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Month-by-Month Gardening Guide: October

Bulbs, Corms, Roots and Rhizomes:

Summer blooming bulbs like caladiums, dahlias and gladioli are not frost hardy in Tennessee and should be dug up this month and stored until next spring. To store bulbs cut back the top growth and dig the bulbs prior to frost.  Remove the dirt and lay the bulbs on paper to dry.  Store them in paper bags with dry potting soil in cool temperatures (45-50°F).  Gladioli bulbs can be stored loose in a mesh bag.

October marks the last month for planting your spring blooming bulbs.  Some bloomers like daffodils should have already been planted because they need a longer growing season before winter.  However, many can still be planted.  Consider sunlight when choosing a planting site. Most bulbs need at least 4 to 6 hours of sunlight daily to develop large blooms. Good drainage should also be of concern.  Select bulbs that are large, free of blemish, and have good color and weight. Planting should be done before the ground freezes in the fall. Try massing bulbs for a more natural appearance in the landscape.  Planting depth for bulbs vary but the rule of thumb is 2 to 3 times as deep as the height of the bulb.  Plant your bulbs too shallow and you may risk loss to frost damage.

Fruits and Nuts:

Your strawberry planting should be mulched to protect against winter damage to strawberry crowns and flower buds.  Apply a loose mulch to a depth of four inches after there have been several light frosts, but before a hard freeze.  Applying the mulch too early can increase crown rot disease and may inhibit the plant from going dormant.  Good options for mulch materials include pine needles, rye or wheat straw. Removing the mulch next spring is as important as applying it in the fall.  Remove the mulch when new growth first occurs.  Blooming of plants can be delayed by leaving a mulch in place and will reduce your yields.

When you think about your strawberry plants in the fall, mulch should be the first thing to mind. Mulching strawberries provides protection from cold temperatures, reduces weed competition and conserves moisture, all necessary to a strawberry’s success.  Apply 3 inches of pine needles or rye or wheat straw after several light frosts have occurred, but before a hard freeze.  Don’t forget next spring after heavy frost periods have ended to rake the straw from the plants to the isles.

Controlling weeds at the base of apple, peach and grapes helps reduce competition for moisture and nutrients, but more importantly, helps to lessen vole problems.  Meadow or Pine Voles (similar to field mice) feed on the bark of trees during winter months and can at times completely girdle and kill a tree.  Grass and weeds growing at the base of these fruit trees create a suitable habitat for the vole. Your first treatment with herbicides to eliminate weeds can be safely applied late October through early December. The second application should be made in the spring just after pruning. For apples and peach the weed-free-zone should reach from the trunk to the drip-line of the canopy. Three feet on both sides of an arbor is a sufficient weed-free-zone for grapes.

Groundcovers and Lawns:

Cool season lawns, like fescues, do most of their growing in cooler temperatures. They will benefit from an application of 1 pound of Nitrogen per 1000 sq. ft. this October.

If you have finally given up on the thinning, yellow grass you have been trying to grow in the shade why not consider perennial groundcovers. Groundcovers can be a solution to that troublesome shaded lawn and provide the additional benefits of quick growth while adding interest, either by color or texture, to a corner of your yard.

The best time to establish groundcovers is in the fall. In flat areas, it is recommended that you amend the soil by incorporating four inches of organic matter into the top six inches of soil. This will improve drainage and enrich the soil to give your plants a healthy start. On steep banks, spray unwanted vegetation with a weed killer but allow the dead plants to remain in order to prevent erosion while your new groundcover plants are getting established. If you are planning to plant under trees, you should not till the soil since this process will damage the small feeder roots of the trees. Instead, purchase smaller plants and place them around the roots of the trees to avoid excessive damage. Water newly planted groundcovers every five to seven days with an inch of water. The soil should be moist to a depth of four to six inches after adequate watering. Applying an organic mulch two to three inches deep will help reduce evaporation of moisture and weed emergence. A soil test will show how much fertilizer your plants will need and suggest any changes needed to the soil pH. The proper groundcover will add year-round beauty to your landscape and save you money on grass seed in the future. The following are some groundcovers to consider for full or part shade:

  • Bugleweed (Ajuga) – creeping growth habit with blue or purple flowers
  • Cotoneaster – flat, horizontal-growing plant with red berries
  • Liriope – grass-like, evergreen
  • Periwinkle (Vinca)- evergreen, trailing plant with purple, blue or white flowers
  • St. Johnswort – semievergreen, turns red in fall, yellow flowers in summer

Do you have trouble growing grass in shady areas? Chances are you will never see a nice dense lawn in heavy shade. Competition for water and light usually results in a sparse and spindly lawn. In these areas, consider mulch or groundcovers like Vinca minor or Pachysandra as a lawn replacement. However, if you have light shade there are some improvements that can be made this fall. Trimming lower limbs and “dead wood” from large trees can greatly increase the amount of light reaching your lawn. Also, remove fallen leaves and don’t allow them to pile up under trees.

Remember that cool season lawns, like fescues, do most of their growing in cooler temperatures. They will benefit from an application of 1 pound of Nitrogen per 1000 sq. ft. this October.

If you reseeded your lawn in September and have been watering daily with a light mist, its time to switch your watering schedule. When grass seeds are germinating they need small amounts of water frequently (almost daily). Once they are growing they need more water but not as often (about 1 to 2 inches weekly). This will encourage the roots to develop deep in the soil, which will better prepare your lawn for the dry seasons next summer.

Perennial Flowers and Vines:

If you are considering planting a vine for your trellis this fall look no further than the showy Clematis. There are over 250 species and hybrids of this vine and each differs in flower form, color, blooming time, and height. There are three general flower forms: 1) small, white flowers in clusters 2) bell-shaped flowers and 3) flat, open flowers. The largest of these blooms may grow ten inches in diameter.

Clematis require full sun, although they will respond well to light shade during the hottest part of the day. Select an open site to allow for good air movement around the plants. The soil should be rich and well-draining with a pH near 7.0. Unlike the vine’s stem and foliage, the roots of clematis should be kept shaded, cool, and moist. Select a strong support for clematis. Since this plant climbs by twining petioles, it is important that thin materials such as plastic coated wire be used to allow the vine to grab hold. The wire can be connected to wooden trellis or other supports by fastening the wire with eye hooks, leaving enough gaps for good air circulation. Clematis that are purchased in containers can be planted in the fall or spring, but bareroot plants are best planted in the spring while they are dormant. Dig a hole large enough to spread out the roots of the plant and amend the soil with an organic material. Prune the stems of the clematis back to 12 inches in height to encourage branching and to reduce stem breakage. The crown of the plant should be one to two inches below the soil surface. Water well after planting and consider planting other perennials with shallow roots around the plant to provide the shade the clematis desires. Good examples include Artemisia ‘Silver Mound’, creeping phlox, or coralbells. A two-inch layer of mulch may also be used to keep the clematis cool. Some recommended species and cultivars of clematis include:

  • C. alpina – blooms lavender or purple in April and May, grows to 8 feet
  • C. chrysocoma – blooms mauve-pink in May and June, grows to 20 feet
  • C. maximowicziana – blooms white in September, grow to 30 feet, very vigorous
  • C. tangutica – yellow blooms in July-October, grows 10 to 15 feet in height
  • ‘Barbara Jackman’ – blooms purplish-blue in May and June, grows to 8 feet
  • ‘Comtesse de Bouchard’ – blooms pink in July and August, grows to 8 feet
  • C. x jackmanii – blooms deep purple in July and August, grows to 10 feet
  • ‘Marie Boisselot’ – blooms pink from June to September, grows to 12 feet
  • ‘Mrs. Cholmondeley’ – blooms lavender blue from May to October, grows to 20 feet

Many herbaceous perennials can still be added to the garden in October. They should be planted, however, before a hard freeze to allow roots time to become established. Remember that October is typically dry in Tennessee so don’t forget to water during establishment.

Wait until spring before cutting back the tops of ornamental grasses. Many grasses will hold their seed heads and drying blades for months creating winter interest in your garden.

Many perennials are noted for their fall blooms. Garden mums typically top the list for autumn color but consider Sedums and Patrina as two alternatives to the norm. Sedum varieties Autumn Joy and Matrona are top choices for their showy blooms, succulent foliage and size (24”). Plant Sedum in sun or light shade with well-drained soil. Patrina (Patrina scabious) grows up to 4 ft. and produces bright gold blooms. These do best in full sun with well-drained soils.

Plants in Pots:

Before bringing in your houseplants for winter be sure to give each plant a careful inspection for hitching pests first. Often pests can be removed by washing plants with soapy water, handpicking pests, or using a cotton swab soaked in alcohol to rub and remove pests. Occasionally, insecticides will be need for good control, but when possible, use low risk pesticides such as horticultural oil and insecticidal soap. The following is a list of some of the pests you may expect to find on houseplants and how to control them:

  • Aphids – These pests are very common on houseplants and typically found on the underside of leaves, stems, or flower buds. They have a pear-shaped body with long legs and antennae and may be winged or wingless. Use horticultural oil or insecticidal soap to control heavy infestations.
  • Mites – Cyclamen Mites are very small pests that require a magnifying lens to be seen. They cause twisted, curled and brittle leaves where they feed and may cause injury to flower buds as well. Trim off badly infected plant parts to reduce mite populations. Emerge the infested plant (pot and all) in 110°F water for 15 minutes for control of the remaining mites.
  • Fungus Gnats – The larvae stage of this insect feeds on roots and the crown of plants. The adult gnats, a dark-colored flying insect, cause no damage but are a nuisance in the home. Avoid overwatering plants and use insecticide sprays to kill adults.
  • Scales – Several species of scale occur on houseplants, most occurring on the leaves and stems of plants. Scale suck juices from the plant causing stunted plants. If only a few scale are seen, washing with soapy water will be successful, however heavily infested plants should be discarded.
  • Thrips – Thrips are a slender, barely visible, pest that fly or leap about on a plant when disturbed. They are found most often on the leaves and flowers of plants feeding on the plant juices. Damaged foliage may be blotched or drop and flowers may be streaked or distorted. Spray the plant and soil surface three to four times on a four-day interval with an insecticide labeled for control.
  • Whiteflies – Adults of this pest have white wedge-shaped wings and resemble small snow flakes when disturbed. Whiteflies feed on leaves causing them to turn yellow and die. As with aphids and some scale, whiteflies excrete honeydew that will leave a sticky substance on the leaves. Spray with a labeled insecticide at weekly intervals for control.

If your houseplants have been enjoying a double life as porchplants, now is time to bring them indoors. Plants that have been basking in full sunlight may exhibit some signs of shock (mainly leaf drop) as they are moved indoors. You can minimize this problem by placing plants where they can receive the most sunlight, usually near windows on the south side of your home. Over a four-week period, gradually move these plants away from the window and nearer to their normal display area. Humidity indoors differs greatly than outdoors and plants may have trouble adjusting to this change. When you notice leaf drying or curling, spray the leaves with a mist of water in the morning to add moisture. Plants that require high humidity may do better in kitchens or bathrooms.

It’s also important to carefully inspect the plants for insects before they are brought in the home. You may expect to find whitefly, spider mites, thrips and even cutworms on some houseplants. Giving your plants a bath in soapy water (2 teaspoons of mild detergent to gallon of water) can remove the bigger portion of these pests. Handpicking is most effective for removal of cutworms, snails and mealybugs.

Trees and Shrubs:

There are many advantages of applying mulch around the base of your trees and shrubs this fall. In addition to helping regulate soil moisture, mulch also protects roots from winter damage and prevents mowers and string trimmer from damaging the bark of trees. However, as with most things in life, too much of a good thing can also be damaging. Often, over-zealous landscapers pile mulch a foot or more deep around the base of tree. These ‘mulch volcanoes’ appear as if a tree has just erupted from the large pile of mulch. Don’t make the same mistake in your yard because excessive mulch can lead to many problems. For example, mulch that touches the trunk of trees creates favorable environments for disease and insects. Also, it provides habitat for voles and other rodents which may feed on the bark and roots of younger trees during the winter. Maintain a mulch-free area around the trunk of the tree and at least six inches from the trunk to avoid these problems. Mulch should never be applied over three inches thick since thick layers may keep soil temperatures warmer and delay dormancy of trees. This delay can often lead to winter damage. Consider using organic mulches, such as pine bark, hardwood, or pine needles for mulch, since they will add organic matter to the soil as they decompose. Never use fresh grass clippings, sawdust or bark since they deplete nutrients, especially nitrogen, from the soil and may be toxic to trees.

Although native trees abound in our natural landscapes, it has been fairly recent that they have begun being planted in urban landscapes. This is primarily due to availability and an under-appreciation of these trees. The most compelling reason to consider planting native trees is their ability to tolerate Tennessee weather better than many other introduced plants. Although many native trees are considered drought and cold tolerant, it is important to remember that differences exists between natural landscapes and urban landscape and unless these conditions can be reproduced, including shade density or rich organic soils, your success with natives may be variable. Nevertheless, many native trees provide wildlife benefits and interesting color, form, fruits and aroma, and should not be overlooked. If you are considering a new tree for your landscape, check out some of the following natives first.

  • Buckeye Aesculus spp.
  • Silverbell Halesia carolina
  • Yellow-Poplar Liriodendron tulipifera
  • Willow Oak Quercus phellos
  • Sassafras Sassafras albidum
  • American Linden Tilia americana
  • Serviceberry Amelanchier arborea
  • Pawpaw Asimina triloba
  • Fringetree Chionanthus virginicus
  • Smoketree Cotinus obovatus
  • Sweetbay Magnolia virginiana

We are very fortunate to have so many natural woodland areas in Tennessee and perhaps there is no other time when they are more noticeable than in autumn. Fall color is a response to cooler temperatures and shorter day lengths, which signals the tree to stop producing chlorophyll, the pigment that gives the tree its green color. As the chlorophyll breaks down, we are left with the Yellows and Golds. Some trees like maples and dogwoods produce pigments that mask the Yellows and make Reds and Purples. They are intensified by sugars produced in the leaves. The average peak period is the last week in October through the first week in November. Regardless of how fall happens, it certainly is beautiful. You can add fall color to your own home lawn by simply selecting and planting trees noted for their autumn beauty. If you would like to see more Reds consider planting Dogwoods, Crape myrtle, Sourwood, Sumac and some Maples. Yellows are found in Paw Paw, American Hornbeam, American Smoke Tree, Eastern Hop hornbeam and Galaxy Magnolia. The trees listed here are considered small trees (under 40 feet tall); however even small trees need space. Consider the mature size of the tree and plant where it will have room to grow. Under a power line or 3 feet from the side of the house is usually not adequate space.

Annual Flowers and Vines:

Some annuals like pansies, violas, snapdragons and dianthus can survive mild winters in Tennessee. These can be planted in September or October and bloom to next spring. Use pine straw to give some winter protection.

Flowering cabbage and kale are slowly gaining popularity in winter gardens. These hardy annuals can be planted in the landscape in fall. After a heavy frost, when garden mums start to lose their luster, these guys can really shine. The color of flowering cabbage and kale develops when green chlorophyll begins to fade from the leaf (when temperatures drop below 50°F) and is replaced with reds, pinks and whites. Flowering cabbage has smooth leaves while flowering kale is divided into fringed-leaf and feather-leaf cultivars. All three cultivars have varieties with outstanding color.

Vegetables and Herbs:

What are you going to do with all your leaves this fall? Good gardeners know that composting makes sense. One way that takes minimal time and helps you gain maximum benefit is to apply your leaves to the garden. A layer about 2 to 4 inches deep can be spread over your garden and tilled in this fall. As the leaves decompose they add enriching organic matter to the soil, increase aeration and help hold moisture. This method also limits the amount of work required when composting in bins.

Even if you don’t till in leaves to your garden you should till under your vegetable debris. Dead plants left in the garden can become reservoirs on which many common garden pests, such as the cutworm, can continue to develop or overwinter. Overseeding your garden plot with Crimson Clover, Red Clover or rye can help provide additional nitrogen and organic matter. In the spring, this covercrop can be tilled in to the soil.

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