Donna Lee, Singh, Raghuwinder, Strahan, Ronald E., Fontenot, Kathryn, Fields, Jeb S., Kirk-Ballard, Heather
Never miss an issue of Horticulture Hints from the LSU AgCenter!
Visit the Horticulture Hints website at
Then click on the Subscribe button!
LSU AgCenter agents from the Northeast Region and the parishes they serve:
The LSU AgCenter Soil Testing and Plant Analysis Laboratory is the only laboratory that incorporates the latest Louisiana-specific soil fertility research in its recommendations system. Kits include directions for gathering soil samples, a soil test request form, a sealable plastic bag and a pre-addressed, postage-paid box.
It is that time again — time to clean out the summer garden and make way for your winter garden. Pull all spent vegetable plants and dispose of them away from your garden, especially if any of your vegetables were symptomatic of disease. Pull all weeds and, again, dispose of them away from your garden so that mature seeds cannot germinate in the garden.
You may want to think about adding organic matter to your garden. Organic matter improves the soil structure for better drainage and water-holding capacity and reduces compaction. It also serves as a pool for nutrients. Some examples of organic matter would be compost, grass clippings, dried animal manure, leaf litter and, if you are lucky enough to live close to a cotton gin, gin trash. Organic matter may be purchased from nurseries and garden supply stores.
There are two ways to apply organic matter. One is to use mulch and apply to top of soil. Over time the organic matter will be incorporated into the soil itself. The second method is to till the organic matter into the soil. Obviously, you will see the benefits of using organic matter faster than by using the first method.
If you are not planning a winter garden, think about rowing up for next spring. Once you have rows in place, try using a cover crop through the winter. Cover crops hold soil in place, reducing erosion, suppressing cool-season weeds, creating a better seedbed for spring planting and adding organic matter. Examples of cover crops are annual rye grass, wheat, vetch and Austrian peas. Mustard greens can also be used.
Donna R. Lee
Horticulture Agent for East Carroll Parish, West Carroll Parish and Madison Parish
Fall is coming, and it is time to begin gardening again for our second growing season.
Colorful containers using the beautiful purples, reds, yellows and oranges of fall are a must. For our north Louisiana weather, these planted containers will last until Thanksgiving and possibly longer.
Once you have chosen your container, you will need to add a potting mix. If you used your pot or container from spring through summer, you probably need to replace the soil with a high-quality potting mix. At a minimum, refresh by adding organic matter, such as compost.
Keep in mind the cheaper the potting soil the higher the sand content in most of the mixes. Water drains very well in high-sand-content potting mixes, but you lose the water retention capabilities.
Ornamental kale, snapdragons and sorbet violas make a dazzling container plant display.
Photo by Heather Kirk-Ballard
For larger containers consider mixing perennials with annuals. Carex, with its light green grasslike blades, makes an excellent spiller and filler. Add ornamental kale, mums and pansies for additional color, texture and leaf shape. Another beauty is blood dock with its burgundy red leaf stems and veins. Heuchera, pennisetum, dianthus and snapdragons all come in a large variety of fall colors that coordinate well together and with other perennials and fall annuals. Dusty miller adds beautiful lacy gray foliage, while lamb’s ear adds a touch of softness.
If you do not already use irrigation misters for your pots and containers, consider setting up a system now that your fall container is planted. Easy to use kits are available online and at plant nurseries and big box stores. Easy to follow instructions are included in these kits along with sample layouts. While you are at it, add a timer to your irrigation system to make your containers almost self-sufficient
Once planted, top off your container with a 1- to 2-inch layer of mulch. This gives a finished look to the plantings and helps hold moisture in for less watering.
Once the first frost arrives you can exchange any fall annuals that were used to winter annuals. Add some pine cones if you are lucky enough to have them available to you.
Donna R. Lee
Horticulture Agent for East Carroll Parish, West Carroll Parish and Madison Parish
Before we begin talking about which seeds to save, let’s talk about pollination.
Self-pollinator plants are those that have flowers that self-pollinate. Both male and female parts are included in the flower.
Open pollination is when pollination occurs by birds, insects, wind, humans or other mechanical means. If open pollinators self- or cross-pollinate with the same type and variety of plants, then the seed will be somewhat true to the parent plant. Heirloom type plants fall into this category.
Some plants have separate male and female flowers on the same plant. Multiple plants are needed for pollination. Think of sweet corn and field corn. If planted close together they can and will cross-pollinate, losing the traits of the sweet corn and the field corn. The fruit will be affected, and seed from this cross will not resemble the parent plants.
Hybrid plants are plants that have been crossed with two varieties and will have traits of both plants. These seed will not be identical to the parent plant and will have new traits, which can be good or bad.
You really need to know what type of pollinator your vegetables or flowers are to know what you will get from pollinated plants at the end of the growing season.
If you have never saved seeds before, you may want to start with simple seeds, like peas, beans, tomatoes and peppers.
To harvest peas and beans, allow the seeds still in the pod or shell to dry down. Once dry, you can then shell them and save.
Peppers will need to be left on the plant until the pods turn red, yellow or orange before trying to save the seeds. If you try to save from green peppers, the seed will not be viable since it is not mature.
Watermelon is probably one of the easiest to save. Simply gather the seeds from the melon, rinse them off, lay out to dry and then store.
Other melons that are held by fibers will need to be separated from the fibers and then rinsed and allowed to dry.
Saving seeds of squash leaves the fruit on the vine. Harvest as late in the fall as possible. Rinse, dry and store.
Tomato and cucumber seeds will need to be fermented to save. To do this, place the seeds in a container, add the same amount of water as seeds, place in a warm spot and stir daily. Once fermentation begins, you will see bubbles in the liquid. Good seed will lie on the bottom of the container, and the bad will float. You may or may not see a white mold on the surface, and this is OK. This process generally takes up to seven days to complete.
Once you have gathered your seeds, you need to store them properly for next year. A jar or paper will work well. Place them in your refrigerator, and you are done until next year.
Donna R. Lee
Horticulture Agent for East Carroll Parish, West Carroll Parish and Madison Parish
Bean seeds can be stored for next year’s planting.
Store seeds in a cool, dry place like a refrigerator.
In the fall, October is traditionally one of the driest months in Louisiana. Turfgrass and lawns will suffer in the drought and heat with weeds, insects and diseases jumping at the opportunity to bring a weakened plant down.
How do plants combat a shortage of water coupled with temperatures approaching 100 degrees? Plants’ first line of defense is closing pores on the leaves and stems, preventing further water loss, followed by wilting. Eventually, plants drop their leaves in an effort to survive and go into dormancy to conserve everything they have. Ultimately, with no relief, some plants will die.
There are things we can do to help. First, select plants that can tolerate drought. Plants differ in their use and requirements for water. Some are tougher than others. Succulent plants, especially sedums, cactus, yuccas, aloe vera, crown of thorns and kalanchoe plants are some great examples.
Unlike turfgrasses, ornamental native grasses are great drought-tolerant plants. Mostly grown for beautiful foliage, many display gorgeous flower spikes called plumes. Some commonly used ornamental grasses for Louisiana landscapes are zebra grass (Miscanthus sinensis Zebrinus); pampas grass (Cortaderia selloana); fireworks fountain grass, (Pennisetum setaceum Fireworks), which is a Louisiana Super Plant; pink muhly grass (Muhlenbergia capillaris); and panic grass or switchgrass (Panicum virgatum).
In general, many native plants tend to be the most drought-tolerant plants for the landscape because they are adapted to our climate. No one can predict just how long droughts and heat will occur. So, we can plan and plant for just this occasion. If things continue as they are and climate change occurs, we will continue to see swings in temperatures coupled with decreased water availability in the years to come.
Choosing drought-tolerant plants and native plants is a good place to start. Where you plant them is also important. Plants that are growing under the canopy of a large tree are the first to wilt because they are no match for the extensive root system of trees, so avoid planting there. Turfgrasses tend to especially suffer.
Incorporate organic matter into your soil, use mulch, weed regularly, and supplement with additional water during droughts to help. The best time to water during a drought and hot weather is the early morning and late evening to help prevent evaporation and allow the plants several hours without sun to take up the water into their system. Infrequent but deep water is best. Use soaker hoses or drip irrigation for watering.
Dr. Heather Kirk-Ballard
Assistant Professor of Consumer Horticulture
Pink muhly grass. Photo by Allen Owings.
As crazy as this may sound, preparation for the fall garden begins in August. Yes, in sticky, hot, miserable August, we can start dreaming of cool-season crops. A few vegetable seeds can be planted into trays for later planting, and the ground needs to be prepared. Check out this veggie section for a few tips on growing a wonderful fall garden.
Remove weeds completely down to the roots.
If you see transplants next to a vegetable crop, those seeds were started in August.
Plant transplants or start seed:
Beets, broccoli, Brussels sprouts, cabbage, Chinese cabbage, cauliflower, collards, lettuce, kohlrabi, kale and Swiss chard.
The crops listed next should be seeded directly into the garden:
Beets, endive, carrots, English peas, snow peas, mustard, onions (seeds, mid-to-late September), parsley, snap beans (early September), radishes, rutabaga, spinach and turnips.
Garlic toes are planted in mid-to-late September. Shallot sets can be planted all month long.
Plant transplants of:
These crops can be direct-seeded or planted by transplant:
Kale, parsley, spinach, leaf lettuce, celery, Swiss chard and endive.
These crops should be direct-seeded:
Mustard, turnips, radishes, beets, onions (early to mid-October to create sets for later) and carrots.
In south Louisiana, continue to plant transplants of:
Cabbage, cauliflower, broccoli, kale and Swiss chard.
In all of Louisiana, direct-seed:
Beets, Swiss chard, spinach, kale, radishes, mustard, carrots and turnips.
Continue to plant:
Shallots and garlic in the first part of the month.
Onion seed may be planted for transplants from mid-September through mid-October. Keep the soil moist because seed coats are hard. It may take two weeks for onion seed to germinate to a stand. Some people start the onion seed directly in the garden (planting it thick) and later pull up and transplant into final spacings. Other people start their onion seed in germination mix in trays. I prefer the germination mix in trays because it is easier to plant and maintain on a bench rather than in the ground. However, I have also seen gardeners sow the onion seed directly into the row at proper spacing. But to me this is risky especially in clay soils.
Transplant the onion sets into the garden from mid-December through the end of January. Several drills of seed may be planted on one row. Leave 6 to 8 inches between drills. I like a spacing of 4 to 6 inches between bulbs.
Pay special attention to weed control in direct-seeded onions. Control winter weeds before the onset of wet soils and cool weather. Consider planting onion plants in black plastic mulch. The mulch controls weeds, enhances growth and keeps the onion bulbs cleaner. You will also need to watch out for cutworms and thrips. For the cutworms use Dipel dust or Sevin dust on the ground. Thrips can also be controlled with spinosad, neem oil or horticultural oils. You know you have thrips when you see gray discoloration on the foliage.
Fertilize plants sparingly prior to planting in the ground. This will prevent excessive growth. The thinner the set is, the more resistant it will be to bolting when the temperatures drop. If your onions begin to bolt or bloom, pinch the blooms off to continue to increase the bulb size. About 2 to 3 pounds of 0-20-20, 7-21-21 or 8-24-24 per 100 feet of row are sufficient. Side-dress onions in the spring just before they bulb. Side-dress two additional times at two- to three-week intervals.
Dr. Kathryn Fontenot
LSU AgCenter Extension Vegetable Specialist
Bulbing onions after harvest. Photo by Kiki Fontenot
The Louisiana Super Plants program identifies superior plant material for Louisiana landscapes. Louisiana Super Plants have undergone rigorous trials at multiple LSU AgCenter locations across the state of Louisiana and have been vetted and approved by the Louisiana green industry. Louisiana Super Plants are considered university tested and industry approved.
As the summer winds down, we begin to look forward to fall and all the wonderful woody plants that thrive in the landscape. We generally recommend most woody plants be planted in the fall or late winter. This allows these plants to establish roots well before our extremely hot summers. In addition, many fall landscapes highlight amazing color provided by shrubs and trees. It is a perfect time to go get some Louisiana Super Plants to enhance your landscape.
The fall of 2020 inductions include two amazing woody plants that are well known throughout Louisiana and are popular among gardeners, landscapers, nursery growers and naturalists.
American beautyberrry (Callicarpa americana) is a native woody shrub that grows throughout the state of Louisiana. They are often found in wooded areas but can be grown as specimen plants in the landscape. While sometimes considered an understory plant, American beautyberry prefers part sun or dappled shade to thrive. American beautyberry is adapted to many soils. It can thrive in moist and drier areas but prefers acidic soils. The lime green opposite-leaved foliage provides an excellent contrast to the vibrant and eye-catching purple fruit that surround the stem at leaf nodes.
While the late summer onset of fruit is often a deep purple, forms are available in a variety of attractive colors of white, pink, burgundy and more. Birds, especially songbirds, love the large berry clusters. As a result, these are the perfect plants for someone interested in attracting wildlife to the landscape as this plant will attract birds in late summer and fall while offering a marvelous pop of color. American beautyberry is a very low-maintenance landscape plant, only needing light thinning if desired. Sheering will remove the flowers and fruit. Try planting many together to create an attractive native screen or hedge. Inconspicuous flowers fill the branches in midsummer and begin to develop green berries, which ripen into the vibrant colors in late summer to early fall.
The baldcypress (Taxodium distichum) is the state tree of Louisiana and is already iconic throughout the state. These native trees are prominent and can be observed growing throughout Louisiana and the entire southeastern U.S. They do well in moist soils and flooded areas; however, they are also adapted to dry soils, allowing them to thrive in almost any Louisiana environment. Baldcypress trees thrive in very hot humid environments, with faster growth during hot growing seasons, making it a perfect fit for Louisiana summers. Baldcypress is a deciduous conifer, which means it is one of the few cone-bearing plants that loses its leaves in the fall. At maturity, a baldcypress will grow up to 50 to 70 feet tall and as much as 25 feet wide.
The baldcypress is known for attractive pyramidal shape with lacy green needles. These needles turn a wonderful rust color in the fall prior to dropping, where they provide natural mulch and serve as protection for a host of wildlife. Baldcypress provides some of the best fall color seen throughout the state of Louisiana. Additionally, baldcypress is desired for its ornamental bark. When grown in wet conditions, baldcypress will form “cypress knees,” which provide additional aesthetics for ponds. A host of aquatic, avian and ground-dwelling wildlife rely upon these trees for nesting, food and shelter throughout the year. Baldcypress makes a great addition to any landscape, natural area or public space throughout the state and provides a conceptual connection to nature and the great state of Louisiana.
For more information on Louisiana Super Plants, please contact your local LSU AgCenter extension office or visit www. LSUAgCenter.com/SuperPlants.
Dr. Jeb S. Fields
Assistant Professor and Extension Specialist
Hammond Research Station
Storm drain clogged by leaves and lawn debris. Photo by Heather Kirk-Ballard
Louisiana usually stays warm well into the fall, and lawns continue to grow until nighttime temperatures dip into the 50s. So be sure to mow and water your lawn, as needed, to keep it healthy.
More than likely, however, it is time to put up your fertilizer spreader. Fertilizing warm-season grasses during the fall with high nitrogen (summer-type) fertilizers or winterizing fertilizers containing high levels of nitrogen are not recommended for Deep South lawns.
Stimulating fall growth of St. Augustinegrass, centipedegrass and zoysiagrass with nitrogen leads to increased large (brown) patch disease and winter kill. Bermudagrass may be fertilized into September, but I would not make any more applications of high percentage nitrogen-containing fertilizers after late August on St. Augustinegrass, centipedegrass or zoysiagrass.
If you would like to extend the green color in home lawns this fall, apply foliar iron spray or spreadable iron granules. This will give you a nice flush of green color without increased growth.
I’m sure that you have heard of winterizer fertilizers. Potassium (the last number in the analysis on fertilizer bag) is the nutrient associated with winter hardiness and increased disease resistance with turfgrass. There is an advantage to having the correct amount of potassium in the soil. Get a soil test before applying high potassium fertilizer, however, since there is no advantage to applying excessive amounts of this nutrient. If a soil test indicates that potash is lacking, choose a potassium containing fertilizer with zero or a very low percentage of nitrogen (the first number on a fertilizer bag) during the late summer or early fall since we are not trying to stimulate growth for the reasons discussed above. If a soil test calls for adding potassium, you can apply during September while temperatures are still warm, and the lawn is still growing (very slow growth occurs as day lengths get shorter by late September and October).
An important fact to consider if you bag your lawn clippings - the removal of grass clippings from lawns can severely deplete the soil of potassium. Grass leaves and stems contain very high levels of potassium. Keep in mind that when a lawn is mowed appropriately, it is better to leave clippings to decompose on the lawn as a good source of turf nutrients, including potassium. Clippings from a lawn that is mowed regularly have only a small role in the overall buildup of thatch in turfgrass.
Fall is the best time of the year to get your soil tested by the LSU AgCenter Soil Testing Lab.
Soil testing really is the first step to a beautiful lawn next spring and is the best way to determine exactly what your lawn needs to become thick and healthy. If you haven’t tested your soil in the past several years, do it now.
To test your soil, submit a pint of soil to the LSU AgCenter Extension Service office in your parish. The pint should be a composite of soil samples collected from several different areas in the lawn. You only need to go about 4 inches deep. Also, to simplify the soil sampling and submission process, there are pre-addressed submission boxes with sampling instructions at several garden centers throughout the state. There is a small fee for testing.
The sample results will be sent to your home mailbox and email in less than two weeks. An LSU AgCenter extension agent can help you interpret the results from the soil sample. The sample results may indicate that lime is needed to increase soil pH. If so, fall/winter is a good time to apply lime, since it takes several months to activate in the soil. Elemental sulfur may be recommended to reduce soil pH in alkaline soils.
If your lawn was full of winter weeds last spring, this fall is your first opportunity to reduce infestations with pre-emergence herbicides. Pre-emergence herbicides such as prodiamine, pendimethalin, dithiopyr, isoxaben, and indaziflam may be applied in mid to late September to help manage the first flush of winter weeds like annual bluegrass, chickweed and lawn burweed. Consider reapplication in early November. These herbicides work prior to the emergence of the weeds, so timing the application before the weeds germinate is critical. Atrazine can be applied on most southern lawns for annual bluegrass and broadleaf weeds in October except for bermudagrass. Atrazine could be applied on bermudagrass after the bermudagrass is dormant. MSM (metsulfuron) can be highly effective postemergence on broadleaf weeds such as white clover and lawn burweed.
Ron Strahan Ph.D.
Associate Professor, LSU AgCenter
Annual bluegrass is the most common grass infesting winter lawns.
Lawn burweed germinates in the fall and produces painful stickers in the spring.
Wild geranium is a common winter broadleaf infesting fall lawns.
Home gardeners are often distressed by the appearance of slime molds during extended periods of overcast skies and warm and wet weather, which is very common in Louisiana.
Slime molds appear as crusty or powdery coatings on any surface, including wooden planks used for making raised beds, garden mulch, lawns or even on the leaves and stems of different kinds of plants grown in gardens.
The encrusted cover is usually a powder buildup that wipes off easily. This dusty coating may appear in different colors, like ashy gray, brown, charcoal gray, dark red, purple or bright yellow. One slime mold is named as “dog’s vomit” because of its appearance.
During favorable weather slime molds may remain in your garden or turf for a few days to more than a week.
Slime molds are nonparasitic organisms that are classified as myxomycetes, a group of free-living amoeboid protists. Slime molds feed primarily on bacteria and other microorganisms.
Slime molds’ life cycles are a bit complicated and have two different stages, an amoeboflagellate stage and a plasmodium stage. After feeding on soil microbes, fungi and organic matter, the amoeboid cells during the amoeboflagellate stage grow and multiply to form a plasmodium stage with a greasy, viscous slimy appearance.
The greasy-looking slimy plasmodium may take on one of many colors or remain clear. It creeps upward on grass leaves, low-growing plant materials and ground covers to support itself up off the ground for better spore dispersal.
The plasmodium further bunches up and develops into a fruiting or sporangium stage. This stage is the most visible and is commonly noticed in gardens and lawns.
In this elevated stage, the mature spores are released for dispersal by wind, rain or other vectors. As grass and plants dry, the sporangia dry to a crusty or dusty “crud.” Slime molds tend to reappear in the same general areas when conditions become favorable again.
Slime molds are harmless to plants and turfgrass and do not cause any diseases on them. However, if the plant tissue is heavily covered with slime mold for more than a week or so, it can shade out the plant tissue. The plant tissue may turn yellow and become susceptible to secondary disease infection.
Control of slime molds is often not needed. They start disappearing with the onset of dry weather. Slime molds can be hosed or brushed off the plant tissue but avoid hosing or brushing off during wet weather.
Gardeners who desire to remove the slime molds by hand must wear disposable gloves as spores may cause irritation to sensitive skin.
Excessive thatch buildup in lawns favors slime mold development; therefore lawns should be dethatched at regular intervals.
If chemical control is desired, contact your local extension agent to find a product that can be used to manage slime molds in landscapes, gardens and lawn turf.
For information on slime molds, please call 225-578-4562 or email firstname.lastname@example.org.
Dr. Raj Singh
Plant Pathologist and Director of Plant Diagnostic Center
Figure 1: Slime mold at base of a tomato plant grown in a raised bed. LSU AgCenter photo
Figure 2: Slime mold growing on the leaf blades of turfgrass. Photo by Raj Singh, LSU AgCenter
Figure 3: Slime mold growing on leaf surfaces of Greek oregano. Photo by Leigh Ann Cabaniss
Figure 4: Slime mold growing on the surface of wet mulch. Photo by Andre Brock, LSU AgCenter