Planting Azaleas in the Fall

Azaleas can be planted in fall or spring

Bill Sevier: Ask a Master Gardener

Saturday, October 15, 2016

Q: What time of the year is it best to plant azaleas? How best to plant them? K.D., Tulsa

A: Ideally, azaleas should be planted either in early spring or in fall after it cools. Either time is acceptable.

When planting in fall, it is suggested that you delay mulching until after the first frost so the plants will be assured of developing dormancy for winter.

Azaleas have some cultural needs that are a bit different from many other shrubs, at all times of the year. The chief difference is that they need an acidic soil, with a preferred pH (measure of acidity) in the 4.5 to 5.5 range. Our native soils do not normally have this degree of acidity, so some adjustments are usually needed.

To determine soil acidity, along with information about the nutrients nitrogen, phosphorus and potassium, have a soil test performed before planting. Instructions on how to perform a soil test and also how to plant azaleas may be found on the Master Gardener website.

If more acidity is needed, there are two options. The best option is to mix peat moss 1:1 or 1:2 with native soil. Peat moss is acidic and will usually produce an adequate pH. Another way to add acidity is to use elemental sulfur (pure sulfur) and mix it into the soil. The amount of sulfur to add depends on the pH, but a safe amount to use would be 7 tablespoons for every 10 square feet of soil. Sulfur will not immediately lower pH; it takes a few months for this to occur.

Azaleas have fine, shallow net-like roots. To plant them, create a blunt cone of soil, spread the roots out over the cone like an umbrella and cover with several inches of soil.

In well-drained soils, plant azaleas at the same level as they grew at the nursery — never deeper. If your soil is heavy clay, as it often is, it is best to plant above ground in a large mound of prepared soil. Spread the roots out and plant them on top of the mound, with a few inches of soil for cover.

In both cases, they should receive generous amounts of loose mulch at the time of planting and yearly thereafter. There is no best mulch. Any mulch that is loose is useful. Contrary to popular belief, there is no mulch that will add acidity to the soil.

All the plants need generous irrigation during establishment and subsequently in all seasons.

A slow-release fertilizer, such as Osmocote, may be mixed with the soil at the time of planting and, if so, no further fertilizer will be needed the rest of the following growing season. Azaleas, in general, need less fertilizer than other shrubs and will suffer if excessively fertilized. If mulched yearly, adequate nutrients may be supplied by the decaying mulch.

Garden tips

• Peonies, daylilies and other spring-flowering perennials should be divided or planted now.

• Dig and store tender perennials like dahlias and caladiums in a cool, dry location. Cannas and elephant ears can also be dug, but most will survive the winter fine if mulched heavily and in a sheltered area.

• Plant fall mums and asters, and keep them watered during dry conditions. Don’t crowd because they take a couple of years to reach maturity.

• As leaves begin to drop, keep them off any newly seeded fescue lawns

Fall is the Best time of the Year to Plant Trees, Shrubs and Perennials

Fall is good time to plant trees

Brian Jervis:  Ask a Master Gardener

Saturday, October 8, 2016 12:00 am

Q: Is it best to plant trees in the spring or fall? B.F., Tulsa

A: The question brings to mind the adage, “The best time to plant a tree was 20 years ago. The second best time is now.” — Chinese Proverb

The short answer is that fall is an excellent time to plant trees; but spring and fall are acceptable times of the year to install trees, shrubs and perennials. There are some exceptions, however, depending on the plant type.

An appeal of fall planting is that many gardeners are enthusiastic about returning to the garden following the heat of summer. In addition, one is likely to find some bargains in the nursery stock in fall.

The advantages of fall planting is that trees are entering dormancy and no longer expend energy on making new leaves. This means that most of the plant’s energy can be directed toward growing a root system, in preparation for next year’s growing season. The soil usually remains warm enough for roots to grow well into winter.

Due to high demands and a limited root system, plants installed in spring or during summer may experience water loss from leaves that exceeds the plant’s ability to deliver. In spring, all newly-planted trees need careful irrigation and mulching.

Fall planting gives trees a head start. OSU performed a study comparing a variety of 2-year-old trees that were planted in spring and fall. They found trees planted in fall had up to 50 percent larger root balls and trunk thickness when compared with spring-planted trees after one growing season. This advantage applies not only to trees, but also to shrubs and ornamentals.

However, most bare-root plants should not be planted in fall but in spring between mid-February and mid-April or up to the end of the frost period. They must grow tiny rootlets to absorb water, and this happens as buds begin to swell in spring. Other than seedling-sized evergreens, only deciduous plants can be transplanted with bare roots, and then only when dormant or leafless.

Another exception to fall planting are evergreen shrubs. These shrubs will continue to lose water in winter, and the demand may exceed the root’s ability to deliver. If they are planted in the fall, they must be watered frequently, sheltered from wind and have a thick layer of mulch.

An additional concern about fall planting relates to crape myrtles. Carl Whitcomb, a retired OSU professor and expert on crape myrtles, recommends they be planted in June through early September and not after October. They need warm soils to grow water-absorbing roots, and the cool soils of winter prevent the development of these roots.

For more information about tree planting, obtain the OSU fact sheet “Planting Trees and Shrubs” online. This fact sheet has the what, when and how to plant trees in all types of soil. Also see Whitcomb’s book, “Establishment and Maintenance of Landscape Plants,” for additional authoritative information.

Garden tips

§  Plant cool-season annuals like pansies, ornamental cabbage or kale, snapdragons and dusty miller when temperatures begin to cool.

§  Prune trees or shrubs anytime there are dead or diseased limbs. Do not perform routine pruning now. Pruning before winter dormancy may stimulate new growth sensitive to the cold. Fall pruning also removes energy stores needed for winter survival.

§  For summer-blooming shrubs, prune in late winter before spring growth starts, and prune spring-blooming plants, such as azaleas, after blooming is completed.

§  Continue to replant or establish cool-season lawns like fescue. Mow and neatly edge warm-season grasses before the first killing frost.

Pine Wilt Disease is Fatal

Disease affects pine trees

By Bill Sevier Ask a Master Gardener | Posted:

Saturday, October 1, 2016 12:00 am

Q: My Austrian pine has started turning brown. It involves most of the tree. I don’t see anything abnormal other than brown needles. What should I do? Doris, Tulsa.

A: Unfortunately, the most common cause of pine trees turning brown and dying in the latter part of summer and fall is a condition called “Pine Wilt Disease.”

This condition is due to an infection of the tree’s circulation with a microscopic worm called a nematode. This infection is spread from tree to tree by an insect, the pine sawyer beetle. Because this infection is native born, native trees, such as loblollies, are less susceptible than the imported ones like the Austrian pines.

This beetle becomes infected by feeding on trees containing the nematode. The nematodes do not harm the beetle, but the infection is spread when it feeds on a healthy tree. The nematodes build up in the infected tree until they block all the circulation. The limbs become brittle and have little sap or resin. The needles stay fixed to the tree (as opposed to other conditions in which they drop) and the tree dies. Often there is an associated fungus that stains the wood of the tree blue. If a limb is cut, in addition to the lack of sap, bands of blue discoloration may be seen.

This is a fatal disease. The tree should promptly be removed and either chipped, burned or sent to the landfill. It is infectious, and if left in place, will infect a new crop of pine sawyer beetles the following spring that then spread the disease.

The other significant causes for browning of pine needles occur at certain times of the year. In spring, a disease called “Tip Blight” or Sphaeropsis or diplodia, appears as stunting and die-back of new needles (candles) on the tips of lower limbs. There may be dried resin and pepper-like specks on needles and cones. Also in spring, the pine tip moth may attack the new growth on tips of limbs, producing hollowed out limbs and webbing. These conditions involve only the tips, sparing the rest of the limb.

Another cause for brown needles is winter damage due to low temperatures and drying winds. This is often one-sided and is noted in early spring.

In late summer, another fungal disease called Dothistroma Needle Blight may appear, involving the tips of lower limbs. It may spread inward. The needles have discolored bands and die during the winter. The tree sheds them the following spring and summer.

Lastly, one of the more common causes, and one the Master Gardeners are often called about, is “normal needle drop.” Pines shed needles in the fall similarly to deciduous trees shedding their leaves. This involves the older needles, the ones closer to the trees trunk.

For the problems with pines other than pine wilt disease, there is treatment. Contact the Master Gardeners office for recommendations for control of the fungal and insect issues.

Garden tips

Begin preparing your outdoor plants for a move indoors. Move houseplants indoors when the outside and indoor temperatures are about the same. For plants in full sun, move to shade. Begin with light and then heavier shade over a week’s time to prepare the plant for the low light indoors. If you move the plant from full sun to a low light indoor situation, the plant may experience “shock,” lose leaves and perform poorly inside.

Inspect plants for insects and disease and treat accordingly. In many cases, a few insects can be controlled by hosing down the plant and removing them by hand. Another option is to use an insecticidal soap spray. This is effective and safe for you and your plant.

Also consider drenching the pot with 2-3 pot volumes of water to help remove insects and residual fertilizer salts.

Plants for the Shade Garden

Options for shade plants are plentiful

Brian Jervis, Ask a Master Gardener

Saturday, September 17, 2016  

Q: I am wondering what plants you would recommend for a shady area. I am interested in some shrubs and perennials that are low maintenance. Terri, Tulsa.

A: Most of us have to deal with shade in some areas of our gardens. The good news is that there are many plants — shrubs and ornamentals — that do well in shade; some must be in shade. A good source for shade-tolerant plants is found in OSU fact sheet HLA-6608, “Managing Turfgrass in the Shade in Oklahoma.” This fact sheet lists shade-tolerant ornamentals and shrubs from which to select for shade too dense for grass.

For shrubs, azaleas do well with a few hours of sun, but Encore or reblooming azaleas need mostly sun with afternoon shade. Additional shade shrubs to consider are aucuba, leatherleaf mahonia, nandina, various hollies, yews, dogwoods and others. The aucuba is a favorite that grows in full shade. Its large evergreen variegated leaves have a tropical appearance.

While many perennials must have sun, a large number have excellent tolerance of shade. High on the list are hellebores and hostas. Several cultivars of hellebores are not only evergreen with thick leathery leaves but also are unique in blooming in mid-winter to early spring. Hostas are widely used because of the appeal of form, shades of green, variegation and different sizes.

Many varieties of ferns do well either in a mixed bed or as a distinct fern garden. Other shade perennials are Astilbe, coral bells, toad lilies, Italian arum, sweet woodruff, goatsbeard and bleeding hearts; they add the eye-catching appeal of blooms and unique foliage colors and patterns.

Chinese ginger is a shade favorite with attractive leaves, which, like hellebores, are evergreen. It will spread slowly after established and do well in the shade year after year.

Perennial groundcovers to fill the shade garden are numerous. English ivy is an old favorite and is tough, evergreen and problem-free. One of the varieties of lamium is useful. Most are variegated and are semi-evergreen. They spread rapidly. An additional good choice for a shade groundcover is one of the pachysandras. They are evergreen and slow to spread but are worth the wait.

Some other plants to consider for groundcovers are ajuga, liriope (lily turf or monkey grass) and Mondo grass. A sedge called Carex or “Ice Dancer” was one of the Oklahoma Proven selections this year. It grows to 12 inches in full shade and would be an interesting addition to the shade garden.

Annuals that have some color and tolerate heavy shade are cultivars of coleus, impatiens, begonias, caladium, fuchsia and sweet alyssum. Coleus and caladium come in many colors and are used for their attractive foliage. Impatiens and sweet alyssum are much used. They both have a range of blossom colors; the white-blossomed ones will light up their spot in a dark shade garden.

There are many others, but, as stated, these are readily available and proven to do well in our area.

For more information or to ask a question about gardening, contact the Master Gardeners at 918-746-3701 from 9 a.m.-4 p.m.

Garden tips

§  Watch for fall specials at garden centers and nurseries because fall is a great time for planting many ornamentals. Choose spring-flowering bulbs as soon as available.

§  Fertilize established fescue lawns with one pound of actual nitrogen fertilizer per 1000 square feet now and again in November. Do not fertilize Bermuda or zoysia lawns until next spring. Late fertilization of these warm-season grasses may promote disease.

§  Winter broadleaf weeds like dandelion will begin to emerge in late September, which is also the best time to control them with a 2, 4-D type herbicide.

Plant Garlic Now for June Harvest

Now is time to plant garlic

Bill Sevier: Ask a Master Gardener

Saturday, September 10, 2016

Q: When is the best time to plant garlic? Lynn, Tulsa

A: Most everyone likes garlic; it is easily planted and grows well here. Garlic is found in the recipes of a huge number of our favorite foods and has been used around the world for 7,000 years as a pungent seasoning.

The essentials of growing garlic are that it should be planted from mid-September through mid-October, using bulbs, and should be harvested in early June the following year. Bulbs can be planted in early spring, but fall planting with early summer harvesting produces larger and more flavorful bulbs.

There are three types of garlic — softneck, stiffneck and great-headed (elephant garlic). Softneck is best for the south and stiffneck for the north, but both do well in our area. The great-headed variety is actually not a garlic but a leek.

There are many varieties of garlic from which to select. Grocery store garlics are not good choices; they may not grow well here and are often treated to extend shelf life, which interferes with growth. The best source is from local garden centers or, for a wider variety, order from a seed company. Always try to get the largest bulbs because they produce larger bulbs at harvest time.

OSU in its fact sheet “Vegetable Varieties for Oklahoma,” suggests four varieties: Garlic German Red, Inchilium Red, Silverskin and Spanish Roja. There are many more, and often, garlic-growing enthusiasts will have multiple varieties in their gardens.

The individual cloves of garlic are the seeds. Break them apart, but leave the husks in place. They should be planted in full sun in well-drained soil generously enriched with organic matter. If you have heavy clay soil, use a raised bed and fill with good loam. Plant the bulbs 4 inches apart and 2 inches deep with the pointed end facing up. They can have their own place in the vegetable garden or they will do well planted with your flowering ornamentals.

In spring as the tops are growing, they need an inch of water per week and extra nitrogen fertilizer. Some of the new garlic tops will develop a type of flower called “scapes.” These should be removed to allow all the plant’s energy directed toward growing bulbs. These scapes have a mild garlic flavor and are edible.

In June, after the garlic tops begin to yellow, it is harvest time. Dig the bulbs with a garden fork, brush off the soil and place in a cool, dry area for a couple of weeks. After drying, the softnecks tops can be braided to hang in the kitchen as a trophy of your gardening prowess. For long-term storage, they are best kept in a cool, dry, dark place in a well-ventilated container (mesh bags are ideal), where they will keep for several months.

Plan on planting a crop this fall. Look at the varieties available and order from a seed catalog if you cannot find them locally.

Garden tips

It is time to begin to divide and replant spring-blooming perennials like iris, peonies and daylilies, if needed.

In fall, strawberry plants build up food reserves and form fruit buds for the next year’s crop. They should be fertilized between mid-August and mid-September with a nitrogen fertilizer such as ammonium sulfate at a rate of 1.5 pounds per 100-foot row. Apply 1 inch of water if no rain is expected.

You have all of September to plant cool-season vegetables like spinach, leaf lettuce, mustard and radishes, and until the middle of September to plant rutabagas, Swiss chard, garlic and turnips.

Leaf Scorch on Japanese Maples and Others

Leaf scorch seen on area trees

Brian Jervis: Ask a Master Gardener

Saturday, September 3, 2016

Q: The leaves on my Japanese maple turned brown on the edges this summer. What is this? Could it be a disease? A. G., Tulsa

A: Brown leaves on plants have many causes. The diagnosis as to the particular cause depends on the type of plant, the season, the environment and the amount of water available.

Japanese maples are notorious for developing brown-edged leaves during summer. This is called “leaf scorch.” It is seen in many plants unable to keep up with their leaves’ water demand during hot summers. Sometimes this is due to lack of water, but with Japanese maples, it often is due to their genetic makeup. They evolved in regions that are cooler and wetter than ours. Their circulation, which was adequate in those areas, often has difficulty coping with our heat and hot winds.

Water flow in any plant begins in the roots where it is absorbed. It is then carried up the trunk through the plant’s cambium layer, located just under the bark of trees. Cambium is the tree’s circulation. As it travels up the tree, leaves are the last stop and the last place water reaches after entering the outer edge of a leaf. So when water is deficient in a heat-stressed tree, the outer parts of leaves initially dry out and turn brown. With worse stress, the whole leaf may die.

While it may not seem logical, too much water in the soil can block delivery of water to leaves. Excess soil water forces oxygen from the soil, damaging the small roots that are needed to absorb water and nutrients. This results in water deficiency in leaves.

Trees that are not ordinarily stressed by our summers often develop brown leaves after planting, before mature roots are able to develop. In young trees, the demand for water exceeds the ability of the immature roots to deliver. That is why it is suggested that newly planted trees be watered regularly, throughout the year for three years after planting.

Other causes of water deficiency in leaves are one of many conditions that damages the tree’s circulatory system. Fungal root rot, systemic infections clogging the flow of sap and trauma to the trunk. Lawn equipment and sometimes rabbits and squirrels may damage the cambium and interfere with circulation.

Diseases may cause browning of leaves as well; the most common of which are fungal diseases. These diseases, for the most part, do not just limit the browning to the edge of a leaf. They often create browning with some yellowing in the form of spots, circles, streaks or holes in random patterns within the leaves. Leaves with disease often turn yellow and drop from the plant rather than curl up at the edges and remain on the tree as often seen with leaf scorch.

In most cases brown leaf scorch on any tree is not fatal, the tree will survive after the stress has passed. It is important to irrigate trees, especially the younger ones.

Garden tips

§  Now is a good time to submit a soil sample to the OSU Extension Office for testing. Do this before reseeding fescue or creating a garden bed this fall. Call the Master Gardener office at 918-746-3701 for instructions.

§  Now is the time to apply a pre-emergent herbicide to lawns to control winter weeds such as henbit. Do not use on fescue if you plan on overseeding it this fall. OSU suggests the pre-emergent herbicide brands containing either dithiopyr, pendimethilin, or prodiamine would be an excellent choice.

§  Tall fescue should be mowed at 3 inches and up to 3½ inches if it grows under heavier shade. Don’t fertilize fescue lawns until it cools later this month, then fertilize again in November.

§  Begin to reduce the amount of light on outside tropical houseplants by placing them under shade trees before bringing them indoors for the winter.

Dragonflies are Good Insects--They Eat Mosquitos

Dragonflies among beneficial insects

Bill Sevier: Ask a Master Gardener  

Saturday, August 27, 2016

Q: I have a pond and there are a number of dragonflies on the plants around it. They often hover over the water dipping their tails into the water. Are they harmful? N.D. Tulsa

A: These insects are not harmful, indeed they are grouped into the category of “good insects,” and they eat the “bad” insect pests.

There are several common names for these insects, which are related to myths. One is “snake doctor,” commonly used in the South. It is related to the myth that they are able to repair injuries of snakes. There are other names, such as “devils needle” and “water witch,” but the proper name is dragonfly. The name dragonfly comes from a belief that they are reincarnation of dragons. If you look at a dragonfly up close, one can see where the “dragon” part of the myth came from.

Dragonflies are classified in the order Odonata and have been with us for millions of years. There are fossils showing evidence of some dragonfly species with wingspans up to 30 inches across. The largest living dragonfly has a wingspan of about 7 inches and locally the largest has about a 4-inch span.

The adult female dragonfly lays eggs either in water or plant material near water. The eggs hatch into nymphs, and they end up in water where they may live for up to 5 years. The nymphs are large, often 1-2 inches in length; they feed on other insect larvae (especially mosquitoes) and sometimes on tadpoles and small fish fry. After maturing, they leave the water and develop their adult form.

Adult dragonflies live weeks to months and spend their time reproducing or feeding. They are fast and agile fliers that are able to catch other insects in the air. They catch and eat large numbers of mosquitoes, flying ants and termites, moths, butterflies and other insects.

Also in the Odonata order and seen in the same environment as dragonflies are their cousins, damselflies. These are generally smaller and at rest usually fold their wings over their back, rather than keeping them outstretched as dragonflies do. Many are blueish iridescent. Their feeding and reproductive behaviors are similar to dragonflies. Two damselflies are commonly seen coupled while flying as a part of reproduction behavior.

The dragonflies, like all beneficial insects, need to be protected. Their status is being threatened by loss of habitat and use of insecticides. Do your part in caring for these insects by avoiding indiscriminate use of any insecticide. They, in turn, will help you keep down the population of mosquitoes.

Garden tips

• Always follow directions on the labels of synthetic and natural pesticide products. Labels will always list where the product may be used and which pest it is certified to cover. If you spray pesticides, do it early in the morning or late in the evening after bees have returned to their colony.

• If your tomatoes are too tall and gangly, now is a good time to prune the top of the plants by as much as 1/3 to ½, depending on the plant. This will stimulate new limb growth and new fruit production after it cools.

• Reseeding fescue is best done from mid-September through mid-October. If you plan on reseeding, begin scouting for good seed. There is no “best” variety. Purchase a fescue blend of 3 or more varieties, with or without Kentucky bluegrass. Read the label on the seed bag. A good blend will have 0.01 percent or less of undesirable “other crop” seeds.