Selecting and Planting Onions in Oklahoma

Time to plant onions is approaching

Bill Sevier:  Ask a Master Gardener

Saturday, January 30, 2016

Q: When is the best time to start onions in my garden? What is the best type? Kim, Tulsa

A: A general rule of thumb is that onions should be planted about 4-6 weeks before the average date of the last spring frost. For our area — because the average last frost is in the first part of April — they are best planted between mid-February and mid-March.

There are many varieties of onions from which to choose. You need to select one rated for our area. OSU fact sheet “Vegetable Varieties for the Home Garden in Oklahoma,” available from the Master Gardener website, lists types that do well in Oklahoma.

Onions are classified several ways. They are grouped by color — yellow, white and purple — and whether they form bulbs. The ones not forming bulbs produce scallions, or green onions. The bulb-forming onions are further divided into the length of days needed to start bulb formation. Long-day varieties are grown in the northern United States; the short-day or intermediate-length types do best in Oklahoma.

Onions are also classified as to taste, ranging from sweet to pungent or hot. This is related not only to the variety but also to the amount of sulfur in the soil. Sweet onions such as Vidalia and Texas 1015 are grown in low-sulfur soils resulting in fewer sulfur chemicals. These chemicals cause onions to be pungent.

Onions are planted as either sets (bulbs) or transplants (sprouts) in rows 1½ feet apart and about 3-4 inches between individual plants. One can plant them closer together and then thin the plants for green onions as they grow. They need full sun and will need ample amounts of water and fertilizer during the growing season. They also prefer loose well-drained soil. If you add an organic fertilizer at the time of planting, this will improve drainage, as well as supply nutrients as the organics decompose.

A generic recommendation for fertilizing onions is to use one cup of a 21 percent nitrogen fertilizer as a side dressing 2-3 weeks after planting and every 3-4 weeks thereafter.

Onions are biennial plants, which means they grow leaves and bulbs one year and then flower and produce seed the following year. If onions grow flowers at the wrong time, it is called “bolting” and impairs their quality. Bolting may be due to stress, or if the onion transplant or set is too large. Try to buy small sets and transplants that are no thicker than a pencil.

Weather is the most common cause of bolting. Onions planted in warm soil begin to grow, and if it turns unexpectedly cold afterward, the plant goes into dormancy until it warms again. This causes the onion to think it is in the next year and “bolts.”

Green onions may be harvested at any point after established. Bulbs onions are best harvested after the tops flop over and turn brown. Most store well when properly cared for. Onions have been grown domestically by man for more than 5000 years and everyone continues to enjoy them.

  

Garden tips

§  Begin planting blackberries, raspberries, strawberries, grapes, asparagus and other perennial garden crops in February.

§  One can continue, in the month of February, spot-spraying weeds in dormant Bermuda lawn. Use a product containing glyphosate, found in Roundup and others when the temperature is above 50 degrees. Read the label carefully before using.

§  Tomato seeds are best planted in indoor flats around Valentine's Day for mid-April garden transplants. Should you decide to grow your own tomato transplants from seeds consult OSU fact sheet “Growing Tomatoes in the Home Garden” which may be found on the Tulsa Master Gardener web site (tulsamastergardeners.org). In that same section of the web site, you will find additional tomato fact sheets on growing conditions, pests and diseases which are very helpful.

Fungus Infections of Trees are Often Fatal

Fungi on trees may indicate infection

Brian Jervis: Ask a Master Gardener

Saturday, January 23, 2016

Q: There are mushrooms growing from the bark of my oak tree. What should I do about this? Gene, Tulsa

A: Mushrooms are a part of a fungus, which is used for reproduction called a “fruiting body.” It is usually only a small part of the overall fungus. These may be on trunks, limbs or extend up from underground roots. Some have the usual mushroom shape, while others form a saucer-like structure extending from the bark. These are often referred to as “conchs” or shelf fungi.

When present on the trunk of a tree, or on the roots of a tree, it implies that the tree has a significant infection, which most often is fatal. Generally, there is no chemical treatment effective for an infection such as this. Good general care of the tree in terms of water and nutrition is the only recommendation.

The usual story is of the tree having experienced a wound due to weather damage, lawn equipment and root damage related to excavation or severe stress due to environmental factors such as drought.

With the right condition and the right fungus, an infection can occur. Fungi have chemicals that are able to break down and feed on the wood, eventually causing a generalized infection. Most trees die of this, but it may take a few years.

As the infection spreads, evidence of general decline in the tree may be seen. Leaves are smaller and annual stem growth is shortened. Leaves often turn fall colors and drop prematurely in the fall. As the infection spreads, the limbs in the top of the tree usually die first. Later, supporting structure of limbs, trunk and roots are greatly weakened. They then become a hazard to you and your property when a wind storm develops.

It is best to start thinking about the removal and replacement of a tree once mushrooms develop and tree decline is observed. This should be done by an ISA-certified arborist. A list of those certified in our area may be found on the website treesaregood.com.

There is a common fungal infection of trees in our area that is worth mentioning. It is called hypoxylon canker (HC). It occurs especially in oaks but may infect many others.

HC is unlike other fungi in that heat and drought stress allows it to infect oaks. This type of stress reduces immunity and the fungus, which is normally wide-spread in nature, invades the tree. The terrible hot and dry summers we had in 2011-12 caused enough stress that many oaks developed this disease.

This fungus does not produce mushrooms, but it does produce massive amounts of grey to brown to black spores, which lift bark from the trees. The first indication that HC is present is often loose bark and powdery residue. When this is found in oaks, or any tree, considerations for removal of the tree should be made.

Garden tips

§  Even though there may be adequate moisture in the ground, it is normal for evergreen broadleaved shrubs to appear “wilted” during extreme cold. This is rapidly reversible after the temperatures warm. This is a way some plants have in dealing with the cold.

§  Try to keep fallen leaves off newly seeded fescue. Fescue is capable of growing roots in winter unless the ground gets extremely cold. A good root system will help fescue to better tolerate the heat next summer. To grow roots, the grass needs sunlight.

How to Control Weeds in the Lawn

Identifying weeds, how to treat them

Bill Sevier: Ask a Master Gardener

Wednesday, January 20, 2016

Q: I have weeds in my Bermuda that have wide leaves and look like dandelions. How can I identify this weed and decide what herbicide to use? M.S., Jenks.

A: The practical answer to this question is that you generally do not need to know the specific identity of a plant to decide what herbicide might be best.

Any green weed located in fully dormant Bermuda (brown when dormant) can be sprayed with glyphosate, an herbicide found in Roundup and many other brands. It will kill any green plant in Bermuda and can be done without risk to Bermuda grass during most Januarys and Februarys. However, glyphosate cannot be used on zoysia lawns at any time, dormant or not.

For weed control in general there is no need to specifically identify a weed, one need only to decide what category of weeds it is in. There are three types of weeds in lawns — grassy weeds, broadleaf weeds and sedges. Each category has certain herbicides that are recommended for their control.

Grassy-type weeds are those that have leaf veins parallel to each other such as found in crabgrass. Grass-specific herbicides are available, some of which may be safe to spray on ornamentals and even in the vegetable garden.

Sedges are plants that usually have triangular stems leading to the aphorism “sedges have edges,” making them fairly easy to identify. A sedge commonly found in lawns that is difficult to control is yellow nutsedge. Nutsedge and other sedges have specific herbicides, which are useful.

Broadleaf weeds are those with fan-like veins. This is a huge category of plants such as dandelions, henbit and wild strawberries. The herbicides, which often contain a mixture of chemicals such as 2,4-D, are specific for these broad leaf weeds, have no effect on grasses and often little or no effect on sedges. They are effective when used properly.

Timing is often critical for best effect of herbicides. Most of the chemicals used for broad leaf weed control are modified growth hormones. They are most effective when the weeds are actively growing, usually either spring or fall. After weeds have reached maturity with flower and seed production, there is less linear growth and less herbicide effect.

So the key to weed control is to have the healthiest lawn possible and, if needed, use a herbicide specific for the category of weed at the proper time. There is usually no need to know the specific name of a weed, you just need to know the category.

For information about general care needed for best lawn care, go to the turfgrass section of the Master Gardener website and look for the Bermuda and the fescue Maintenance Calendars. These documents have recommendations, what to do and when to do it, for optimal lawn care in Oklahoma.

Garden tips

§  Make sure indoor plants are receiving enough light or set up an indoor fluorescent plant light.

§  Till garden plots without a cover crop to further expose garden pests to harsh winter conditions.

§  Visit the Master Gardeners office at the OSU Tulsa County Extension Building to obtain gardening fact sheets for the new gardening season. The office is located at 4116 E. 15th St.

§  Choose fruit varieties that have a proven track record for Oklahoma’s conditions. OSU fact Sheet HLA-6222, “Home Fruit Planting Guide” has a recommended list.

Growing Vegetable Sprouts for Transplants

Tips on planting vegetables from sprouts or seeds

Brian Jervis: Ask a Master Gardener  

Saturday, January 9, 2016

Q: Which vegetables should be planted as sprouts? If I grow my own, when should I start from seed? Kurt, Tulsa.

A: Some vegetables do best when planted as sprouts, rather than sown directly as seeds. To obtain the information as to which vegetables should be planted as sprouts and how long it takes them to grow from seed to transplants ready to be planted in the garden, obtain the OSU fact sheet “Growing Vegetable Transplants.” This has complete information about commonly grown vegetables in Oklahoma.

Many of the vegetables take from 5-7 weeks — some shorter — to reach the stage where they are ready to be transplanted into the garden. To decide when to start the seeds, you should get another OSU fact sheet “Garden Planning Guide,” which gives a suggested date to plant each vegetable. From these two documents, you can decide when to start the sprouts from seeds. The Garden Planning Guide also lists how to plant and the time to maturation of all vegetables.

Vegetables that you should consider starting from seed now are tomatoes and those in the tomato family (peppers and eggplant), as well as cabbage, broccoli, cauliflower, Brussels sprouts, squash, watermelon and others.

Fresh seeds may be obtained from all the local garden centers, by ordering online or from a catalog. Some of the catalogs have extensive varieties of vegetables, which may not be available locally as sprouts.

To be successful in growing transplants, one needs to understand and control several factors. This includes having the proper fertile soil in which to plant, ensuring adequate lighting and controlling the temperature, as well as water and humidity.

The soil in which seeds are started is important. It should be sterile and drain well to prevent a common fungal disease of sprouts called “damping off” (some seeds are coated with a fungicide to help prevent this). You may make soil from a combination of various amounts of topsoil, peat, sand and/or vermiculite. However, if you make your own, it must be sterilized by placing it in an oven — a messy and stinky process. It is best to buy sterile soil mixes available in most garden centers.

After planting, the soil should be kept moist and never allowed to become dry or soggy. If your container is placed in a large, clear plastic bag, good humidity can be maintained and less frequent watering will be needed.

Seeds germinate and sprouts grow best next to a sunny window. However, if this is not an option, one of several types of grow-lights are available in most garden centers. However, sprouts grown under artificial light tend to be leggy and weaker than those grown in the sun.

Gradually harden the plants for a week before planting. This may be done by placing them outside during the day and bringing them in at night. Then they will be ready for transplanting into your garden.

Garden tips

§  Ornamental perennial grasses such as pampas grass may be cut back to 4-6 inches anytime in winter. However, because of winter attractiveness, most gardeners choose to wait until early spring to cut them back. All of the dead tops of these grasses should be removed by early spring, allowing sun to get to new growth.

§  Liriope or "monkey grass"—which is not a grass, but in the lily family—stays green year-round; it also benefits from trimming to 2-3 inches before new growth begins in spring. Liriope and all ornamental grasses will benefit from nitrogen fertilizer in spring when pruned.

§  Prune fruit trees in January, February and March. OSU has a good fact sheet on pruning fruit trees, "Annual Pruning of Fruit Trees".