Saturday, March 25, 2017 0 comments By: Jack Downer

Planting sweet and Irish Potatoes

Don't confuse sweet potatoes with Irish potatoes

Bill Sevier: Ask a Master Gardener

Saturday, March 25, 2017

Q: I would like to grow some sweet potatoes, or yams. Are they grown the same way as Irish potatoes? John, Tulsa
A: No, they are not grown the same way as Irish potatoes, and sweet potatoes are not actually yams.
There is so much confusion about these potatoes and yams that it is worthwhile to try to sort it out.
The only thing Irish potatoes and sweet potatoes have in common is that they are both grown underground and are great sources of food worldwide. Both are nutritious.
Sweet potatoes, which are grown widely, are tasty and have several vitamins, beta-carotene and abundant antioxidants. The Irish potato, also nutritious, was the chief source of food in Ireland until the mid-1800s when a potato disease (blight) devastated the crops. Almost 1 million Irish people starved and another million emigrated to Canada and the U.S.

Sweet potatoes are a tropical warm-season plant and botanically are true roots. They are planted in early June after the soil warms as “slips” — which are small plants grown from the surface of a mature sweet potato. These parent potatoes are either partially immersed in water or shallowly planted in moist sandy beds where the small plants, or slips, develop on the potato. They are removed and planted individually. The process is a bit more involved but can be done by anyone. Full instructions are outlined in OSU Fact Sheet HLA-6022, available at
Irish potatoes, on the other hand, are cool-season crops, which should be planted mid-February through mid-March. These potatoes are not roots but underground stem-tubers. Like above-ground stems, they have buds from which a new plant may grow. To grow this type of potato, a whole potato is cut into generous sized sections, called seed pieces, which contain two or more of these buds or “eyes.” After planting, new plants grow from the eyes. It is best to use only potatoes sold for seed pieces; those in the market may have been treated to prevent sprouting.
Both types of potatoes require a long growing season, the sweet potato 3-4 months and the Irish potato about 2-3 months.
A misconception about sweet potatoes concerns “yams.” Most of us have eaten, or at least heard of, candied yams, a traditional Thanksgiving food for some. However, candied yams are not actually yams. Yams are tropical root crops grown in South America and Africa. They are not at all related botanically to the sweet potato. The term yam originated to distinguish certain types of orange sweet potato and is a corruption of an African word for the actual yam.
One question that Master Gardeners are often asked is whether ornamental sweet potatoes such as the cultivar “Margarita” are edible. The answer is that they are edible, but it is said that they do not have a pleasant taste. However, interestingly, is that not only do they have an attractive vine, for which they are grown, but also most have unique purple potato skins.

Garden tips
All cool-season vegetables, strawberries, asparagus and other small fruit may be planted this month.
Established broadleaf weeds can easily be controlled in lawns at this time with postemergent broadleaf herbicides. These herbicides are most effective in spring and fall when weeds are rapidly growing.
Cut down dead pine trees as soon as possible. Most of these trees died of pine wilt disease due to a nematode infection. The infection is spread by the pine sawyer beetle, and dead pines are a source of infection carried by these beetles.

Saturday, March 18, 2017 0 comments By: Jack Downer

Versatility of Gardening in Containers

Grab a container and start gardening

BRIAN JERVIS Master Gardener

Saturday, March 18, 2017

Q: I would like to grow some vegetables in pots on my patio. What can I grow and how do I get started? Barb, Tulsa
A: There are many advantages to growing both ornamentals and vegetables in containers. For people in apartments with limited space or those not wishing to create and maintain a traditional garden, containers may be the answer.
Many types of vegetables and most herbs lend themselves well to this type of gardening. Tomatoes, peppers, zucchini, squash and a variety of salad greens can be grown separately or mixed with any of your favorite herbs. The main thing is to pick plants that have the same growing requirements.
Containers can be as attractive and elegant as colorful glazed pots; as whimsical as an old wheelbarrow or leather boots or as traditional as clay, plastic or metal. They not only can add to the d├ęcor of an outdoor living space such as a patio, but have the added advantage of being portable, allowing one to be flexible about this design.
Whichever type of container you select, it must drain well. You should also be aware that some pots, such as clay, are porous and will need to be watered more often and are more likely to freeze and crack in winter. Be aware also that light-colored pots are cooler in summer than those of darker shades.
The potting soil is very important. It is best to select a good brand of soil; they are not all created equal. Most contain variable mixes of compost, peat moss, sand, vermiculite and other materials. Slow-release fertilizer with both the major and minor nutrients are added to many potting soils. Do not use soil from the garden as it may contain disease and drain poorly.
After planting your container, water and fertilizers are the next most important considerations. Since potting soils must be loose and porous, they do not retain water and nutrients as do soils in your garden.
Containers should be watered when the top of the soil is dry. Enough water should be added to allow drainage from the bottom of the pot. Drainage water should be discarded, it contains undesirable fertilizer residues that may be harmful to your plants if not removed. In summer, many containers will need irrigation every day or every other day. Drip irrigation, which may be easily installed, is perfect for conveniently irrigating all of your containers.
All plants have their individual needs for fertilizer. But a generic suggestion is to use a general liquid fertilizer once every two to three weeks. Do not over-do it; too much nitrogen fertilizer may be harmful. This is especially true with tomatoes, which would do best with the above schedule using the fertilizer at half strength of what is recommended on the label.
Container gardening has unlimited possibilities fitting into most gardener’s plans, not only for attractive flowers, but for many types of vegetables.
For more information, contact the Master Gardeners at 918-746-3701 from 9 a.m. to 4 p.m.

Garden tips
·       Cool-season lawns such as bluegrass, fescue and ryegrass may be fertilized now with the first application of the season. Usually, four applications of fertilizer are required per year, in March, May, October and November. Never fertilize these lawn grasses in summer.
·       Start your routine fruit tree spray schedule prior to bud break. Contact the Master Gardener Office for a document outlining recommendations for all fruit tree types — they are not the same.
·       Don’t prune out parts of plants which may look like they have “winter-kill”. They may still be alive and may rebound with spring-time weather.

Saturday, March 11, 2017 0 comments By: Jack Downer

Hows and Whens to Fertilize Lawns

Tips for how and when to fertilize Oklahoma lawns

Bill Sevier: Master Gardener | Posted:

March 11, 2017

Q: When and how often should I fertilize my lawn? A.K., Tulsa

A:One should fertilize lawns during their growing seasons, which are different from one grass species to another. How often to fertilize depends on the quality of lawn desired and how often you are willing to mow it. Information about lawn care, including fertilization, is available in condensed form in the “Bermuda Maintenance and Fescue Maintenance documents” on the Master Gardener web site.

It sometimes is frustrating to try to understand what to do, when to do it and with what, when it comes to lawn care. Each type of grass should receive fertilizer only during its active growing season — warm season grasses grow in summer, cool season ones in spring and fall.
We live in a transition zone between where warm-season and cool-season turf grasses grow best and often our lawns have both types; usually a mix of Bermuda and fescue. The recommendations for each type are quite different, so a plan is important.
Warm-season grasses — Bermuda, zoysia and buffalo grass — prefer hot weather and actively grow in summer, April into September. They become dormant (turn brown) in winter; any brown grass in winter is one of these types of grasses.
Tall fescue and Kentucky bluegrass are cool-season grasses that grow best in spring and fall. They stop growing but remain green all winter. These grasses do not tolerate summer’s heat and must be irrigated.
Fertilize warm-season lawns from green-up in April to the first of September. Apply 2 to 5 pounds of actual nitrogen fertilizer per 1,000 square feet, in divided doses, during this time. Zoysia lawns need about half as much and buffalo grass about a third the amount of the Bermuda recommendation. If warm-season grasses are fertilized after early September, dormancy may be delayed causing them to be susceptible to winter kill and diseases.
Tall fescue and Kentucky bluegrass are often found growing together and benefit from each other’s strengths. Cool-season grasses should be fertilized during their active growing periods. Apply 1 pound of nitrogen fertilizer per 1,000 square feet in March or May and again in September and November. The fall applications are the most important. Never fertilize fescue in summer; it will make the grass susceptible to heat damage and disease.
The type of fertilizer is important. It is always best to base the type of fertilizer on the results of a soil test. In the absence of a soil test, and if you have fertilized the lawn in previous seasons, you need a fertilizer containing only nitrogen (nitrogen is the first number on a fertilizer bag). Soil test results in our area show adequate, or more often, excessive amounts of phosphorus and potassium and adding more may be harmful.
Fertilizers also come as immediately released and slow released versions. With the slow release types one can apply double the amount (2 pounds per 1,000 square feet) half as often than what is recommended.
Check out the Master Gardener website,, for more information.
For more information, contact the Master Gardeners at 918-746-3701 from 9 a.m. to 4 p.m.

Garden tips
Remove flowers from spring blooming bulbs after blooming is completed. This will allow the plant to direct its energy into its bulb for next year's blooms, rather than producing seeds.

Allow foliage of these bulb plants to die and turn brown naturally before removal. As long as the leaves are green, they are storing energy for the following year.

These bulb's root systems become inactive after blooming and cannot absorb fertilizer. It is best to fertilize them when planting or in the fall or in the spring when their leaves first emerge

Saturday, March 4, 2017 0 comments By: Jack Downer

Oklahoma Proven Plant Selections for 2017

These plants are proven winners in Oklahoma gardens

Brian Jervis, Ask a Master Gardener

Saturday, March 4, 2017

Q: I need some information about plants that would be useful for our new home. E.P., Tulsa
A: There is no better place to start your search than to review the selections on the Oklahoma Proven website. This program, as the name suggests, has unique plants that have demonstrated the ability to grow well in our area.
The organization was formed by OSU horticulture faculty and involves nurserymen around the state. Every year, the experts select a tree, shrub, perennial, annual and a “collector’s choice” plant.
The selections for 2017 are:

Jujube or Chinese Date (Jujuba ziziphus), Collector’s Choice: This tree grows to 15-30 feet in full sun to part shade. It is tolerant of a wide range of well-drained soils and is cold hardy to USDA zone 4-9, which covers all of Oklahoma. It has nice summer and fall foliage. It has olive-sized tasty edible fruit that are reddish brown when ripe. Two of the commonly grown cultivars are “Li” and “Lang.”

Fringetree (Chionanthus virginicus), tree: This is another small to medium tree growing to 12-20 feet. It needs full sun to light shade and tolerates most soils. This tree is dioecious, which means each tree is either male or female. Both bloom, male flowers showier than female, but only females have blue-black berries. This tree is a showstopper when in full bloom. The blossoms are clusters of small ribbon-like flowers that may turn the tree totally white in spring.

Dwarf Palmetto (Sabal minor), shrub: This is one of the few palm varieties native to the United States, including Oklahoma. This plant thrives in wet boggy, partially shaded areas but does have some drought tolerance once established. It has fan-shaped evergreen leaves and grows to 4-6 feet. Once mature, it will produce ivory colored flowers and small edible black berries. This is the most cold tolerant of native palms and is rated for USDA zones 7-10.

Milkweed (Asclepias species), perennial: Milkweed has been elevated in stature due to the recent decline of monarch butterflies, which are dependent on milkweed. Oklahoma has about 20 species, some only found in one or two counties. Butterfly milkweed (Asclepias tuberosa) is a native and is popular. Several others that do well in flower gardens or naturalized areas. They perform best in full sun.

Firecracker Flower (Crossandra infundibuliformis), annual: This annual flower is native to India and Sri Lanka, where it is an evergreen and grows up to 3 feet. As an annual in beds or containers, it grows 18-24 inches. “Orange Marmalade” is a recommended cultivar having frilly orange flowers all summer. Important for our area is that it is tolerant of high heat and humidity. It performs best in full sun to partial shade. The name comes from the seed pods that may open suddenly, “exploding,” when exposed to high humidity or rain.
It is worth your time to check out the Oklahoma Proven website,, and review the selection of plants for the past 17 years.

Garden tips
§  If you had previous damage to the tips of pine tree limbs, especially non-native pines, it may be diplodia tip blight (a fungus) or Nantucket pine tip moth damage. Both are controlled with pesticides starting this month. Call the Master Gardener office at 918-746-3701 for recommendations.
§  Pre-emergent herbicide to control crabgrass and other summer weeds should be applied by the middle of March.
§  Divide, share with friends and replant overcrowded summer- and fall-blooming perennials.

Saturday, February 25, 2017 0 comments By: Jack Downer

Oklahoma State Horticultural Fact Sheets

Get the facts on gardening education, problem solving

BILL SEVIER Master Gardener

Saturday, February 25, 2017

Q: What are the fact sheets you mention in this column and how do I find them? T.S.
A: Each state has a land grant college, and each of those colleges has an extension department in each county whose goal is to educate homeowners and farmers about horticultural techniques and problem solving. Our extension office, a part of OSU, is located at 41116 E. 15th St., gate No. 6 at the Tulsa State Fairgrounds.
OSU has many hundreds of “fact sheets,” which are used for educational activities for commercial agriculture and homeowners. Each fact sheet is concerned with a specific horticultural topic.
The Master Gardener Office, which is located in the OSU Extension Building, has many of these fact sheets preprinted and available for free. You may come by the office from 9 a.m. to 4 p.m. Monday-Friday to not only get these fact sheets but also to get help with gardening problems. You may also phone (918-746-3701) or bring in a plant sample or photo relating to your problem.
The OSU Master Gardener website,, has most of the commonly requested fact sheets, and those not listed may be found by using an internet search of Oklahoma State and the name, fact sheet number or topic of interest.
Below are some of the more commonly requested and most helpful fact sheets with a brief description of content:
F-6004 Oklahoma Garden Planning Guide: This lists most all of the vegetables grown in Oklahoma and describes how and when to plant, along with days to maturity. This is the most requested fact sheet in spring.
HLA-6032 Vegetable Varieties for the Home Garden In Oklahoma: Individual varieties of common vegetables that do well in our area are listed.
F-6436: Healthy Garden Soils: This is an approach to preparing soils using Organic Gardening techniques.
F-6007: Improving Garden Soil Fertility: General information about planning a garden and correcting for any nutritional deficiencies.
F-6033: Raised Bed Gardening: The best approach for gardening if you have unfavorable soils.
F-6020: Growing Vegetable Transplants: How and when to start, care for and transplant sprouts.
K-State: Top or Side Dressing Nitrogen Fertilizer for Vegetables and Ornamentals: While not an OSU document, this is a useful list on what, when and how to fertilize different vegetables.
Bermuda Maintenance Schedule and Fescue Maintenance Schedule: These two documents are available from the Master Gardener website in the turfgrass section. They have complete recommendations for lawn care — mowing, weeding, irrigation, seeding and more.
HLA-6419: Establishing a Lawn in Oklahoma: Complete details on how to seed or sod a lawn.
HLA-6608: Managing Turfgrass in the Shade in Oklahoma: This addresses the problem of growing grass in shade. It has several options and planting alternatives for an area too shady for a lawn.
These fact sheets will give you most all of the information you may need for growing vegetables, ornamentals and turfgrass in Oklahoma. Another plus is that they are totally free and are your tax dollars at work.

Garden tips
·       Finish pruning shade trees, summer flowering shrubs and hedges by the end of the month. Spring-blooming shrubs such as forsythia may be pruned immediately after flowering. Do not top trees or prune just for the sake of pruning. Get OSU fact sheet “Pruning Ornamental Trees Shrubs and Vines” for more information.
·       By Feb. 15, many cool-season vegetables like cabbage, carrots, lettuce, peas and potatoes can be planted.
·       Spray peaches and nectarines with a fungicide for prevention of peach leaf curl before bud swell.
·       Collect and store graft wood for grafting pecans later this spring.

Saturday, February 18, 2017 0 comments By: Jack Downer

Pruning Crapemyrtles

Don't commit 'crapemurder'

Brian Jervis: Ask a Master Gardener

Saturday, February 18, 2017

Q: When and how should I prune my crapemyrtles? E. W., Tulsa
A: Crapemyrtles, along with all trees and shrubs, should only be pruned for a reason. The best time to prune these and other trees and shrubs is late winter or early spring, before leafing out. An exception to this time are the spring-blooming shrubs, such as azaleas and forsythias, which should be pruned after blooming, if needed. Delaying pruning of spring-blooming plants is only to preserve the flower buds formed the previous year.
There is a common belief by many that crapemyrtles should be pruned back to an ugly set of horizontal nubs in the spring time. Nothing could be further from the truth about good crapemyrtle care. Crapemyrtles should be allowed to let nature have its way and to grow to their full height.
Some people think that blooming will be increased by drastic pruning (many horticulturists call this “crapemurder”), but Dr. Carl Whitcomb, a retired OSU professor and developer of crapemyrtle cultivars, cites evidence that blooming is less, not more, with drastic pruning. Light pruning of endmost 12-18 inches, back to a lower limb, can increase numbers of blossoms. However, these plants were engineered by nature to bloom profusely without this type of pruning. In summer, one can promote a second wave of blossoming by pruning off old blossoms after they fade.
Reasons to prune crapemyrtles are to confine it to the space available or to improve the shrub’s shape and structure. Removal of dead or diseased limbs and elimination of internal crossing branches should be done anytime.
For those plants that are too big for their space, rather than trimming them back each year, consider removal and planting one of the smaller crapemyrtle cultivars. There are many sizes available, ranging from 18 inches to 25 or more feet when mature.
One question that sometimes arises relates to the seed pods left over in fall after blooming is completed. The plant will remove them naturally as they have been doing for thousands of years, and they need no pruning.
Another pruning suggestion one should consider with crapemyrtles concerns those plants with a multitude of trunks. These are best reduced to three to five trunks, which will not only have more curb appeal, but also will allow more energy to be directed toward further growth and blossom formation. To further improve appearance of these shrubs, consider removing the limbs from the lower third or half of the trunks.
Crapemyrtles are notorious for sending up shoots or sprouts from the base of the plants, especially in the spring. These should be removed by pulling off if able, or clipping close to the ground, if needed.
We have an advantage over our northern neighbors in being able to grow these magnificent plants, which are the mainstay of color in Tulsa during the summer. They deserve the best care we can give them, they should not be subjected to “crapemurder.”

Garden tips
§  Now is a good time to cut back your perennial ornamental grasses, such as pampus grass. Cut back to remove the dead grass, but avoid damaging new buds and early green growth at the base.
§  Begin planting blackberries, raspberries, strawberries, grapes, asparagus and other perennial garden crops this month. Contact Tulsa Master Gardeners at 918-746-3701 for specifics about these plants.

Saturday, February 11, 2017 0 comments By: Jack Downer

Dormant Horticultural Oil for Crapemyrtle Scale

Treating the rapidly spreading crapemyrtle bark scale

Bill Sevier Master Gardener

Saturday, February 11, 2017

Q: I was told that a dormant oil should be used to treat scale insects, which have covered my crape myrtles. When should I do this and what should I use? Mike, Tulsa.
A: Dormant oil treatment for crape myrtle bark scale may be environmentally the safest, effective treatment available. It should be used in dormant concentrations and should be used now, before the trees come out of dormancy.
The benefit of oil for plant pest control has been known going back to the time of the Romans. To be effective, these oils must be applied directly to the insect or the insects’ eggs. The oil kills insects by blocking the insects ‘breathing passages.
In the past, oils came in two varieties, a thick heavy oil which was used as a “dormant oil” (used in late winter and early spring before bud swell and bud break). These oils, if used during the growing season, were toxic to plants. The other, thinner oil, called a “summer oil” was used safely in the growing season.
Things have changed now with what is recommended and available to treat many different pests. Most of the newer horticultural oils are petroleum-based mineral oil. They are labeled as superior, supreme or ultra-fine oils. These oils have been refined to remove undesirable compounds toxic to plants. Therefore, they may be used in winter as dormant oil and in summer as summer oils by simply changing their concentrations. The winter dormant preparations are much more concentrated and more viscous than the summer preparations but are the same oil. Most of these oils contain an “emulsifier” to help the oil mix with water.
They should only be used during outdoor temperatures of 40-90 degrees. If used in colder weather, the preparation may not mix and cover the insects well. If oils are used during high temperatures or high humidity or on drought-stressed plants, the chance of plant damage is increased.
Examples of some of the commercial brands of petroleum oils available at garden centers are Sunspray Ultra-fine, Volck Oil Spray and Bonide “All Season” oils; there are many others and are available locally.
Other than the petroleum-based preparations, there are those of vegetable origin. They are made from neem seeds, cottonseed, canola, cloves and rosemary. These are used mainly as summer oils. Neem oil is unique in that it also has effective anti-fungal activity. It is a good choice for a summer oil. However, for a dormant usage, the petroleum-based mineral oils are probably best.
These products are effective for many different types of insects. During the growing season they are used to treat scales, aphids, mites, whiteflies and others. They are used extensively by commercial fruit and nut tree farmers.
For homeowners, crape myrtle bark scale and euonymus scale are significant problems to deal with. A dormant oil applied now is more effective and safer than synthetic insecticides. As with any pesticide, one must read and follow the instructions on the label. There are some plants which are intolerant.

Garden tips
·       Most bare-rooted trees and shrubs should be planted in February or March. The roots of these plants are easily damaged and should never be left exposed to air. Plant them at the same depth as in the nursery and make sure good root and soil contact is made by gentle tamping and irrigation after planting.
·       Finish pruning shade trees, summer flowering shrubs and hedges. Spring blooming shrubs such as forsythia and azaleas may be pruned immediately after flowering. Do not top trees or prune just for the sake of pruning.
·       With our warm temperatures, applying pre-emergent herbicides earlier rather than later may be desirable to prevent crabgrass and other summer weeds.