David W. Marshall
| Guest columnist
I usually prefer being outside working in the garden to being inside working at the desk. But as I write this, we still seem to be in the dog days of summer. Nevertheless, there are things to be done as fall is just around the corner, as promised in this week’s cool mornings.
In mid-August and there were still no signs of tropical sod webworms in the lawn, though a neighbor told me he has seen the moths flitting around his lawn. Now that tropical systems are beginning to move closer to us, they can move the moths from south Florida.
The moths don’t feed on the lawn, but they indicate that you should keep an eye on your lawn for the telltale signs of chewed grass blades from the caterpillars’ feeding as we move into September. It literally can occur overnight, as the caterpillars are nocturnal, and if left unchecked, can result in you losing areas of your lawn.
Sod webworms
If you confirm sod webworm damage, apply a lawn insecticide that lists control for sod webworms on the label. There are some granular formulations that can be applied with a fertilizer spreader, but they must be watered in to activate them. I personally feel that the liquid insecticide formulations applied with a hose-end sprayer in the recommended amount of water will give better control than a granular formulation.
No matter which insecticide you use, monitor the infestation and damage, and be prepared to make another application later as needed. Once sod webworms appear, they may persist for several months, until the weather gets cool enough to stop them.
If your St. Augustine grass lawn has thin or bare spots in sunny areas, in early September you may also choose to apply a low-nitrogen, high-potassium fertilizer such as 5-0-20 or 5-0-15. This can be especially helpful if your lawn has been damaged by sod webworms.
But avoid fertilizing with fertilizers that contain more nitrogen (the first number), because the lush growth stimulated by the nitrogen will be more attractive to sod webworms. Centipede lawns probably won’t need this late summer application. Make sure you water the fertilizer in lightly.
Fighting off fire ants
If you have a problem with fire ants, don’t forget that you can apply a fire ant bait to your whole yard using a hand spreader. Follow the label directions, and you will find that this is a quick and relatively inexpensive method to control fire ants in your yard for up to six months.
The application rate is low, and two applications per year are all that are needed. Just be sure that you’re using a bait material and not a contact insecticide. Before you buy an insecticide, read the label directions and be sure that it is appropriate for broadcast application.
Mosquito watch and watering
Regularly change the water in birdbaths and other such areas now so as to prevent mosquito larvae from developing. Anywhere that collects standing water, such as low spots in gutters, can be breeding grounds for mosquitoes. Use insect repellents that contain DEET to protect yourself from mosquitoes and ticks when working outdoors, especially in the early morning and evening hours.
Rainfall was fairly frequent in August. However, rainfall usually decreases in late September and October, so don’t forget to water plants as needed, especially plants that you planted this year. In north Florida, your lawn should stay green until frost, which usually doesn’t occur until November or December. Continue mowing your lawn regularly, too, as we move into fall.
If you are troubled significantly by weeds in your lawn in very early spring, October, when night temperatures fall to 55–60 degrees for 4–5 days, is the time to apply a pre-emergent herbicide such as atrazine, Dimension, or Gallery to prevent the emergence of cool-season annual weeds. Be sure to check the label of any herbicide before buying it to make sure it’s safe on your type of grass, and follow directions carefully.
Where are the zebra longwings?
Temperatures begin to drop slightly as September progresses, and fall will be a pleasant time of year for gardening activities. One of my favorite flowering plants this time of year is the firebush (Hamelia patens), a large bushy perennial that, if grown in a sunny location, will be full of dark red-orange flowers this time of year.
Hummingbird and butterfly traffic to these flowers is usually heavy, especially with zebra longwings, the state butterfly. However, this year there has been a significant decline in zebra longwing sightings, probably because of this year’s ice storm and severe cold for days. Hopefully the zebra longwing population will gradually increase again.
Fall perennials
Other excellent fall-blooming perennials include cigar flower (Cuphea micropetala) and various species of Salvia such as Mexican bush sage (Salvia leucantha) and pineapple sage (Salvia elegans) for sunny areas, as well as firespike (Odontonema cuspidatum) for partially shaded areas.
In mid-October you can begin planting cool-season annuals such as petunias, Calibrachoa, Nemesia, Diascia, Dianthus, Verbena, alyssum ‘Snow Princess,’ and wallflower (Erysimum spp.). In late October to November add pansies and violas. Practically all the cool-season annuals will need full sun.
Container gardens
Don’t forget the option of container plantings, which quickly add color to sunny porches, patios, or decks. If you wish to add some flowers before mid-October, you can still plant warm-season annuals such as Angelonia, Torenia, zinnias, impatiens, or Melampodium.
They will likely last until late November or early December when we usually have a freeze. You could even still plant pentas in a sunny area. Visit local nurseries for many options.
Plants trees and shrubs
Fall and winter are great times to plant trees and shrubs, as long as you remember to water the new plants regularly. Try to add some trees that have fall color, such as Oriental persimmon, crepe myrtle, Chinese pistachio, American hornbeam, Japanese maple, hickory, red maple, sweetgum, ginkgo, bald cypress, and black gum.
As we move into fall and the camellia flowering season, it is a good time to visit the nursery to select camellias while in bloom. The sasanqua camellias will be among the first to bloom, generally followed by the japonica types.
Cool season veggies
As nights cool in late September in our region, it’s time to start planting vegetables and herbs for the cool season. Seed arugula, beets, cabbage, carrots, cauliflower, collards, lettuce, mustard, radishes, and turnips. Set out bulbing onions and strawberries.
In October, add broccoli, Chinese cabbage, kohlrabi, spinach, bok choy, tatsoi, and mizuna. Herbs to seed include cilantro, parsley, French sorrel, salad burnet, sage, and thyme. Be sure to plant in a spot in full sun. Fertilize your plants periodically with a balanced fertilizer such as 20-20-20. If you don’t have much garden space, remember that some of these can even be grown in large pots.
Persimmons
Oriental persimmons ripen in the fall. If you don’t have a persimmon, now is a fine time to plant. There are two basic groups of persimmon types: astringent and non-astringent. The astringent ones are generally sweeter and juicier, but you must wait until they get completely ripe and jelly-soft to the touch.
The non-astringent types may be eaten while still firm and crisp and generally have a milder or mellower taste. Regardless of which type of persimmon you choose, plant it in full sun or at least partial sun. Good drainage is very important, too. Also, plant where you can enjoy the spectacular view of the colorful fruit in the fall.
It really is a good landscape plant, though it can be messy when the fruit drops, so it’s best not to plant it near a patio or other high-traffic area.
Citrus trees
Many citrus fruits are well developed and only months from maturity now. Give the citrus its final fertilizing of the year in September. Continue watering into fall as needed, as that will help the fruit continue developing well. If you have very young cold-sensitive types of citrus, plan now for those hard freezes that can occur from late November onward. It’s much easier to calmly get the materials together now rather than hurriedly at the last minute when a cold front is approaching.
David W. Marshall is a horticultural consultant and an Extension Agent Emeritus with UF/IFAS Extension Leon County, an Equal Opportunity Institution. For gardening questions, email the extension office at AskAMasterGardener@ifas.ufl.edu.
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