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.