Gardening Speakers at the State Fair!

The 2011 Tulsa State Fair celebrates the 200th Anniversary of Modern Agricultural Fairs in the United States. Come celebrate with us and Ask a Master Gardener your horticulture questions, or visit one of the scheduled presentations listed below. We will be located on the lower level of the Quick Trip Center, October 5th thru 9th (in the Sugar Arts Show location from the previous week).

In addition to the talks we will have "Oklahoma Proven" plants on display and the "Insect Adventure" from OSU for children of all ages. Each day we will give away some Chinese Pistache seedlings. The tree giveaway is sponsored by the Tulsa MG Foundation and Tulsa State Fair. Call 918-746-3701 for more information.

October Lawn and Garden Tips

Garden

Continue to plant garlic bulbs through mid-October.
Plant radish and mustard from seed until October 10th.
Other vegetables can continue to be planted in a cold frame. For more information on cold frames, visit our website.
Plant cover crops now for weed suppression, to prevent soil erosion and to add nutrients when turned under in the spring. For more information see fact sheet HLA-6436 or see article below.

Lawn

In mid-month, fertilize cool-season lawns. Remove leaves from cool-season grasses or mow with a mulching mower. Continue mowing cool-season lawns on a regular basis, even if warm-season grasses have quit growing. See fact sheet HLA-6420.
Seeding of cool-season grasses for perennial lawns can continue through mid-October. See fact sheet HLA-6419.
Over-seeding of warm-season lawn with cool-season grasses for winter should be performed late this month. Warm-season lawns are healthiest if winter over-seeding is not performed! See fact sheet HLA-6419.
October is an excellent time to control broadleaf weeds in well-established warm or cool season lawns with a post-emergent broadleaf weed killer. Do not apply to seedling fescue. See fact sheet HLA-6421 and article below.
Mow and edge neatly before killing frost.

Landscape

Plant spring flowering bulbs now in well-drained soils with good sunlight. Planting depth is two times bulb diameter.
Plant pansies, kale and cabbage.
Dig and store tender bulbs and tubers in a cool, dry place.
Container-grown shade trees and pines are most successfully planted in the fall. Broadleaf evergreens or bare-root plants are best planted in the spring. See fact sheet HLA-6414.
Clean up marginal water garden plants after first frost kills the tops.
Place a net over the water garden to prevent leaves from falling in the water.
Remove diseased plant material from the landscape to reduce disease problems next year.

Get the Jump on Lawn Weeds Now

Controlling weeds can get complicated and is often frustrating. The problem is there are so many types of weeds and many options for different herbicides. Ideally, the best weed control in lawns is a thick healthy stand of turfgrass, which makes it unfavorable for weed seeds to sprout and grow. Most lawns don't fit the definition of ideal, and thin spots will naturally become weedy. Early October is the best time to overseed a fescue lawn to fill in bare spots and help crowd out weeds.

However, once weeds are established in lawns, the best option is to use post-emergent herbicides. Post-emergents should be applied in the fall, and at specific germination times for various weeds throughout the year. Click here for a bermuda lawn maintenance schedule or a fescue lawn maintenance schedule. There are many different types of post-emergents and even more brands of these types. For weeds such as dandelions and other broadleaf weeds (as opposed to grass-like weeds and sharp-edged sedges), a mixture of herbicides containing 2,4-D and others such as Dicamba and Mecoprop, is the recommended approach. Popular brands like Weed-B-Gon or Triamec contain these chemicals.

The best use of these herbicides requires a little understanding of how they work. Most of them have a growth hormone effect and work best while the plant is rapidly growing. They tend to be poorly effective after weeds mature and start to develop flowers and seeds. In our area, the best time of the year to use these chemicals is in October and November, when weeds are smaller and are growing rapidly.

A note of caution: this group of herbicides is volatile, especially when the temperature is above 80 degrees, and they may drift for long distances to damage other plants. Always read and follow the labeled instructions to prevent untoward effects.

When spring comes, preemergent chemicals are the easiest, cheapest and most environmentally friendly of the weed-control options. These are used mainly to prevent crabgrass, and again in August/September to prevent winter annual weeds such as henbit (above) and Poa annua (below). For more information see maintenance schedule links above or visit the Turf page on the Master Gardener website.

Beauty and the Bulb

You don't have to wait until spring to enjoy the beauty of bulbs. Winter flowers can be yours by "forcing" bulbs...that is, bringing them into their flowering stage inside your home. The queen of them all, the amaryllis (Hippeastrum) is easy to force.

Getting the Most from Amaryllis
Start with a big bulb. Amaryllis bulbs are sized by their circumference...large ones are about 32-34 cm. around. The bulb should be firm to the touch with a brown papery outer skin.

Give it a good home. Use a container with good drainage that is about 6-7 inches in diameter, so the bulb is cozy with about an inch of soil between the bulb and the container wall. Fill the bottom one-third of your pot with sterilized potting soil and carefully spread out the bulb's roots. Gently tamp in additional soil so that the bulb is about two-thirds covered with soil. Set the pot in a saucer in a sunny windowsill or direct light at room temperature.

Easy does it on the water. Water after potting and then only when the soil feels dry on top. After the first bud emerges, water regularly like any houseplant. Do not let the pot sit in water in the saucer. Do not get water down into the "nose" or top of the bulb.

Have patience. Sometimes amaryllis are slow starters. Allow eight to twelve weeks from potting to blooming. This may or may not coincide with the Christmas holidays. If it is later, you can enjoy spring flowers indoors while the snow is flying in January!

Don't discard your bulb after flowering. Remove stems and keep watering the bulb regularly. Leave the large strap-like leaves which are working hard to store up food and energy into the bulb for next year's bloom. Then when all danger of frost has passed, put the pot out on the patio in a shaded area. About the first of September, start gradually reducing water until the leaves wither and turn brown. Cut them off, remove the bulb from the soil and store in a cool place until the first of January. Then re-pot the bulb in new soil and start the cycle over again.

Amaryllis come in both single and double-flowering types and in many colors. A particularly fun thing to do when the first bud stalk arises is to "till" the soil in the pot around the bulb by roughing up the surface with a plastic fork. Then use left-over grass seed (fescue and wheat grass work well) from overseeding your lawn and sprinkle it over the soil. Mist the grass seed (not the bulb or leaves) daily for about ten days and your amaryllis will arise from a bed of grass - both pretty and unusual. If the stem is especially tall, it may need staking to support the flowers, especially the double-flowering varieties as their blooms are heavy. For more information, click here.

Keep Your Garden Green
With Cover Crops

Cover crops are plants grown in idle garden beds, most often in vegetable gardens. These crops may be types of grain grasses or certain legumes (plants in the bean family). After planting and growing these crops, they are usually tilled into the soil a few weeks before the next spring's vegetable planting.

There are several reasons to plant cover crops. They prevent erosion, may reduce the numbers of soil pests such as nematodes (microscopic worms in the soil) and prevent invasion of weeds into the garden patch. However, the main benefit is to add organic material and nutrients, especially nitrogen, to the soil.

Legumes have the unique ability to take nitrogen from the air and make nitrogen fertilizer in the soil, a process called "nitrogen fixing". The process is made possible with the assistance of some bacteria in the soil. This is in effect, free fertilizer.

Different types of crops may be planted and at different times of the year, depending on the need. Most people plant cold tolerant crop varieties in the fall and then plow under early the following spring.

Some of the commonly used plants for fall planting are hairy vetch, Austrian peas, garden peas, fava beans, several types of clover-all legumes. Winter wheat and winter rye are commonly used grain grasses. They all have different cultural requirements and are outlined in Fact sheet HLA-6436.

Fall Foliage Display in Drought

After a dreadfully hot and dry summer, fall has arrived! This means it is almost time for nature's annual stunning display as the leaves change color. We are fortunate enough in eastern Oklahoma to have enough hardwood forest stands and rolling hills to give our region an excellent show. But why do leaves change color in the first place? Three factors influence autumn leaf color: length of night, leaf pigments and weather.

Length of night

The timing of color change and leaf fall is mainly regulated by the calendar. None of the other environmental influences (temperature, rainfall, food supply, etc.) are as reliable as the steadily increasing length of night during fall. As days grow shorter, and nights grow longer and cooler, biochemical processes in the leaf begin the transformation.

Like all living organisms, plants must eat, but they do it in a much different way than we do. In order to make food energy, in the form of glucose (a type of sugar), plants need water, carbon dioxide and energy from the sun. To capture sunlight energy, plant leaves have a green pigment called chlorophyll. This pigment is what makes leaves appear green. Thus, leaves can be thought of as a plant food factory which turns sunlight into food.

It takes a lot more energy for a tree to accomplish this in the winter, when, due to lower temperatures, water transport from the ground into the tree's trunk and leaves becomes a problem. It is more energy efficient for the tree to shut down in the winter and go dormant. Thus, as winter approaches, the shorter and cooler days trigger trees to essentially hibernate for the winter. The leaves will not be needed for food production and are shed.

Leaf pigments

When a tree prepares for dormancy, the chlorophyll (green) pigment begins to break down. But, chlorophyll is not the only pigment that a plant has at its disposal. There are other colored pigments, whose appearance is typically masked by the green chlorophyll during the growing season. The two main ones involved in leaf color change are carotenoid and anthocyanin. Carotinids are pigments that create the bright yellows and oranges that we see in some fruits and vegetables (e.g. carrots, pears). Anthocyanins impart a red color to plants (e.g. cranberries, cherries). When a tree stops making new chlorophyll, and the existing chlorophyll breaks down, the bright carotenoid and anthocyanin pigments are able to show through. So the fantastic array of leaf colors that we see in fall are always there, but remain hidden until the changing season allows them to shine through.

Weather

The amount and brilliance of the colors that develop in any particular autumn season are related to weather conditions that occur before and during the time the chlorophyll in the leaves is dwindling. Temperature and moisture are the main influences.

When the autumn days are sunny and cool, but nighttime temperatures do not freeze (usually the 35-45 degree range is best), these conditions foster a color show with more red pigments. This happens because the cool nighttime temperatures prevent the glucose (a sugar that feeds the plant) from flowing down from the leaves through the branches and trunk to be stored. Anthocyanin pigments come to the rescue to help the tree recover these nutrients before the leaves fall off, and in the process, make the leaves appear redder in color. The yellow, gold and orange colors in leaves, created by carotenoid pigment, remain fairly constant and do not change in response to weather conditions, and thus change little from year to year.

The amount of rain in a growing season can affect the autumn leaf colors, and severe droughts as we are currently experiencing, can delay the arrival of the fall color show for weeks. Warm, wet autumns tend to lower the intensity of fall colors. A summer with ample rainfall can enhance color, but too much rain can promote disease which compromises the plant health and reduces color. And severe early frost...or extreme summer heat and drought...will kill the leaves, causing them to turn brown and drop.

The best autumn colors seem to result from a combination of seasonal patterns such as:

a spring that was warm and wet.
a summer that was not too hot or dry.
a fall that had a series of warm sunny days and chilly (but not freezing) nights.

Given the weather conditions this summer, the fall colors this year are unlikely to be up to par...especially since many native hardwood trees lost a considerable amount of foliage by August! But after such a dreadful summer, we will all still enjoy the color this fall brings as the days grow shorter and the weather gets cooler.

^Q&A

Question: With the additional rain we have been receiving, should I continue to give my large trees supplemental water?
Answer: Absolutely! Severe drought conditions continue in spite of recent rain and cooler temperatures. It is very important that any vegetation does not go into a freeze without adequate water because damage or death can occur. For larger trees and shrubs especially, continue to implement an irrigating plan that will allow water to slowly seep down into the first twelve to sixteen inches of the soil. Placing the garden hose at the base of shrubs for an hour a week at a slow steady stream that does not run off is good. Also, placing a hose end or small soaker sprinkler around the drip line of large trees and moving it periodically around the entire perimeter of the tree is another way of providing adequate water that reaches deep into the root zone. Continue to water perennial gardens and fall vegetable gardens, as needed. It is not necessary to irrigate Bermuda grass as much, because it will soon be going dormant after our first frosts. Tall fescue needs supplemental water now since it has entered a major growing time with the cooler nights. It is especially important to irrigate if you have recently over-seeded or applied a pre-emergent, which needs to be watered in within 72 hours to be effective. Finally, remember to monitor containers with fall color for water needs.

Question: We are interested in over-seeding our Bermuda lawn with rye. Do you recommend the annual or perennial seed?
Answer: While neither variety likes extreme temperature differences, perennial ryegrass can handle them better than the annual variety. Perennial ryegrass can extend growth into the warm season longer than the annual variety and is less susceptible to dying out in hot temperatures. It also tolerates lower temperatures than the annual variety, which can be winter-killed or damaged by extreme cold temperatures. Perennial rye prefers sun but will tolerate moderate shade. It is used for greenery in the winter when warm season turf, such as Bermuda or Zoysia, goes dormant and turns brown, and in early spring when warm season grasses are becoming fully established.

Question: Our hydrangea bushes look awful and have a lot of brown on them. Can we prune them back now before winter?
Answer: Brown limbs on hydrangea and most other shrubs can be pruned back to the base of the shrub now. If the entire bush is brown, only prune off about one third of the brown branches to the base and cut back all dead branches. There are different types of hydrangeas and each are pruned differently, but the pruning discussed here will be appropriate for all types and will not remove the majority of flower buds for next summer. Mopheads and Lacecaps (H. macrophylla) set buds at the end of the summer and healthy branches should not be pruned after the end of July. The same is true for the Oakleaf (H. quercifolia) variety. Endless Summer, one of the everbloomers, and Peegee (H. paniculata) can be pruned at anytime during the growing season before they set buds. Routine deadheading, or removing the flowers for vases or drying, can be done by cutting below the flower and above the first set of long leaves. For best drying results, allow blooms to dry naturally on the bush until September or October. Alternately, hang hydrangea blooms upside down in a cool place, like the garage, to air dry, or simply place in a vase with or without water, and they can be enjoyed into the winter months. Continue to monitor the water needs of all shrubs until we receive adequate rainfall.

Click here to send your question to the Tulsa Master Gardeners or see Answers to other Questions on the Web site .