Watering Lawns in Summer

Watering Lawns in Summer

Tom Ingram: Ask A Master Gardener

Tuesday, July 25, 2017

Q: It’s so hot outside. How do I know how much I should be watering my lawn? E.K.

A: If your lawn is Bermuda grass, it needs about 1 inch of water per week this time of year, while fescue needs about double that or 2 inches of water per week. This answer usually leads to another question: How long do I run my sprinkler? The answer to that question necessitates you doing what we call a “simple irrigation audit.”

For a simple irrigation audit, you are going to need nine collection cups, pen, paper and a calculator (at least most of us will need a calculator). Collection cups can typically be purchased from an irrigation supply store or you can use clean metal cans that might previously have contained tuna, cat food or perhaps tomato paste. Using the same type of can for all your collection cups will make your data more reliable.

If you choose cans, you can use a ruler and a fine-tip permanent marker to mark the outside of the cans in ¼-inch increments. Or you can just measure the collected water by sticking a ruler directly into each collection can.

To collect your measurements, locate your nine collection cans about 8 feet apart in something close to a 16-by-16-foot grid.

Next, let your sprinkler run over your collection grid for 20 minutes. After the collection period is over, measure the amount of water in each of your collection cups, add up the total amount collected (calculator time) and divide the total by nine because you were using nine collection cans. This will give you an average amount of water your collection grid area received in 20 minutes.

So let’s assume your average measured amount was ½ inch. This means for every 20 minutes your sprinkler system runs, your turf will be receiving half of an inch of water. If you have Bermuda grass, which needs 1 inch of water per week, you are going to need to water 40 minutes per week. You can split this up into two watering sessions per week of 20 minutes each.

If you have a fescue lawn, which needs 2 inches of water per week, the math says you would need 80 minutes per week, which can be split up into two watering sessions of 40 minutes each.

Garden tips

• Spider mites are a difficult pest to deal with, and they love hot, dry and dusty weather. One of their favorite targets are tomatoes, where they cause a stippling or sandblasted appearance on the leaves. They are small but may be seen if you tap a leaf over a sheet of white paper and look for moving dots. Treat with jets of water to wash them off and use either horticultural soap or oil according to directions. Neem oil is a good choice for a safe organic insecticide. If you use an insecticide of any sort, it is best to spray  early or late in the day, when honeybees are in their hive.
• Tomato growers are aware that fruit production usually stops in the heat of summer. Most tomato pollen becomes infertile and blossoms drop off when night temperatures are above 70 degrees and daytime is above 92 degrees for a few days. This also occurs in peppers, some varieties of beans and other vegetables. As it cools in late summer, fertility returns. If your tomatoes are too tall and gangly, you may cut them back a third. New growth and fertile blossoms will develop when it cools in fall.

Mulch Benefits all Gardens in Many Ways

Many Benefits of Mulch in Your Garden

Brian Jervis: Ask A Master Gardener

Tuesday, July 18, 2017

Q: I’ve heard a lot of suggestions about using mulch in my garden. Is it really worth the effort? A.M., Tulsa

A: Mulching garden soil is not only worth the effort, but also for a variety of reasons is probably the most beneficial cultural practice you can engage in to help your plants, vegetables, trees and shrubs achieve their full potential.

First of all, mulch can greatly decrease the amount of time you need to spend weeding your garden, which all of us would agree is a plus. But, in addition to less time weeding, less weeding means less chance of damaging plant roots through cultivation and weed removal.

Mulch also increases water absorption and reduces evaporation of moisture from the soil. With a good layer of mulch, we don’t need to water as often, and the water we use is put to more efficient use. This mulch layer also helps protect our plants from soil-borne diseases by reducing splashing from rain and watering.

Regulation of soil temperature during our hot Oklahoma summers is another valuable reason to add mulch to our gardens. Research has shown that nonmulched garden soil at a depth of 1 inch can vary in temperature by as much as 40 degrees during an average summer day, reaching temperatures of close to 120 degrees. Adding a layer of mulch can reduce that temperature increase by approximately 30 degrees, to a high of about 90 degrees. Reducing these extreme variations in daily soil temperature is beneficial to plant root systems.

Oklahoma soils tend to be low in organic matter, so we recommend organic mulches that can be incorporated into the soil at the close of each gardening season. Examples of organic mulching materials would include bark chips, compost, grass clippings, pine needles, sawdust and straw. Shredded leaves from the previous season’s yard cleanup also make great mulch, and you can’t beat the price.

Mulches such as sawdust or wood shavings have high carbon to nitrogen ratios that can cause them to leach nitrogen from the soil as they decompose. To compensate for this, nitrogen fertilizers should be increased by about one-fourth.

We generally recommend a mulch layer of between 2-4 inches, but the depth of mulch depends on the texture of the mulch you will be using. For example, if you were to use sawdust, peat moss, or cotton seed hulls, an appropriate mulch depth would be 1 inch because these are fairly dense mulches. However, if you were to use straw, hay, or other more coarse materials, you may need 4 to 8 inches for an appropriate mulch cover.

Mulching your garden may take a little effort, but your efforts will be rewarded with a more beautiful, productive and healthy garden.

Garden tips

·        When watering your lawn, ornamentals or vegetables, always do so in the morning, if possible. If watered in the evening, plants will go into the night still being moist. Most disease-causing organisms need moisture, and because they grow best at night, leaving leaves wet in the evening will promote many plant diseases.

·        Bulb onions are ready to harvest when the tops fall over. They should be removed and allowed to dry in a well-ventilated, shaded area. After the tops are completely dry, they may be stored in a cool, dry area.

·        Tall, spindly tomato plants with scarce fruit are usually due to either too much nitrogen fertilizer or too much shade.

Consider A New Experience with an Old Technique--Keyhole Gardening

Unique Keyhole Gardening Explained

Allan Robinson: Ask A Master Gardener

Tuesday, July 11, 2017

Q: Over the years, I have heard the term “keyhole gardening” from time to time but don’t know anything about it. Is it better than regular gardening? Tom A., Jenks

A: As Oklahoma summers continue to get hotter and drier, gardeners are looking for ways to prolong the growing season while responsibly maintaining natural resources. Keyhole gardens may just be the answer by providing several advantages to conventional gardening, such as simple construction, soil enrichment, moisture retention, labor savings and extended vegetable production.

Originally developed for use by the chronically ill in third-world countries, keyhole gardens have proven to be an effective way to grow vegetables year round in moderate climates, semi-arid environments and locations with poor soil because they are constructed in such a way as to warm, nourish and retain moisture in the soil.

This type of garden has helped many populations vulnerable to hunger and food insecurity improve resiliency to shocks such as drought. Because Oklahoma has experienced semi-arid environmental conditions in recent years, coupled with the fact that our horticultural population is living longer and wanting to garden longer, keyhole gardens may very well have a natural place in our area as well.

The name comes from its original design as a relatively small round garden with a low outer wall and a space in the middle to allow a person (especially those who are physically weak or have a disability) to work the garden with minimal effort. The raised bed is surrounded by stones or equivalent material, literally of any type. Inside, the walls are built-up of layers of rapidly decomposing organic material that serve the dual purpose of continually adding nutrients to the soil and retaining moisture, making it much more productive than a conventional garden, even in cold and dry winter months.

Once built, the garden requires little ongoing maintenance; it does most of the work. Also, few additional inputs, such as fertilizer, are required.

Construction of a keyhole garden is rather simple and fun and promotes the use of inexpensive and locally available resources. You can even get your kids involved.

The outer wall can be constructed of anything resilient (brick, stone, wood, hard plastic, old tires, etc.). Internal materials include rocks and a combination of organic materials, such as small tree branches, loose twigs, wood chips, cardboard, newspaper, grass clippings, green or brown leaves, manure, compost and soil. The typical garden is only 6-7 feet in diameter.

Garden tips

·        For all your plants, ornamental or vegetable, mulching and correct watering are keys to surviving the heat of the summer. Mulch conserves water and reduces ground temperature.

·        Fescue lawns need 2 inches of water per week to survive summer; Bermuda grass needs about half that amount. Watering less frequently and more deeply is better than daily shallow watering.

·        Brown patch disease of fescue lawns is appearing now, related to excessive rains, heat and high humidity. Wet grass leaves promote the disease. Therefore, if you water in the mornings, allowing the leaves to dry during the day, there will be less likelihood of infections. Fungicides are available, but OSU feels the fungicides available to homeowners are not nearly as effective as those available to professional licensed applicators. None of these chemicals will cure existing infections; they only prevent new disease at best.

Plant Fall Vegetables Now

Time for Fall Vegetable Garden is Now

Tom Ingram: Ask a Master Gardener

Tuesday, July 4, 2017

Q: I want to try a fall vegetable garden this year. What does well here in Oklahoma and when do I plant? N.J., Tulsa

A: For those of us who love the taste of fresh fruits and vegetables, gardening is a year-round activity. The fall gardening season, which begins around July 15, can actually produce some of the tastiest garden vegetables in northeast Oklahoma, as we typically have warm sunny days followed by cool nights. Under these conditions, plant metabolism slows down, which helps produce high-quality and tasty vegetables.

Vegetables grown in fall gardens can be divided into two categories: tender vegetables, which need to be harvested before the frost, and semi-hardy vegetables that can continue to grow and be harvested through several frosts.

Examples of tender vegetables would be beans (bush, pole, lima), cilantro, corn, cucumber, eggplant, pepper, pumpkin, squash and tomatoes. Semi-hardy vegetables would include beets, broccoli, cabbage, carrots, potatoes, kale, lettuce, peas, radish, spinach and swiss chard.

The brutally hot temperatures we often have in July and August demand we pay special attention to any vegetables we intend to direct seed in our fall gardens. As a rule, seeds should be planted no deeper than three times the diameter of the seed. With small seeds, such as carrots, this would mean planting no more than 1/4-inch deep. At these depths, hot soil temperatures will discourage germination. Supplemental watering or perhaps shade cloths will be needed to reduce soil temperatures so germination can occur.

The good news is many of our fall vegetables can be started from seed indoors, which helps us avoid having to deal with the soil temperature issue. Plants that perform well as transplants include cucumbers, squash, peppers, pumpkins and tomatoes. Before moving transplants into the garden, they should be conditioned or toughened by reducing watering and exposing them to full sunlight in limited amounts.

If space allows, potatoes are also a wonderful fall garden crop. Seed potatoes need to go in the ground the first two weeks of August to complete growing before the first freeze.

The first of September is the time to plant garlic, leeks and onions, as they will continue to grow through the winter for a harvest in late spring the following year.

We have several fact sheets from OSU, which not only provide you with the planting dates for fall crops but also contain recommended varieties of vegetables that can be grown successfully in Oklahoma. Just give us a call, drop by our office, or check our website, tulsamastergardeners.org. We are here to help.

You can get answers to all your gardening questions by calling the Tulsa Master Gardeners Help Line at 918-746-3701, dropping by our Diagnostic Center at 4116 E. 15th Street, or by emailing us at mg@tulsamastergardeners.org.

Garden tips

• Vigorous, unwanted limbs should be removed or shortened on new trees. Watch for forks in the main trunk and remove the least desirable trunk as soon as it is noticed.
• Most varieties of mums are more productive if “pinched back” now. Either pinch off with fingers or cut to remove an inch or so of limb tips above a leaf. This results in the growth of new limbs and a fuller plant. Do not pinch after mid-July or it will interfere with fall blooming.
• Watch for tiny, sap-sucking insects called aphids on roses, perennial flowers, shrubs and vegetables (especially tomatoes). They produce a sticky substance called “honeydew.” Many can be dislodged with a hard spray from your garden hose, or two applications of insecticidal soap will usually greatly reduce any aphid damage to your plants.
• Crape myrtles are one of the few shrubs that should be planted in the middle of summer. Growth of new roots of these plants occurs best with summer soil temperatures.