Horticulture Tips are provided by the Department of Horticulture and Landscape Architecture and the Oklahoma Cooperative Extension Service, Division of Agricultural Sciences and Natural Resources, Oklahoma State University.



  • Base any plant fertilization on a soil test. For directions, contact your county Extension Educator.
  • Provide feed and unfrozen water for your feathered friends.
  • Clean up birdhouses before spring tenants arrive during the middle of this month.
  • Avoid salting sidewalks for damage can occur to plant material. Use alternative commercial products, sand or kitty litter for traction.

Trees & Shrubs

  • Fertilize trees, including fruit and nut trees and shrubs, annually. (HLA-6412)
  • Most bare-rooted trees and shrubs should be planted in February or March. (HLA-6414)
  • Finish pruning shade trees, summer flowering shrubs and hedges. Spring blooming shrubs such as forsythia may be pruned immediately after flowering. Do not top trees or prune just for the sake of pruning. (HLA-6409)
  • Look for arborvitae aphids on many evergreen shrubs during the warmer days of early spring.
  • Gall-producing insects on oaks, pecans, hackberries, etc. need to be sprayed prior to bud break of foliage.
  • Dormant oil can still be applied to control mites, galls, overwintering aphids, etc. (EPP-7306)


  • Force spring flowering branches like forsythia, quince, peach, apple, and weigela for early bloom indoors.
  • Forced spring bulbs should begin to bloom indoors. Many need 10-12 weeks of cold, dark conditions prior to blooming.
  • Feed tulips in early February.
  • Wait to prune roses in March.

Fruit & Nuts

  • Spray peaches and nectarines with a fungicide for prevention of peach leaf curl before bud swell. (EPP-7319)
  • Mid-February is a good time to begin pruning and fertilizing trees and small fruits.
  • Collect and store graftwood for grafting pecans later this spring.
  • Begin planting blackberries, raspberries, strawberries, grapes, asparagus and other perennial garden crops later this month.
  • Choose fruit varieties that have a proven track record for Oklahoma’s conditions. Fact Sheet HLA-6222 has a recommended list.


  •  A product containing glyphosate plus a broadleaf herbicide can be used on dormant bermuda in January or February when temperatures are above 50°F for winter weed control.


  • Cool-season vegetable transplants can still be started for late spring garden planting.
  • By February 15 many cool-season vegetables like cabbage, carrots, lettuce, peas and potatoes can be planted. (HLA-6004)

Cutting Back Ornamental Grasses by David Hillock

Ornamental grasses should be cut back in late winter before new growth emerges. It can also be done in fall, but the seed heads provide nice winter interest, and some birds will also feed on the seed. To make the job easier, you can tie up the stalks with string. Depending on the size and density of the grass you may use any of the following tools: house scissors, shears or hand pruners. For smaller grasses, trim to about 2 to 3 inches from the ground; for larger grasses cut 6 to 8 inches from the ground. One exception is Mexican feather grass (Nassella tenuissima), it does not like to be cut back hard; instead give it a very light trim, cutting only about a third to not more than half of the foliage back.

Thinning Peaches by David Hillock 

Many fruit trees require thinning of the fruit to lighten the fruit load which results in larger, sweeter fruits.

Thinning also helps avoid stress to the trees from an over-abundant crop and reduce potential damage that can occur to the tree from a heavy fruit load. Thinning is not always required. Some years, late spring freezes thin out some or all of the fruits. Other years, particularly in years following a freeze, the tree produces too much fruit, often to compensate for poor fruit production the previous growing season.

Peaches are thinned when fruits reach the size of a dime or nickel in diameter, before the pit hardens. A good rule is to use your hand for spacing fruit along the branch. Leave one to two fruits at intervals spaced a hand width apart. On short side shoots it is best to leave only one or two fruits. Other stone fruits such as plums, apricots, and nectarines are thinned in a similar manner to peaches.

Pome fruits, which include apples and pears, produce fruits in clusters. To thin fruits from these trees we want to both reduce the number of clusters and reduce the number of fruits per cluster. Thin the fruit clusters by pinching them off, leaving one cluster every 6 to 8 inches. Reduce the number of fruits in each cluster to 2 or 3 fruits. 

Planting Strawberries by David Hillock

Strawberries are a relatively simple fruit to grow in the home garden. They can be grown successfully throughout the state. Of course, the plants will require weekly irrigation when the rains subside, so be sure the location you choose is accessible to water. Also look for a spot that receives full sun, as shade can reduce fruit set. Strawberries have several diseases in common with other berry plants as well as crops like tomatoes, potatoes and peppers. Be sure the site you select has not been used for any of these crops for several years.

Strawberries are grouped into three general categories. The first are June-bearing strawberries, which produce a single crop from May through mid-June in Oklahoma. They are the best adapted for Oklahoma and are available in early-, mid-, and late-season cultivars. Everbearing strawberries produce berries from May to mid-June, and again in the fall. Overall production may not be as high as that of June-bearing varieties. The final type of strawberry is called day neutral. These produce fruits all season, but they are sensitive to heat and are not recommended for Oklahoma.

When selecting cultivars and purchasing plants, be sure to buy certified, disease-free plants from a reputable supplier. Planting more than one cultivar with different maturation times is a great way to extend the harvest season.

Strawberries can be planted in a raised bed, in mounded rows or simply in beds in the ground. However, when you raise the soil, you improve drainage. Mix a thick, 3 or 4 inch layer of compost into the soil to add organic matter. As you prepare the bed, limit the width to around 3 or 4 feet so that you can easily reach in to harvest. If you are planting multiple rows of strawberries, leave 4 feet between the rows.

Strawberries are planted in February or March, but you want to watch the weather. Avoid planting just before a cold spell. There are a number of planting systems that can be used for growing strawberries, but in the home garden, the most common method is the matted row system. This system uses wide plant spacing and relies on the strawberry plants ability to send out runners and establish new plants as a means of filling the bed. As strawberries grow, they send out runners along the soil surface. New plants develop along these runners, take root and produce new plants. This is how the plants will spread throughout our beds.

Plants can be rooted runners that have been removed from a mother plant. Strawberry plants are typically sold bare-root, and should be protected from drying out as they are planted. Keep them in a bucket of water or wrap them in a damp towel. Before setting out the plants, remove all but the three strongest leaves. Space the plants 1 ½ to 2 feet apart in the row. Allow the runners to grow in all directions and fill the bed. It seems like a lot of space to fill, but a single plant can produce 30 to 50 runners in a season.

The depth at which we place the strawberry is critical. If it is set too deep, the crown will rot, too shallow and the roots will dry out. Set the plants so that the crown, which is the point where the leaves arise, is level with the ground surface. Also, spread the roots out as you plant. If the roots are long, you may choose to trim them with a scissors or sharp knife.

One way to set strawberries at the correct depth is to dig wide holes and mound soil piles in the center of the hole. Adjust the height of the mound so that the plant crown is at the surface level. Spread the roots over the mound and refill the hole with soil. Hold the plant at the crown as you work, making sure it remains level with the soil line. Double check the planting depth when you finish. Once you have finished setting out all the plants, water each one in well with at least a pint of water a piece.

Strawberries are shallow-rooted and need one inch of water each week. Mulching around plants will help retain soil moisture and also combat weeds. June-bearing berries will not produce a crop until the summer following planting. If flowers appear, remove them by hand. You want all of the plant’s energy to go into vegetative growth and not fruiting. The everbearing plants should produce a fair crop the first fall.

OSU Fact Sheet HLA-6214 Growing Strawberries in the Home Garden provides more information on strawberry production.

Disease and Insect Pests in the Orchard by David Hillock

Fire blight is a common disease of pome fruits, such as apples and pears. Fire blight is a bacterial disease which can severely damage apples and pears. Blossoms, fruits, fruit spurs, twigs, and branches are affected and sometimes the entire tree may be killed. The first sign of fire blight is a watery, light tan bacterial ooze that exudes from branch, twig or trunk cankers (small to large areas of bark killed by the pathogen during previous seasons). The ooze turns dark after exposure to air, leaving dark streaks on branches or trunks. However, cankers may be inconspicuous and infections may not be noticed until later in spring when flowers, shoots, and/or young fruit are affected. Blighted twigs and watersprouts wilt at their tips giving the appearance of a shepherd's crook. They then shrivel and turn black in color. These blackened areas appear burned and give fire blight its name.

Prevention is the key to managing fire blight, especially in large trees. A copper-based fungicide can be applied during the dormant season, though coverage on a large tree can be very difficult. Smaller trees are more easily managed. Affected tissue can be pruned, cutting back affected tissues to a healthy side branch. Always disinfect equipment after pruning a diseased tree to avoid spreading the disease to other plants in the landscape. In addition to pome fruits, fire blight can affect Quince (Pyracantha species), Hawthorn (Crataegus species), Spiraea Cotoneaster, Photinia species, Juneberry or Serviceberry (Amelanchier species), Loquat, Mountain Ash (Sorbus species), and other related plants.

Vigorous young growth is highly susceptible to infection. Another management strategy is to limit nitrogen applications to pear trees. There are also many resistant cultivars available when selecting fruit trees for the landscape.

Another pest common this time of year is the plum curculio, a small beetle belonging to the weevil family. Plum curculio (Conotrachelus nenuphar) is one of the most important insects attacking tree fruits. Despite its name, a wide range of plants serve as host to this pest including apple, nectarine, plum, cherry, peach, apricot, pear and quince. The plum curculio can also survive on wild plum, hawthorn and native crabapple. Plum curculio is capable of causing great damage and is considered a difficult pest to control. The female makes distinctive, crescent-shaped wounds on the skin when laying eggs. The larvae that hatch from these eggs then cause internal injury by burrowing in the fruit to feed. Most of the larvae-infested fruits drop to the ground during June. Plum curculio can be managed using a carbaryl or malathion based insecticide. Organic growers can use pyrethrum products to manage this pest.

Starting Seeds Indoors by David Hillock

Many gardeners choose to start their own seeds at home, rather than purchasing transplants. The advantages include savings in cost, and also the availability of a much wider selection of cultivars. You can also time seed sowing according to your expected planting date so that transplants are ready when you need them. Of course, planting seeds and tending seedlings is also a great way to spend a winter day.

You can start seeds in flats purchased from a plant supply company or garden center, you can use expandable peat pots or you can use a variety of household items. When selecting a container to start your seeds, consider drainage. You do not want water sitting in the bottom of the container. You also want to make sure the container holds enough media that it will not dry out too quickly and will have plenty of room for roots to develop.

The potting media you use is also important. Often you can find a media labeled specifically for seeding. Look for media with both good drainage and high water holding capacity. These things seem contradictory, but you want your soil to hold adequate moisture for seeds to germinate without drying out too quickly, but you also want excess water to freely drain from the medium.

Light is often a limiting factor with starting seeds indoors. To produce hardy seedlings, you need 12 to 14 hours of light per day. Natural lighting is generally not enough. Supplement natural light using a shop light with alternating cool- and warm-white fluorescent bulbs.

To plant the seeds, sow in rows 2 to 3 inches apart. Use a fairly tight spacing within the row. As a general rule, sow seeds to a depth of approximately 3 times the diameter of the seed. Most seeds will germinate well at a temperature around 70 degrees F held constant during day and night. After germination, temperatures can be lowered according to the type of plant you are growing. Refer to OCES Fact Sheet HLA-6020, “Growing Vegetable Transplants” for ideal growing temperatures. For many tomatoes, a day temperature between 70 and 80 degrees F and a night temperature between 60 and 65 degrees F is ideal.

Managing water in seed trays can be tricky. Over-watering is a common problem. The seeds do not use much water until they have germinated and seedlings are actively growing. However, the seeds need moisture to germinate. Misting the soil until it is thoroughly damp is a good way to provide moisture. Then, cover the seed tray loosely with plastic, checking soil moisture periodically. Remove the plastic once you see seedlings emerge.

Though fertilizer labels recommend weekly fertilizer applications, an application every two to three weeks is usually sufficient. The first application is not needed until seedlings are ready to be transplanted, two to three weeks after sowing.


Each year a set of plants is chosen by horticulturists that will help consumers choose plants appropriate for Oklahoma gardens. The program began in 1999 by selecting a tree, shrub, perennial and annual worthy of Oklahoma landscapes. In 2009 a new category was added, the Collector’s Choice. This plant has the adventuresome gardener in mind. It is a plant that will do well in Oklahoma and may need special placement or a little extra care, but will be very rewarding and impressive in the garden.  Selections for 2015 are listed below:

Collectors Choice – Sour Gum (Improved cultivars), Nyssa sylvatica

Black gum, also known as black tupelo or sour gum is an eastern native. In general black gums are slow to moderate growers reaching as much as 50 to 60 feet or more, are picturesque, and make excellent shade trees with beautiful summer foliage and gorgeous fall color. In fact, when it comes to red fall color, many consider this species to be the most reliable of native trees. Black gums prefer well drained, acidic soils, but adapt well to poorly drained soil and are even quite tolerant of dry soils. In high pH soils it may grow slower and develop chlorosis. Black gum has few pest problems and is easy to grow, though leaf spot can sometimes be a problem. New selections of black gum are more resistant to leaf spot and have excellent form. Wildfire (N. sylvatica ‘Wildfire’) is a selection that grows slowly to 60 feet high by 25 feet wide developing a pyramidal form when young and becoming more rounded with age. A unique characteristic of Wildfire is new growth emerges red. As the leaves mature they are shiny dark green; the fall color is bright red. Fire Master™ (Nyssa sylvatica 'PRP1') grows about 50 to 60 feet tall and 25 feet wide with a strong central leader. Fire Master™ has shiny, dark green summer leaves with a crimson red fall color. Red Rage™ (N. sylvatica ‘Hayman Red’) exhibits more leaf spot resistance than other cultivars and appears to be slightly smaller, growing 30 to 50 feet tall. Flowers of black gum are insignificant, but an important nectar source for bees and pollinators. The small, black fruits that follow are loved by birds. Black gums are an excellent tree for urban and street plantings and their neat habit requires little to no pruning to maintain their excellent shape.

  • Exposure: Full sun to part shade
  • Soil: Prefers moist, well-drained, acid soil, but adaptable
  • Hardiness: USDA Zone 4-9

Tree – Hedge Maple, Acer campestre

Hedge maple is a small to medium sized tree slowly growing to 25 to 35 feet high and wide. Because of its small size it is perfect for smaller, urban landscapes and even under utility lines. Hedge maple has beautiful green summer foliage that is free of ailments; fall color is yellow to yellow-green in color. Branches often develop very low to the ground providing excellent cover for wildlife, though it can easily be limbed up if desired. Hedge maple is really not too picky of soils; though it prefers rich, well-drained soil it grows well in compacted and alkaline soils. It also tolerates severe pruning and has often been used as a hedge, even walls, especially in Europe. Hedge maple is one of the tougher maples, which is underutilized in the U.S., has few problems, and is very urban tolerant. Golden leaf and variegated leaf forms are available.

  • Exposure: Full sun or light shade
  • Soil: Tolerates wide variety of soils
  • Hardiness: USDA Zone 5-8

Shrub – Barberry (Columnar forms), Berberis thunbergii

Barberries are, in general, pretty tough and offer a wide variety of leaf color. The newest of forms are the columnar types of shrubs offering a vertical element in the landscape. These forms of barberry include the Rocket and Pillar series. In the Rocket series there is Golden Rocket, Rosy Rocket, and Orange Rocket. In the pillar series there is Sunjoy® Gold Pillar and Helmond Pillar. Each offers upright, narrow plants in different foliage colors of golden, to red, and orange. Depending on cultivar, plants grow 3’ to 5’ high and not more than 2’ wide. Barberries prefer moist, well-drained soils, but are adaptable to a wide range of soils and once established can be quite drought tolerant. Barberries have no serious pest problems, and require very little maintenance making them excellent for the urban landscape. Grow columnar forms of barberry as a specimen, in groupings, in shrub and flower borders, and as a foundation planting.

  • Exposure: Sun to part shade (foliage color is best in full sun)
  • Soil: Moist, well-drained
  • Hardiness: USDA Zone 3-8

Perennial – Summer Phlox Volcano® series, Phlox paniculata Volcano®

Plants of the Volcano® series are more compact, more floriferous, and more powdery mildew tolerant than other varieties of summer phlox. Flowers of the Volcano series are larger, fragrant, and borne in an abundance on sturdy stems, with deep green leaves, 24-28” tall. Colors range from red, pink, ruby, white, lavender, and purple. Flowers may also have eyes of pink, red, or white or may be bicolored such as with Lilac Splash. Flowers appear from June to September if you cut plants back after the initial bloom. Volcano phlox does not mind most soils, but needs well-drained soil. Irrigate with soaker or drip irrigation to keep foliage dry. Full sun is the best exposure for Volcano phlox, but it will grow in part shade; too much shade and poor air circulation will increase chances of mildew developing, though it still does not seem to inhibit flowering. Once established, phlox is very adaptable. It is grown as an accent and in groups or masses. It also works well in native plant gardens, wild gardens, meadows, naturalized areas, perennial borders, and cottage style gardens. Butterflies and hummingbirds are attracted to the colorful, fragrant flowers.

  • Exposure: Sun, part shade
  • Soil: Tolerates about any soil
  • Hardiness: USDA Zone 4-10

Cultivars include:

P. paniculata ‘Barphlopanflaliblue’ Volcano Lilac Splash
P. paniculata ‘Barthirtyfour’ Volcano Pink with Red Eye
P. paniculata ‘Barthirtyfive’ Volcano Pink with White Eye
P. paniculata ‘Barthirtythree’ Volcano Purple with White Eye
P. paniculata ‘Barthirtysix’ Volcano Red
P. paniculata ‘Bareightytwo’ Volcano Ruby
P. paniculata ‘Bareightyone’ Volcano Soft Pink with Dark Pink Eye
P. paniculata ‘Barthirtytwo’ Volcano White
P. paniculata ‘Barsixty’ Volcano White with Rose Eye

Annual – Spider Flower (Improved types), Cleome hybrids

Spider flower is a unique plant with palmately compound leaves, interesting, fragrant flowers, and an old fashion look. Flowers have abnormally long stamens that gives the flower a frilly look and is likely where the common name of Spider flower comes from, resembling spider legs. Flower colors come in shades white, pink, blue, and purple. Plants can grow 3 to 6 feet tall depending on type. Spider flower grows well in full sun to part shade, and well-drained soils. Spider flower responds well to an abundance of moisture, but is also quite drought and heat tolerant. Improved hybrids provide an abundance of flowers on stocky plants. The Sparkler series are hybrids that are short, 3 to 4 feet tall, bushy, and ideal for containers. The Spirit series comes in several colors and foliage is light green with a silvery cast; plants are compact, thorned, have sticky foliage, and require deadheading, but are heat and humidity tolerant and produce seed. Senorita Rosalita (vivid pink blooms) and Senorita Blanca (white blooms with pale lavender blush), are compact, multi-flowering, plants with dark green leaves that do not need deadheading. Plants of Senorita types are sterile, thornless, and do not have sticky foliage. Spider flower is excellent in attracting butterflies and hummingbirds and goes well with a cottage style, wildflower design, or mixed border.

  • Exposure: Full sun to part shade
  • Soil: Moist, well-drained soil
  • Hardiness: Use as an annual

For more information about Oklahoma Proven or to see all the plants recommended by the Oklahoma Proven Plant Selection Program, go to or contact David Hillock, 405-744-5158,

2014 Tomato Trial Results by Lynn Brandenberger

The tomato trial program was begun in 2012 because of encouragement from two forward thinking tomato growers within the state.  From the beginning the program has depended on individual farmers volunteering to carry on trials on their own farms, planting, caring for, and collecting data.  OSU involvement has included obtaining seed, producing transplants, organizing data collection and completing reports.  This would not have been possible without the help and support of farmers and also financial support from the Oklahoma Department of Agriculture, Food, and Forestry, many thanks to all those who made 2014 a success. 

The 2014 tomato trial program resulted in the completion of eight trials using the twelve cultivars selected for testing.  Selection of cultivars to include in the trial has been done each year based upon farmer-cooperator feedback.  Cultivars that have been included for more than one year were repeated because of requests by farmers that carried out trials.  Below you will find some information about the cultivars included in the 2014 trials.  Individual trial results are in the 2014 Vegetable Trial Report (MP-164).

2014 Tomato Trial Entries




Days to Maturity

Years in trial

Seed Co. descriptions

Bella Rosa




9 oz., heat tolerant, Resistance to SW





10 oz. early blight tolerance, FR, TMV, VW. Heat set, excellent fruit and interior quality





10 oz. FR123,GLS,TYLC, excellent firmness and red color

Florida 91




10-12 oz. Intermediate resistance: Aal, Fol (1,2), Ss, V

Red Morning




Early, good cover, Resistance to V,F12, TSWV

Solar Fire




8-10 oz. Heat set and crack tolerance. Res: F123,V1,St

Valley Girl




7-8 oz fruit. Cracking resistant






6-8 oz. High yields, good shelf life, heat set FW123,V1

Top Gun




7-8 oz. heat set, V1, St,TSWV,F1,ASC, FW12





10 oz. Heat set. Intermediate resistance:  Fol(1,2), S, TSWV (0), V (0)  






9-10 oz Highly resistant: Aal, Fol(1,2), Ss; Intermediate resistance: TYLCV, TSWV





10-12 oz. Resistance to Aal, Fol12, Vd1; Limited resistance to Intermediate Resistance to Ss, TSMV 

Disease key

Aal or ASC = Alternaria stem canker, ALS = Angular Leaf Spot,
Fol, F, FR or FW = Fusarium Wilt (#s indicate race), GLS, Ss, or St = Gray leaf spot (Stemphylium),      
SW or SWV = Spotted Wilt Virus, TSWV = Tomato Spotted Wilt Virus,
TMV = Tobacco Mosaic Virus, TYLCV = Tomato Yellow Leaf Curl Virus, V or VW = Verticillium Wilt

Deadline for Pecan & Grape Management Classes Quickly Approaching by Becky Carroll

The Pecan Management and Grape Management Courses will again be offered in 2015. The Grape Management Course will begin on March 5 and the first Pecan Management Class is scheduled for March 10. The courses continue to provide present or potential growers with grape or pecan management requirements throughout the growing season. Participants get to learn in both a classroom and vineyard or orchard setting. Engaging in discussions and meeting other growers allow participants to network and learn from each other as well.

The courses not only can help growers learn but is a great opportunity for County Extension Educators to hone their skills with these crops. Educators can take the course at no cost.

The online Pecan Management Course is also available to county educators who would like to learn more about pecans.

For questions about the classes, please contact Becky Carroll at or 405-744-6139.

Pecan Graftwood Sources for 2015 by Becky Carroll

The pecan graftwood sources for 2015 are listed at the following website:

Summer Opportunity for Oklahoma Teens by Shelley Mitchell

Camp TURF 6 will run from May 31 through June 12 this summer. The camp is a summer academy sponsored by the Oklahoma State Regents for Higher Education, and camp is FREE for all participants. Camp TURF is hosted by the OSU Department of Horticulture and Landscape Architecture. Participants stay in OSU residential suites and do hands-on activities in horticulture-related fields such as grafting, cloning, making dish gardens, filming a segment of Oklahoma Gardening, touring hydroponic farms and botanic gardens, creating a landscape model out of chipboard, etc. All activities are led by professors and/or professionals in the field. Other activities include the ROPES course, insect fun at OSU Insect Adventure, a group painting class, swimming, volleyball, movies, etc. Up to 25 participants will be chosen; students currently finishing either 8th or 9th grade in Oklahoma are eligible to apply, and minorities are encouraged to apply. For more information, contact Dr. Shelley Mitchell at Applications will be screened in mid-March and selection will start April 1.

Upcoming Horticulture Events

Current Challenges in Floriculture
June 11, 2015
Wes Watkins Center – Stillwater, OK

Hunger and Horticulture
July 30, 2015
Food and Agricultural Products Center – Stillwater, OK

September 26, 2015; 10 AM – 4 PM
The Botanic Garden at OSU – Stillwater, OK

Tree Care Issues Conference
October 29, 2015
Wes Watkins Center – Stillwater, OK

For more information about upcoming events, please contact Stephanie Larimer at 405-744-5404 or

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