contact buildings or affect maintenance as needed.

Possibly you have the wrong tree for the site. While the maple is small, move it to a location where it has room to grow. Good substitutes might include a tree ligustrum, bottlebrush, crape myrtle, or yaupon holly.

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I have a magnolia tree that has grown over 20 feet tall and never flowered. Is there any way to help it bloom?

Magnolias may head the list of trees that take a long time to mature and flower. Often it's the trees grown from seed that seem to need extra time. Some newer varieties produced from cuttings including Little Gem and Saint Mary begin opening blooms as small trees.

There is little you can do to speed the flowering process. Give the tree adequate moisture, and feed lightly when young. After a year or two, the tree be able to grow with seasonal rains and nutrients from nearby feedings. Keeping the trees on this leaner diet often encourages early maturity and flowering.

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Our Holly tree has lots of dead branches and twigs that eventually fall off. What is the problem, and is there a control?

American, Chinese, and numerous holly hybrids have become susceptible to a gall-forming fungus known as sphaeropsis that causes the ends of branches to swell and then die back into the older wood. Dieback, a disease, has spread rapidly in recent years, and many gardeners are noticing holly limbs and even whole trees declining.

There is no good control for the sphaeropsis fungus. Gardeners can remove the affected limbs as noted to help prevent the fungus spreading, but they should sterilize the pruners between cuts.

Fungicides such as Thiomyl or Halts Systemic Fungicide may give some short-term control, but the disease always returns. Many landscapers are simply avoiding hollies and replanting with other trees to eliminate the problem.

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We recently moved into a home with a magnolia tree that has brown on the backs of the leaves and white spots on the top. What do we need to do to correct these problems?

At least part of what seems to be a problem may be normal growth for your magnolia. Several of the varieties naturally have the brown fuzz on the bottom of the leaves. They are called brownbacked magnolias. So just enjoy this feature.

White spots are normally the magnolia scale. Though this may be a bit unsightly, it's usually not a serious pest, and most gardeners ignore the blemishes. Often the scale has been parasitized by a wasp, and you can see a small pinsize hole in the top of the white scale where the insect has exited. If needed, a low-toxicity natural oil spray can be used to control the scale insects.

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We added an angel's trumpet to our landscape last spring that is now higher than the fence. It appears to be tropical. What should I do about cold protection?

Your observations are correct; the angel's trumpet won't like frosts or freezing weather. The size of mature in-ground plantings make them difficult to protect. A quick covering with sheets tossed over the limbs when a frost is expected might give some protection, but it won't prevent freeze damage.

Mostlikely you would have to create a tentlike covering over the plant to the ground and add heat to guard against temperatures dipping much below freezing. This is usually too much of a chore for most gardeners to undertake for one plant.

The good news is even if a plant freezes, it usually recovers from buds near the ground to regrow as a shrub or tree when spring weather returns.

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I have an older oak tree that is producing shoots we call suckers from the roots. I have a weed control product that says it controls oaks and other plants. Would it be safe to treat the oak shoots? If not, what can I do?

Don't spray the shoots if you want to keep the oak tree. The herbicide is designed to control unwanted trees - roots and all. If you spray even the suckers, the chemical is taken down into the roots and then into the main portions of the tree where it causes decline.

Often suckers are produced in response to the roots being damaged during mowing and while adding plants under the trees. Gardeners with sucker-control problems can prune them out and hope the tree stops production. Adding a mulch over the root system can also help reduce the sprouts from the root system.

Some garden centers carry a new product called Sucker Stopper, a growth regulator that is labeled to prevent the re-growths. It is applied to the new shoots from the roots when they are less than 10 inches tall; follow llilbel instructions. This should stop additional shoots from developing.

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Is the yaupon holly tree the same as the East Palatka holly? I have a yaupon holly, but it is a bush

The plants are both native to Florida, but that is where the similarity ends. The East Palatka holly is believed to be a naturally occurring hybrid of the American holly and dahoon holly that grows to more than 25 feet tall. It is an upright growing tree with oval leaves that mostly have a smooth edge with a spine at the tip.

The yaupon holly tree has a rounded to irregular shape and grows to about 20 feet tall. The leaves are narrow and have a lightly scalloped edge. Besides the tree forms, there are also weeping and shrub types. A common selection is Schelling's Dwarf, most likely the plant in your yard, marketed for foundation and hedge plantings.

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We have an elm tree in our yard that is being attacked by ball moss. It has been suggested I use a copper fungicide to control this parasite. Will this work?

Moss is a plant that just hangs around taking needed water and nutrients from the air and rain. Ball moss and its relative, Spanish moss, are epiphytes that use the tree only for support.     Both are members of the bromeliad family that contain plants sensitive to copper compounds. Application of a copper fungicide properly labeled for use on your tree will likely cause the moss to drop from the limbs. Removal of the moss seldom makes a declining tree grow better. You should check for other cultural and pest problems.

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My daughter has built a home in a dry area. What low-maintenance trees could she plant?

Topping the list of all-time favorites for dry soil are the live and laurel oaks. Less well-known but perhaps even more drought tolerant are the myrtle and sand live oaks, often found in some of the sandiest soils. Other favorites that can normally survive on their own with normal rainfall include the loquat, sand pine, Southern red cedar, tabebuia, winged elm and yaupon holly.

Getting these trees established is the key to helping them survive on their own. Make sure the trees have adequate water for up to a year after planting. This usually means watering daily for two to four weeks and then every other day for a few months. Then give the trees at least weekly waterings for the rest of the year.

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Soon it will be time to apply a weed-and-feed fertilizer to the lawn. Will it hurt to apply the product under oak and citrus trees?

Check the label. I think you will find most companies recommend not using their products under trees or near shrubs. These products are weed killers and often cannot tell your trees from the unwanted vegetation. Often the damage they cause is not noticeable, but it can weaken the trees and shrubs, which may lead to more extensive decline.

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I recently noticed hundreds of holes about 1/8 inch in diameter on the trunks of my oak trees. They were in a straight line and encircling the trunks. What caused the damage, and is it harmful?

Most gardeners agree the holes are not attractive, but they cause minimal harm to the trees. Possibly you have noticed a redheaded bird with a yellow belly frequenting your trees. The yellow-bellied sapsucker has been at work making the holes.

This bird has a twofold plan: to puncture the bark of the tree and lap up the sap that flows from the wounds; and to attract insects to the holes to provide additional food. The holes don't appear to affect tree growth.

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I have a crape myrtle that is being crowded by several large shrubs. Can it be replanted to a better site now?

It's time to make the move while the weather is cool and the crape myrtle is dormant. Make sure the soil is moist at the time of transplanting and gather a large root ball with intact soil. Keep the plant moist after the move and feed it in about six weeks.

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Several years ago, I planted a pink tabebuia that is now 25 feet tall, but it has not bloomed. I see much smaller trees in bloom. What is wrong with mine?

Most tabebuia trees are grown from seed. Consequently, there is a great deal of variability among the offspring. You might notice some are deep pink and others are a much lighter color. Trees right next to each other may begin to bloom a week or two earlier than others, and some like yours take an extra year or two to start flowering.

Have patience, and your tree will still produce the flower display you see in other yards. Also water only when needed. These are drought-tolerant trees.

Also, once they reach flowering size, stop the feedings. The trees can obtain the needed nutrients from nearby feedings of lawns and shrub plantings. Putting the tabebuia on this lean diet can help promote flowering another year.

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Is forming an air layer a good way to start tabebuias?

Air layers would be one way to obtain a new tabebuia tree but probably not the easiest. The technique would involve making a wound along a stem and encasing the area in moist sphagnum moss or soil to encourage root growth. It would take several months to root, and you would get a new plant just like the parent.

Most gardeners simply wait until the seedpods form to start the plants. Tabebuia seeds are ready to germinate when the seedpods turn brown and start to open. Just cover the seeds lightly and in a few weeks you should have all the young trees you want and many for friends. The new trees may show some variability as they reach flowering size, but most are similar to the parent.

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I have two tall-growing viburnums. Could I train them to be trees?

Larger-growing viburnums can reach 25 or more feet in height. They can be shaped into trees much like tree ligustrums. You have the option of leaving several trunks or limiting the tree to one.

Prune out what you don't want, and start shaping a crown to form a tree. Viburnums are cold sensitive and often develop trunk problems as they grow older; expect them to live about 20 years.

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I recently removed a tall oak tree near my home. Other than renting a stump grinder, how can I eliminate the remaining trunk near the ground?

All stumps rot in time. You might consider using the stump as a spot to set a birdbath or even a container garden until it naturally declines. If you want to speed decomposition, try drilling numerous holes in the trunk and packing them with soil. Keep the trunk moist, and the microorganisms in the soil will help the trunk to rot. The process still takes time.

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We have two large oak trees with extensive roots, but we would like to have grass too. What is the best type of sod for our yard? Should we add a layer of topsoil first?

Skip the sod and go right to the garden center for a ground cover. Adding turf to this shady location with the root competition likely would be a waste of money. Instead, select from Asiatic jasmine, bromeliads, cast-iron plants, English ivy, ferns and mondo grass. You also can add color from begonias, caladiums, eucharis lilies and impatiens.

Save the turf for the sunny areas with much less root competition. If you decide to add a layer of topsoil, the limit is 2 inches over the roots of trees.

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During the winter, we noticed small tufts of gray-green moss on the limbs of our crape myrtle. Should the moss be removed?

The growths cause little or no harm. They obtain needed nutrients and water from the air - thus the name air plants.

With crape myrtles, the life of lichens and moss is often short-lived as these trees and shrubs shed their bark to cleanse the surface. By early to midsummer, much of the bark peels off and so does almost a year's worth of the clinging vegetation. If you wanted to hasten the demise, a copper fungicide labeled for use with crape myrtles could be applied as instructed on the label for pest problems.

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I would like to trim some of the lower limbs from my magnolia tree to encourage more growth in the middle and the top. When is the best time to prune?

Feel free to remove the bottom limbs any time. But trimming that removes these lower limbs won't add growth to the center and the top of the tree. Removing these limbs with the food-producing leaves could slow growth.

In time, most trees produce the new shoots from buds already present on the upper limbs to fill in the gaps. Just keep the soil moist, and feed lightly once monthly in March and June.

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What are some small trees I can plant?

The list might include evergreen trees of hollies, cherry laurel, tree ligustrum, loquat, myrtle oak, sand live oak, and sweet acacia plus deciduous selections of Chinese elm, red bud, river birch and winged elm. Most of these grow less than 40 feet tall and not as wide.

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Our oak trees have developed small brown swollen spots on the leaves. Is this a pest or a cultural problem?

These brown puckered spots are called oak leaf blister. It's a late-winter disease that may go unnoticed until the yellowish-green tissue caused by a fungus turns dark brown. If you check the trees carefully, most of the foliage damage should be on the lower branches. Leaves found here are the last to dry, which gives the fungus a good place to grow.

By the time you notice the damage, it's too late to apply a spray. In order for the fungus to infect the foliage, damp spring weather is needed. Fungicides can help, but it's difficult to time the sprays to prevent the disease. It's also difficult to treat large trees. Most gardeners ignore this disease and accept a few brown spots on the foliage.

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We planted several trees about 8 feet tall this spring and have been watering them every other day. How much longer do we have to water the trees?

Trees have an amazing ability to survive after planting with minimal care. But if you place them on a good care program, they grow quickly and become well-established in a minimal amount of time. Continue your care program for about three months; then you can reduce the waterings to twice a week for another three months. Any rain that thoroughly wets the soil within the root zone can be considered an adequate watering.

Watering then should be continued weekly until the trees becomes established. It can take up to a year for the roots to grow out of the root ball and into the surrounding soil.

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Various experts have told us dogwoods don't do well In Mount Dora. Is this correct?

Dogwoods have a stress-filled life in Central Florida. They barely receive enough cold to begin leaf and flower growth each spring. Also, it's often too hot and humid during the summer for good growth. Can they survive? They can, but you have to baby them.

Start with a locally grown tree and a variety such as Weaver's white. Next, plant tree in a filtered-sun location.

Improve sandy planting sites with lots of organic matter, and add a mulch layer after installing the tree. Keep the soil moist, and feed lightly on.ce month in March and June. Most trees need two years of constant care to become established.

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After last year's hurricanes, we had two new oak trees planted. One appears to be doing fine, but the other gets new leaves that eventually turn brown. Will it survive?

Your tree is a struggler that is losing as much foliage as it is gaining. Most likely, it's telling you it's having trouble taking up the water and nutrients needed for growth. Perhaps the tree has not been able to establish as good a root system as the other oak planted at the same time.

There are many possible causes of the problem, but now you have to decide what you can do to save the tree.

Start by keeping the soil moist. Make sure there is a berm around the edge of the root ball to catch water and direct it down through the root system and then out into the surrounding soil. Watering every other day should be adequate if it doesn't rain.

Resist the temptation to give the tree extra fertilizer. More food is seldom the answer to a struggling tree problem. A light feeding or two with a lawn fertilizer won't hurt, but too much could burn the roots or encourage top growth that the root system cannot support. Summer is a good time for trees to grow new roots. With a little care, your tree is likely to continue growing slowly but steadily.

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My newly planted crape myrtle has black sooty mold on the lower leaves. Some leaves have fallen. What should I do?

It's the end of the growing season for crape myrtles, and what you are seeing is normal leaf discolorations and decline. Many gardeners also are noticing the leaves turningy yellow and red, which might be an early hint fall finally has arrived. Such leaf loss is normal and cannot be prevented.

The black on the leaves is a fungus that results from the feeding of insects. By the end of summer, many crape myrtles have large aphid or whitefly populations that produce excreta to feed the sooty mold fungus. At this time of the year, the discoloration is tolerated.

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I have harvested red magnolia seeds. What is the next step to grow some trees?

Considerable patience will be needed to produce the trees from seed. They have several dormancy factors that must be overcome to get them in a germination mood.

First, remove the red coating from the hard inner seeds. This coating keeps the seeds from sprouting until it's rubbed off.

Next, plant the seeds in containers of potting soil. Cover them with a layer of soil equal to the seed's thickness. Moistenthe soil, and set the container in a refrigerator for 120 days. This helps the seed overcome a maturity factor that also prevents germination.

When the cold treatment is over, place the containers of seeds in a sunny location and keep them moist. The long-awaited germination should begin within a month or two.

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My magnolia has silvery spots on the lower leaves. What is the cause, and how do I treat the problem?

A silvery tinge to the leaves and a few bright lights might make this tree a great holiday decoration for your yard. Even if you are not interested in this festive idea, you will be happy to learn this is a minor blemish called algal leaf spot; typically, it is ignored.

You could break out a copper fungicide, available from your garden center, to help contain the spotting, but the tree won't mind no matter what you do. The silvery spots are formed by a plant growing on the surface of the leaves that takes advantage of the available light and moisture.

Most magnolia leaves drop naturally during spring and, with them, the algal leaf spots causing the concern. Don't worry. Your tree gets new blemishfree leaves at this time too.

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We lost the trees the builder planted in a damp area of our yard. What trees grow in wet areas?

Most trees don't like wet feet, but a few do grow in swampy areas and might flourish in these problem spots. One that's often found in boggy sites but also grows in dry areas is bald cypress, a deciduous but evergreen-looking tree with attractive fernlike foliage during the warmer months. This native tree grows to 80 feet tall and half as wide.

Another native tree for the wet area is loblolly bay growing to 40 feet tall and 15 feet wide. This is a true evergreen with a dark-green, broad leaf. The tree comes with a bonus of white blooms for the summer season.

Trees that could survive on the edge of the wet spots include dogwood, dahoon holly, red maple, river birch and Southern magnolia. Each needs well-drained soil to begin growth before sending out roots into the wetter zones.

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An oak tree recently has sprouted in a bed about 5 feet from our house. Is this too close to our home?

One thing hurricanes have taught us is not to allow large trees to grow too close to the home. In time, the limbs could rub against the roof or even break off to damage the structure of the house.

Another potential problem is, the foundation of the home does not allow the roots to spread out and anchor the tree securely into the ground, making it more susceptible to winds from any storm.

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My 3-foot East Palatka holly seems to be growing slowly although it has a lot of berries. It also has two equal-size trunks. Should I remove one of the trunks?

Double trunks might make the tree look fuller while it is young, but they can cause lots of problems in later years.

Keep the best, straightest trunk and remove the other. This is the only way to produce a strong, wind-resistant tree for the future. A solitary trunk can grow and become taller faster. Trees with competing trunks often split during storms as they grow older.

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Our crape myrtles need light trimming. When can we begin to remove the overgrowth?

Wait a little longer. Allow the trees to go through most of the winter in a dormant state; pruning encourages growth. You can begin the needed trimming around mid-February when most of the cold weather is over.

When pruning time arrives, be gentle. Most crape myrtles need only a light trimming to remove old seedpods and twiggy growths among the lower limbs. Also keep shrub clusters to between three and five main trunks to give them an attractive appearance and to allow room for spring growth.

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I have a 5-foot-tall Norfolk Island pine that consists of four individual trees. I want to separate them without causing any damage. What do I need to do?

Don't even think of trying to do that. By now the roots have become intertwined, and separating the trees likely would cause them all to decline. Perhaps the best advice is to accept the cluster as a multistemmed, shrublike plant or eliminate all but one of the best shoots to get a more treelike look. If you want a tree, trim off all but the straightest trunk. The remaining shoot then would grow a normal Norfolk Island pine to keep in a container or add to the landscape.

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