Q&A

 Ask a Master Gardener

Question: When is the best time to start an herb garden?

Answer: Most herbs require warm soil temperatures, well-drained soil, and sunny warm days to do their best. At least six hours of full sun will make your herbs thrive. Mint and Lemon Balm do well in partial shade. Start planning now on which herbs you will use most in your kitchen. One or two plants at the most of each kind of herb will be plenty for cooking purposes. The more you snip the plants the more they flourish and stay tender for harvesting

Basil, chives, lemongrass, parsley and thyme can be started from seed, while mint, rosemary, and tarragon are easily propagated from cuttings or bought as plants. Waiting to move transplants or seedlings outside after our average last frost date of April 15 is wise. You can place your herbs in pots in a sunny location, or place herbs among other flowering plants in the garden to add a pleasant aroma. It is wonderful to plant herbs along a pathway and then enjoy the fragrance of their oils as you brush pass them. Remember to shop the MG plant sale for a variety of herbs that will arrive just in time to plant. Click here for more information and order forms. Deadline for ordering is March 18.

Question: How early can I prune my rose bushes?

Answer: It is tempting to prune roses on the warm days of early March, but it is best to wait until mid-March when buds begin to swell. Pruning too early can lead to cold damage to the new growth that forms at the pruning site.  

Remove dead or black canes and any canes that are crossing or rubbing against others. Prune out canes growing from the rootstock. These "sucker shoots" grow straight up and can usually be found connected to the plant just below ground level. These suckers sap energy from the rose.

To prune a desirable cane to make it shorter, cut at an angle (to allow runoff) above a leaf bud. The highest part of the angle should be next to the bud which is facing outward; this encourages outward growth or a vase-like shape. Do not fertilize until after you complete your pruning process. Click here for Data Sheet 6403, "Roses in Oklahoma."

Question: Our peaches always seem to rot before our very eyes. What can I do to prevent this?

Anwer: Peach cultivars can be selected that will give a long season of harvest. Click here for OSU Fact Sheet 6210, "Apple and Peach Varieties for Oklahoma," which describes cultivars that do well in Oklahoma. Choosing cultivars that are resistant to bacterial leaf spot is the most effective way to control this disease. The recommended rootstocks for Oklahoma are 'Lovell' or 'Halford' seedlings. Follow a routine fruit spray schedule to prevent a host of other diseases and pest infestations. Click here for a spraying schedule for the homeowner.

Question: Is there any special care I should give my landscape plants after those record low temperatures?

Answer: Continue to check soil moisture during winter, especially when it follows a drought. Make sure mulch is covering root zones and no soil-heaving of the roots has occurred. Do not do any major pruning on shrubs that appear to have sustained cold damage until the plant begins to leaf out and the plant's health can be assessed. If dieback does occur, prune back to a leaf bud just below where green or swollen buds can be seen. 

In mid-March, when the time is right to begin fertilizing, do not overcompensate. Usually, a stressed plant will respond better to a little food. Too much nutrients could burn roots and new growth. There is some question whether plants that are borderline for our zone will survive this winter, but the reported soil temperatures did not dip below the 10-degree level believed to cause death in many plants. Cold damage can be identified by browning of leaves or the discoloration of evergreens. Some winter dieback is normal. Click here for more information.

Question: When can I use Roundup on lawn weeds?

Answer: Roundup is the original glyphosate herbicide. The Monsanto Company's patent on Roundup expired in 2000, and glyphosate herbicides are now sold under many names. Glyphosate products should be applied when it is not windy, when temperatures are between 60 and 85 degrees and when no rain is expected for several hours.  

Glyphosate will kill or damage any green plant it comes in contact with, including the Bermuda grass that is now beginning to green up. It is a systemic herbicide and kills by being absorbed through the leaves of actively growing plant material. Allow product to dry thoroughly before allowing foot traffic by pets or people, and follow label directions carefully.

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15 lawn and garden tips for March 

Garden

• Be sure your soil has dried adequately before you start working in your garden. Record snowfalls in February left many gardens saturated. To check, dig down to planting depth, take a handful of soil and squeeze. If water comes out, it is too wet. Soil should crumble, not compress into a clump. Working the garden when it is wet can damage the structure of the soil and leave you with clods that won't break apart all summer.
• Spring cultivation and addition of organic compost to annual flower and vegetable beds improves soil performance. These actions add nutrients, improve aeration and water conservation, while helping to control winter weeds.
• Cool-season vegetables like broccoli, cabbage, carrot, lettuce, onion, peas, etc. should be planted by the middle of March. Start warm-season vegetable transplants indoors.
• Prune roses after March 15. Remove dead canes, prune for shape, better air circulation and to stimulate blooming.
• Fertilize roses at pruning time with a slow release, balanced chemical fertilizer. Scratch into soil; keep 6 inches from rose stems. Follow label directions. Too much nitrogen will decrease blooms.
• Horticulture oil spray, used in dormant dosage, can still be applied to control mites, galls, and overwintering aphids in plants susceptible to these pests. Ornamentals such as roses and many fruit trees are examples.
• Spring is the time to divide and replant crowded summer- and fall-blooming perennials such as hostas, daylilies and ornamental grasses.
• Summer-blooming shrubs (such as crapemyrtle) and non-blooming broad-leafed evergreens (photinia, boxwood and laurels) are best pruned before spring growth begins. Wait to prune your spring-blooming shrubs such as azaleas until immediately after flowering.
• Cut back Liriope and other ornamental grasses before new growth begins.
• A soil test is key to understanding which fertilizer nutrients may be needed for lawns and garden beds.

Trees and shrubs

• Bare root trees and shrubs should be planted now to give them a head start on the heat of summer.
• When planting trees, remember that the hole needs to be wider than deeper. Studies show that a tree will grow three times faster if you mulch around it. Click here for more information on planting trees.

Lawn

• Pre-emergent herbicides need to be applied before weeds germinate, usually no later than March 15. Crabgrass germinates when the soil reaches 55 to 60 degrees. To be effective, be sure to water in after applying. Don't apply preemergent on your fescue lawn if you plan to overseed.
• Fertilize your fescue lawn now (March) and again in early May with 1 lb. of nitrogen per 1000 square feet. Do not fertilize again until late September. Use a quick release fertilizer.
• You can still use glyphosate (Roundup) to spot kill weeds in your Bermuda lawn, but only if the grass is still dormant.

Tulsa Blooms! at the Home and Garden Show

Are you ready to start gardening? Ready to put some color in your landscape? If you are looking for ideas, a good place to start is the annual Home Builder's Association Home & Garden Show, which runs March 10-13. Tulsa Master Gardeners will be there to help you with gardening ideas and to answer questions.

Show hours are 5-9 p.m. Thursday, March 10; 10 a.m. to 9 p.m. March 11-12, and 11 a.m. to 6 p.m. Sunday, March 13.

This year's theme for the Master Gardeners' booth is "Tulsa Blooms!" This is an OSU Master Gardener initiative for beautifying commercial and residential areas with colorful, flower-filled containers. As usual, we will offer free tree seedlings every morning. This year's offering is a chokecherry. Order forms for April's Master Gardener Plant Sale also will be available.  

Dr. Andrine Shufran from Oklahoma State University will bring her traveling insect farm again this year, and children can learn even more at the craft center. Click here for more information on the Home and Garden Show.

2011 Oklahoma Proven selections

Every year a group of nurserymen and OSU horticulturists selects plants to be "Oklahoma Proven." They are selected on the basis of appeal, weather tolerance and disease resistance. The yearly picks are one each of a shrub, tree, perennial, annual and a category called "collectors choice."Since its start in 1999, the Oklahoma Proven list has grown to more than 50 plants. The selections for 2011 are:

Tree - a collection of American Elms with resistance to Dutch elm disease, the disease that decimated our native elms. The trees are "Princeton," "Valley Forge" and "New Harmony." These trees are tolerant of a wide range of conditions and may grow to more than 100 feet tall.

Shrub - cultivars of an old favorite, glossy abelia. The choices are "Kaleidoscope," "Little Richard" and "Rose Creek." This collection has interesting variations of patterns and colors of leaves and stems. Blossoms range from white to pink and may bloom over the summer.

Perennial - a native plant, the Giant Coneflower, which blooms in Northeastern Oklahoma prairies in early summer. It is a Rudbeckia, one of four genera called "coneflower" more closely related to the Black-Eyed Susan than purple coneflower. This plant tolerates moist and dry soils and needs to be in the back of a sunny bed; it grows to 5-6 feet.

Annual - an attractive ornamental grass called Pink Crystals Ruby Grass. It has blue-green foliage and ruby-pink flower heads that bloom in late spring. It prefers full hot sun and may grow to 18-22 inches. It is often suggested that container plantings have a trio of "thriller, filler and spiller" plants. This grass will play the role of a thriller perfectly.

Collector's choice: the Silver Linden tree, Tilia tomentosa. It is a beautiful shade tree growing to 70 feet with attractive leaves and small white flowers in mid-summer. It is tough and would be a good choice for a lawn shade tree.

Click here for photos and descriptions of the entire Oklahoma Proven collection.

Plant sale order deadline: March 18

Have you turned in your order for the Master Gardeners' Plant Sale? There's still time. The deadline is Friday, March 18. Not sure what a plant looks like, how big it gets, how close together to plant them? Don't have an order form? Contact a Master Gardener or click here to get an order form as well as lots of information about each plant and links to pictures of the plants.

Purchasing quality plants at attractive prices is a great way to kick off spring. You will also be supporting the many Master Gardener programs serving our community.

Plants may be purchased two ways:

1. Preorder - Place an order for bedding plants, hanging baskets, herbs, ornamental grasses and accent plants. Orders must be prepaid. Pick-up day is Thursday, April 14, from 9 a.m. to 7 p.m. at Central Park Hall on the Tulsa County fairgrounds.
2. Day of Sale - Additional plants, including a wider selection of herbs, vegetables, perennials and native plants, will be available on a first-come, first-served.

Order forms and payment must be received in the Master Gardener office by 4 p.m. Friday, March 18. They can be mailed or delivered to:

Tulsa County Master Gardeners

4116 East 15th Street

Tulsa, OK 74112-6198