Growing Turfgrass in Shady areas

Find tips for growing grass in shady areas

Brian Jervis: Ask a Master Gardener   

Saturday, June 25, 2016  

Q: I simply cannot get grass to grow under my oak tree after reseeding it several times. Is there a best grass to use? Dwayne, Tulsa

A: This is a common problem in Tulsa, where we have these wonderful huge shade trees. The shade is good, but growing grass under them is challenging.

Of the turfgrasses commonly grown in our area, tall fescue and Kentucky bluegrass are the most shade tolerant, followed by zoysia, which will tolerate some shade, but still needs a lot of sun. Bermuda and buffalograss must have full sun. Neither will grow in full shade.

When there is not enough sunlight for the grass you wish to grow, there are some steps you may take to improve chances of success. These are outlined in a very helpful OSU fact sheet, “Managing Turfgrass in the Shade in Oklahoma,” available from the Master Gardener website, tulsamastergardeners.org, in the turfgrass section.

If your situation is such that pruning of trees and shrubs could be done for shade management, without harming the plants, this may allow more sunlight and may improve chances of success.

Plus, alterations in how you manage the grass may improve shade tolerance. If you mow the lawn tall in shaded areas (3 inches or more for tall fescue and 2 inches for Bermuda and Zoysia) it will produce more grass blade surface to absorb available sunlight.

Grasses in the shade have improved chances of survival if they receive less fertilizer than the usual amounts recommended. Also, it is better to use more frequent applications of smaller amounts to avoid a surge in growth demand. These grasses also need less water since they take longer to dry out after rain or irrigation. Look to see if the soil is dry before irrigating.

Try to keep the weed competition under control by hand or with herbicides. If using herbicides read the label carefully about the use in shaded areas, some may be more toxic in shade. It is also helpful to remove leaves or other debris that has fallen onto the lawn as soon as possible to prevent blockage of available light.

And if you continue to fail in growing grass in shade after two to three years, it may be time to consider a different strategy to manage your shaded areas. These shady spots can go from being a problem to an asset by planting shade-tolerant ground covers, ornamentals and installing some hardscape (stone element) structures. After establishment the need for maintenance is much less than struggling with turfgrass.

The OSU fact sheet referred to above has a useful section on alternative plantings for areas too shady for lawn grass. Suggestions for annuals are plants such as caladium, impatiens; perennials suggestions include such things as hellebores, hostas, ajuga, Japanese painted ferns and many others. There is also a list of groundcovers, vines and several shade-tolerant shrubs. From this information, you should be able to design and build an attractive shade garden.

6-25-16 Garden Tips

·       Mulch ornamentals, vegetables, and annuals. This reduces soil crusting, cools soil and conserves moisture during hot summer months. Mulch also helps prevent weeds and reduces likelihood of mechanical damage from lawn equipment.  Mulching will reduce about 70 percent of the summer yard maintenance.

·       A disease called “fireblight” is prevalent now. It may infect over a 100 plants in the rose family, but especially apples, crabapples, pears, quince and pyracantha. The bacterial disease is spread by insects and rain and enters the plant through open blossoms. Once infected, the leaves on the involved limb turn brown looking like they have been scorched (hence the name) and that limb dies. The only treatment is to remove the dead limbs. An antibiotic spray can be helpful but only during full bloom and only used to prevent the disease. Some trees are more susceptible than others, consideration should be given to planting disease resistant varieties.

Fertilizing Vegetables During the Growing Season

Soil test will guide you on garden nutrients

Bill Sevier: Ask a Master Gardener  

Saturday, June 18, 2016

Q: I tilled in some organic compost before planting in my vegetable garden. Do my vegetables need more fertilizer now? B.C., Tulsa

A: Most of the rapidly growing vegetables perform best with added fertilizer during the growing season, some more than others. Usually this is done in the form of sidedressing, which means applying fertilizer between vegetable rows.

Plants are already growing, but ideally it would have been desirable to obtain a soil test before planting. At that time, any amendments needed as determined by the test could be tilled into the garden. A soil test will guide you to use only the needed nutrients. Excessive amounts may be detrimental to your plant’s health. This is especially true with phosphorus; do not add this unless it has been shown to be needed.

All fertilizers have three numbers on the container which represent the percent concentration of that nutrient. The nutrients are nitrogen, phosphorus and potassium, in that order. Nitrogen, the first number, is needed much more than the others by most plants.

When fertilizing, many people understandably wish to use all organic. This can be done, but requires more planning and understanding of various materials. The nutrients in organics may be released slowly depending on the temperature and microorganism activity. Firstly, most of the composted manures have low levels of nutrients. Cow manure may have numbers of 1-1-1, whereas a typical commercial lawn fertilizer may have numbers such as 32-0-10, which is 32% nitrogen, no phosphorus and 10% potassium.

Some organics, such as blood meal have numbers of 15-1-1, milorganite has 5-3-2 and cottonseed and cottonseed and soybean meals are in the range of 7-2-2, much higher than manures.

A chart of recommendations for sidedressing for both vegetables and ornamentals is available on the Master Gardener website, tulsamastergardeners.org, in the vegetable section. Specific amounts of both manufactured and organic fertilizers are listed for each vegetable and common ornamental.

The amounts of the fertilizer recommended are widely different and the chart should be consulted for this information. The times and frequency of fertilization for some of the common vegetables are:

·       Asparagus — in spring before growth or after harvest

·       Cabbage, broccoli — three weeks after planting

·       Cucumber, squash, pumpkin — one week after blossoming and three weeks later

·       Onions — 2-4 weeks after planting

·       Peas and beans — after heavy bloom and set of pods

·       Peppers and eggplants — after first fruit sets

·       Potato — when plants are 4-6 inches tall

·       Spinach, kale, turnip and mustard greens — when plants are about 1/3 grown

·       Sweet corn — when plants are 8-10 inches tall and one week after tassels appear

·       Sweet potatoes, watermelons, herbs — none, excessive amounts may reduce yield

·       Beets, carrots, turnips, lettuce — none needed if fertilized at planting

·       Tomato — 1-2 weeks before the first tomato ripens, then 2 weeks and 6 weeks later

·       Blueberries — monthly April through July

·       Brambles (blackberries) — April at start of growth

·       Strawberries — amount depends on type of plant, refer to chart

·       Annual flowers — monthly until frost

·       Daylilies, garden phlox, astilbe, mums — once after blooming

Consider going to the Master Gardener website to print off this useful information.

Garden tips

§  Remain alert for insect damage. Add spider mites to the list. Foliage of most plants becomes pale and speckled; juniper foliage turns a pale yellowish color. Shake a branch over white paper and watch for tiny specks that crawl. Watch for first-generation fall webworm.

§  Some pests can be hand-picked without using a pesticide. Do not spray if predators such as lady beetles are present. Spraying insecticides early in the morning or late in the day will avoid spraying honeybees and other essential pollinators.

Gardening for Butterflies

Gardens help protect declining butterflies

Brian Jervis: Ask a Master Gardener   

Saturday, June 11, 2016  

Q: I need help in planning a couple of garden beds to be butterfly friendly. What do I need to plant? W. G., Tulsa

A: Butterflies and other desirable garden insects are struggling with the loss of habitat and other factors that have reduced their numbers. Monarch butterflies have been on decline due to loss of milkweed and other nurturing plants in their flyways. We can do several things to aid these garden friends, which are discussed in the OSU fact sheet, “Landscaping to Attract Butterflies, Moths and Skippers,” available online from OSU or from the Master Gardener website in the Monarch and Milkweed section.

It is clear that when you make your landscape “butterfly friendly,” you also create a favorable environment for many other beneficial insects, some of which are pollinators and others that keep harmful pests in check.

Butterflies are classified in the order Lepidoptera, which also includes moths and skippers, insects similar to butterflies, although there are significant differences. Moths mainly feed at night and are often seen around nighttime lights outdoors. Skippers are usually brownish, small and have a darting flight habit. They are commonly found on flowers. Discussion below applies to butterflies, moths and skippers for the most part.

To create a butterfly habitat, it is important to consider sunlight and shelter from the wind. Sunlight is needed to warm up butterfly’s bodies to 85 degrees before they can function. Plant selection is important. Select ones that are a food source for the immature larvae (caterpillars) and the adults. These are not always the same plants.

Butterflies also need a water source and often drink from shallow mud puddles. Artificial puddles may be created by placing gravel in a large dish containing a shallow amount of water. Fruit slices also serve as a water source, as well as supplying some nutrients.

Obviously, all insecticides, as well as electronic bug killers, should be avoided.

When planning and selecting plants for your garden, go to the OSU fact sheet cited above, which has more than 100 plants recommended, not only for nectar sources, but also serve as food to nurture caterpillars.

For monarch butterflies, milkweeds are the only plants on which they thrive. Monarch caterpillars feed on leaves of milkweed, and the flowers provide nectar for the adults. It is of interest that milkweed contains a toxin, which if eaten may make people and animals sick. However, it is not toxic to monarchs and, in fact, gives them protection in nature from predators.

In Oklahoma there are more than 20 varieties of milkweed, which are hosts to monarchs. A list of most milkweeds in Oklahoma may be found on the Master Gardener website, tulsamastergardeners.org, under tips and techniques. Go to the long list of plants in the OSU butterfly document and select those plants that will work for you in terms of benefiting butterflies, as well as being an attractive addition to your garden.

Garden tips

§  Renovate overgrown strawberry beds after the last harvest. Start by setting your lawnmower on its highest setting and mow off the foliage. Next, thin crowns 12 to 24 inches apart. Apply recommended fertilizer, pre-emergent herbicide if needed and keep watered.

§  White grubs will soon emerge as adult June Beetles. Watch for high populations that can indicate potential damage from grubs of future life cycle stages later in the summer.

§  Feed established mums and other perennials.

§  When picking fresh roses or removing faded ones, cut back to a leaflet facing the outside of the bush to encourage open growth and air circulation.

Bermuda Lawn Spring Dead Spot

Spring Dead Spot affects Bermuda lawns

Bill Sevier: Ask a Master Gardener

Monday, June 6, 2016

Q: There are some dead spots in my Bermuda lawn. What might cause this and what can I do? Troy, Tulsa

A: While there are several factors that may kill areas of Bermuda lawns that are noticed in spring, winter-kill and a fungal disease called “Spring Dead Spot” (SDS) are the chief causes in Bermuda lawns in our area.

To sort this out after you have eliminated such things as chemical spills, animal urine and soil compaction, you should address the questions of whether it was there last year.

Almost without exception, winter kill spots were not there last year and are found only after a wet and cold winter with snow cover for an extended period of time.

SDS once started tends to enlarge and shrink in the same area from year to year. This disease is due to one of two fungi that infect and damage Bermuda grass in the fall, but the consequences are not seen until the following spring due to the lack of greening of the dead grass, hence the name.

SDS patches may be a few inches to several feet wide. When the roots and rhizomes are inspected, they are usually black as opposed to a cream color of healthy plants. The open patches may harbor weed invasions in the summer. The fungus does not usually affect weeds or other plants.

After a decision is reached about the presence of SDS, how to prevent and cure it is the next challenge. This is not something for which one can run down to the garden center and obtain an effective fungicide to eliminate it.

Most of the control is cultural, that is to say, altering the way you grow and manage your grass. It also depends on the variety of Bermuda; some are more disease resistant than others.

The timing of fertilizer applications is important for disease susceptibility. Studies have revealed that fertilizing Bermuda lawns late in the growing season — after Sept. 1 — is associated with an increased incidence of this disease. Late fertilization delays winter dormancy, which reduces tolerance to disease.

Raking out all the diseased Bermuda will help the healthy grass spread into the bare spot during summer. Core aerification and dethatching may help by improving the health of the grass; however, it should be done in winter, to avoid spreading the disease.

Fungicides are available for treatment of SDS. Some of these are restricted-use chemicals available only to licensed applicators. Some are expensive, as well.

If a fungicide is used, it should be sprayed in September after the temperature is below 70 degrees and repeated in 30 days. Some suggest using two different types of fungicides for these applications.

Oklahoma State Extension information lists fungicides to use in SDS, but the head of the turfgrass department has concluded the organism that causes the disease in Oklahoma is so poorly responsive that he does not recommend them.

Garden tips

§  Insect Alert: Now is the time to be on the lookout for bagworms on juniper and arborvitae and lace bugs on sycamore, pyracantha and azaleas. Contact Tulsa Master Gardeners at 918-746-3701 for control suggestions.

§  Thatch is a layer of dead and living stems, shoots and roots that pile up on top of the soil at the base of lawn grasses. If it is more than ½-inch thick it should be removed with either a core-aerator or power-rake. Now is the time to de-thatch Bermuda and zoysia, if needed. Dethatch fescue in the fall.

§  Bermuda lawns will benefit from up to 2-5 pounds of nitrogen fertilizer per 1000 square foot in divided applications from now until the end of August. Apply the first application now. Fertilize tall fescue lawns now if you have not fertilized this spring. Do not fertilize these lawns in summer, it will make them susceptible to heat and disease damage.