November 2016

Oklahoma Cooperative Extension Service Division of Agricultural Sciences and Natural Resources Oklahoma State University

Gardening Tips for November

David Hillock

Lawn and Turf

  • Fertilize cool-season grasses like fescue with 1 pound nitrogen per 1000 sq. ft.
  • Continue to mow fescue as needed at 2 inches and water during dry conditions.
  • Control broadleaf winter weeds like dandelions (HLA-6601).
  • Keep falling leaves off fescue to avoid damage to the foliage.

Tree and Shrub

  • Prune deciduous trees in early part of winter.  Prune only for structural and safety purposes.
  • Wrap young, thin-barked trees with a commercial protective material to prevent winter sunscald.
  • Apply dormant oil for scale infested trees and shrubs before temperatures fall below 40 degrees Fahrenheit.  Follow label directions.
  • Continue to plant balled and burlapped and containerized trees.
  • Watch for arborvitae aphids, which tolerate cooler temperatures in evergreen shrubs.


  • Tulips can still be successfully planted through the middle of November.
  • Leave foliage on asparagus, mums, and other perennials to help insulate crowns from harsh winter conditions.
  • Bulbs like hyacinth, narcissus and tulip can be potted in containers for indoor forcing.


  • Leftover garden seeds can be stored in an airtight container in the refrigerator or freezer until next planting season.  Discard seeds over 3 years old.
  • Gather and shred leaves.  Add to compost, use as mulch or till into garden plots.
  • Clean and store garden and landscape tools.  Coat with a light application of oil to prevent rusting.  Drain fuel tanks, irrigation lines, and hoses.  Bring hoses indoors.

Fruits and Nuts

  • Delay pruning fruit trees until next February or March before bud break.
  • Harvest pecans and walnuts immediately to eliminate deterioration of the kernel.

Sweet Potatoes are Super Roots!

Lynn Brandenberger

Sweet potato (Ipomoea batatas) is in the morning glory family and although it is grown as an annual root crop, it is actually a perennial.  This crop is thought to have originated in Central and South America and does well in hot climates.  Orange fleshed sweet potatoes supply high levels of Beta carotene and vitamin C and all varieties have lots of carbohydrates and fiber (Peirce, 1987).  So why all the fuss about sweet potatoes?  Well for starters, many growers and gardeners in Oklahoma have a tough time growing summer vegetable crops due to the high temperatures that we experience most summers.  There are two ways to approach that problem, first you can do everything possible to improve the environmental conditions for crops that don’t do that well in hot situations i.e. tomatoes, or you can find a crop that loves heat i.e. sweet potatoes!  The choice is yours. It all depends on if you want to fight the heat, or find a crop that appreciates the heat.  Sweet potato can be grown in a fairly wide range of soils and once it is established will grow fast enough to shade out weeds thereby solving another problem that we often face in vegetable production, weeds! 

Sweet potato is planted in soil using slips which are basically shoots that are grown from the “seed” roots saved from the previous year’s crop.  Fact sheet HLA 6022 Sweet Potato Production outlines the steps in growing sweet potatoes commercially or in the garden.  HLA 6022 also covers how to grow your own slips and all the pertinent information on production i.e. crop spacing, fertility, etc.  It is available at:

During the past few years we have done several sweet potato trials and found that there are several varieties that perform well in Oklahoma including:  Covington, Beauregard, and Evangeline.  All of the varieties mentioned above are orange fleshed which is great for their nutritional quality.  There are also some white or cream-fleshed varieties including Bonita and O’Henry.

So. . . If you are worn out from fighting with the summer heat in your garden, give sweet potatoes a try, I think you’ll be amazed at how they grow and produce.

Fall Cleanup

David Hillock

As plants in the landscape go dormant or are killed off by colder temperatures, it is a good time to do some fall cleaning in the landscape.

Leaves falling from trees are a good source of mulch and compost. In wooded areas where there is little understory growth it is best to leave the leaves to decay naturally. If there are groundcovers or turfgrasses growing in the area then it is best to remove the leaves and compost them or use them as mulch.

Most landscape debris can be chipped or ground up to be used in compost piles or as mulch. However, if plants have been plagued with diseases and insects it may be best to remove them completely from the garden by burning them (if allowed in your community) or sending them off to collection facilities. Debris infected with diseases or insects remaining in the landscape will only become a source for infection next year.

Sanitation is an important step in reducing outbreaks of pest problems. A good example is the twigs that frequently fall from trees like pecan. It is very possible they are infected with the larvae of a twig girdler. Larvae overwinter in the dead twigs, eventually pupating in the twig and emerging as an adult next summer. Another good example is the numerous foliar diseases that also overwinter on dead leaves and debris only to spread to new growth the following spring. Removing these organisms from your garden will reduce the chances of them recurring the following year.

Another practice during the fall and winter months that helps keep pests at bay is occasionally tilling fallow ground. Flower or vegetable beds that remain empty during the winter months can be tilled just before freezing temperatures. Hibernating insects are brought to the surface where they will be exposed to and killed by the cold temperatures.

Houseplant Care

David Hillock

With cooler temperatures of fall and winter fast approaching our gardening interest often turns from plants outside to plants indoors. Success with houseplants is governed by one’s careful management of light, temperature, water, nutrients, and humidity, along with using the proper potting medium.

Light – Very few plants tolerate dark corners. Most houseplants require the light that would be found within four to eight feet of a bright south window. Some will tolerate a spot very near the window, while others will prefer less light some distance away. Too little light can result in tall, lanky, small-leafed plants. Too much light can cause leafburn on sensitive species like African Violet. If the room is not naturally lit, artificial lights should be used.

Temperature – Most houseplants prosper in a temperature of 65°F to 75°F, but the humidity of the average home is too low to suit them. A plant prospers in relative humidity of about 50 to 60 percent, which is more than most people like. This can be helped by using a humidifier or by setting the pot on a tray of moist gravel or pebbles. Do not allow the water to touch the bottom of the pot, as the water would then be wicked into the potting medium and keep the plant too wet.

Watering – More houseplants succumb from improper watering than from any other single cause.

In general, most houseplants need to be thoroughly watered and then allowed to nearly dry before the next irrigation. Use tepid water when watering houseplants. Enough water needs to be poured over the potting medium to allow water to drain freely through the drain hole at every watering. If water does not drain out the bottom, rewater until it drains freely. Never leave a houseplant standing in water, as this will cause the roots to rot.

Drainage – Drainage is an integral part of watering a plant. Do not include aggregates in the bottom, since the aggregate actually slows water’s movement through a pot. If a decorative, drainless pot is desired, it would be better to use a “pot within a pot” technique: pot the plant in a container with drain holes and then set that into the larger, decorative pot. Never allow excess water to collect in the outer pot.

Potting Medium – Consult your local garden center, greenhouse, or florist for help selecting an appropriate potting medium. It is important that the potting medium has good water holding capacity, yet is loose enough to promote good drainage and aeration.

Fertilizers – The easiest way to fertilize your houseplants is while watering. Select a houseplant fertilizer and dilute according to label directions. Houseplants can be fertilized at every watering with a very dilute rate, or fertilized at a slightly higher rate once every third or fourth watering. Do not fertilize as often or as much in the winter, in dimly-lit rooms, or in potting mixes that contain soil.

For more information about growing and maintaining houseplants see OSU Extension Fact Sheet HLA-6411 Houseplant Care.

When Should I Cut My Perennials Back?

David Hillock

A common question this time of year is, “When do I cut my perennials back?”  Most plants are going dormant for the winter and may seem a bit ugly to some.  However, most perennials would benefit from keeping their dormant foliage during the winter.  The canopy of dead foliage actually provides protection to the crown of the plant against the harsh winter months (a natural mulch) and at the same time catches and distributes valuable precipitation to the plant roots.

An added benefit is winter beauty.  You may have to stretch your imagination a little, but the natural tones of brown, tan, gray, white, etc., adds a subtle beauty and purpose to the garden.  Picture if you will the leaves, flowers, and stems of ornamental grasses swaying back and forth in a breeze, the black seed-heads of black-eyed Susan, and the faded blossoms of Autumn Joy sedum.  Some perennials may also be useful in attracting winter wildlife to the garden.

There are, however, a couple reasons you may want to cut back the foliage of your perennials.  If they have been riddled with pests, it is a good idea to get rid of the affected foliage so that the pest does not overwinter.  Another reason may be to reduce rodent populations, which may take up residency in such a nice environment.

Plants Provide Winter Interest

David Hillock

Landscapes can be somewhat boring and uninteresting during the winter months. However, there are several landscape plants that provide ornamental interest and even color during the dormant season. Listed below are a few suggestions.

Plants with attractive bark/twigs (some more attractive when defoliated):

Heritage River birch – Betula nigra ‘Heritage.’ The bark of the Heritage river birch exfoliates on young trunks revealing a white to salmon-white bark color on young stems that darken to a salmon-brown as tree ages. River birch prefers acid soil (6.5 or below) and moist areas though they survive drier soils.

Redosier dogwood – Cornus sericea. The stems of the redosier dogwood are slender, bright red to dark blood red. The bright red color of the stems is very effective against a light background particularly when it snows. Dogwoods do best in moist soils. A cultivar of the redosier dogwood is the yellowtwig dogwood – C. s. ‘Flaviramea.’ Stems are yellow. Yellowtwig dogwood also does best in moist soils and will often become inflicted with canker under stressed conditions.

Japanese kerria – Kerria japonica. Japanese kerria forms a low, broad-rounded, dense shrub with upright-arching stems. The twigs are slender and green throughout the winter. The stems have a zigzag pattern and are smooth, glossy, and supple. This plant grows well in full shade.

Harry Lauder's walkingstick – Corylus avellana ‘Contorta.’ The stems of Harry Lauder’s walkingstick or contorted filbert are curled and twisted, which can be quite the attraction. Leaves are also twisted, making some think the plant is sick, thus the winter effect is better appreciated.

Plants with showy, fleshy fruits/seed heads:

Deciduous Holly – Ilex decidua cultivars. There are many evergreen hollies available but the holly I like most is the deciduous. There are several cultivars available with fruit colors in red, orange, yellow, and red-orange. Warren’s Red is a common cultivar that is usually loaded with bright glossy red fruit that persist into the winter. Deciduous holly is particularly appropriate for harsh conditions where evergreen selections would normally suffer. Plants are either male or female, and in general, need both for female to bear fruit.

Black and red chokeberry – Aronia melanocarpa, A. arbutifolia respectively. The fruit of chokeberry are blackish purple or glossy red. These plants will often sucker forming large colonies. Chokeberry makes a nice planting when planted in groups or massing and is well adapted to a wide range of soil conditions, tolerating both wet and dry soils.

Hawthorn – Crataegus spp. There are many hawthorn species several being native to Oklahoma. The fruit display can be spectacular in the fall and into the winter. Color of fruits can be bright to dull red, scarlet, orange, yellow, purple, or blue depending on species/cultivar. This small tree can be severely affected by pests but the fruit display is usually worth it.

Ornamental grasses, sedges, etc. Numerous ornamental grasses and sedges offer vertical texture for the garden as well as flower heads that change in color as they mature. Winter colors are often a mellow tan, gray, gold, and brown.  Flower and seed heads capture light and sway in the slightest breeze.

Plants that flower late or early in the year:

Witchhazels – Hamamelis spp. Witchhazels are unique in that they flower during the winter months from November through March depending on species/cultivars. The flowers are yellow, orange to red also depending on species/cultivar. The flowers are fragrant, very small and thus should be planted in the landscape in an area where they can be viewed up close. Witchhazel prefer moist, acid soils in sun or part shade.

Winter jasmine – Jasminum nudiflorum. Winter jasmine is a tough, broad-spreading mounded shrub that flowers from January to March. The flowers are slender tubular-shaped, and bright yellow. If winters are mild the plant responds to the slightest degree of warm weather and may flower earlier than normal.

Winter honeysuckle – Lonicera fragrantissima. Flowers of winter honeysuckle are creamy white, lemon-scented and extremely fragrant. Flowers open in January, peak in February, and may still be flowering in mid-March. Not the showiest flower, but certainly among the most fragrant.

Winter Protection of Broadleaf Evergreens

David Hillock

A group of plants that often experience winter damage are the broadleaf evergreens such as hollies and boxwood. Water loss can cause severe damage to broadleaf evergreens during winter when high winds or temporary warm weather causes a plant to give off an unusually high amount of moisture.

When this water loss occurs at times when the ground is frozen, roots cannot take up moisture to replace lost water. The result is a browning or burning of the foliage.

Various management practices may help to prevent winter damage. Make sure the plants enter the dormant season in a healthy and vigorous condition with adequate soil moisture. Check to see that the center of the plant is free of dead leaves and other debris. And be sure to continue watering during the dry winter months. Monitor weather conditions and water during extended dry periods or about one to two times per month. Water only when air temperatures are above 40 degrees F. Apply water at midday so it will have time to soak in before possible freezing at night. Mulch the plant with wood chips to reduce water loss from the soil. Mulch also protects the plant by preventing rapid temperature changes at the soil surface.

Boxwoods seem to be more susceptible to winter damage. Boxwoods placed in sites exposed to winter winds tend to experience more damage. Provide wind protection for plants in exposed situations by creating a simple wind break. Use snow fences or stretch burlap between stakes or over a lattice frame set next to the boxwood. Or you can stick pine boughs in the ground around plants to form a wind break. When planting boxwoods, it is best to avoid exposed, windy sites.

Large boxwoods may be protected against ice damage by wrapping the outer branches with strong nylon cord. Tie the cord securely to a low branch, pressing the boughs upwards and inward; wrap cord in an upward spiral around the bush, having cords 8 to 10 inches apart. Have cord tight enough to prevent breakage from excess weight of snow or ice, but not tight enough to exclude air circulation around the plant.

Star Pine - the Mini Christmas Tree

David Hillock

When I got married we lived in a studio apartment where there wasn’t much room for a full sized Christmas tree. Instead of the traditional tree we opted for something a little smaller and manageable – the Star Pine or Norfolk Island Pine, Araucaria heterophylla.

Not really a pine at all, but a tropical evergreen with needles and a wonderful layered branching habit that can double as a houseplant and a Christmas tree. The branches of star pine are not as sturdy as pines and other evergreens used for Christmas trees so decoration should be light and simple. We used ribbons and beads and other natural materials to decorate our tree. Depending on the size of the tree (from 12” plants packaged and sold specifically for the Christmas season or as larger containerized plants several feet tall) various Christmas ornaments may be used if done sparingly. The traditional Christmas glass balls, which come in many sizes, work very well. Just remember that simplicity is the key as overloading the branches could put undue stress on the plant.

Stare Pines do best in brightly lit areas, but out of direct sunlight. A fertile, well-drained potting soil works best for optimum growth. Keep the soil slightly on the drier side, only barely moist. Overwatering will result in yellowing and shedding of the needles. Fertilize every few months with a complete fertilizer. Pests such as spider mites can occasionally be a problem. Spray only when needed and with the appropriate houseplant insecticide.

Upcoming Event

Global Horticulture Conference
November 17, 2016
Wes Watkins Center, Stillwater, OK

This conference is designed to allow attendees a better appreciation of horticulture and related disciplines throughout the world.  Speakers will address both ornamentals and edible crops.  Presenters also have the option of commenting upon customs and traditions of countries discussed.  For more information visit


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