In the last couple of weeks, I’ve had multiple questions regarding trees and shrubs that aren’t looking too hot. These types of calls are common this time of year – it has gotten hot and dry, and plants have fully emerged from winter, causing issues that have been hiding under the surface during the dormant season to manifest as crown or branch dieback. While there are a wide variety of things that can cause dieback, in most cases a little detective work can help pinpoint the issue. Let’s look at a few of the most common causes of dieback and some corrective measures that may help restore the plants to health.
The first thing to do when you notice a plant in decline is nothing. Don’t try and oversaturate it with water. Don’t run out and dump a bunch of fertilizer around it. Many times, these panic measures exacerbate the stress the plant is already under. Instead, I encourage you to give us a call at your local UF/IFAS County Extension Office. We can likely help identify the cause of the problem through a site visit to your property or by you sending us diagnostic photos of the plant with a description of what’s been going on with it – the more information you can provide about the plant and the management practices it has experienced, the better (you can email diagnostic images/information to d.leonard@ufl.edu).
The most common cause of tree/shrub dieback that I see arises from improper planting practices. Most landscape plants should be planted at or just above the surrounding soil level, preferably where the topmost root arises from the trunk. To accomplish this, planting holes should be dug slightly shallower than the rootball’s height and about twice as wide. Planting any deeper than that is probably too deep and can cause problems like trunk and root decay, which lead to crown dieback. Unfortunately, once a plant is planted too deep, it cannot be corrected other than digging up and replanting at the proper depth, which may or may not be possible depending on the size of the tree. Another common issue that can arise after planting is girdling roots. This occurs when plants are grown in plastic containers and develop a root system that circles the inner wall of the pot. If not trimmed, the plant’s root system will continue to grow in this manner, eventually encircling the plant’s trunk, cutting off water and nutrient flow, and leading to crown dieback. Fortunately, this condition can be prevented by cutting, removing, or redirecting these roots at planting.
The next most common cause of plant dieback occurs due to soil disturbance by people. It’s easy to forget but the root zone of trees and shrubs can reach out several times farther than the plant is tall and is easily damaged. Disturbances to the root zone from digging or trenching near trees or compaction from prolonged vehicle travel over the area cause damage that might be slow to appear but can lead to plant decline. If you are doing construction or building near a shrub or tree, try to keep digging machinery as far out of the root zone as possible and avoid repeatedly parking or driving vehicles over the root zone area. Like below ground root damage, trunk damage that occurs from injury by string trimmers, mowers, or animal feeding activity can all disrupt the flow of water and nutrients in plants and prove deadly. There is no cure for this type of damage, so employing physical barriers to prevent damage is key.
The last major stress is environmental in nature and is caused by a water imbalance – either too much or not enough. Dry soil conditions during the planting and establishment phases (first several years after planting) should obviously be avoided if possible – keeping the developing rootzone moist and allowing plant roots to establish in their native soil is critical. Too much water can also cause problems for trees planted in poorly drained soil. Excessive moisture leads to root diseases, which ultimately presents as dieback in the canopy. If planting in an area that tends to stay wet, select a species of plant adapted for that sort of site – some species are more tolerant of “wet feet” than others. While many people expect disease and insect damage to be the cause of an unhealthy plant, they’re often not the biggest culprit and, if they occur at all, are generally secondary to one of the above issues.
Florida is a fun state to live in for many reasons. You are never more than an hour or two away from a great beach, it never gets bitterly cold, and the fishing is phenomenal. I could go on. More than all that though, my favorite thing about living in Florida is the ability to have something blooming year-round, even in the cool months. This year, the stars of the spring show in my backyard container garden have been new selections of an old favorite, the Petunia.
Petunias, a close relative of Tobacco, originally hail from South America. And while the original petunia species were not a valuable crop like Tobacco, enterprising European explorers realized the group had horticultural potential. By the late 1800s, plant breeders had begun hybridizing wild petunia and the petunias gardeners now recognize took shape! Fast forward to today and petunias are the most popular bedding plants in the US, with annual petunia sales topping $260 million (USDA’s Census of Horticultural Specialties). More than 700 petunia cultivars have received plant patents, comprising all manners of sizes and flower colors. This year, there is even a controversial genetically modified petunia called ‘Firefly’ hitting the market that displays bioluminescence – it literally glows in the dark!
Petunia ‘Jazzberry’ growing in a container. Photo Credit: Daniel Leonard, University of Florida/IFAS Extension – Calhoun County
In the past, petunias struggled in the Deep South, as they were often ravaged by various fungal pathogens induced by our too-warm weather. These old-fashioned petunia cultivars, while pretty on store shelves, don’t perform as well in the heat as newer varieties bred for warmer, wetter conditions and that possess enhanced vigor and disease resistance. When shopping for petunias in the Panhandle, avoid anonymous petunia varieties of questionable quality and look for modern named hybrids, for example the Supertunia Series, the SuperCal series, and the Wave series. These improved hybrid petunias are resilient to pesky diseases like Botrytis Rot, flower heavily over a longer period, and tolerate temperature extremes better. Within these series, individual cultivars vary in flower color, flower size, and overall plant size (ranging from mounding monsters growing 4’ in diameter to tiny dwarfs that barely span 18”). I grew several varieties from each of these series this year and all performed wonderfully. There’s a petunia variety for every garden!
Petunia ‘Supertunia Royal Magenta’. Photo Credit: Daniel Leonard, University of Florida/IFAS Extension – Calhoun County
Once you’ve picked a quality cultivar, petunias are relatively easy to grow! In the Panhandle, petunias are grown as cool season annuals – planted in the fall (October-November) and grown through about May, finally playing out once the summer heat arrives. Petunias prefer full sun and are at home in containers filled with a quality potting mix (container size will vary from medium to large depending on the growth habit and mature size of the petunia). Petunias are not particularly drought tolerant and prefer regular water and fertilizer to look their best. I water my containers each day during sunny and warm conditions, backing off to every other day or less during cooler, cloudy weather. Because of their floriferous nature, petunias are also relatively heavy feeders and appreciate supplemental fertilizer. I top dress petunia containers with Osmocote or similar slow-release fertilizer at planting and supplement with liquid fertilizer every week to ten days during the peak of the flowering season.
Petunia ‘Supertunia Mini Vista Scarlet’. Photo Credit: Danial Leonard, University of Florida/IFAS Extension – Calhoun County
Though it’s past petunia planting time this season, be on the lookout for petunias to hit nursery shelves next fall. Simply pick a good hybrid cultivar, plant in a container in full sun, water and fertilize regularly, and you’ll be rewarded with no-fuss, months-long color until the summer heat finally draws the curtain on the show! For more information about petunias or any other horticultural topic, feel free to contact us at the UF/IFAS Calhoun County Extension office. Happy gardening!
It’s no secret that fall, October specifically, is the best month for wildflower watching in the Panhandle. From the abundant vibrant yellow-gold display of various Sunflowers, Asters, and Goldenrods to the cosmopolitan bright pinks and purples of Mistflower, Blazing Star, and False Foxglove, local native landscapes light up each year around this time. However, if you’re lucky and know where to look, you can also spot two species, Azure Blue Sage (Salvia azurea) and Forked Bluecurls (Trichostema dichotomum) that sport that rarest of wildflower hues – vivid blue.
Forked Bluecurls begins its flower show in late summer, picking up steam in fall, and reaching its peak now as nights get cool and the days grow short. The species’ flowers are easily among the most unique around. Each flower has two distinct “lips” – the lower lip is white and dotted with blue specks, while the top is distinctly pure blue – with characteristically curled blue stamens rising to preside over the rest of the flower below. Though individual flowers are very small and only bloom in the morning, they appear by the hundreds and are very striking taken together. Various pollinators, especially bees, also find Forked Bluecurls flowers to their liking and frequent them on cool fall mornings. Though the flowers are obviously the highlight, the rest of the plant is attractive as well, growing to 3’ in height and possessing small, light-green fuzzy leaves. Forked Bluecurls, while not exceedingly common, can be found in sunny, sandy natural areas throughout the Panhandle, including well-drained flatwoods, sandhills, and open, disturbed areas.
Forked Bluecurls blooming in an open natural area in Calhoun County, FL. Photo courtesy of Daniel Leonard.
The second blue bloomer, Azure Blue Sage, is possibly even more striking in flower than Forked Bluecurls. Aptly named and blooming around the same time as Forked Blue Curls, Azure Blue Sage is a much larger plant (often 4-6’ in height) and holds its abundant sky-blue flowers high above the surrounding landscape. Because of their height and their propensity to occur in bunches, Azure Blue Sage’s brilliant tubular flowers are immediately noticeable to passersby and the myriad bee and butterfly pollinators that visit. Beyond its flowers, Azure Blue Sage is a very unusual looking perennial plant, tall and spindly with dark green, narrow leaves held tightly to square stems, a giveaway of its lineage in the Mint family. The species can be found in similar areas to Forked Bluecurls – natural areas in the Panhandle that possess abundant sunshine and sandy, well-drained soil.
Azure Blue Sage blooming in a recently replanted pine forest in Calhoun County, FL. Photo courtesy of Daniel Leonard.
Both species would make excellent additions to mixed perennial landscapes where the soil and sun conditions were right, as they are exceedingly low-maintenance and have the propensity to reseed themselves from year to year. Unfortunately, they are rarer in the nursery trade than they are in the wild and can only be found occasionally at nurseries specializing in Florida native plants. (Visit PlantRealFlorida.org to find native nurseries in your area!) However, even if you are unable to source a plant for your home, both these somewhat rare, blue-blooming fall beauties, Forked Bluecurls and Azure Blue Sage, are worth searching out in the many State Parks and public natural areas across the Panhandle! For more information about Forked Bluecurls and Azure Blue sage or any other natural resource, horticultural, or agricultural topic, contact your local UF/IFAS County Extension Office. Happy fall wildflower watching!
I don’t know if you’ve noticed, but it’s been hot outside. Like really, scorching, hellacious, dog days hot. In this weather pattern we’ve been in, it’s hard to make yourself do non-essential stuff outside that doesn’t involve swimming and so our gardens go by the wayside. In my opinion, that’s totally okay! Give yourself a rest from the garden and landscape chores for the next couple of weeks and get your fall gameplan ready. The following are some things to think about over the next few weeks to prepare yourself for the coming cooler weather!
Soil testing in centipedegrass. Photo courtesy of Daniel Leonard.
Get your soil tested. If you’re an in-ground vegetable gardener or just like to have an attractive lawn/landscape, performing a simple soil test can offer either peace of mind that your soil’s pH and fertility is good or give you a nudge to schedule some needed amendments. Though I don’t recommend fertilizing lawn grass this late and there’s no need to fertilize the garden before it gets planted in mid-late September, you can certainly begin to source and price fertilizer for the appropriate time based on your test results. However, now IS the perfect time to get lime out in a vegetable garden if your pH has sunk beneath the recommended 6.5. Lime takes weeks to months to begin to alter soil chemistry so the sooner the better if it is needed!
Order seeds. While I love to support local farm stores and plant nurseries, you are limited with the vegetable and flower varieties you can plant by what they have in stock. I enjoy trying new/improved and heirloom plant varieties each year and, most of the time, these can only be found by ordering online. For the latest in vegetable and cut flower varieties with a nice mix of heirloom cultivars thrown in also, I can recommend Johnny’s Selected Seeds, Baker Creek Heirloom Seeds, Seed Savers Exchange, and other similar purveyors – all of these are great places to look. Continue to purchase your more common standbys through local outlets but, this year get different and try new things by ordering online!
Develop a garden/landscape plan. I doubt there’s a gardener amongst us who wouldn’t like to rearrange things a bit outside. Maybe you planted your lettuce a little too closely together last year, you’ve been dreaming of installing a new flower bed, or you really want to do a full garden/landscape renovation. The best way to be successful at any of these things is to get outside (or at least look out from behind a window in the A/C), take stock of what is already there, the space that is or might be available, research what plants or varieties might do well in your yard/garden (your local UF/IFAS Extension office is a great resource for this), and begin to sketch your ideas out. This planning step WILL save you time and money by ensuring you don’t purchase too many plants, by picking plants that will do well, and ensuring you install everything at the correct time.
So, take advantage of the heat, stay inside, and work up your garden gameplan together this August – fall is just around the corner. For help with soil testing, recommendations on plant varieties to purchase, or working up a garden/landscape plan tailored to you, contact your local UF/IFAS County Extension Office. Stay cool and happy gardening!
Since Ponce de Leon first set foot in Florida around Easter in 1513 and gave the state its name – he called it La Florida, which loosely translates to flowery in English – Florida has been known for its amazing native wildflower displays. Florida’s primary native flower shows do indeed occur in the spring (the one observed by Ponce de Leon) and fall, but my favorite Florida “wild” flower is neither a native nor does it bloom in April or October. Rather, the Philippine Lily (Lilium formosanum) does its thing each year in the heat of the summer, when not much else wildflower-wise is blooming.
Hailing from Taiwan and the Philippines but naturalized throughout the Panhandle, the Philippine Lily is easy to spot. Often confused with Easter Lily (Lilium longiflorum), which blooms much earlier in the year, Philippine Lily blooms mid-July to August and sports classic lily-type flowers held high on study stems that may reach 7’ or higher. Emerging from the drab green of the surrounding summer landscape, Philippine Lily’s very large (10” or more), very fragrant, trumpet-shaped, creamy-white flowers are showstoppers. The propensity of the flowers to appear in elegant, “nodding” clusters of a dozen or more also adds to the effect. Admired by gardeners and other passersby during the day, at night these wonderfully scented flowers become a whirring site for evening pollinators, particularly the enormous Hummingbird, or Sphinx Moth.
Philippine Lily in bloom in late July. Photo courtesy of Daniel Leonard.
In addition to being a beautiful surprise in natural areas, Philippine Lily is among the easiest and most versatile of landscape plants to grow. The species prefers partial shade, but the thousands growing along roadsides in full sun speak to its adaptability. It is also right at home in our often dry, sandy Panhandle soils, and no special soil amendments are needed for the species to thrive. To get plants started, one may use either seeds or transplants from existing stands. If using seeds, simply sow them in your desired garden location into loosened garden soil, cover lightly, and water – the same seed sowing method can be used in pots for transplanting or sharing with friends later. Alternatively, you can dig or pull bulbs from natural areas where Philippine Lily already exists – assuming you have permission from the property owner. These newly dug and planted Lilies will need babying with regular water for several weeks to reduce transplant shock and improve survival.
Philippine Lily is probably best sited in the back of landscape beds to take advantage of the plant’s height and display its flowers over lower growing perennials. Siting in the back also allows pre and post bloom Philippine Lily stalks to hide amongst other plants as they don’t add much aesthetically when not in flower. Philippine Lily pairs very well with other low-maintenance summer-blooming perennials like Black-Eyed Susan (Rudbeckia hirta), Garden Phlox (Phlox paniculata), Milkweed (Asclepias spp.), and others.
While not a native wildflower, Philippine Lily certainly adds to North Florida’s reputation as La Florida! They are among the easiest to grow, highest impact “wild” flowers Panhandle gardeners have at their disposal. Enjoy them this summer in natural areas and consider adding a few to your landscape! For more information on Philippine Lily or any other horticultural topic, contact us at the UF/IFAS Calhoun County Extension Office. Happy gardening.
