August Newsletter

August Newsletter

August Gardening in the Greater Jacksonville Beaches area!

The heat and humidity are still with us, but it’s been a much drier summer so far on the beach. Without the normal afternoon thunderstorms in July, it has been more difficult to keep our landscapes sufficiently watered. By the end of July, some rain activity finally brought some relief. Moving into August, having both drought tolerant plants and a design which can handle excess rains may be equally important. Here are some suggestions of plants, garden tasks and ways to enjoy your yard this time of year.

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What to Plant

Many of the same plants that were standouts last month can still be cultivated in August. Here are suggestions of plants that are particularly useful in late summer.

Annuals (Or Grown As Annuals): The heat is beginning to take its toll on many of the annuals. Still reliable for August are African daisy (Osteospermum), angelonia, caladium, celosia, coleus (Plectranthus), crossandra, diamond frost (Euphorbia), gold dust (Mecardonia), gomphrena, melampodium, ornamental pepper (Capsicum), pentas, portulaca and purslane (Portulaca), sunpatiens (Impatiens), torenia, vinca (Catharanthus), and zinnia.

Perennials: Some perennials which can be planted in August heat include agapanthus, baby sunrose (Aptenia), beach (dune) sunflower (Helianthus), blanket flower (Gaillardia), bulbine, bush daisy (Euryops), canna lily, cat whiskers (Orthosiphon), cigar plant and Mexican Heather (and other Cupheas), coneflower (Echinacea), crinum and many other lily types, firecracker plant (Russelia), gaura, hibiscus, jacobinia (Justicia), lantana, Mexican petunia (Ruellia), milkweed (asclepias), plumbago, powderpuff (Mimosa), salvia, shrimp plant (Justicia), tickseed (Coreopsis), Turk’s Cap (Malvaviscus) and yarrow (Achillea). You can install groundcovers and border plants like African iris (Dietes), Asiatic jasmine (Trachelospermum), autumn fern (Dryopteris), Aztec grass (Liriopogon), blueberry flax (Dianella), daylily (Hemerocallis), foxtail fern (Asparagus), holly fern (Cyrtomium), liriope, mondo grass, Persian shield (Strobilanthes), purple queen (Tradescantia), Regina iris (Neomarica), and society garlic (Tulbaghia). Ornamental grasses include fakahatchee (Tripsacum), fountain grass (Pennisetum), muhly grass (Muhlenbergia), pampas grass (Cortaderia) and sea oats (Uniola).

Tropicals: These are one of the few groups of plants that appreciate our summer heat, and many should be flowering at this time.Some of the great tropicals we grow here seasonally or with occasional protection are allamanda, bird of paradise (Strelitzia), bougainvillea, copperleaf (Acalypha), croton (Codiaeum), dipladenia (Mandevilla), elephant ear (Alocasia and Colocasia), heliconia, hibiscus, mandevilla, oyster plant (Tradescantia), papyrus (Cyperus), schefflera, snowbush (Breynia), spathe plant (Spathiphyllum), stromanthe, variegated shell ginger (Alpinia), tapioca plant (Manihot) and Ti plant (Cordyline). For ideas on including tropicals in your landscape and suggestions for plants, see our handout called Tropic Life. CLICK HERE!

Succulents: Most succulents thrive in heat. We have a large area full of cacti and succulents, including some beautiful Crown of Thorns (Euphorbia).

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Vines: Vines which can be planted this month include black-eyed susan vine (Thunbergia), bleeding heart vine (Clerodendrum), blue sky vine (Thunbergia), bower vine (Pandorea), butterfly vine (Mascagnia), Carolina jessamine (Gelsemium), confederate jasmine (Trachelospermum), coral honeysuckle (Lonicera), crossvine (Bignonia), dutchman’s pipe (Aristolochia), English ivy (Hedera), hyacinth bean (Lablab), Mexican flame vine (Senecio), moonflower (Ipomoea), morning glory (Ipomoea), passion vine (Passiflora) and sweet potato vine (Ipomoea).

Palms, Shrubs and Trees: Even with the heat, August can be a good time to plant palms, shrubs and trees as long as we get frequent rains. Palms include cabbage, cardboard, Chinese fan, Christmas, coontie (not a true palm), European fan, lady, needle, palmettos, pindo, ponytail, pygmy date, sago, queen, Washington, and windmill.

Shrubs and trees that can usually be found at this time are abelia, arborvitae (Thuja), aucuba, azaleas (Rhododendron), bamboos (Bambusa), bananas (Musa), blue porterweed (Stachytarpheta), bottlebrush (Callistemon), boxwood (Buxus), camellia, cassia (Senna), clusia, crape myrtle (Lagerstroemia), cypress (Cupressus), duranta, Eugenia (Syzygium), fatsia, firebush (Hamelia), gardenia, hollies (Ilex), hydrangea, Indian hawthorn (Rhaphiolepis), junipers (Juniperus), ligustrum, loropetalum, oleander (Nerium), pineapple guava (Acca), pinwheel jasmine (Tabernaemontana), pittosporum, podocarpus, princess flower (Tibouchina), pyracantha, rose (Rosa), Rose of Sharon (Hibiscus), Texas sage (Leucophyllum), thryallis (Galphimia), viburnum and yesterday-today-tomorrow (Brunfelsia). Don’t forget edibles – blackberries, blueberries, citrus, culinary ginger, figs, goji berry, grapes, papayas, pineapples, pomegranates, raspberries, and turmeric. We carry blackberries and raspberries with low chilling-hour requirements to grow in our mild climate, and a grape that can take the heat.

Vegetables and Herbs: Except for sweet potatoes, pumpkins, okra, Malabar spinach and southern peas, few vegetables are growing in the garden now. With warm weather crops waning, this is a good month to start planning for your fall garden (see What to Do). Once the garden is renovated these seeds can be sown: bush, lima and pole beans, summer and winter squash, and cucumber. Later in August, especially if the temperatures start to drop, add seeds of turnip, carrot, and celery, and onion sets. These are all plants which do better when grown from seed sown directly into the garden. You can also start seeds either in ground or starter pots of tomatoes, eggplants and peppers, and cool season crops like beets, broccoli, brussels sprouts, cabbage, cauliflower, Chinese cabbage, endive, kale, collards and mustard (take a little extra care if transplanting mustards instead of direct sowing). This is probably the last month of the year to start Malabar spinach. See our handout Planting Guide for North Florida Vegetables, for vegetable growing information. CLICK HERE!

The article at the end of this newsletter will help you decide which tomatoes to grow.

Many herbs don’t grow well after late spring, but these can stand up to the summer heat: African blue basil, basil, bay laurel, chives, Cuban oregano, cilantro, lavender, lemon balm, lemon grass, lemon verbena, Mexican tarragon, mint, oregano/marjoram, purslane, roselle, rosemary, and stevia. Fennel seeds can be started this month. Herbs needing a cooler setting can be moved to a shadier area if they are potted. Low-growing herbs may be more susceptible to the fungal problems associated with humidity. It may help to thin the base of Rosemary. For mints that grow large and choke themselves out in a container, smaller portions of the root and stem can be transplanted to another pot. See our handout Planting Guide for North Florida Culinary Herbs for additional growing information. CLICK HERE! Also see Herbs for North Florida, for some specific variety and usage information for many of the herbs we carry. CLICK HERE!

Plants that can also be grown indoors: “Houseplants” don’t have to be kept inside your house! Growing conditions for much of the year here support these transitional plants outdoors where more favorable conditions of fresh, humid air and brighter light may help them fight off potential pests and disease. Outdoor beneficial insects may also contribute to their well-being. If you put them outdoors, introduce them gradually to the increased light, avoiding direct sunlight for most. These include aglaonema, air plants, anthuriums, arboicola, bromeliads, dieffenbachia, dracaena, ferns, hoya, palms, philodendrons, pitcher plants, polka dot plants (Hypoestes), pothos, rubber plants (Ficus), snake plants, spathe plants, spider plants, succulents, ti plants (cordyline), zz plants and more.

What to Do

Start a Fall Garden: August is the time to at least be planning your fall vegetable garden. You can refer to our handouts Start a Fall Vegetable Garden CLICK HERE! and Starting Plants from Seeds Indoors CLICK HERE! to get you started. If you’ve had previous crops, you should consider some crop rotation to avoid building pests in your garden. See our handout Planting Guide for North Florida Vegetables CLICK HERE! for family designation of crops so you can avoid planting successive families. The What to Plant section of this newsletter lists the appropriate crops to start this month.

Clean out the summer crops that are spent and remove any other debris. Don’t compost anything that looks diseased as the heat may not kill certain diseases and nematodes. Reinforce raised bed structures if needed or clean up the boundaries of your beds. A soil test would be advisable at this point, either by using the Duval County Extension Service or you might try a home soil test kit. The LaMotte Garden Kit is the only one tested by an independent laboratory that is sufficiently accurate. Based on the test, add recommended amounts of fertilizer. Next add organic matter. Compost improves soil and plant growth regardless of the type of soil you’re adding it to. Spread a 3-4 inch layer over the bed and lightly work in. Refer to Start a Fall Vegetable Garden to complete planting.CLICK HERE!

Irrigate: Complete watering restrictions and schedules for Duval County can be found at this link: www.sjrwmd.com/wateringrestrictions. Adjust automatic irrigation based on rainfall and apply no more than 1/2 to 3/4″ at a time, to avoid runoff. To determine how long it takes to deliver the correct amount of water to your landscape, you can use the ‘can method’ suggested by the University of Florida (http://gardeningsolutions.ifas.ufl.edu/care/irrigation/calibrating-your-irrigation-system.html). Alternatively, Rockaway, Inc.’s Maintenance Service Division can check the operation and delivery for you.

When afternoon thundershowers begin this time of year, it may be better to run automatic irrigation systems manually to avoid over-watering, or to use a Shut-off Device that detects rainfall. There are even devices and apps that allow you to control your irrigation from offsite. If you are concerned whether your landscape is receiving enough water, look for these symptoms of drought stress:

  • Grass leaf blades folding in half lengthwise.
  • Grass taking on a blue-gray tint rather than maintaining a green color.
  • Footprints or tire tracks remaining visible on the grass long after they are made.
  • Plant wilting may be observed on landscape plants.

When drought stress becomes apparent in 30-50% of the yard, then water should be applied on the next allowed watering day. Always water in the morning.
It’s a good idea to check your sprinkler system for any breaks or misaligned spray heads at least monthly.

Mow: At the highest summer temperatures, grass growth slows. Never remove more than 1/3 of the leaf blade at a time and mow to the highest recommended height to support root growth. Here are the recommended mowing heights for several N. Florida grasses: Bahia grass at 3-4 “, Zoysiagrass coarse textured varieties at 2 to 2½” and fine textured at 1″, Centipedegrass at 1½ to 2½”, Seashore Paspalum at 1½ to 2″, and St. Augustinegrass at 2½” for dwarf and semi-dwarf cultivars such as Delmar, Seville and Captiva, and 3.5 to 4″ for standard St. Augustinegrass, especially if growing in shade. To maintain at a height of 4″, grass should be mowed before it grows to a height above 6″. Sharpen mower blades frequently, even monthly, to avoid damage to the grass which allows disease to enter. Avoid mowing when grass is wet.

Prepare for possible hurricanes: Prune any dead limbs and open up trees to allow for better airflow. Install lightning protection on tall high value trees. Avoid planting fast growing trees that have brittle wood. Wind resistant trees for North Florida include Live Oak, Sand Live Oak, Dogwood, Dahoon Holly, Yaupon Holly, Inkberry, American Holly, Crape Myrtle, Southern Magnolia, Podocarpus and Cabbage Palm. Most palms in general, except Queen Palm and Washington Palm, are more resistant than broad-leaved and conifer trees.

Prune: For annuals and perennials, general deadheading is helpful any time of year. Remove spent flowers on hydrangea, salvia and society garlic. Pinch back Chrysanthemums by the end of August to allow time for buds to form for winter bloom. It’s too late to prune spring flowering shrubs such as azaleas. To do so would remove next year’s flower buds which have already begun forming. On palms, only remove fully browned leaves as the plant will resorb needed nutrients from leaves as they die. Also, if you imagine the palm vegetation as a clock face, don’t prune leaves above 3 and 9 o’clock. After harvest, prune mature blueberry plants (those at least 4-6′ tall). Cut back 1/4 to 1/5 of the older canes to a strong lateral or to the ground to stimulate new growth. If your Drift or Knockout roses missed an early summer pruning, then it’s probably time. See our Drift and Knockout Rose Care Guides. CLICK HERE!

Divide: Divide and transplant spring flowering bulbs in August.

Harvest: Some varieties of blueberry should be fruiting now, as should some figs. Although few citrus are probably producing at this time, there may be some lemons and limes to harvest. And of course, continue to harvest any vegetables to keep them productive, but don’t hesitate to remove any in decline. Most herbs benefit from regular trimming of leaves.

Mulch: Replace deteriorating mulch with a new 2-3″ layer to moderate soil temperatures, retain soil moisture, and reduce erosion and weeds. Organic matter is added to the soil as mulch decomposes. Mulch also creates an attractive unified look to highlight your plantings. Florida’s warm and often wet weather can lead to rapid breakdown of mulch. We can help you determine how much mulch you need for a specific area.

Solarize the soil: If you want to give your garden a rest this time of year, this is a good time to use a cover of clear plastic over garden soil as a non-chemical method to control soil-borne pests such as nematodes, insects, weeds, and pathogens. The plastic raises the temperature of the soil and speeds the breakdown of organic material so more soluble nutrients are available. The soil temperature should rise above 105°in sunny areas. Dig a trench around the area to be solarized, wet the soil to 12″ deep, cover the area with 1-4 mil clear plastic and fill in the trenches over the plastic so there is a tight seal over the soil. Keep this down for 6-8 weeks, repairing any tears that might occur. When the process is finished, disturb the soil as little as possible so weed seeds which were deep below the surface aren’t brought up.

Fertilize: The recommendation for low maintenance lawns is to receive 2 fertilizations yearly with the second coming next month in September. However, specific direction depends on the species of turf, it’s current nutrition and fertility of the soil. An annual soil test can prevent over and under-fertilization of lawns, both of which can be harmful. A landscape maintenance program is a convenient way to keep up with the needs of your lawn.

Fruiting shrubs and trees generally need more fertilizer during the year than other shrubs and trees. Recommendations for fruit tree products and frequency depends on the type of tree, but a peach/pecan or citrus formula can be used for most following harvest. Citrus are heavy feeders and need several applications of fertilizer during the growing season, from March to early October, so it’s likely time to fertilize them. See our handout Citrus Care Guide for more information. CLICK HERE! Fertilize blueberries lightly every other month. Figs and bananas should be fertilized monthly.

Fertilize palms about every other month during the growing season. Palms need a high potassium to nitrogen ratio plus added magnesium so an 8-2-12 fertilizer with 4% magnesium works well. Azaleas could use an application of a slow release acid fertilizer.

Discontinue or minimize fertilizing if herbs and vegetables go into obvious decline with the heat. Otherwise, feed vegetables a slow/continuous release organic fertilizer applied every 3 to 4 weeks (herbs at half strength). In general, even though it’s a little costlier, try to use a slow release fertilizer or fertilizer with at least 30% as a slow release component. These feed plants more consistently and lessen pollution.

Control Weeds: Proper maintenance of turf (mowing, irrigation, fertilization) is the best way to control and prevent weeds. Unless weeds are extensive, non-herbicidal methods of weed control should be considered first, and now that the weather has heated up its even more important to know your limits with chemical options. Post-emergent herbicides shouldn’t be used on lawns if summer air temperatures are greater than 90° since this could damage the turf. Post-emergent herbicides are also less effective if the weed is mature, producing seed, under drought stress, or if mowed within several days of herbicide application. Maintaining proper mowing height and frequency can eliminate many annual weeds in lawns. Alternative methods may be needed for weeds which establish and flower below the recommended height of the grass. If weeds aren’t extensive, its simpler to manually pull them. In beds and paths and where turf isn’t grown, a deep layer of mulch can smother weeds. In nonflammable areas such as sidewalk cracks, weeds can be torched.

If herbicides are required, Fertilome Weed Free Zone is a post-emergent herbicide for broad leaf weeds useful in 45-90°F temperatures. Fertilome Selective is useful for spot treatment in temperatures between 50-85°. To control nut-sedge and dollar weed, make sure you’re not creating favorable conditions by over-watering your lawn. Always choose an herbicide that lists your lawn type on the label and follow instructions carefully as they can vary.

Monitor and Control Disease: Continue to monitor disease on lawns and gardens. Fungal disease can occur almost any time of year, especially if the landscape is over watered or watered at the wrong time of day. Bonide Infuse Systemic Disease Control can prevent and control fungal growth.

In lawns, watch for discolored, irregular yellowing and thinning patches which may be a sign of disease. Take-all root rot is a fungal disease of lawns, occurring in St. Augustinegrass and bermudagrass, and often showing in spring or early summer when the turf is emerging from dormancy. A stressed lawn or prolonged periods of rain can also bring on the disease. Control is extremely difficult, so prevention is best. Fungicides need to be applied early, generally from June to August, so planning for next year is especially important if you have issues with this disease. Preventive applications of select fungicides can be applied generally from June – August. The University of Florida recommends that homeowners employ a lawn and landscape service for fungicide applications. Those determined to make their own applications should exercise caution and make informed decisions. Turfgrass decline can be difficult to diagnose but a maintenance program with Rockaway is a first step to controlling and identifying these problems.

Monitor and Control Insects: Frequently scout houseplants, the vegetable garden and landscape plantings for insects as they are easier to control when first noticed. Pest pressure may be high for fall crops.

  • Thrips, scale, and mites become more active in warm weather. Check for thrips on leaves and flowers of roses, hibiscus and gardenias. Spinosad is particularly effective on thrips and caterpillars (also leafminers, spider mites, mosquitoes, ants and fruit flies) and lasts up to 4 weeks. Additionally, it is safe for people, beneficial insects and adult butterflies, and safe for bees once it has dried.
  • Inspect annuals, pyracantha and junipers for spider mite damage. These almost invisible pests live on the underside of leaves, sucking out their juice, and sometimes create webbing across the leaves. Spray with horticultural oil or use insecticidal soap in several applications.
  • The native mealy bug can be a problem on fakahatchee and muhly grass. These 2-3 mm gray insects have a white cottony covering and drink sap by piercing stems and leaves. Its best to remove plants with a heavy infestation, or cut them back and apply a horticultural oil spray to the remainder.
  • Aphids feed on tender new growth. They can sometimes be controlled with sprays of water or by picking them up with a vacuum or sticky tape. Insecticidal soaps can be used but these will also harm Monarch butterflies and their young, so typically not used on Butterfly Weed/Asclepias.
  • Cabbage palm caterpillars may appear in late July. To control, apply Dipel or Sevin to palms.
  • Fire Ants may be a problem this time of year. Baits are available for treatment.
  • Neem oil is a good combination product that can be used to combat insects, mites and fungus.
  • Soft-bodied insect pests can be controlled by beneficial insects such as ladybug beetles and lacewing. To maximize the effectiveness of these natural enemies, provide habitat and relief from high temperatures by increasing the amount and diversity of plants in your landscape. Refer to our handout Ladybugs, for storage and release information. CLICK HERE!

The major lawn pests active this time of year are Southern Chinch Bug and Fall Armyworm, and possibly to a lesser extent Tropical Sod Webworm.

Chinch bugs prefer hot, dry conditions. They suck the juices from St. Augustinegrass at or just below the soil level. Yellowish to burnt-brownish patches are often first noticed in sunny areas along sidewalks and driveways, or in poorly irrigated areas. Young chinch bugs will be reddish with a white band across their back. They become black as they mature, with white patches on their wings. To help control the problem, limit nitrogen fertilizer and reduce thatch thickness to minimize the bug’s habitat.

Newly hatched larvae of tropical sod webworm skeletonize grass blades while older larvae chew on grass blades near soil surface. Small patches of grass may look ragged and irregular. The adult moth does not cause damage but the life cycle from egg to adult only requires 5-6 weeks at 78°F.

Fall armyworm caterpillars skeletonize grass blades then later create bare spots.

Younger caterpillars of both armyworm and webworm are more easily controlled with reduced-risk products like B.t., halofenozide and spinosad. Bifenthrin also targets both these caterpillars and Chinch bugs. You can use a product like Hi Yield Bug Blaster Plus Above/Below. Rotate combination products to reduce resistant populations and spot treat when possible.

In weedy areas and open fields, Lubber Grasshopper adults may be found from March to November. It may be possible to avoid the use of an insecticide by hand-picking the grasshoppers and mowing vegetation to appropriate heights.

Be aware of areas that collect water so you can minimize breeding sites for mosquitoes. Dump and flush manageable containers at least weekly. Flush clogged gutters. Use dunks containing Bt to control larval development.

Many insect problems require a combination of pest management products and techniques. But keep in mind that for any problem, it may occasionally be less costly and more environmentally friendly to replace infected plants with another species that would be more appropriate for the site. Don’t be reluctant to remove a plant that just isn’t working.