Fall a Good Time to Divide Iris and Lilies

Dividing Iris and Daylilies

Allan Robinson: Ask a Master Gardener

Tuesday, September 26, 2017

Q: When should I divide my irises and daylilies? And how should this be done? Francis R., Tulsa

A: Irises 
Of the many types of irises, the most commonly grown are hybrids or bearded irises. Bearded irises are the ones that have a hair-like structure on one of their lower flower blades, along with showy, multicolored blossoms.

They usually bloom in spring or early summer but then go dormant until the fall. These irises should be divided every three to four years during late summer to early fall.

Irises have a root-like structure called a rhizome from which they reproduce. It is a slender potato-like structure. As a plant grows and blooms, it produces small baby rhizomes at the edge of the mother plant.

It’s these young rhizomes that produce new plants. The mother rhizome will not bloom again. These new rhizomes will have small buds where they will produce new plants.

To divide: Dig up the whole structure, trim the iris blades to 6-8 inches in length and separate out the new rhizomes by cutting or breaking away from the parent structure. The goal is to get young rhizomes that have one to three small buds, along with a few healthy leaves and some roots. Discard the rhizomes that are mushy or appear diseased.

To prepare the soil: The new planting area should be prepared beforehand. Irises do well in a range of full sun to afternoon shade, but they must be planted in well-drained soil to prevent rot. If you have a clay soil, incorporate several inches of organic compost to aid in drainage. A slow-release fertilizer mixed into the soil is optional, but beware that too much nitrogen will increase disease susceptibility.

When planting, cover the roots well, but the rhizome should be shallow, preferably less than 1 inch deep with the top of the rhizome slightly out of the ground. If planted any deeper, it likely will not bloom. Do not mulch, as it may cause disease.

Dividing and transplanting bearded irises will improve health and produce more blossoms, but be aware that they may not bloom the first year after moving.

Daylilies

Division of daylilies, as well as hostas, may be done in either the spring or fall. But in our area, fall division is preferable as replanting will allow for considerable root growth before next spring.

Before digging, trim the leaves to 6 inches or so and water the plants to loosen the soil. Dig the plant with a large root ball and wash the soil from the roots with a hose. This will allow you to tease out individual plants without cutting them. The goal is to have plants with three or more leaf fans and a healthy-looking clump of roots. A large clump of daylilies may yield several new plants for you and your gardening friends.

When replanting, prepare your site beforehand by mixing in a generous amount of good organic compost and making sure the new location will get several hours of sunlight. Adding a slow-release fertilizer into the soil at planting is optional.

Garden tips

·       Begin preparing your outdoor plants for a move indoors. Move houseplants indoors when the outside and indoor temperatures are about the same. For plants in full sun, move to shade. Begin with light and then heavier shade over a week’s time to prepare the plant for the low light indoors. If you move the plant from full sun to a low-light indoor situation, the plant may experience “shock,” lose leaves and perform poorly inside.

·       Inspect plants for insects and disease and treat accordingly. In many cases, a few insects can be controlled by hosing down the plant and removing by hand. Another option is to use an insecticidal soap spray. This is effective and safe for you and your plant.

·       Also consider drenching the pot with 2-3 pot volumes of water to help remove insects and residual fertilizer salts.

Fall is the Best Time to Reseed Fescue

Reseeding Fescue in the Fall

Brian Jervis: Ask A Master Gardener

September 19, 2017

Q: My fescue thinned out during the summer. How should I reseed it and when is the best time? SJ

A: Tulsa is located right between the ideal climates for growing turfgrass. Warm-season grasses do much better south of here, and cool-season grasses do better north of here. As you can imagine, this complicates our turf choices and how we care for those grasses.

Fescue is a good choice for areas of your landscape that are shaded, although no grass can grow without any sun. Fescue thrives in spring and fall, stays green in winter but struggles with Oklahoma summers. As a result, most of us need to re-seed our fescue each year to keep a healthy, thick turf.

Cool-season grasses, like fescue, germinate best when the soil temperature is in the 70-degree range. This happens in the spring and the fall, but fall is the best time to re-seed as this gives the turf more time to develop a healthy root system. The last half of September through the first half of October usually gives us the soil temperatures we need.

For best results, we recommend purchasing seed with a blend of at least three different types of seed, rather than a single cultivar. Doing this not only increases your likelihood of success, but also by combining grasses, the incidence of disease is typically reduced, as each type tends to mask the weaknesses of the others.

It is also a good idea to prepare your soil, rather than just sprinkle seed on the ground. The upper layer of soil can develop a crust so seeds dropped on this hard surface will either blow or wash away before they have a chance to germinate. Breaking up the soil can be done with a rake or by perhaps renting a tiller or verticutter for difficult situations.

Seed should be sown evenly with either a rotary or drop spreader. A drop spreader gives you more control over where your seed goes but either will work. Fescue seed should be applied at a rate of 3-6 pounds per 1,000 square feet when reseeding and a rate of 6-8 pounds per 1,000 square feet when seeding a new lawn.

The seeds must have water to germinate, which may mean watering twice a day for a few minutes for the first 2-3 weeks. Once the seedlings are 1-2 inches tall, you can begin watering less frequently and for longer periods.

Fertilization will also be necessary, and we recommend getting a soil test from the OSU Extension so that you will know exactly which nutrients your soil requires for best performance.

We have quite a bit of information at our Diagnostic Center and on our website, tulsamastergardeners.org, to help you maintain your new and existing turf. Ask for fact sheet HLA-6419.

Garden tips

·        Watch for fall specials at garden centers and nurseries because fall is a great time for planting many ornamentals. Choose spring-flowering bulbs as soon as available.

·        Fertilize established fescue lawns with one pound of actual nitrogen fertilizer per 1,000 square feet now and again in November. Do not fertilize Bermuda or zoysia lawns until next spring. Late fertilization of these warm-season grasses may promote disease.

·        Winter broadleaf weeds like dandelion will begin to emerge in late September, which is also the best time to control them with a 2, 4-D type herbicide.

·        September and early October is garlic-planting time with an aim for harvest in June of next year. There are many varieties from which to choose. OSU suggests German Red, Inchilium Red, Silverskin and Spanish Roja for varieties, which do well in our area.

Most Wasps are Beneficial

Wasps Should be Respected, But Most Are Beneficial

Allan Robinson: Ask a Master Gardener

Tuesday Sept. 12, 2017

Q: I have noticed a lot of wasps buzzing around and landing in my yard lately. What is going on, and should I be concerned? Beth H., Tulsa

A: There are several types of wasps that we encounter throughout the year. The more popular ones are red wasps and yellow jackets, both of which are quite aggressive toward humans and produce a painful sting. But there are a couple of other less common wasps that are much more beneficial, as they tend to attack other pests rather than humans.

First, digger wasps come in many sizes and colors including yellow/black-striped, black, blue, brown, white/orange or yellow. In general, they will use the same area of the yard over and over until their population is eradicated. While they are not aggressive and do not defend their nests, stay clear of them because their sting and venom may cause an unexpected allergic reaction. The first year these pests start to nest, they usually go unnoticed but then grow exponentially each year thereafter. Working in the same area, most prefer to dig in bare ground between grass and plants, through cement mortar joints and even under walkways. Most are predatory feeders, foraging for grubs, small flying insects and ground-dwelling pests. Once food is found, it is stung to death, brought back to the nest and buried. Eggs will be laid on it so that hatching larva will have a ready food supply.

They are generally beneficial and do not need to be controlled. But if you choose to do so, control is fast, easy and effective once the general nest site has been found, using an insecticide dust labeled for wasps. It generally works as a desiccant and will dehydrate all active wasp stages in just a few minutes.

Secondly, the cicada killer is a large black, orange and yellow wasp that prefers to nest in bare areas around homes and in flower beds feeding on flower nectar. The females catch and paralyze cicadas, place them in a burrow in the soil and lay an egg on them to provide a fresh food source for their larva. Because they specialize on one type of prey, they tend to become more numerous as cicada activity increases in late summer and fall.

In spite of its formidable size and burrowing habit, this wasp is unusually docile and harmless. Although capable of inflicting a painful sting, the female cicada killer wasp is usually difficult to provoke. Mating males are aggressive and are more easily disturbed but cannot sting. An unsightly mound of soil surrounds the burrow of each cicada killer as they prefer to nest in areas of sparse vegetation.

Garden tips

·        Now is a good time to submit a soil sample to the OSU Extension office for testing. Do this before reseeding fescue or creating a garden bed this fall. Call the Master Gardener office at 918-746-3701 for instructions.

·        Tall fescue should be mowed at 3 inches and up to 3½ inches if it grows under heavier shade. Don’t fertilize fescue lawns until it cools in September, then fertilize again in November.

Attracting Birds into the Landscape

Attracting Birds to the Landscape

Tom Ingram: Ask a Master Gardener

Tuesday, September 5, 2017

Q: I love watching the birds. What can I do to help attract more birds to our yard? SM

A: Birds are not only beautiful and fun to watch, but they also help manage insect populations and maintain an ecological balance in outdoor environments. To attract birds, you are going to need three things: food, water and shelter.

Many plants are beautiful but not all provide a food source for birds. Filling the yard with plants that bear fruit or seeds are best for habitat development. Native plants are always a good option, as native birds are adapted to these plants that are often drought-, heat- and cold-tolerant, as well as proven bird attractors.

Vines on fences are also prime real estate for food, nesting and shelter. Clematis, honeysuckle and grapes would fit in this category.

A healthy lawn can also contribute to attracting birds, such as robins, mockingbirds and flickers, as they love to eat insects and worms.

You may want to consider supplemental feeding via a bird feeder, especially in bad winter weather. Just remember not to locate your feeder closer than 10 feet to shrubs and trees so birds have time to escape in times of danger.

A source for water is often overlooked but is nevertheless an important component in your bird sanctuary. When we think water for birds, we typically think birdbaths. However, a variety of water features or fountains may make for a more interesting water source. Whatever you choose, the water should not be more than two inches deep and have a clear area of 10 feet in diameter to prevent predators from sneaking up on your birds while they are enjoying the water. A rock in the water for standing is also a good idea. Be sure to wash your water feature every three or four days and disinfect with bleach once or twice a year.

Last but not least is shelter. Shelter can be provided in a variety of ways. A pile of broken branches or pruning clippings will attract cardinals, wrens, towhees and sparrows. Trees and shrubs with dense branches, leaves or perhaps thorns will also provide excellent shelter. In addition, birdhouses or nest boxes can be added to your landscape.

We have an excellent fact sheet with information on Landscaping and Gardening for Birds that is available on our website, tulsamastergardeners.org, or by contacting the Master Gardener office. Ask for fact sheet #HLA-6435.

Garden tips

·        In fall, strawberry plants build up food reserves and form fruit buds for the next year’s crop. They should be fertilized between mid-August and mid-September with a nitrogen fertilizer such as ammonium sulfate at a rate of 1.5 pounds per 100-foot row. Apply 1 inch of water if no rain is expected.

·        You have all of September to plant cool-season vegetables like spinach, leaf lettuce, mustard and radishes, and until the middle of September to plant rutabagas, Swiss chard, garlic and turnips.

·        The last nitrogen fertilizer application of the year on warm-season grasses should be applied no later than Sept. 15.