Fertilizing Annual and Perennial Flowers in the Garden

Fertilizing Ornamental Flowers

Brian Jervis: Master Gardener

Tuesday, May 30, 2017

Q: How often should I fertilize my flowers and what type of fertilizer should I use? Sue, Tulsa

A: How often to fertilize and what fertilizer to use, of course, depends on the type of soil and the variety of ornamental in your garden.

It is always best to start with a soil test. A test will determine the nutrient content of your soil and serve as a guideline for deciding which fertilizer to use. Instructions for collecting soil samples are in the soil section of the Master Gardeners website, tulsamastergardeners.org.

Generally, most annual plants will benefit from fertilizer during the growing season. Perennials, if mulched regularly, will usually get enough nutrients from the mulch.

As a rule, extra nitrogen fertilizer will be needed by most plants. Nitrogen is used in large amounts by plants and what is not absorbed is often washed deep into the soil.

The other nutrients — phosphorus and potassium — do not migrate in the soil, remaining where applied if not used by plants. Their behavior is such that they leave a residual if a landscape has previously been fertilized. Applying more of these two, especially phosphorus, can be harmful to the environment. A soil test will sort this out.

When deciding on what fertilizer to use, there is a choice between conventional and organic fertilizers. Although the major nutrients in each are exactly the same — plants can’t tell the difference — there are some pros and cons of each type.

With commercial fertilizer, you are aware of the exact amount of each nutrient, it is easier to apply and, overall, cheaper.

Organics are great in that they not only add nutrients but also help to make sandy and clay soils more plant friendly by improving structure. Another advantage of organics is that they also have minor nutrients and beneficial soil organisms not found in most commercial preparations. One of the downsides to organics is they have a lower concentration of the major nutrients and need to be used in larger amounts. This often means that it requires more effort and may be more expensive.

Some of the organic fertilizers with the highest concentration of nitrogen to consider for use are cottonseed meal, blood meal, bat guano, fish meal, fish powder, fish emulsion, soybean meal and milorganite.

A general take home message for fertilizing flowers might be this: Fertilize annuals and perennials at the time of planting with slow-released commercial or high-nitrogen organic fertilizer. In the growing season, perennials can be fertilized once again. Most annuals will benefit from fertilizing with a liquid nitrogen fertilizer or an organic preparation every 2-3 weeks during the summer and while blooming.

The last thing one should do is to develop the “more is better” mindset and use too much fertilizer. Most experts think that there is more harm to plants by over-fertilizing, than not fertilizing at all.

Garden tips

Clean out water garden and prepare for the summer season. Divide and re-pot water garden plants. Begin feeding fish when water temperatures are higher than 50 degrees.

Plant warm-season vegetable crops such as watermelon, cantaloupe, cucumber, eggplant, okra, sweet potatoes, etc., now.

Fruit trees, especially apples and peaches, must be thinned out for best production. Prune apples 4-6 inches apart and peaches 6-8 inches. This will ensure larger fruit and less damage to limbs. If not thinned, the tree's resources will be used to such an extent that next year’s crop will suffer.

Late May is the best time to control borers in the orchard. Contact OSU Tulsa Master Gardeners for fruit tree spray recommendations.

Master Gardener School Programs are Fun and Very Popular

Bill Sevier: Master Gardener

Master Gardener School Programs are popular

Tuesday, May 23, 2017

Q: I teach second grade and would like to have a Master Gardener school program for my students. How do I go about this? N.M., Tulsa

A: These programs are popular, and the demand often exceeds what can be supplied. The programs consist of Master Gardeners going into a classroom and teaching one of the eight different preset presentations.

The average classroom size is about 24 children at the K-1 through fifth-grade level. The Master Gardeners are busy with this program and taught one of these gardening-related programs to 645 different classes this past year. This amounted to teaching 15,592 Tulsa children.

To get started with your request, go to the Master Gardener website (tulsamastergardeners.org) and select “School Programs” on the home page to access a form having information about each program’s content and availability. A school program will then be scheduled, if available.

The set programs presented by Master Gardeners are outlined below.

Insects and Spiders: Friend or Foe — Students are taught the difference between insects and spiders, as well as which of these to avoid.

Seedy Side Show — Teaches about the different types of seeds, what they consist of and how they germinate and form plants. They get to dissect their own seeds.

Six-Legged Super Heroes — Discussion and video about beneficial insects, including pollinators, and why it is important to protect them.

Soil Detectives — Discusses what soil consists of and how it was formed. Students will use a supplied hand lens to inspect the different components of soil.

Something to Sprout About — Informs students about how seeds “sleep” until it is time to germinate. They learn about the different types of sprouts and get to plant and germinate their own seeds from materials supplied by the Master Gardeners.

Tree Time — Students are taught about the parts of a tree, including how to determine its age by counting rings. The importance of trees to our environment is stressed. Comparisons are made between the needs of humans and trees.

Whirling Wings — Teaches how to tell the difference between butterflies and moths and how their behavior is different. The fact that they are not only pretty but also serve as important pollinators is taught. Visual aids of samples of flowers that attract both types of insects are presented.

Worms to the Wise — Students learn about how earthworms are “nature’s plows.” What worms eat and what makes them so valuable to gardeners and farmers is stressed. Students get to observe their own worms from the Master Gardener’s portable worm farm.

As mentioned, these programs are in great demand. They also cost money for supplies. The OSU Tulsa Master Gardeners have no outside source of funding for their volunteer activities and depend on profits from the spring plant sale, garden tour and donations to be able to offer these activities to Tulsa-area schools.

Garden tips

·        Insect alert: Now is the time to be on the lookout for bagworms on juniper and arborvitae and lace bugs on sycamore, pyracantha and azaleas. Contact Tulsa Master Gardeners for control suggestions.

·        Do not work soil if it is too wet. Tilling it while wet will cause damage to the structure, and it will take a long time to recover.

·        Thatch is a layer of dead and living stems, shoots and roots that pile up on top of the soil at the base of lawn grasses. If it is more than ½-inch thick, it should be removed with either a core-aerator or power-rake. Now is the time to de-thatch Bermuda and zoysia. De-thatch fescue, if needed, if the fall.

Moving Plants Outdoors for Summer

Moving Plants Outdoors for Summer

Brian Jervis: Master Gardener

Tuesday, May 16

Q: Is it a good idea to move my houseplants outside for the summer? Should they be repotted? K.S., Tulsa

A: Yes, it is a good idea to move most houseplants outside for summer, but you must respect their individual requirements for temperature and sunlight.

Most houseplants are tolerant of reduced lighting indoors, but they usually originated as outdoor plants. Your plant would like to be outdoors again if the conditions are favorable.

Do not move houseplants outdoors until all danger of frost has cleared and the outdoor temperature is about the same as indoors. When moving plants, they should be placed in shade for a couple of weeks, then gradually moved to full sun or sun/shade, depending on their requirements.

Some plants, such as one of the Chinese evergreen cultivars, cannot tolerate sunshine. They get sunburned and should be located in dappled or full shade. Other plants such as the cacti, bougainvillea, hibiscus, plumeria and others do best in full sun.

Because houseplants usually grow much more rapidly outdoors in summer, they need more water and fertilizer. Depending on the plant, a balanced liquid fertilizer every 2-3 weeks or so should be a good plan. Water requirements during the hot summer may mean watering every day or even twice daily, depending on the plant, the weather and the type of potting soil.

Inspect the plant’s roots when moving outside. If the plant has filled the pot with roots (called being “root-bound”), it grows more slowly and may eventually die. Hints that the plant has this problem are if the plant needs frequent watering or if large numbers of roots come out of the container’s drainage holes. Remove the plant from the pot, and if you see mostly dense roots growing in circles, it probably should be repotted. An exception to this is if the plant looks healthy, and you do not wish for it to grow any faster or taller, keep the plant as is.

Another indication for repotting is if a white crust has formed on the soil. This is an undesirable accumulation of salt residue from fertilizers.

Select a new pot an inch or two larger than the old one. The soil for the new pot should be a commercial potting soil, which will ensure good drainage. Never use soil from your garden; it drains poorly and may carry disease. Before planting, consider making three to four vertical slits in the root-ball of root-bound plants, which have large numbers of circling roots.

Place a coffee filter or fine screen at the bottom of the pot to keep soil from leaking out. It is not recommended that a pile of potting shards or gravel be used on the bottom. Rather than improving drainage, these materials placed over the pot’s drainage holes may actually prevent drainage by producing a “perched water table” zone just above the gravel. This has to do with the physics of water drainage and can be unhealthy for the lower roots.

Garden tips

• Clean out water garden and divide and repot water garden plants. Begin feeding fish when water temperatures are higher than 50 degrees.
• Plant warm-season vegetable crops such as watermelon, cantaloupe, cucumber, eggplant, okra, sweet potatoes and other warm-season crops now.
• Fruit trees, especially apples and peaches, must have their fruit thinned for best production. Prune apples 4-6 inches apart and peaches 6-8 inches. This will ensure larger fruit and less damage to limbs. If not thinned, the tree's resources will be used to such an extent that next year’s crop will suffer.
• Late May is the best time to control borers in the orchard. Contact OSU Tulsa Master Gardeners for fruit tree spray recommendations.

Controlling Weeds in Your Lawn

Controlling Weeds in Your Lawn

Bill Sevier: Master Gardener

Tuesday, May 9, 2017

Q: What is the best way to get rid of weeds in my lawn? J.A., Tulsa

A: The most effective way to prevent weeds is to have a green, thick, healthy lawn, which will prevent weed seeds from sprouting. Unfortunately, most of us don’t have a uniformly thick lawn and have to deal with weeds growing in the thin or bare spots. There is a wide range of tolerances for weeds in the lawn. The purist wants no weeds while others may adhere to the adage “one man’s weed is another man’s wildflower.”

OSU’s lawn maintenance information sheets — one on Bermuda, the other on fescue — are available on the Master Gardener website, tulsamastergardeners.org, in the lawn and garden section. These sheets describe all aspects of lawn care, including weed control, and may contain all the information you need for your lawn care.

In terms of chemical control, there are two approaches — prevention with pre-emergent herbicides and eliminating existing weeds with the post-emergent variety.

Pre-emergent herbicides are best used in the spring to prevent crabgrass and most summer weeds and again in fall to deal with the winter weeds such as henbit, chickweed and annual bluegrass (Poa annua). Pre-emergent herbicides recommended by OSU are listed on the above referenced information sheets. It should be understood that when using these herbicides, you will never get 100 percent prevention, and they will be of no benefit unless the instructions are followed in detail.

Post-emergent herbicides available are based on the type of weed. There are three main botanical weed types — broad leaf, such as dandelion; grassy weeds such as crabgrass, and sedges like yellow nutsedge (nutgrass).

Most broad-leaved weeds are best treated with one of the many brands of herbicides containing a chemical called “2,4-D.” It usually is mixed in with other herbicides to enhance control. The chemicals in this category are mostly derivatives of plant growth hormones and have the greatest effect on growing weeds in spring and fall. After a weed reaches maturity and blooms or produces seeds, their effectiveness is greatly reduced.

Grassy weeds are difficult. The best herbicide for weeds such as mature crabgrass, Dallisgrass, orchard grass and the like has been taken off the market. Herbicides available now for mature crabgrass contain a less effective but useful chemical called quinclorac.

The most common sedge in the lawn is yellow nutsedge. This is the slender weed that pokes its head up above grass two days after mowing. Although some broadleaf herbicides are labeled for nutsedge, they are not effective. Products containing imazaquin (Image), halosulfuron (Sedgehammer) and bentazon (Basagran) and sulfentrazone (many brands) are effective.

Again, suggestions by OSU about which chemicals to use and when are in the lawn maintenance documents from the Master Gardener website mentioned above. Be aware that the chemical names mentioned are found in many brands. Also, remember to always read and follow instructions on the label of each brand.

Garden tips

·        Nutsedge weeds are emerging now. Post-emergent treatments are best applied for the first time this month. Make certain warm-season grasses have completed green-up. Nutsedge requires specific treatment for control; standard broadleaved post-emergent herbicides are not effective. Contact the OSU Tulsa County Master Gardeners for recommendations.

·        Plant summer bulbs such as cannas, dahlias, elephant ear, caladiums and gladiolus.

·        Apples and other fruit need thinning for best production. If apples are not thinned, the crop will be of poorer quality this year and small next year. Thin to one apple every 4 inches.

·        Remember, working wet soil will cause significant damage to the soil structure. Give it time to drain from recent rains, before tilling. Damage from tilling while wet may last for a long time.

Common Vegetable Garden Problems

Vegetable Garden Problems

Brian Jervis: Ask A Master Gardener

Tuesday, May 2nd

Q: Last year, my cabbage plants had a problem. They were yellowish and didn’t grow well. What could I be doing wrong? S.C., Tulsa

A: There are a number of problems vegetable growers may face during the growing season. Your stunted and yellow plants may result from a host of things, some of which involve the lack of fertility or unfavorable soil acidity (pH). A soil test will sort this out.

Other causes are compacted poorly draining soil and poor quality of seeds or transplants, along with various insects and diseases. In addition, planting too early in the season when soils are still cold may cause a problem as you describe.

Disease and insect damage is often easy to identify. Insects frequently leave evidence of holes or nibbled areas and may cause yellowing of leaves. Some of these pests are small and difficult to see without a hand lens. Diseases of plants are often associated with brown spots, powdery deposits or rusted areas.

If soil compaction is a problem due to clay soil or planting in a high-traffic area, tilling in composted organic material will help, but the best option for this problem is to plant into a raised bed with good soil.

Other common problems in the vegetable garden involve roots. Inspect them, and if small and poorly developed, the problem may be due to overly wet soil or root damage due to fungal disease or nematodes.

If you experience “blossom drop,” where blossoms form but do not produce fruit and drop from the plant, the cause is usually environmental. The temperatures are either too hot or the nighttime temperatures too cold or the soil is too wet or too dry. Excessive nitrogen fertilizer can also produce blossom drop. The plant can overcome this as conditions improve.

When sun-loving plants are planted in shade or part shade, they often become tall, spindly and unproductive. They grow tall looking for sunlight. Over-fertilization may also cause this problem.

There are some steps you can take to cope with these problems. First is to do a soil test every two to three years and apply only the types of nutrients needed and never develop the mind-set that “more is better.” Another step is to plant your vegetables with attention as to their need for sunlight.

Next is to inspect your garden as often as possible to identify problems, such as insects and disease, which may be dealt with early. Always remove weeds and use mulch to prevent new weed growth, conserve water, moderate temperature and help prevent disease spread.

Something else one can do to improve success is to not walk in or till the garden when soils are wet such as they are now. Tilling wet soil destroys the structure for years to come.

Garden tips

Prune and feed all spring-blooming shrubs, such as azaleas and forsythia, immediately after blooming, if needed. Azaleas need less fertilizer than many shrubs and often a yearly addition of mulch, as it decays, it will add all the nutrients they need.

Cool-season lawns — tall fescue and bluegrass — can be fertilized again. If you did not fertilize in March and April, do so now. Do not fertilize these grasses in summer.

Seeding and sodding of warm-season grasses such as bermudagrass, Buffalograss and zoysiagrass, is best performed in mid-May through the end of June. The soil temperatures are warm enough for germination and growth. These grasses need a long summer growing season to promote winter hardiness.