by Donna Arnold | Sep 25, 2025
When the Ground Moves.
It started with a quiet day, and a curious bag of sand brought into the extension office but inside was more than just sand. It was crawling with tawny crazy ants (Nylanderia fulva), one of Florida’s fastest-spreading invasive pests. Known for their erratic movement and massive colonies that can make the ground seem alive, these reddish-brown ants are now a growing concern for gardeners across some Florida counties. Unlike fire ants, tawny crazy ants don’t sting, but they can nip with their chewing mouthparts. Their sheer numbers can overwhelm outdoor spaces, crawling on people and spoiling the enjoyment of patios, gardens, and recreational areas. They nest in moist, protected areas such as leaf litter, potted plants, and under debris, often forming sprawling colonies with multiple queens.
Beyond being a nuisance, these ants pose serious risks. They’ve been known to cause electrical shortages by infiltrating equipment, sometimes leading to costly damage. In some Caribbean islands, they’ve harmed organic crops, and in Colombia, infestations have even led to the death of small animals due to asphyxiation. Larger animals have been attacked around sensitive areas like the eyes and hooves. Tawny crazy ants also disrupt local ecosystems. Their aggressive spread displaces native ant species and reduces biodiversity. While Florida hasn’t reported agricultural damage yet, the potential remains, especially in organic farming systems.
Identification Tips
Workers are small (less than 1/8 inch), monomorphic, and covered in fine hairs that give them a matte appearance. They have one petiole segment and 12 antennal segments, including a long first segment called the scape. Colonies don’t form mounds but may tunnel in sandy soil. Queens are often found among workers, especially in warmer months. If you suspect an infestation, contact your local UF/IFAS Extension office.
Management Challenges
Controlling tawny crazy ants is notoriously difficult. Spraying alone is ineffective, and most insecticides only work for a few days before ants’ return. Integrated Pest Management (IPM) is the recommended approach. IPM combines multiple tactics, starting with accurate identification and monitoring, followed by strategic product application and habitat modification. Professional pest control services that specialize in IPM are often necessary. Timing is critical, and overuse of products is not only ineffective but may violate legal limits. Keep records of infestation locations to anticipate reinvasion, which typically occurs annually. While complete eradication is unlikely in established areas, population suppression is achievable. Interestingly, research suggests that within about a decade, populations may naturally decline, allowing native species to rebound.
Tawny crazy ants are more than just a backyard annoyance they are a complex ecological and household threat. Awareness, early identification, and professional management are key to minimizing their impact. As these ants continue to spread, staying informed and proactive will help protect your property and Florida’s delicate ecosystems.
For more information call or visit your local extension office or follow the link below.
https://edis.ifas.ufl.edu/publication/IN1076
by Donna Arnold | Aug 15, 2025
Kalanchoe Species in Florida: Invasive Threats and Management
Several species of Kalanchoe, widely distributed through horticulture as popular containers and landscape plants, have escaped cultivation and become invasive in Florida. Of the approximately seven species reported outside of cultivation, two have been documented as particularly problematic: Kalanchoe pinnata (commonly known as Cathedral Bells) and Kalanchoe × houghtonii (known as Mother of Millions). Both are listed as Category II invasive plants by the Florida Invasive Species Council (FISC), indicating they have the potential to disrupt native ecosystems. “In Central and South Florida, the plant is listed as invasive; hhowever, there is a cautionary note for North Florida.”
Photo Credit: Donna Arnold, FAMU Extension
Kalanchoe × houghtonii is a hybrid of K. delagoensis and K. daigremontiana, which has led to some confusion in reporting and distribution records. These species belong to the Crassulaceae family and are characterized as succulent herbs with hollow, fleshy stems. K. pinnata features rounded, scalloped leaves, while K. × houghtonii has slender, pointed, fleshy leaves. Their bell-shaped, pendulous flowers range in color from green to red. In Florida, these plants are primarily found in South Florida and along the East Coast, extending as far north as Nassau County.
Photo Credit: Donna Arnold, FAMU Extension
The ecological impacts of Kalanchoe species are significant. Reproduction occurs both sexually and vegetatively, with plantlets forming along leaf margins and even on inflorescences. This species high reproductive rate and ability to thrive in dry, arid environments allow them to invade coastal dune habitats, where they form dense carpets that crowd out native species. Shallow root systems contribute to destabilization of sandy areas by displacing native plants such as sea oats, which are essential for anchoring sand and preserving dune integrity.
Effective management begins with prevention. Homeowners are advised not to plant Kalanchoe species and to avoid dumping landscape material in natural or disturbed areas. Physical control methods include hand-pulling and secure disposal of plant material to prevent regrowth. Chemical control can be achieved using a 5% glyphosate foliar spray, which is effective in killing individual leaves that might otherwise produce new plantlets. Follow-up removal of detached leaves is essential to prevent further spread. Currently, there are no known biological control methods for these species.
For more information and personalized management recommendations, homeowners should consult their local UF/IFAS Extension office. Additional resources are available through the UF/IFAS Center for Aquatic and Invasive Plants, and the Florida Invasive Species Council Plant List.
by Donna Arnold | Jul 6, 2025
Zinnia Woes: What’s Causing Terminal Shoot Curling?
On a quiet stroll to the greenhouse early Monday morning, something unusual caught my eye—our zinnia plants looked noticeably different. Their vibrant green shoots had begun to curl at the tips, a subtle but clear sign that all was not well. Do not be alarmed if your zinnias are showing similar symptoms—it is a common issue. Curling at the terminal shoots is often a plant’s way of signaling stress. Whether it is due to environmental factors, pest activity, or nutrient imbalance, these twisted tips are clues worth investigating. Understanding the “why” behind the curl is the first step toward helping your zinnias return to their radiant, blooming selves
Common Culprits Behind Curling Zinnias
Environmental Stress: Zinnias are sun-lovers, but extreme heat, strong winds, or sudden temperature swings can cause their terminal shoot to curl as a defense mechanism.
Watering Woes: Both overwatering and underwatering can lead to leaf curls. Too much water suffocates roots, while too little causes drought stress—either way, the plant reacts by curling its leaves.
Pests: Aphids, thrips, and spider mites are notorious for feeding on tender new growth. Their sap-sucking habits distort leaves and can transmit viruses.
Diseases: Fungal infections like powdery mildew or bacterial leaf spot can cause curling, especially when combined with poor air circulation.
Nutrient Deficiencies: A lack of nitrogen, magnesium, or manganese can lead to curling and yellowing of new growth. Soil testing can help pinpoint the issue.
What You Can Do:
- Ensure consistent watering—moist but not soggy soil is ideal.
- Inspect regularly for pests and treat with neem oil or insecticidal soap.
- Improve air circulation by spacing plants properly and pruning overcrowded areas.
- Feed with a balanced fertilizer and consider a soil test if symptoms persist.
- Remove and destroy severely affected plants to protect the rest of your garden.
Healthy zinnias reward you with bold, cheerful blooms. A little detective work now can keep your garden dazzling all season long. For more information on Zinnias, contact your local Extension office or follow the links below.
https://gardeningsolutions.ifas.ufl.edu/plants/ornamentals/zinnia/
https://edis.ifas.ufl.edu/publication/FP623
https://nwdistrict.ifas.ufl.edu/hort/category/annuals-2/page/2/#:~:text=When%20planting%20zinnias%2C%20it’s%20recommended,than%20the%20foliage%20whenever%20possible.
by Donna Arnold | May 22, 2025
Spring and summer bring an explosion of color to gardens, and among the most resilient yet misunderstood flowers are marigolds. Growing up in a small Caribbean town, marigolds were everywhere. Locals called them “Stink and Pretty” or even “graveyard flowers” for their bold scent, but their benefits were undeniable. Whether used in traditional medicine, religious rituals, or tucked into garden beds to keep pests at bay, marigolds have always been more than just a flower.
More Than Just a Bloom
Belonging to the Tagetes genus, marigolds come in a variety of cultivars, each offering unique traits and advantages. Beyond their beauty, they play essential roles in soil conditioning, pest control, especially against nematodes, and companion planting.
A Closer Look at Marigold Varieties
Marigolds fall into distinct categories, each with different growth habits, flower forms, and benefits. The two most common types are Tagetes patula and Tagetes erecta.
- French Marigold (Tagetes patula)
Compact and bursting with warm hues of orange, yellow, and mahogany, French marigolds are excellent pest deterrents. Often planted alongside vegetables, they help manage soil nematodes while thriving in borders and containers.
- African or Perfection Yellow Marigold (Tagetes erecta)
Despite the name “African,” this species hails from Central America. Taller and more dramatic than French marigolds, it produces large, showy golden blooms ideal for cut flowers and mass plantings.
- Signet Marigold (Tagetes tenuifolia)
Delicate foliage, small dainty flowers, and an edible twist—Signet marigolds are a favorite for adding color to salads and attracting pollinators. Plus, their milder scent makes them perfect for gardeners sensitive to stronger fragrances.
A Common Mix-Up
It’s worth noting that while often called “Pot Marigold,” Calendula officinalis is not part of the Tagetes genus. Though it shares similar colors and benefits, calendula is better known for its medicinal properties and edible petals.
Calendula in the Royal Botanical Garden of Madrid, Spain. Photo by Jean-Pierre Dalbéra.
Next time you pass a tray of marigolds at a plant sale or see them brightening a garden bed, take a second look. These unassuming blooms do far more than add beauty—they may just be the unsung heroes of your summer garden.
by Donna Arnold | Apr 10, 2025
Snapdragon in bloom: Photo credit Donna Arnold FAMU Extension.
Snapdragons (Antirrhinum majus) add vibrant color to fall and winter gardens in North Florida with their wide range of hues. Colors include red, orange, yellow, and maroon. Their growth varies; tall varieties reach 2–3 feet, intermediates 1–2 feet, bedding types 6–15 inches, and rock garden hybrids about 6 inches. Dark-colored flowers often have reddish stems, while pale blooms grow on light green stems. Snapdragons’ warm-colored flowers stand out in garden beds, especially when paired with white flowers, enhancing their red, orange, and maroon tones. Their fine-textured foliage contrasts nicely with large-leaved plants and compact shrubs.
Though not native to North America, they are widely cultivated and are not considered invasive. Snapdragons are versatile and ideal for mass plantings, containers, cut flowers, and edging. They are generally available within their hardiness range, making them a popular gardener choice.
Cultivars
Dwarf: ‘Floral Carpet,’ ‘Floral Showers,’ ‘Kolibri,’ ‘Royal Carpet,’ ‘Tahiti’
Intermediate: ‘Princess,’ ‘Liberty,’ ‘Sonnet,’ ‘Pixie,’ ‘Sprite,’ ‘Cinderella’
Tall: ‘Panorama,’ ‘Burpee’s Topper,’ ‘Spring Giant,’ ‘Rocket’
Photo credit: Donna Arnold FAMU Extension.
Care and Management
Caring for Snapdragons requires minimal work. They thrive in slightly acidic garden soil but struggle in unamended clay. Therefore, ensuring the soil remains acidic is key to their survival. They require full sun and moist soil. After the first bloom, cutting plants back to five or six nodes encourages a second flowering. Also, fertilizing at bud formation improves growth.
You can increase numbers through propagation. Propagation can be done through seeds or cuttings. Seeds germinate in 10–14 days at 70°F and should not be covered with soil. Prechilled seeds germinate best. Pinch seedlings with two to three leaf sets, except for dwarf varieties. Plant in fall for winter blooms in zones 9–11. In zone 8b and south, snapdragons may survive mild winters. Space plants 6–10 inches apart.
Pests and Diseases
Aphids: Feed on young growth, weakening plants.
Greenhouse leaf tier: Chews and webs leave; pesticides are ineffective once leaves roll.
Mites: Cause bronzed, stippled foliage, especially in hot weather.
Common Diseases
Rust: Brown pustules with yellowed leaf tissue; use proper spacing and resistant varieties.
Anthracnose: Causes sunken spots on stems and yellowing leaves; destroys infected plants.
Gray mold: Leads to wilting and stem browning; worsens in wet conditions. Remove infected stalks.
Stem rot: Cottony growth near soil line; infected plants should be removed.
Snapdragons offer rich color, versatility, and seasonal interest in gardens, making them a valuable addition for novice and experienced gardeners.
For more information contact your local extension office or click on the following links.
FPS-44/FP044: Antirrhinum majus Snapdragon
ENH1285/EP549: Planting and Propagation of Snapdragons in Florida
