Preparing Your Landscape for Winter

Preparing Your Landscape for Winter

Brian Jervis: Ask a Master Gardener

Tuesday, November 21, 2017

Q: While the main growing season is over, there must be some things that I can do to prepare my landscape plantings for winter. What are some of the things that I should and should not be doing? Lisa M., Tulsa

A: The average winter temperatures we experience are normally not sufficient to cause extensive winterkill in established plants rated for our hardiness zone (6b to 7). Most plants that do suffer from weather stress are unhealthy to begin with or are simply unsuited for our environment.

If you have been fertilizing over the summer, now is the time to taper off. Hardy plants like trees, shrubs and perennials need to be allowed to go dormant. Fertilizing at this stage may cause a delay in this process and may encourage tender new growth that is especially susceptible to freeze damage. If plants appear weak or a soil test shows serious nutrient deficiencies, wait until after a frost to do any correction. Always follow label instructions and water well.

Pruning should also be kept to a minimum when you are prepping your landscape for winter. Not only can pruning stimulate unwanted new growth, but also in many spring-blooming plants, you will be removing next season’s buds. In addition, you will remove some of the energy that plants made in summer and have stored for winter use. It is perfectly acceptable to cut out any dead or diseased wood, and you should remove all debris from around plantings, thus discouraging any overwintering pests or rodents.

Lack of moisture is a major cause of winter stress for plants. It’s important to keep up with a watering schedule, especially if we are not experiencing timely rains. Longer, deeper watering is always recommended over frequent, shallow watering. You want to get moisture down below any frozen ground. Don’t overlook container plants or plants under eaves that won’t benefit from rains or snow.

And don’t forget the mulch. Not only will a good layer of mulch protect stems and roots from freeze damage, but also it will help moderate soil temperature and moisture. The key is not to mulch too early. Wait until after the first killing frost to lay any additional mulch. And when placing mulch, take care not to pile it around and next to tree trunks and stems as this can cause unnecessary damage. If your roses have not been mulched, do so now. This is a good place to use those fall leaves that have been shredded with a mulching mower. Mulch not only prevents cold damage to susceptible plants, but also will prevent warming of soil on warm winter days, which may promote premature cold-sensitive new growth.

Another consideration is to leave last year’s plants that have seeds on them (such as the purple coneflower) in place until spring. Coneflowers have seed heads that finches love to feed on in winter.

Finally, don’t forget to keep the compost pile watered. The decay process to produce garden-friendly compost continues into the winter if the pile is large enough and kept watered and turned.

Garden tips

• Fertilize cool-season grasses like fescue with 1 pound nitrogen per 1,000 square feet. This should be the last fertilization for fescue until next spring. Do not fertilize Bermuda or Zoysia until green-up next April.
• Spring-flowering bulbs like hyacinth, narcissus and tulip, which are sold for “forcing,” can be potted in indoors for a colorful winter display.
• Tulips can still be planted outdoors through this month.
• Autumn leaves have good uses other than placing them in the trash. They may be mowed directly into the lawn, which will add nutrients and organic matter; shredded with a lawnmower and added to the compost pile; used as mulch or tilled into the soil of your garden beds.

Controlling Pocket Gophers

Controlling Pocket Gophers

Tom Ingram: Ask a Master Gardener

Tuesday, November 14, 2017

Q: I’ve got these mounds of dirt appearing in my yard. Are these moles or gophers, and how do I get rid of them? GM

A: What you are describing are the mounds of excavated soil the pocket gopher pushes to the surface as they tunnel looking for food. The mounds are usually semicircular in shape, possibly 18-24 inches in diameter and about 6 inches high. The opening through which soil is pushed is finally plugged, which leaves the familiar small circular indention on one side of the mound.

Pocket gophers are members of the rodent family and get their name from their ability to carry food in fur-lined external cheek pouches. They have short legs, a stocky body and strong claws used for digging. Pocket gopher’s favorite foods include roots of trees, grass, seeds, leaves, tender stems, tubers and bulbs.

A single pocket gopher may make as many as 200 soil mounds in a year and are most active in the spring and fall. They are primarily solitary creatures, except during the breeding season and when young are present.

In large fields, we would encourage you to take no action toward your guests as they contribute to the formation and condition of the soil while providing food for larger predators. However, control may become necessary when they begin eating garden crops, roots of fruit trees and shrubs, etc.

While poison baits can be effective in eliminating pocket gopher populations, the danger these baits present to animals and humans usually suggest the use of traps.

The best way to trap pocket gophers is to locate the freshest mound of dirt. Oftentimes, the freshest mound is the darkest in color, as it is still moist. Several inches from the indention side of the mound, stick a probe into the soil 4 to 10 inches in depth to locate the tunnel.

Once located, dig an appropriate sized hole to allow access to the tunnel. Because it is hard to know which direction the gopher will come from, place two traps in the tunnel; one facing each direction.

Now, for an important tip. Always tie one end of a strong cord or wire to the trap and secure the other end to a piece of wood or brick on the surface as trapped gophers may take off down the tunnel with your trap in tow. This is a good way to lose a trap. Once your traps are secured, cover up the hole with a rock or a handful of grass to cut off most of the light, and wait.

Instinctively, pocket gophers will sense their tunnel has been compromised and attempt to fix the breach, which brings them to your trap. If you are not successful after a day or so, recover your traps, rake out the soil from the mounds over your yard, and keep an eye out for fresh mounds.

Garden tips

• Apply dormant oil for scale-infested trees and shrubs before temperatures fall below 40 degrees. Follow label directions.
• Continue to plant balled and burlapped trees.
• Wrap young, thin-barked trees with a commercial protective material to prevent winter sunscald.

The Why What and How of Soil Testing

Soil Tests Explained

Brian Jervis: Ask a Master Gardener

Tuesday, November 7, 2017

Q: I’ve heard people say that it is impossible to know what kind of fertilizer and how much to use if you don’t know the chemistry of your soil. Is this true? RD  

A: The short answer to this question is yes, and, fortunately, we have an easy, cost effective way for you to test your soil chemistry.

The best way to understand how soil chemistry works is through an analogy. Assume we didn’t have the ability to measure the levels of gas or oil in our automobiles. If this were the case, we might just decide to add $10 worth of gas and a quart of oil whenever we went to the gas station. However, if we took this approach, we may not have enough gas to get to our destination and are quickly going to have oil all over our engine.

In this analogy, nitrogen is like the gas for our cars while phosphorus and potassium are like the oil. Nitrogen is the primary nutrient that fuels plant growth and gets consumed in the process. Phosphorus and potassium are similar to the oil in our analogy in that they do not get consumed to the same degree, but appropriate levels of these elements are necessary for effective nutrient absorption. A soil test is the gauge we need to assess the levels of these nutrients in our soil.

To perform a soil test, you will need something to collect your samples with and a bucket. We recommend you get between 15 to 20 samples of soil from locations scattered throughout your yard. Each individual sample does not need to be large but needs to go to a depth of about 6 inches. A bulb-planting device works well to gather these individual samples.

Once you have your samples in a bucket, mix them up and remove any sticks or debris. From this mixture of soil, bring a representative sample to the OSU Extension office. We will only need about a sandwich bag-sized amount of soil for your test.

When we receive your soil sample, we will send it to the Soil Science Lab at Oklahoma State University for analysis, and within two weeks, you should receive the results. Your results will contain the levels of nitrogen, phosphorus and potassium found in your soil, along with the pH level. Included will be a recommendation on the nutrients you need to add and how much, along with recommendations on perhaps the nutrients you need to stop adding.

The test has a cost of $10, but in all likelihood, it will be the best $10 you have ever spent on your lawn or garden. If you want to test a smaller garden or flowerbed, this will require a separate test, as those environments would be unique from your lawn. The same instructions would apply.

Garden tips

·        Leftover garden seeds can be stored in an airtight container in the refrigerator or freezer until next planting season. Discard seeds more than 3 years old.

·        The garden centers still have large selections of spring-blooming bulbs for sale. If you intend to plant bulbs, buy them and plant soon. Tulips can still be successfully planted through the middle of November.

·        Be sure to keep leaves off newly seeded fescue. The sprouts will die without sun and air 

Planting Trees in the Fall

Planting Trees in Fall

Allen Robinson: Ask a Master Gardener

Tuesday, October 31, 2017

Q: I have heard that fall is a good time to plant trees. Is that true? If so, what do I need to do to be successful? Roger L., Broken Arrow

A: Fall is clearly the best time to plant most container-grown deciduous trees and those with balled and burlapped root balls. In the fall, the trees have huge energy stores that may be used for growing new roots, rather than producing leaves and fruit. This will allow the tree to enter the following growing season better able to handle the summer stresses. Also, although the air temperatures are dropping, the ground temperatures are still warm enough to encourage good root development for some time. The exception to this rule is that evergreen trees and bare-rooted plants should be planted in early spring.

Of all the newly planted trees that die in the first few years, the problem is almost always due to faulty planting techniques and inadequate aftercare.

First, it is best to dig a wide but shallow, saucer-shaped hole about three times the diameter of the tree’s root ball and no deeper than the root ball itself. If you simply dig a hole the size of the root ball, particularly in clay soil, it will be similar to planting in a clay pot, and the tree will be either too dry or too wet much of the time. If you are planting in high clay soils, to help with root system drainage, the hole should be shallow enough to elevate the crown of the root ball 2-3 inches above grade.

When planting trees, it is recommended that you use only native soil for backfill. Studies have shown that trees do better if no amendments are added back to the native soil, as it may delay establishment and promote disease. If you decide to fertilize, apply a slow-release type only to the top of the soil after planting.

Eliminating grass from the tree’s base significantly improves its growth rate and health. After planting, apply 2-4 inches of loose mulch to a 4- to 6-foot circle around the base of the tree and keep it well mulched for the first three years. This circle will keep unwanted grass away from the dripline and weed eaters away from the tree trunk.

All newly planted trees need supplemental watering for the first three years until a mature root system develops. They need at least one inch of water per week and more if extremely hot and windy conditions exist. Wilting of the trees’ leaves may indicate a need for more water, but be aware that too much water can also produce wilting. If in doubt, simply feel the soil.

If the tree is on a slope or in a windy area, stake it only until the tree feels firm in the ground, which could take up to one year. After the first growing season, remove the stakes. If not removed, the stakes will adversely affect the tree’s structural integrity and delay tree growth.

Garden tips

• Keep leaves off newly seeded fescue to prevent damage to the sprouts. Also, the soil of newly seeded fescue should kept moist until the sprouts are about 2 inches, then water less often and for longer times to encourage deep root growth of the seedlings.
• Remove garden debris to prevent many garden pests and diseases from overwintering in these materials.
• Plant cool-season cover crops like Austrian winter peas, wheat, clover and rye in otherwise fallow garden plots.
• Cover water gardens with netting to keep out falling leaves.

Take Advantage of the Benefits of Fall Leaves

Dealing With Fall Leaves

Tom Ingram: Ask a Master Gardener

Tuesday, October 24, 2017

Q: Each year, it seems like I spend every weekend bagging leaves. Is there a better way to deal with the leaves that fall from my trees each year? SW

A: It’s easy to view the leaves that will soon be falling from our trees as a nuisance that just comes with home ownership. But, what if we started looking at those leaves as free fertilizer and mulch falling from the sky because that’s what they are?

If we observe what happens in nature with leaves in the fall, our first observation will be a rather obvious one: No one comes through the forest and bags up the leaves. Instead, these leaves are part of a yearly cycle that accomplishes several things.

First of all, when the leaves fall to the ground, they decompose, adding organic matter and valuable nutrients to the soil. By mowing our leaves into the turf with a mulching mower, rather than bagging them up and hauling them away, we have a free source of organic matter to help supplement our soil. Some may suggest that mulching leaves into the turf can contribute to an increased thatch layer and possibly have an effect on soil pH; however, evidence doesn’t confirm these suspicions. In fact, turfgrass with mulched-in leaves tends to perform better than turf without this additional organic matter.

Organic matter is important because it helps with water and nutrient retention, as well as improves soil structure. Oklahoma soils are typically low in organic mater — about 1 percent. So any time we can add organic matter back into our soil, we are helping to improve soil quality. Many gardeners try to achieve an organic content of between 4 percent and 5 percent, and leaves can be a yearly supplement in support of this strategy.

Secondly, leaves that fall to the ground in the forest are an effective mulch. Each spring, gardeners spend a small fortune on mulch, which they could have gotten for free with a little planning in the fall.

Mulch in your garden can help prevent weeds, reduce root damage from cultivation, increase water absorption and retention, decrease runoff and soil erosion, and help regulate soil temperature.

To use these leaves as mulch, you will need to pile them up in the driveway and run your mulching mower over them, or purchase a stand-alone leaf mulcher. Depending on the size of your garden, if you bag these mulched leaves and save them over the winter, you will have a wonderful source of organic mulch ready and waiting for you in the spring.

Garden tips

·        Keep leaves off of newly seeded fescue to prevent damage to the sprouts. Also, the soil of newly seeded fescue should be kept moist until the sprouts are about 2 inches, then water less often and for longer times to encourage deep root growth of the seedlings.

·        Remove garden debris to prevent many garden pests and diseases from overwintering in these materials.

·        Plant cool-season cover crops like Austrian winter peas, wheat, clover and rye in otherwise fallow garden plots.

·        Cover water gardens with netting to keep out falling leaves.

How to Prepare Tropical Plants for Moving Indoors for Winter

Moving Plants indoors for Winter

Brian Jervis: Ask a Master Gardener

Tuesday October 17, 2017

Q: I moved my indoor plants outdoors for the summer as they seem to enjoy it out there. Now that the weather is getting cooler, I want to move them back indoors. What do I need to do to make that move a success for them? Lisa M., Tulsa

A: Houseplants that spent their summer vacations outside are nearing time to be brought indoors. Because tropical plants may be damaged if nighttime temperatures drop into the low 40s, start bringing your plants in when nighttime temperatures start dipping below 45 to 50 degrees.

While outdoors, your plants may have picked up one of several insects, such as spider mites or mealybugs. Inspect the leaves for insects or evidence of insects, such as webbing, wet sticky areas or yellow-speckled leaves. Look in the top layer of potting soil for pill bugs and slugs. Inspect and thoroughly clean the sides and bottom of the pot and its saucer.

If you find insects, a chemical insecticide may be needed. However, if there are only a few insects, consider a different approach. A cotton swab dipped in rubbing alcohol is excellent for removing small numbers of insects. Be sure to follow this by thoroughly hosing the plant with a stream of water, even if you do not see insects, as this will help remove any hidden pests, as well as clean the leaves.

For further pest avoidance, you may wish to spray the plant with an insecticidal soap or light horticultural oil according to the product’s label. You may also mix a dilute solution of an insecticidal soap and pour through the soil, then flush the soil after 15 minutes with fresh water.

Before moving the plants indoors, especially if they have been in the sun, first move them into shade, gradually reducing lighting for at least one month before bringing them inside. Plants, especially ferns, may drop some leaves due to this transition from sun to shade. Once they are brought back into the house, be aware of how much light they are receiving.

For regularly fertilized plants, now is also a good time to leach the soil. Fertilizers cause accumulation of salt residues in potting soil, which is bad for the plant’s health. Running water through the soil and allowing it to completely drain will remove these salts. Irrigate with a volume of water approximately twice the size of the pot. Do this twice yearly.

Reduce the amount of watering and do not fertilize during the winter months. Plants do need some moist air, so a humidifier or bowls of water nearby will help to keep them healthy, but never put them near a heat vent. Plants will typically do better in a 60- to 70-degree environment, rather than overheated rooms. Finally, unless they are extremely overcrowded in the pot, it is best to wait until spring to repot them.

In the spring, wait until outside temperatures are above 50 degrees, then place them in a protected area out of any sun. Repot, fertilize, water and enjoy. Do keep in mind that some houseplants want to stay inside all year, so look up your plants’ needs in a good indoor garden book.

Garden tips

Peonies, daylilies, and other spring-flowering perennials should be divided or planted now.

Dig and store tender perennials like dahlias and caladiums in a cool, dry location. Cannas and elephant ears can also be dug, but most will survive the winter fine if mulched heavily and in a sheltered area.

Plant fall mums and asters and keep them watered during dry conditions. Don’t crowd because they take a couple of years to reach maturity.

Fall is the Best Time To Plant Trees and Shrubs

Planting Trees and Shrubs in Fall is Best

Tom Ingram: Ask a Master Gardener

Tuesday, October 10, 2017

Q: I’ve heard fall is the best time to plant trees and shrubs. Is this true? LK

A: In some ways, this may seem counter-intuitive, but fall is indeed the best time to plant most trees and shrubs. The reason for this is that trees and shrubs planted at this time have the fall, winter and spring to develop a healthy root system before our Oklahoma summer arrives.

The best way to help a young tree or shrub acclimate to its new home is to dig the hole two to three times the diameter of the root ball and no deeper than the root ball itself. If you have hard clay soil, you should plant trees and shrubs 1-2 inches above grade. For sandy soils, plant at grade level.

Plan on keeping a 4- to 6-foot grass-free mulched circle around young trees or shrubs for at least 2-3 years. This mulch should be 2-4 inches deep. Be sure to use some kind of organic mulch, such as compost, bark, grass clippings or straw. Do not use plastic under the mulch to prevent weeds, as this will limit your tree’s or shrub’s access to water.

New trees and shrubs have a limited ability to utilize fertilizer until they have an established root system, therefore, fertilization is often not recommended at the time of planting. Optimally, young trees and shrubs can be fertilized from March through July. But, before adding fertilizer, we recommend you get a soil test from the OSU Extension so you know which elements are needed in your soil.

On average, young trees and shrubs need 1 inch of water per week whether this comes from rain or hand watering. In dry conditions, newly planted trees and shrubs may need to be watered 2-3 times per week as their root systems have not developed to the point where they can replenish the water they are losing through their leaves.

Some young trees will need to be staked if top heavy or planted in windy areas. If this is the case, use only the quantity of stakes necessary and leave it a little bit of room to move, as this is how the trunk develops strength. When stakes are left in place longer than 2 years, the tree’s ability to stand on its own will be compromised.

Young trees with thin bark, such as ash, birch, linden or maple, should have their trunks wrapped with a paper tree wrap during winter for the first two years if they are exposed to the southwest winter sun. The heating and cooling by the sun during winter can cause bark damage from which the tree never recovers.

We have quite a bit of information at our Diagnostic Center on varieties of trees and shrubs that do well in our area. Give us a call or drop by; we would love to help you find the perfect addition to your home.

Garden tips

·        Plant cool-season annuals like pansies, ornamental cabbage or kale, snapdragons and dusty miller when temperatures begin to cool.

·        Prune trees or shrubs anytime there are dead or diseased limbs. Do not perform routine pruning now. Pruning before winter dormancy may stimulate new growth sensitive to the cold. Fall pruning also removes energy stores needed for winter survival. Prune summer-blooming plants in late winter before spring growth starts, and prune spring-blooming plants after blooming is completed.

·        Continue to replant or establish cool-season lawns like fescue. Mow and neatly edge warm-season grasses before the first killing frost.